The aim of this study was to evaluate the accuracy of navigation according to the number of markers in terms of target registration errors (TREs) at each anatomical location during the registration process of the navigation system for the mandible.1) Cbyon navigation surgery equipment 2) Polaris optical tracker. Both experiments were conducted to obtain the TREs at the anatomical locations of the mandible according to the number of registration markers during the navigation process. Statistical analysis was performed using the SPSS 23.0 software.The TREs were measured in five different experiments, varying only in the number of registration reference markers, which ranged from three to seven. To measure the TREs according to the number of registration reference markers, two experimental navigation devices were used: At all anatomical locations, errors were 2 mm or less. Further, significant differences in the target errors measured by the Cbyon system were found according to the number of registration markers. Significant differences in the target errors measured by the Polaris optical tracker were found according to the registration markers at the posterior border only. In both groups, the target errors did not decrease as the number of registration markers increased.This study demonstrates that an increase in the number of registration markers is not associated with a decrease in the TRE, and that a specific number of registration markers could reduce the TREs at each anatomical site. It is important to determine the minimum number of image registration markers at which the smallest TRE would be observed for different surgical sites. The recent development of medical imaging technology focuses on obtaining real-time information, as well as data visualization , 2. ReseDuring surgery using computer-assisted navigation, surgeons use preoperative imaging data in real time to view anatomical structures that are difficult to grossly examine , 6. It aImage-guided computer-assisted surgery using the imaging data of patients obtained from a dataset collated before surgery is performed under the guidance of a navigation system connected to a computer. During surgery, the navigation system tracks the surgical tools to obtain the anatomical location of the surgical sites and surgical tools. However, even image-guided computer-assisted surgery is subject to errors, which must be minimized .In image-guided computer-assisted surgery, computer-generated images such as computed tomography (CT) scans are overlaid with the actual anatomical environments of the patients. This technique is widely used in craniofacial surgeries, but to a limited extent in mandibular surgery . AlthougDuring the navigation-assisted surgery of the oral and maxillofacial region, the cranio-maxilla including the upper and lower jaws, continuously move for the surgeon’s convenience or needs. Its position must be maintained even after osteotomy to prevent the loss of its reference point. Hence, a frameless fixator navigation is required. Additionally, the RF located on the jawbone must not interfere with the surgical site or the handling of surgical tools, while being recognized by the navigation system in real time.In mandibular surgery using computer-assisted navigation, special sensor frames are attached to the mandible to allow the surgeon to optically track its location, thereby adjusting the independent and continuous movement of the mandible during surgery. To increase the accuracy of navigation, the location of the mandible is directly monitored rather than being monitored relative to the location of other cranial structures. During this process, the sensor frame must be affixed close to the surgical site such that the surgeon can monitor the positional changes. Once the frame is affixed, the registration process, in which the patient’s actual location coordinates with the lower jaw are matched against the coordinates on the rendered CT scan of the mandible, begins.During the registration process, a number of markers that overlay two coordinates are selected. Several errors can arise during the image-guided computer-assisted surgery. Errors that occur during the image-guided surgery can be classified as technical, image, registration, application, and human errors. Registration errors arise during the process of coupling image data to the patient’s anatomical parts. Registration errors are typical errors in image-guided surgery. A paired fiducial point is the point at which a given image data matches the patient’s anatomical parts.In the head and neck area, template marker-based registration using bite splints may be performed using a registration method involving noninvasive markers , 11. An It is important to reduce registration errors. As they are affected by the number of registration points as error factors, it is necessary to measure the errors and determine the appropriate number of registration points to reduce patient burden during image-guided surgery using a navigation system. Because target registration errors (TREs) reflect the accuracy of the navigation equipment in representing the target anatomical markers, this study aims to evaluate the accuracy of navigation according to the number of markers in terms of TREs at each anatomical location during the registration process of the navigation system for the mandible.Five mandibular  A20 skull models were used in the experimental model. None of the models exhibited distinct surface defects. Screws implanted in clinically accessible locations on the models were used as the registration reference markers. In this study, 2.0-mm titanium intermaxillary fixation screws  were used as markers during the registration. An identical number of screws was implanted on all the models. A total of seven markers were implanted: one at a location 6 mm below the root apex of the mandibular central incisor, two on the alveolar bone above the mental foramen, two on the mandibular body of the mandibular first molar, and one on each ramus. To recognize the sites where errors were to be measured using different overlaying methods, small holes were created on the condylar head and neck, coronoid process, sigmoid notch, posterior border, antilingula, and angle of the mandible to measure the TREs at the anatomical markers, and filled with wax to mark the sites of error measurement Fig. .Fig. 1MaIn this study, TREs were measured at various anatomical locations to investigate the accuracy of navigation according to the number of registration reference markers for each model. TREs were measured in five different experiments, varying only in the number of registration reference markers ranging from three to seven. Screws were implanted on clinically usable and accessible points to mark the locations of the markers. Five methods were selected after considering the symmetry and area Fig. .Fig. 2LoTwo experimental devices were used to measure the TREs according to the number of registration reference markers as described above. The Cbyon navigation surgery equipment  and Polaris optical tracker  were used to measure the TREs.The CT scans of the experimental jaw models were obtained as in real surgical procedures. SOMATOM Sensation  was used to obtain the CT scans. Data were obtained from 0.7-mm-thick slices. Digital imaging and communication in medicine (DICOM) files of the obtained CT scans were imported onto the CBYON SuiteTM navigation system . A reference frame was affixed to the mandibular anterior mentum of the mandibular model.On the image data imported onto the navigation system, the implanted marker screws were used to set three to seven registration reference points for the navigation registration. A probe was positioned on the marker screws to ensure that their locations matched those on the CT scans displayed on the monitor, after which registration was started. The registration process involved matching the reference points of the screw heads on virtual images against the actual markers on the mandibular model using a probe Fig. .Fig. 3ThUltimately, the coordinates on the CT scans were matched against the actual coordinates on the mandibular model. Following the registration process, target points were marked on the condylar head and neck, coronoid process, sigmoid notch, posterior border, antilingula, and angle of the mandible to show the anatomical markers for the TRE measurement.In this study, the number of references required in the registration process was changed from three to seven to evaluate the accuracy of navigation under each condition. The TREs were measured at all target points using a probe. Therefore, the TREs were measured under five different conditions varying in the number of registration reference markers for each of the five models, three times for the left and right sides, separately Fig. .Fig. 4TREach anatomical measurement point was set as the target. The error was measured when the probe was positioned at an anatomical measurement point on the model, at a unit of 0.1 mm using Cbyon. The errors were measured 10 times per anatomical site for each of the five models. One hundred TREs were obtained for each anatomical site at varying numbers of markers.The optical tracking system , and 3D Slicer  were used to verify the reliability of the experiment. For a tracking system for obtaining the spatial coordinates of a mandibular model, Polaris  was used. Navigation registration based on changes in the position of the Polaris probe relative to the reference frame (RF) attached to the mentum of the mandibular model was performed. The RF continuously tracked the patient’s position and movements. It was affixed in the mandible because the mandible is prone to frequent movements. The RF was fixed in the mentum, which is the center of the mandible, to avoid tooth damage Fig. . In addiThe 3D Slicer is an open-source software platform for medical imaging computing that allows multipurpose visualization and provides advanced features for various applications in medical imaging. The 3D Slicer is connected to the image-guided therapy devices through OpenIGTLink. OpenIGTLink, which is a TCP/IP network communication protocol, can be used to wirelessly share various kinds of tracking systems and data in an operation room and in real-time navigation. The Polaris optical tracker (NDI) can be used to reproduce navigation surgical methods. The experimental workflow is as follows: The 2D CT data of the mandibular model in DICOM format are imported to the Slicer program, and rendered into 3D data, as was performed with the Cbyon navigation system. Next, registration was performed using the markers attached to the mandibular model Fig. .Fig. 6ReAfter registration, in which the coordinates on the CT images within the 3D Slicer are matched against the actual coordinates on the mandibular model, is complete, the target points are marked on the condylar head and neck, coronoid process, sigmoid notch, posterior border, antilingula, and angle of the mandible on the Slicer to mark the anatomical markers for TRE measurement. The accuracy of navigation was measured according to the number of registration markers ranging from three to seven, as was performed in the Cbyon experiment. The TREs were measured at all target points using a probe. Therefore, the TREs were measured under five different conditions differing in the number of registration reference markers for each of the five models, three times for the left and right sides separately. Measurements were obtained in units of 0.001 mm. The 3D distance errors were calculated based on the X, Y, and Z coordinates, and the TREs were measured for each anatomical site Fig. .Fig. 7TRp < 0.05 were considered statistically significant.In this study, the mean errors of the TREs measured using two different devices according to the number of markers required during the registration process, which ranged from three to seven, were compared. The analysis of variance was used to test the statistical significance. The SPSS 23.0 software  was used for the statistical analysis. Values of Both experiments were conducted to obtain the TREs at the anatomical locations of the mandible according to the number of registration markers during the navigation process. At both locations, the errors were 2 mm or less. At all anatomical locations, significant differences in the target errors measured by the Cbyon system were found according to the number of registration markers. Significant differences in the target errors measured by the Polaris optical tracker, and 3D Slicer software were found according to the registration markers at the posterior border only. In both groups, the target errors did not decrease as the number of registration markers increased.The smallest target errors were measured by Cbyon at five anatomical locations marked by five markers except for the antilingula and the angle of the mandible Table . Signifip-values were found at the posterior border when the Polaris optical tracking system and 3D Slicer S/W were used. At the posterior border, the smallest mean error of 0.68 mm was found when four overlay markers were used. However, at all sites but the posterior border, no significant difference in the accuracy of navigation was found according to the number of registration markers. The number of errors did not decrease as the number of overlay markers increased. At the condylar head and neck, mean errors of approximately 0.8 mm were found when the registration was performed with six markers. At the remaining anatomical sites, mean errors of 0.68–0.95 mm were found when the registration was performed with four markers.In the additional experiment to verify the reliability of the measurements obtained using the Polaris optical tracking system and 3D Slicer S/W, the smallest target errors were found at five anatomical locations excluding the condylar head and neck when four markers were used Table . In the Significant differences in the target errors measured by the Cbyon system were found according to the number of registration markers used at all anatomical sites. As mentioned previously, significant differences in the target errors measured by the Polaris optical tracker and 3D Slicer S/W were found according to the number of registration markers at the posterior border only. In both groups, the target errors did not decrease as the number of registration markers increased.It has known that three nonplanar markers are required for the registration procedure in the navigation surgery , 12. In However, more time and effort are required during this process as the number of registration markers increases in the clinical settings. Additionally, the number of markers that can be used for overlays may be limited in a real surgery. Furthermore, different decisions regarding the use of invasive markers and marker locations may be made depending on the surgery . In thisThe following factor can be considered for why the large TRE was measured with four markers at the condylar head, while the smallest TRE was measured with four markers at the mandibular angle. During the registration process, the surgical errors can be reduced by setting markers as close as possible to the surgical site. For example, since the marker used in this experiment is at the alveolar bone area under the tooth in the oral cavity, the error can be measured large when the marker is distant from the surgical site, like condyle head. However, in the case of mandibular angle, not only its overall errors are small but the TREs are also small even with few numbers of markers, because it is close to the landmark. The same explanation can be applicable to other cases, including the case of antilingula. Our study focuses on the relation between TREs and the number of markers in the fixed positions of markers. To make clear the relation between TREs and the positions of markers, further study is necessary to compare the error variation according to the marker position in the same number of markers.In the group where the Polaris optical tracker and 3D Slicer were used, large TREs were observed when different numbers of markers were used. However, considering that the largest mean error values at each anatomical site ranged from 1.01 mm to 1.17 mm, it is difficult to conclude a number of markers have caused significantly large errors. Because large errors were observed when 3, 5, and 7 markers were used, it is possible that errors occurred when the markers placed at the center of the mandible were used as the registration points. In the experimental group, no significant differences in TREs were found according to the number of registration markers at all anatomical sites except for the posterior border. Therefore, three markers may be sufficient to register the image in the mandibular navigation surgery. However, considering that the smallest target error was observed when four markers were used at five anatomical sites excluding the condylar head and neck, the use of four markers may also be considered.The differences in the experimental results between the Cbyon and Polaris groups may be attributable to the differences in the optical trackers’ sizes, and the precision in the error measurement, algorithm differences between Cbyon S/W, and 3D Slicer S/W used in the image registration, as well as differences in the methods of image development.Two methods of image registration exist: marker-based registration and marker-free registration. In marker-based registration, reference markers that were clearly visible and identifiable on the CT scans were used . In a maMarker-free registration uses anatomic landmarks. It involves the use of dental cusps, or all occlusal surfaces of the teeth as registration markers . FurtherMany errors can arise during the overlaying of digital images using a computer , 19. TheA paired fiducial point is the point at which the given image data matches a patient’s anatomical part. Registration errors include fiducial localization errors (FLEs), fiducial registration errors (FREs), and target registration errors (TREs). Fiducial localization errors (FLEs) are errors that arise during the localization of fiducial reference points. FREs are errors between the registered points when overlapping an image with the registration references. TREs are positional errors between the image and real human body following the registration of the registered points.An optical navigation system has an accuracy of 0.1–04 mm in marker localization . The optCompared with an optical navigation system, an electronic navigation system tracks smaller areas, e.g., 50 cm × 50 cm × 50 cm, and may be subject to errors caused by metal instruments .Technical errors arise when tracking a dynamic RF attached to the patient, surgical tools using an activated tracking camera (luminescence sensing diode), or manually by the operator. When using a probe or a surgical tool that is precalibrated in the navigation system and registered in the system program after attaching it to the direct RF (DRF), a calibration process is required. The tool attached to the DRF is tracked using a camera.Although the mandible is connected to the cranium by the temporomandibular joint, it can be considered as an independent anatomical structure because the temporomandibular joint undergoes continuous movements. The soft tissue composition of the mandible causes severe movements during surgery where the patient must open and close his/her mouth. As computer-assisted mandibular surgery can allow surgeons to locate anatomical structures that are difficult to view and increase the accuracy of surgery, it has become an interesting topic of research in computer-assisted surgery.When performing image-guided surgery using a navigation system on the mandible, reference points on the mandible itself must be used rather than establishing an overlaying process necessary for navigation surgery using reference points on the cranium or the maxilla. This is because an opened or retracted mandible during mandibular surgery can lead to unilateral displacement. Therefore, methods of mandibular navigation and image-guided surgery using the reference points of the mandible were considered and used in this study. An RF was affixed on the mentum. A stable fixation and prevention of the RF rotation are necessary. Using an optical tracker camera, the RF was affixed at an appropriate angle such that it would be recognized on the monitor. However, the surgeon’s head, in an attempt to view the surgical site, continually obstructed the RF recognition path, rendering real-time monitoring difficult. Methods to overcome this limitation must be devised. Although the use of navigation systems tends to be time consuming initially due to the learning curve, this may gradually improve with time.The target errors did not decrease as the number of marker registrations increased in the two groups when the Cbyon navigation surgery equipment or Polaris optical tracker, and 3D Slicer S/W were used. In the Cbyon group, significant differences in the target errors were observed according to the number of registration markers at all anatomical sites. The smallest errors were observed when five markers were used at five anatomical sites, and when four and seven markers were used at two anatomical sites each. In the group where the Polaris optical tracker and 3D Slicer S/W were used, the smallest error was observed at the posterior border when four registration markers were used. It is important to determine the minimum number of image registration markers at which the smallest TRE would be observed for different surgical sites.Considering the results of the experiment using Cbyon navigation equipment, it is recommended to use five markers in navigation surgery for condyle head, coronoid process, posterior border, condyle neck and sigmoid notch sites. However, the results of the experiment using the Polaris optical tracker and 3D Slicer S/W represented that the TREs of the remaining anatomical structures excluding the posterior border did not show a significant difference from each other. The measurement results in this paper depend on the experimental equipment and target anatomical site. Therefore, further studies are required to clearly determine the appreciate number of image registration markers for navigation-assisted surgery of the mandible.


During conventional catheter endovascular procedures, surgeons needs to adjust the catheter intervention moving direction and velocity according to the direct sensation. Moreover, in the conventional method, both the surgeon and the patient are inevitable exposed to a large amount of, and for a long period of time, X-ray radiation during the surgical procedure. The purpose of this paper is to ensure surgical safety and to protect the surgeon from X-ray radiation during the surgical procedure by adopting a novel haptic-based robot-assisted master-slave system mode. In this paper, a kind of magnetorheological fluids (MR fluids)-based haptic interface has been developed to generate a kind of controllable haptic sensation providing to the catheter operator, and the catheter intervention kinematics parameters measured the motion capture part to control the salve robotic catheter operating system following the master side kinematics. The slave catheter operating the mechanical system has also been designed and manufactured to manipulate the clinical catheter by mimicking the surgeon operating the catheter intervention surgical procedure, which has a 2-DOF  catheter motion characteristic; in addition, the interaction force between the catheter and inner wall of vasculature can be measured by its force sensing unit and the feedback to the master system. The catheter intervention synchronous evaluation experiments between the master and slave system are tested. Also, the advantages of integrating the controllable haptic sensation to the master-slave system experimental evaluations have been done in vitro. The experimental results demonstrated that the proposed haptic-based robot-assisted master-slave system mode can reduce the surgical time and protect the surgeon from X-ray radiation. Cardiovascular diseases are the major cause of mortality in developed countries, causing roughly 34% of deaths each year . The treCompared with conventional endovascular surgeries, the advantage of minimal catheter interventional surgery has been accepted by the public, such as short recovery time, a small incision to the health issue, good surgical outcomes and little post-operative pain have facilitated in the adoption of endovascular surgical techniques . HoweverHowever, most mature surgical scenarios are equipped with robot-assisted master-slave system. These include, da Vinci , Raven However, the absence of haptic feedback has been considered a major drawback in these robot-assisted master-slave surgical systems due to physical separation between the surgeon and the patient . SeveralAs described above, it is necessary to provide haptic sensation in robot-assisted master-slave surgical system mode as well as keeping system stability. However, two main challenges exist in developing compelling haptic interfaces. One challenge is how to generate a kind of controllable haptic sensation. The designed haptic interface should exhibit low intrinsic friction and inertia to minimize dynamic distortion of the user’s perception and to be controlled. Meanwhile, operation dexterity and habituation also need to be considered in haptic interface design especially in a surgical application scenario. The critical factor in controllable characteristics of a haptic interface design is the haptic actuator chosen and the structural design of the mechanism. Traditionally, most haptic devices mainly rely on electric motors, pneumatic actuators, or electric motors and pneumatic integration.It is worth pointing out that magnetorheological fluids (MR fluids), a kind of smart material, has been chosen as an actuator in haptic interface design due to viscosity controllable characteristics such as: Experimental performance of small-scale MR fluid-based clutches in haptic interface was evaluated in ; the mulAnother challenge in the area of robot-assisted catheter minimally invasive surgery (MIS) is the interaction force measurement, which is the critical point to artificially generate haptic sensation in the master system. The interaction force between catheter tip and vasculature wall has been studied in depth by Guo et al. ,23,24. . The designed and manufactured RCNS can replicate the dynamic characteristics of a surgeon in the master site. Besides it, the interaction force at the proximal end of the patient-side catheter can also be measured by a force measurement mechanism. Haptic-generating control strategy is dependent on the feedback force that comes from the slave site. The performance and effectiveness of the developed master-slave system has been evaluated in this study.The remainder of this paper is organized as follows: The developed MR fluids actuated catheter master-slave haptics system is described in This section studies the proposed MRF-actuated haptic-based master-slave system, shown in Magnetorheological fluids (MR fluids), a kind of smart material, are nonhomogeneous suspension of microsized ferromagnetic particles dispersed in a carrier medium such as silicon oil or water, which undergo a rheological behavior change when an external magnetic field is applied. The mutual interaction among the magnetizable particles form into columns (chains structure) aligned to the direction of the applied external magnetic field ,26, show−3 from pre-yield regime to post-yield regime, which is called a yield point [During the Bingham plastic model formation process, it can be divided into pre-yield regime and post-yield regime. The Bingham plastic model is a linear behaviour description of the formation process. The shear stress increased with the increased magnetic induction, when d regime , the chald point , shown iThe degree of resistance depends (chain structure) on the yield stress in MR fluids and has a relationship with the strength of the external magnetic field. MR fluid usually works in three modes. Shear mode is shown in In a teleoperated robot-assisted catheter operation scenario, to ensure the safety of the surgery, the haptic sensation obtained in the master site is of critical importance. According to the catheter intervention experienced expert and operational habitation, a kind of force sensation can be used to guide the surgeon with the right speed catheter intervention as well as catheter intervention direction adjustment immediately. Therefore, the key point of the haptic interface design is the design of a high-fidelity force-reflecting system, which makes the surgeon feel like he/she operates the catheter nearby the patient. As has been described above, MR fluids can form a chain structure when applying the external magnetic field to the MR fluids. When inserting the catheter through the chain structure to destroy or change the formed chain structure, a kind of resistive force sensation can be obtained. Moreover, in essence, MR fluid’s chain structure is formed by controlling the viscosity of MR fluids. According to this idea, MR fluids container has been developed as shown in The container was filled with MR fluids, , with the characteristic of low permeability, which can never be magnetized during the external magnetic field. The MR fluids container is a cylinder which is in the center of two magnetic poles, its diameter is 10 mm and its length is 100 mm. The catheter goes through the MR fluids, and it is coaxial with the MR fluids container.The working principles of the catheter intervention through the MR fluids to generate a haptic sensation show in  are discIn the absence of a magnetic field, the particles are statistical law distributed, which can be viewed as a kind of Newtonian fluid, as shown in ydτ(B) is the magnetic field-dependent yield stress, B is magnetic field, η is the plastic viscosity, and du(r)/dr is the velocity gradient in the direction of the field. The total resistance force can be written as:ydF is the controllable force due to controllable yield stress, Fη is the viscous force, fF is the mechanical friction force , d is the diameter of the input catheter, L is the length of the input catheter which is overwhelmed by the MR fluids.As mentioned above, MR fluids actuated catheter haptic interface can be realized by controlling the external magnetic field. Therefore, MR fluids viscosity control is the critical important point to generate catheter intervention haptic sensation. In order to obtain precise haptic sensation, the resistance force of MR fluids chain structure change is needed analysis, shown in η of the carrier fluid is 0.042 Pa·s . As mentioned in [The viscosity ioned in , the visIn the conventional bedside technique, only the sudden change of the resistance force of patient catheter manipulation can be perceived by the surgeon. So, the control strategy of the catheter haptic sensation generation should consider Weber’s law ,28. In WWhat is more, the surgeon can hardly distinguish the collision force from other resistance forces during the catheterization procedure . Tan andDuring the haptic interface design processing, human capability of haptic sensation should be considered, which is determined by two factors: absolute threshold (Absolute Limen) and difference threshold (Difference Limen) according to the psychophysics knowledge. Absolute threshold is defined as the smallest amount of stimulus energy necessary to produce a stimuli sensation, which is dependent on the resolution of the sensory system shown in . The difAccording to the requirements of human haptic sensation, the amount of intrinsic system friction force generated by an MR fluids seal should be taken into consideration. Meanwhile, on condition that the increased intrinsic friction force less than the absolute thresholds and difference threshold, there is no effect on human haptic sensation. To meet these requirements and solve MR fluids leakage from hole of the clinical catheter goes through, a kind of MR fluid seal method has been presented and shown in rµ = 3 − 7. According to the MRF chosen, the above-mentioned MRF haptic working principles and the human operator just notice difference (JND) as well as Weber’s Law, it is a complex system design to obtain the ideal catheter haptic intervention sensation. Therefore, finite element analysis was performed by using the magnetic software; the simulation results are shown in At the external magnetic field design stage, various design parameters including the MR fluids container design, MR fluids seal, coil turns and the supply current, should be considered. Generally, the magnetic flux density shows a non-linear relationship with the applied magnetic field due to hysteresis effect and it cannot increase infinitely with the external magnetic field due to the saturation of coil material . The fluIn the master site, the human operator (surgeon) operated the MR fluids actuated haptic master interface with the haptic sensation of the catheter interaction situation in the remote site; meanwhile, the catheter operational dynamics are also measured by the developed dynamics measurement parts integrated in the master haptic interface and are transmitted to the slave robotic catheter navigation system as control commands. Therefore, the catheter haptic master system consists of two parts: One is the human operated catheter intervention dynamics measurement part and the second part is the MR fluids actuated haptic generation. In order to improve the performance of haptic sensation during catheter insertion through the MR fluids actuated haptic generation part. A new kind of non-contact kinematic measurement method for surgeon catheter interventional surgery is presented and shown in The Robotic catheter navigation slave system (RCNS) has two functions. One is to manipulate the catheter just like the surgeon catheter intervention, and another is to measure the interaction force during the catheter intervention surgery procedure. Therefore, in the slave system, the catheter manipulator is designed to actuate the patient catheter in transitional ways: To push, pull, and rotate, as shown in Robot-assisted catheter navigation mechanism and control system are developed instead of the traditional catheter operation method. It needs to be pointed out that the traditional method needs the surgeon doing the clinical catheter surgery to be nearby the patient and to expose themselves to the X-ray. Therefore, the proposed method can solve this issue. Another problem is measuring the interaction force between the catheter and vasculature during catheter intervention. So, the force measurement mechanism has been developed, as shown in The control of the master haptic interface and slave catheter manipulator is achieved through a computer console  via RS-232 serial communication. Control software was implemented using C++ in a windows system, and the data update rate between the master and slave system is 1000 Hz. The motion data of the master haptic interface is transmitted to the computer console by the analogue-to-digital (AD) board (AD 16-16U (PCI), CONTEC, Osaka, Japan), and the motion command is sent to the motor actuators of the slave catheter manipulator via the motion control board . The interaction force of the catheter intervention is measured by a force measurement mechanism attached on the robot catheter navigation system, and it is transmitted to the master site where the different levels of haptic force sensation will be generated.In this section, an evaluation of the lag times of radial and axial motion transmission between the master haptic interface and catheter manipulator is carried out. To quantify the response time of the master-slave system, the input catheter was actuated by the stepping motor with different step motion profiles in axial  and radial  directions ; the motions were measured by the sensor part of the master haptic interface, and then transmitted to the slave system to actuate catheter manipulator to recopy the catheter intervention happened in the master system. Each speed of insertion or rotation catheter operation was measured 10 times. The rotation motion was repeated in both clockwise and counterclockwise directions.The kinematic characteristics tracking performance of catheter intervention and rotation between the master system and the robot catheter navigation system has been evaluated. In this section, haptic advantage experimental evaluation is illustrated by adopting a robot-assisted teleoperated catheter operation scenario.Ten right-handed volunteers, aged from 22 to 28, were recruited by the Guo Laboratory, Kagawa University, to operate the developed MR fluids actuated catheter haptic interface. They had no catheter interventional experience or experience of manipulating the haptics-based master-slave robotic-assisted system. Inexperienced operators were chosen because of their higher kinematic requirements of clinical catheter operation. The volunteers were provided with 20 min of training on the designed system before the experiment. The operators were instructed to operate a 7-Fr clinical used catheter intervention through the master haptic interface to control the slave robotic-assisted catheter operation system with the 5-Fr catheter tip to the disease target. The 5-Fr catheter went through a rigid model of cerebral vascular and then directed the catheter tip into the wide neck aneurysm.In order to simulate 2D fluoroscopy guidance during the experimental process, a web camera was mounted above the vascular phantom to provide the volunteer with vision sensation by image feedback. The processed image was projected on a screen in the master system to help volunteer catheter operation. The catheter operation process is shown in On the slave side, the catheter was inserted into the blood vessel phantom oto the disease target, as shown in In order to provide haptic sensation to the catheter operation volunteer on the master side, the contact force sensation needs to be measured in the slave system and fed back to the master haptic interface. Here, one kind of catheter operational experimental set was chosen; the catheter insertion speed was planned at 10 mm/s, the rotation kinematics are not considered. The contact force measurement experiments were performed 10 times with successful catheter operation on the disease target point in the slave system by the volunteers; the experimental results are shown in According to the above experimental results, the haptic sensation control design in the master side is as follows: Considering the real clinical surgery and the complicity of the force of sensation. Here, in the real time haptic generation control algorithm, when the measured contact force was less than 0.3 N, no haptic sensation was provided to the volunteer; in this situation, the MR fluids actuated catheter haptic interface was in ‘off-situation’, which means MR fluids still in ‘Newtonian fluid’; when the measured contact force is between the ranges of 0.3 N to 0.4 N and less than 0.4 N, it is needed to provide haptic sensation to the volunteer with the corresponding resistance force sensation about 0.3 N or 0.5 N at the external magnetic field intensity was set at 80 mT or 150 mT, according to the experiments done by our group and the published paper .(1)Task completion time: Representing the time required to complete the catheter interventional task.(2)Contact force: Representing the encountered force of the patient catheter insertion.Two modes were presented during haptic’s advantage evaluation in this paper. In mode 1, there was no haptic feedback on the master side, just the screen visual feedback. Mode 2 was employed to provide the haptic sensation to volunteers. All volunteers were instructed to complete the same task under mode 1 and mode 2. Each volunteer operated the catheter 10 times in each mode. The performance metrics are defined as follows:p < 0.05 are considered significant.Analysis of variance (ANOVA) was used to analyze the differences between mean values of performance measures and their corresponding procedure; levels of p = 1.25 × 10−6) in the mean completion times, which indicates that the value of the completion time was affected by the provided haptic feedback.Generally, when the catheter tip meets the inner wall of the blood vessel phantom, the resistance force will increase. Then, with the length of the path in the phantom increased, the contact force between the catheter body and inner wall will also increase.In mode 1, the volunteer only used the visual feedback to avoid the collision. In mode 2, the haptic sensation was generated during the whole procedure; the catheter operation volunteer can feel variable haptic sensations based on the feedback changes of the resistance force measured in the slave site by operating the developed MR fluids actuated catheter master haptic interface. It will assist him/her to make decisions in finding suitable directions to reduce the contact force with the help of haptic sensation.Experimental results show b that whIn this paper, MR fluids actuated haptic-based master-slave system has been developed to address the large amount, and the longtime of X-ray radiation during the real surgical procedure by introducing the master-slave robotic-assisted formation. The master-slave system performance has been evaluated and the advantage of haptics in the master-slave catheter operating system has been verified.Findings from this study indicate that haptic guidance is effective in training based on task completion time in the catheter experiment. Meanwhile, experimental results illustrate that haptic sensation has a larger benefit than visual feedback on the condition that the volunteer of the catheter operation experienced haptic sensation training. As in , haptic Despite the fact that extremely promising results have been obtained for the advantages of haptic evaluation, it is important to point out that the study is limited by the fact that in vitro experiments were used to conduct the performance evaluation of the collision protection; the limitations manifest in two ways. Firstly, the used vascular phantom has great rigidity and cannot produce vascular-like deformation during the catheter interventional experiments. Moreover, the curvature of the vascular vessel does not bend the same as the real vessel system, which will lead to an increase of the contact area between the wall of the catheter and the inner wall of the vascular phantom. Secondly, the viscous resistance of the catheter cannot be measured in the slave site, which can be solved by the addition of blood-like lubrication to make the resistance force measure more closely to the real catheter intervention. Therefore, the future research of haptic sensation generation control algorithm will depend on more precise catheter intervention force measurement. Once the more precise force measurement is obtained, more real haptic sensation will be achieved, which can be used in haptic training to improve the skills of the catheter operator.In this paper, a MR fluids actuated haptic-based master-slave system has been developed to address the large amount, and the longtime of X-ray radiation during the real surgical procedure by introducing the master-slave robotic-assisted formation. MR fluids-based haptic master catheter haptic interface design procedure has been described in detail to provide haptic sensation to the local site surgeon, and the surgeon’s catheter interventional dynamics have been measured. In the slave site, the slave catheter manipulator mechanism has been designed to do catheter intervention instead of the local site of the surgeon; meanwhile, the interaction force measurement part has been developed to feed back to the surgeon to generate a perceivable haptic sensation for the surgeon.Some experiments have been of value to the developed master-slave system. The catheter intervention synchronous evaluation experiments between the master and slave system were tested. Also, haptic sensation experiments were evaluated in vitro. The experimental results demonstrated the proposed haptic-based master-slave system can reduce the surgical time and protect the surgeon from X-ray radiation.The haptic feedback has been utilized to assist the surgeon in decision-making and improving catheter interventional skills. Experimental results also illustrated that haptic feedback was a benefit for providing natural haptic sensation and reducing the human cognitive workload as well as improving the safety of surgery. According to the performance evaluation metrics, we also found that the challenge of improving system transparency in teleoperated robot-assisted catheter intervention surgery can be addressed by adopting haptic feedback control. However, the MR fluid-based haptic interface can only respond to the axial motions of the catheter.In future, some haptic-based training experiments will be done to further verify the advantages of haptics in complexity motor skill training.


Due to the significant multipath and Doppler effects in the underwater acoustic (UWA) channel, the quality of the received signal is degraded, which seriously affects the performance of UWA communication. The paper proposes a time reversal UWA communication method combined with a symbol-based Doppler compensation (SBDC) technique to solve those problems. A single element time reversal mirror (TRM) is used to realize channel equalization and mitigate the inter-symbol interference (ISI) resulting from multipath propagation. The SBDC technique is subsequently used to compensate Doppler effects in the received signal, thereby reducing the bit error rate (BER) and improving the communication performance. In order to verify the performance of the proposed communication method, some simulations with real sounding channels were performed. Moreover, a field UWA communication experiment was conducted in the Songhua River . The UWA communication experiment achieves nearly error-free performance with a communication rate of 100 bit/s in the bandwidth of 2 kHz. The results of the experiment demonstrate the feasibility and robustness of the proposed UWA communication method. Multipath spreads and Doppler effects make UWA channels some of the most challenging wireless communication environments ,2. The lTRM has temporal and spatial focusing capability. The temporal compression recombines the multipath signal and mitigates ISI, while the spatial focusing improves the signal-to-noise ratio (SNR) and reduce the influence of channel degradation. The capability of TRM makes it widely used in UWA communication ,6,7,8,9.In view of significant multipath and Doppler effects in UWA channels, this paper proposes a new UWA communication method using single element TRM combined with SBDC (TRM-SBDC) based on the PDS communication scheme. The proposed method can not only suppress ISI resulting from multipath spreads, but also overcome the Doppler effects induced by relative motion between the transmitter and receiver. The results of the simulations with real sounding channels and the UWA communication experiments conducted in the Songhua River in Harbin (China) verify the feasibility and robustness of the proposed method.The paper applies the time reversal technique and SBDC technique to the PDS schemes and calls it the TRM-SBDC UWA communication system. The PDS scheme used in this paper belongs to the pulse position coding (PPC) scheme. Digital information is typically modulated in the code waveform, while the PDS scheme modulates the digital information in the time delay shift value of the pattern pulse. The different time delay shift values represent different information . Figure As shown in The multipath spreads of UWA channels cause severe ISI, thereby degrading the quality of the communication signals, so it is necessary to perform channel equalization processing on the received signals. In this paper, the TRM based on a single sound pressure sensor is used to process the received signals. Although the single element TRM loses the spatial focusing gain of the vertical array, it can still undo the multipath or channel distortion and suppress ISI. When performing time reversal communication, the transmitter usually sends a probe pulse signal to estimate the channel impulse response (CIR). The sync signal is used instead of the probe pulse signal in the paper, which is beneficial to save communication time and improve communication efficiency. The signal The sync signal is intercepted from the received signal and processed by copy-correlation technique. Then the CIR estimation denoted as Actually, copy-correlation can be viewed as a matched filter that can achieve a maximum SNR gain under ideal conditions. In the paper, we use copy-correlation technique to estimate the UWA acoustic channel and calculate the time delay shift value of each symbol.According to Equations (1) and (3), the received sync signal can be expressed as:Then the TRM is performed to compresses the multipath structure, and in an ideal case, the final sync signal can be expressed as:In the presence of relative motion between the transmitter and receiver in fluctuating underwater environments, the signals will be compressed or dilated due to Doppler effects. As a result, the time delay shift of the encoded pulse will be reduced or increased, that is, a time delay error will occur in each symbol. Moreover, the time delay error will be superimposed in PDS communication scheme, eventually leading to decoding errors. We propose a SBDC method to improve the performance of PDS communication in this paper.Since the received signal has been channel equalized by TRM, we use the copy-correlation technique for decoding ,24. FirsAs shown in In addition, it is considered that within the duration of each symbol the Doppler time delay error remains almost invariable, so the changed position of the pattern pulse can be expressed as:As can be seen from Equation (11), the time delay error will gradually increase. Once the time delay error accumulation exceeds The decoding process using SBDC is explained below. For the first symbol, it is assumed that the time delay error caused by Doppler is not enough to make the decoding error, so the time delay shift of the first symbol can be obtained as:According to Equation (9), the Doppler time delay error of the first symbol can be calculated as:Comparing Equations (11) and (18), each symbol obviously only needs to withstand its respective Doppler time delay error after SBDC, rather than the error accumulation of the preceding symbols. Consequently, no decoding error will occur as long as the Doppler time delay error of each symbol is within the error tolerance:To analyze the performance of SBDC, we assume that the Doppler coefficient is For the PDS communication scheme, the key to correct decoding is to ensure that the time delay error of each symbol satisfies the Equation (20). The corresponding expression is:According to Equations (21)–(23), we can get:Watermark  is a reaWe send the packet into Watermark and then it outputs 7 packets (2800 bits) for each hydrophone channel. The packet 1 of hydrophone channel 8 is taken example to describe the simulations. After we get the Watermark output signal, copy-correlation technique is used to estimate the channel. The communication results are illustrated in In order to verify the feasibility and robustness of TRM-SBDC communication method proposed in the paper, an UWA communication experiment was conducted in the Songhua River in Harbin, in May 2018. The water depth in the experimental area was about 2 m, the sound velocity was about 1487 m/s, the maximum water flow rate was 1.8 m/s, and it was windy during the experiment. A single sound pressure sensor was deployed off the receiving boat which was always anchored, while the sending boat which has a sound source was moored or drifting with the current. Both the receiving sensor and the sound source were deployed to 1 m depth. During the experiment, we measured the speed using a handheld GPS device. In case of drifting with the current, the relative radial velocity between the two boats was about 1.0–1.8 knots. For the communication signal, the detailed parameters were the same as the signal in the simulations and the data length was 4000 bits. A probe pulse signal is usually sent first to estimate the UWA channel. However, this experiment uses the sync signal instead of the probe pulse signal to estimate CIR, thereby improving the communication efficiency. In experimental scene 1, the sending boat is moored. A certain frame data from experimental scene 4 is used to illustrate the communication performance as shown in Aiming at the addressing the issues of multipath spreads and Doppler effects in underwater environments, this paper proposes the TRM-SBDC UWA communication method to improve the performance of UWA communications. TRM based on a single sound pressure sensor is used to reform the multipath structure and achieve energy focusing of the signal, so as to mitigate the ISI. Subsequently, the Doppler effect of each symbol is compensated in real-time by the SBDC method, thereby reducing the time delay error and obtaining a low BER. The results of simulations with real sounding channels indicate that the proposed method can greatly improve the UWA communication performance. In UWA communication experiments conducted in the Songhua River, Harbin, the proposed method achieved nearly error-free performance with a communication rate of 100 bit/s in the 5.5–7.5 kHz band, confirming the feasibility and robustness of the TRM-SBDC communication method, and indicating that the method proposed in this paper could be of great significance for mobile UWA communications.


At the primary care setting, where there are often no or minimal laboratories, examinations often consist of self-testing and rapid diagnostics. Because of this, medical devices must be simple, robust, and easy to operate. To address these concerns, an alternate fluorescence microscope design uses ultraviolet (UV) excitation, since fluorescent dyes that are excitable in the visible region are also excitable by UV. This may allow for the removal of typical excitation, emission, and dichroic filters as optical components absorb UV wavelengths and UV is not detected by silicon based detectors. Additionally, UV has a very low penetration into samples, which may allow for controlling the depth of excitation, and thus the imaging volume. Based on these ideas, we developed a simple fluorescence microscope built completely from off-the-shelf components that uses UV to image fluorescently stained samples. The simple opto-mechanical design of the system may allow it to be more compact and easy to use, as well as decrease the overall cost of the diagnostic device. For biological validation, we imaged whole blood stained with acridine orange and performed a two-part white blood cell differential count. At the primary care setting, such as in the developing world and underserved communities, there are often few laboratories and personnel to address the overall medical need; as a result, most examinations consist of self-testing and rapid diagnostics . BecauseTo address these issues, an alternate fluorescence microscope design uses ultraviolet (UV) illumination as an excitation light source. The idea of UV as an excitation source was first discovered by Sir George G. Stokes in 1852, who observed that the mineral fluorspar emitted red light under illumination by UV wavelengths . Though Based on these ideas, we developed a simple fluorescence microscope built completely from off-the-shelf components that uses UV as the illumination and can image any fluorescently stained sample, given that the fluorophore of interest can be excited by UV. By exploiting excitation in UV and through the proper selection of materials, the lenses and windows in the optical path may serve as natural filters, eliminating the need for swapping dedicated filters for the application of interest. The simple opto-mechanical design of the system may additionally allow it to be more compact, robust, and easy to use at the primary care setting, as well as decrease the overall cost of manufacturing the diagnostic device. To validate the ability of the system to analyze biological samples, we performed a two-part WBC differential count on whole blood stained with the fluorescent dye acridine orange (AO).An optical schematic of the prototype fluorescence microscope using UV excitation is presented in The two illumination systems were aligned at an oblique angle to eliminate the need for a dichroic filter. No excitation or emission filters were needed for the 280 nm LED since the optical components (such as the objective and tube lens) should naturally absorb UV wavelengths, and the detector, a Point Grey Flea3 color camera , was not sensitive to UV wavelengths as it had a silicon based detector tuned for the visible spectrum. Essentially, the optical components and the detector would act as the filter for the 280 nm illumination scheme. However, without excitation and emission filters in the 455 LED setup, images were saturated with the visible LED light and no emission signal was able to be imaged. Thus, a 470 nm excitation filter  and a 532 nm longpass emission filter  were needed to allow for standard fluorescence imaging with the visible spectrum LED. Samples were mounted on an xyz translation stage, where focus was adjusted using the z axis stage and lateral scanning of the sample was facilitated by movement of the x and y stages.A summary of the optical design parameters for the UV fluorescence microscope can be seen in After assembling the fluorescence microscope, performance of the system was verified using a high resolution 1951 United States Air Force (USAF) target . A 455 nm LED was placed in trans-illumination mode to simplify initial testing of the aligned system  and an image was taken, as seen in The total number of WBCs, levels of agranulocytes and granulocytes, and the ratios of the different WBC types are important in determining whether a patient is infected with a bacterial or viral infection . For exaTo find the levels and types of WBCs in a sample, WBCs may be fluorescently stained with acridine orange (AO), a metachromatic dye that binds to both DNA and RNA. AO fluoresce at 525 nm when bound to DNA and 650 nm when bound to RNA; thus, WBCs stained with AO fluoresce a mixture of red and green. The red-to-green (R/G) fluorescence ratio may then be used to identify WBCs and subsequently enable a two-part WBC differential count –13. In aIn an attempt to determine the cause of the blue background, tests were performed with a USB-650 Red Tide Spectrometer . These tests showed that the 280 nm LED appeared to bleed into the visible spectrum, ranging from 350 to 625 nm and with a strong peak around 425 nm. A 300 nm shortpass excitation filter  was temporarily placed in the illumination path in an attempt to cut out the visible light leakage, as the shortpass filter would block any wavelength of light longer than 300 nm from passing through. However, measurements of the average background intensity with and without the filter revealed no significant difference in intensity. Though the objective is an optical polymer and autofluorescence was suspected, images taken of an empty sample cartridge revealed no observable signal on the detector. Additionally, images taken with unstained blood samples exhibited the same blue background when imaged under UV. Therefore, it was unlikely that the blue background signal originated from the 280 nm LED. Insertion of an inexpensive absorption foil, which served as an emission filter, did allow for a decrease in the background signal as seen in A two-part differential WBC count was performed for five separate blood samples, which were obtained from healthy volunteers who gave written informed consent under a protocol approved by the Rice University Institutional Review Board (620119). To segment and analyze the WBCs . All saWe designed and assembled a simple, filter-less fluorescent microscope that took advantage of the unique properties of fluorescent dyes under UV excitation. We also successfully developed automated post processing algorithms to segment WBCs from the designed FOV and performed a two-part WBC differential count. All of the tested samples fell within ±15% of the true WBC count. However, in the future  fewer FOVs may be necessary to obtain similar results to the gold standard. Further research and additional work will be needed to develop the system for three-part or five-part differentials, such as increasing both NA and magnification to allow for imaging the lymphocyte nuclei in more detail and more complex sorting algorithms to distinguish WBCs based on the additional morphological information.The use of UV as an excitation source allows for a simpler fluorescent microscope in design, assembly, and usage. Typically, excitation, emission, and dichroic filters are needed to separate out the weak emission signals from the strong excitation signals, and are tailored for a specific application. This suggests that for every application the microscope would need different filter sets to properly image the sample of interest, which may be both expensive and inconvenient for streamlined use of the system. Optical glass components, such as lenses, naturally absorb UV wavelengths and silicon based detectors are not typically sensitive to electromagnetic waves from the UV range (though there are ways to make them sensitive ). By actThe cost of the UV microscope can be broken down into two main components: the consumables (or the per test cost) and the base cost of the device. The cost of consumables has an important impact on sustainable use, especially in low income, developing world locations. Therefore, the system was designed to use accessible, low cost sample cartridges, which are priced at approximately $1 per test before any optimization  and are compatible with the UV microscope. The chemistry of the cartridge and sample preparation are very basic and require only utilization of AO. This consumable price is much more affordable compared to a commercial system, such as the HemoCue WBC System (used at the point of care), where the cost of specially designed cartridges is approximately $3 per test   rely on fluorescent reporter and classifier beads to detect the presence of a substance such as an antigen. These beads fluoresce at different wavelengths and would normally need separate filters to image each type of bead individually. The use of UV excitation may eliminate the need for swapping filters, allowing one to take a single image and perform analysis on the bead signatures.


Modern engineering problems require solutions with multiple functionalities in order to meet their practical needs to handle a variety of applications in different scenarios. Conventional design paradigms for single design purpose may not be able to satisfy this requirement efficiently. This paper proposes a novel system-of-systems bio-inspired design method framed in a solution-driven bio-inspired design paradigm. The whole design process consists of eight steps, that is, (1) biological solutions identification, (2) biological solutions definition/champion biological solutions, (3) principle extraction from each champion biological solution, (4) merging of extracted principles, (5) solution reframing, (6) problem search, (7) problem definition, and (8) principles application & implementation. The steps are elaborated and a case study of reconfigurable robots is presented following these eight steps. The design originates from the multimodal locomotion capabilities of two species  and is analyzed based on the Pugh analysis. The resulting robotic platform could be potentially used for urban patrolling purposes. A design process is a systematic approach followed by designers while trying to solve a problem, which could be as simple as designing a chair or could be as complex as designing an aircraft , we name it as the System-of-Systems Bio-Inspired Design (SoS-BID) process. The process is firstly introduced and a case study will be demonstrated followed this design process, for designing a reconfigurable robot called Scorpio, which is able to change its morphologies to achieve different locomotion modes, namely crawling, rolling, and wall-climbing.Step 1: Biological solutions identification.Step 2: Biological solutions definition/Champion biological solutions.Step 3: Principle extraction from each champion biological solution.Step 4: Merging of extracted principles.Step 5: Solution reframing.Step 6: Problem search.Step 7: Problem definition.Step 8: Principles application & implementation.Typically, a design process would be dynamic, which changes frequently based on the context of the problem faced and the available solution space .Based on appearances .Based on living conditions and mediums .Based on scientific classifications .Based on social organization patterns .In the very first step of the SoS-BID process, designers start with multiple biological solutions of interest as inspiration sources that will potentially be used to solve a certain problem  in general.This step is to transfer the solution from the biological domain into the engineering domain. In particular, the reframing step forces the designers to think how humans might view the significance of the biological principles extracted. The output of this process would result in a series of useful applications and related constraints of the biological principles in the human-society context, which are labeled as “humanized solutions.”Given the generated humanized solution and related constraints, this step is to find a potential engineering problem that the solution could be applied to. The problem could be an existing one or an entirely newly defined problem.Generating preliminary design criteria.Evaluating intermediate engineering reasonings.Generating system requirements.Merging of system requirements if needed.The problem definition plays an important role in the SoS-BID process, involving deep and higher level understanding and interpretation of the searched problem. Generally, this step includes the following sub-steps:It is worth noting that the resultant criteria generated above may still be abstract, based on which the specific and detailed system requirements are to be derived.This step involves the real transformation and implementation of the principles identified in the biological domain into the engineering domain. In other words, the biological-solution-applicable principles have been translated into engineering terminologies to facilitate the process of implementation. The output of this step results in an embodied principle of the engineering concept that satisfies the need of one or several practical engineering problems as defined in the previous step.To capture the general features of the SoS-BID process, a summary of the full process is presented in Species which can perform planar locomotion.Species which can perform vertical locomotion.To begin the SoS BID process, we decide to look at the species with shared characteristics of their locomotion capabilities. The locomotion aspect of biological species refers to that how biological species in nature maneuver from one point to another. Here the locomotion modes are categorized into two major categories of interests:In such manner, the locomotion in space can be seen as the combination of these two types of locomotion. Based on the two categories, the biological species are identified using academic articles from Google scholar and non-academic articles from other online search engines, and categorized as follows.It is found that most of the species are capable of performing multiple locomotion modes Jenkins, . EspeciaMount Lyell SalamanderSalamanders generate tetrapod postures to help them to walk  locomotion. On the other hand, they have other specialized modes of locomotion other than climbing, which captured our attention the most such as below-branch and knuckle-walking locomotion Jenkins, .SnailSnails move their bodies by gliding through a mucus layer secreted by one of its glands. This layer combined with its smooth flat base enables them to climb walls by creating a strong suction  to select the champion species. Pugh analysis is a decision-making model used when a choice has to be made given a list of candidates Cebrennus rechenbergiThe acrobatic flicflac somersault movement is an active rolling locomotion where it does not require any additional force from the surrounding such as the gravitational pull of the earth.The species does not require any additional initiation gestures such as crawling forward to generate the rolling locomotion.Existing research proves that the species forms an abstract wheel with its legs and rotates its whole body to perform the rolling locomotion King, .Category 1: While performing vertical clinching, the species tends to keep the center of mass closer to the object it is climbing, which in return mitigates the energetic expenditure during climbing Jenkins, .Knuckle-walking is a form of quadrupedal walking which is performed by gorillas and chimpanzees. When they walk forward, the whole-body weight is held on to their knuckles. When they are threatened, they perform an instant long jumping locomotion, where both their knuckles are struck onto the ground together while simultaneously pushing forward its body to the direction of motion.Category 2: Primates (Apes)All the primates are natural climbers where some of them possess specialized attributes to perform other types of locomotion such as vertical clinching locomotion and knuckle-walking/jumping locomotion. Identification of underlying scientific principles in the functions and corresponding behaviors of the species are as follows:Cebrennus rechenbergiThe spider uses eight legs for crawling locomotion.The spider uses four legs for rolling locomotion.The spider forms a pseudo wheel using its half spherical shaped legs while rolling.d) The spider performs active rolling.Category 1: The primate keeps the center of mass close to the object of interest being climbed to mitigate energetic expenditure.The primate (like gorillas and chimpanzees) performs knuckle walking locomotion.Category 2: Primates (Apes)The extracted principles from the locomotion patterns of the species are as follows:The species uses eight legs for crawling.The species uses four legs for and rolling.The species forms a pseudo wheel using its half-spherical-shaped legs while rolling.The species performs active rolling.The species keeps the center of mass closer to the object of interest being climbed to mitigate energetic expenditure.The species can perform knuckle-walking locomotion.The previous step extracts the principles of two species, respectively, but does not merge them. Here the following abstract principles can be refined based on the two sets of principles:Merging these different biological principles is our main contribution that these principles should be reflected in a single platform. In this case study, the merging of spider and primate's locomotive principles is specifically carried out by self-reconfiguration, through which the different locomotive gaits switch between each other.The above-mentioned principles are analyzed once again for solving engineering problems in real applications. Then the corresponding solutions can be obtained after reframing as follows.The spider uses eight legs for its crawling which helps to distribute its body weight to all eight legs equally. In other words, a greater number of legs helps for a more stable crawling locomotion.Out of the eight legs, the spider uses only 4 of its legs to perform the somersault. In other words, in order to perform a task, it is not necessary to make use of all the available resources. The resources have to be precisely optimized based on the required need.The spider creates a half spherical shaped wheel with each of its leg. When two half spherical shaped wheels are put together, it creates a circular wheel which supports for a rolling locomotion. In other words, as an engineering designer, it is possible to create a vehicle or an artifact which can walk as well as roll by being able to reconfigure its physical structure.The spider performs active rolling when on flat terrains especially when threatened by an external factor. But while entering down into an inclined slope, it shifts to passive rolling so that it does not lose its balance on slope. The same concept can be adopted in engineering design in deciding on which scenario active and passive motion should be used.The spider rotates its whole body because the rotation causes a shift of its center of mass. This repeated shift in its center of mass supports its rolling locomotion. The same mechanism can be adopted in engineering design where instead of having side wheels to drive a vehicle, we can roll the vehicle in order for it to move from one point to another.The primate keeps the body close to the tree being climbed. This helps to keep the center of gravity close to the object of interest, reducing the amount of energy used for climbing. Likewise, the same concept could be adopted in the mechanism design for performing vertical locomotion. This in return reduces the overall energy used throughout the wall climbing locomotion and increases the battery lifetime of the artifact.Once the merged solutions are reframed, we realized that most of our observations are more inclined toward locomotion and maneuverability on different types of terrains. The response of the species would be closely related to the terrain conditions. Therefore, one of the potential applications could be the surveillance task in unstructured environments, such as exploration of the urban terrorism. Over the past two decades, deaths due to terrorism have increased dramatically since year 2000. The urban terrorism is probably becoming the new norm where government authorities are taking prevention actions and coming up with new innovative ideas to strengthen their security systems Muggah, . The recThus, the aforementioned reframed solutions could be applied in the context of urban patrolling as the missions in this field are very unpredictable and require different types of behavior in order to execute the task. On the other hand, hiring, and retaining professional security personnel have become a major challenge for such missions. Therefore, the problem shifts to designing an unmanned ISR platform to be sent into a multistory building or space where it could silently navigate on multiple types of terrains, overcome obstacles, and survive from the eyes of the hostile force.A platform which could navigate through a multistory building.A platform which could navigate through multi-type terrains.A platform which could navigate freely through overcoming or avoiding obstacles.A platform which could survive from the eyes of the hostile forces.A platform which could maneuver silently.Based on the problem scope, five preliminary design criteria are identified and presented as follows:A platform can achieve silent motion through its capability to maneuver in slow motion.Most robots are unable to navigate through multi-type terrains due to their fixed morphologies. A wheeled robot can move freely on smooth and obstacle-free terrains based on its wheeled mobility, but the motion becomes highly restricted in marsh and tundra terrains like in a forest area. In contrast, legged robots can move freely in such terrains compared to wheeled robots, but their motion is not efficient enough on smooth terrains due to its speed. Therefore, designing a platform capable of changing its morphology through reconfiguration would be able to solve the problem of maneuvering through multi-type terrains.Most fixed morphology robots motion becomes restricted when they encounter obstacles such as hump and get cornered into a position where it cannot recover itself. Therefore, designing a platform which can reconfigure itself by changing its morphology would be able to solve the problem of overcoming a series of obstacles during its motion.For a robot to survive from the eyes of the activists, it is a compulsory requirement for the robot to be smaller.A robot can achieve multistory navigation in an indoor setting only by flying, staircase climbing, and wall climbing. Flying would create more visibility and could eventually alert the activists. Staircase climbing is challenging due to the miniaturized version of the robot. In other words, the step size of the staircase would restrict the robot's motion which makes wall climbing as the only choice for navigation through a multistory building. Therefore, designing a platform which can wall climb would be able to solve the problem of multistory navigation.The above-mentioned design criteria undergo an intermediate engineering reasoning step for further analysis, based on which the system requirements for the robot are generated. The requirements are a set of specifications of the robotic platform to behave in a certain fashion and will be used as the foundation in the principle application and implementation phase. The summary of the preliminary design criteria, engineering reasonings and system requirements for the robot are presented below:The following system requirements are generated based on these reasonings.SR1: Design a robot platform capable of overcoming obstacles through its ability to reconfigure its morphology and perform multiple modes of locomotion in multi type terrains.SR2: Design a robot platform which can perform wall climbing.SR3: Design a robot which can navigate at variable speeds.SR4: Design a robot platform that is compact, lightweight and portable.The most challenging part of throughout this design process is designing a single robotic platform that can fulfill all the system requirements mentioned above. Based on these requirements, SR3 and SR4 are inherent properties of SR1 and SR2. As a result, the achievement of SR1 and SR2 is more than sufficient to satisfy the overall success criteria.Once the system requirements are defined, we analyze the reframed solutions which we extracted from our biological search at the beginning of our process. Then we apply those reframed solutions to create an engineering artifact [i.e., Scorpio . The gorilla uses its two arms together to struck on the ground while simultaneously pushing forward its body to the direction of motion while performing jumping. The same motion is repeated multiple times to perform wall climbing for Scorpio. The wall-climbing unit involves three pedals where the center pedal is part of the body, and the other two are its arms. A single DC motor coupled with a series of gears and linkage mechanism is used to drive the wall climbing locomotion. This motion can generate the optimal sticking force and the optimal peel of the force required for the stable wall climbing and descending.A summary of the extracted principles, reframed solutions, and its applications in the development of the Scorpio robot and the connections to the system requirements is presented below:The wall-climbing module attached underneath the body is composed of three pedals. The mechanism involves a series of gears and linkage mechanisms. A single DC motor is used to drive this mechanism where the motion generated can achieve an optical sticking force and an optimal peel-off force required for a stable wall climbing and wall descending. In this paper, we proposed a novel solution-based process named “System-of-Systems Bio-Inspired Design” process where the inspiration of the engineering product is originated from multiple biological species to solve multiple problems. The goal is to search through available biological solutions in the features of interests, in order to extract principles that can be translated into engineering context. The framework allows multiple features to be considered with multiple categories, which offers a systematic approach in bio-inspired design with intrinsic compliance. Using the proposed SoS BID process, conceptual design and implementation of a reconfigurable robot with multiple locomotion modes were presented and demonstrated. It is shown that the proposed framework provided a step-by-step guideline in developing a robotic platform which can satisfy most of the essential criteria identified in the problem definition, such as navigation through multistory buildings using its multi-modal locomotion capabilities such as crawling, rolling, and wall-climbing. Through different modes of gait, the Scorpio robot was able to achieve stable crawling and rolling locomotion to maneuver in multi-type terrains such as smooth and rough terrains while overcoming obstacles. We believe that the proposed method can simplify the design process, improve the overall efficiency and efficacy, and thus benefit the designers in designing novel bio-inspired robotic platforms with high compliance in terms of the desired features of interests.It worth pointing out that the proposed framework including eight steps depicts the system-of-systems design process in a generic way, in order to fit in more application cases. The development of the robot in the case study was basically following these eight steps, and of course, the real development process involved some detailed sub-steps in between the eight steps, which are not treated as the skeleton elements of the main framework. These sub-steps might involve specific issues such as material, power, kinematics and dynamics, which should be considered case by case. Here, we are focused on proposing a generic framework which is concise and flexibly open to further add-on treatments. Actually, satisfying both more general and detailed is somehow contradictory. In this paper, we choose the former, namely a general framework, to describe this new design concept and framework for bio-inspired robots, which brings inspiration from multiple species. On the other hand, the most of current available bio-inspired robots in the state of the art are engineering implementations using single species, which adopts different design philosophies from our approach. Thus, if we want to improve the design of such robots in the sense that to integrate more biologically inspired features, the proposed methodology could be used by following the eight steps with certain degree of variation. The key strength of the proposed design process is that it can integrate different inspiration sources. Then, different locomotion modes can be performed by such a unified robot, which outperforms the single-species-inspired robot in versatility of mobility.The limitation of the proposed framework is 2-fold. Firstly, there are some subjective treatments involved in the implementation of the proposed framework, especially, the selection step of the design process is relatively subjective. This is determined by the nature of the bio-inspired design where different biological sources may lead to similar functionalities. The researchers or designers may select the inspiration sources according to their interests, which is fine as long as the problem can be solved. However, it's hard and somewhat impossible to evaluate all the potential designs with similar functionalities for a specific application (and there is no such work so far) and decide which one is the best compared with others. Secondly, we propose this system-of-systems design framework including a critical step of merging different biological principles. However, how to merge these bio-principles systematically and regularly or handling differences in the requirements when merging different biological principles is a huge theme which need to be explored dedicatedly. Merging different biological principles indeed should be treated case by case, and more importantly, so far, there is no matured principle or guidance on how to merge the principles of different species. We put forward the self-reconfiguration as a powerful merging approach, but haven't studied other alternatives deeply enough yet.In the future work, we will improve the framework with more strictly structured elements in a more quantitative fashion. In addition, we will investigate more merging methodologies of different biological principles except for the reconfiguration fashion adopted in this paper. Furthermore, the Pareto frontier and multi-objective optimization method will be explored to optimize the design parameters of the robot.The raw data supporting the conclusions of this manuscript will be made available by the authors, without undue reservation, to any qualified researcher.NT, NB, and RM designed the study and developed the robot prototype. ZS, SV, RS, and KW provided the guideline and feedback in the structure of the design process. NT and ZS wrote the manuscript in consultation with RM and KW. All authors provided critical feedback and helped shape the research, analysis and manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Environmental challenges are part of everyday life for most domestic animals. However, very little is known about how animals cope emotionally and physiologically with cumulative challenges. This experiment aimed to determine the impact of long-term exposure to environmental challenges on the affective state and hypothalamic-pituitary-adrenal (HPA) axis responses to a subsequent additional acute shearing challenge.Sheep were exposed to either a long-term environmental challenge  in order to induce chronic stress (chronic stress group) or control conditions . Judgement and attention bias were assessed as measures of the emotional state following several days of the challenge or control treatment (pre-shearing tests). In addition, the responsiveness of the HPA-axis was evaluated using a combined Corticotropin Releasing Hormone and Arginine Vasopressin (CRH/AVP) challenge. Finally, all animals were exposed to an acute shearing challenge, then judgement bias (post-shearing test), HPA-axis and internal body temperature responses were determined.In the pre-shearing judgement bias test, the chronic stress group slightly increased optimism compared to the control treatment. In the attention bias test, the chronic stress group showed reduced vigilance behaviour towards a predator threat and a quicker approach to the food compared to the control treatment. The chronic stress group also had lower plasma ACTH concentrations in response to the CRH/AVP challenge compared to the control group, no differences in cortisol concentrations were found. In the post-shearing judgement bias test, differences in optimism were no longer evident between the chronic stress and control groups. Plasma ACTH concentrations and body temperatures showed a greater increase in response to shearing in the chronic stress group compared to the control group.Our results suggest that long-term exposure to challenges biased cognitive measures of the affective state towards an increased expectation of a reward and reduced attention towards a threat. The exaggerated ACTH responses in the chronic stress group may be indicative of HPA-axis dysregulation. Despite a period of challenge exposure in the chronic stress group, judgement bias responses to the shearing challenge were similar in the chronic stress and control groups; the reasons for this need further investigation. The altered affective state together with signs of HPA-axis dysregulation may indicate an increased risk of compromised welfare in animals exposed to long-term environmental challenges. Environmental and psycho-social challenges are encountered on a regular basis throughout an animal’s life. Captive animals, such as farm, zoo and laboratory animals may experience several simultaneous challenges, such as barren housing conditions, painful husbandry procedures, rest deprivation and other stressful rearing and handling practices. However, very little quantitative evidence is available on how repeated or continuous exposure to challenges alters the emotional state of animals, which is an important aspect of their welfare. Furthermore, little knowledge exists on how long-term exposure to environmental challenges modulates emotional and physiological adaptation to additional challenges.In response to a challenge, the hypothalamic-pituitary-adrenal (HPA) axis is activated allowing the individual to physiologically and behaviourally respond to the challenge. This is an adaptive response through which the individual attempts to cope with the challenge and regains energy homeostasis , 2. AdjuLong-term or repeated exposure to challenges may also have consequences for the ability to adapt to novel events or additional challenges, due to the already increased allostatic load of an individual under stress . HoweverIn animals, research on affective states is limited because there is no direct objective measure of the affective state. Human psychological studies have shown that there is a bidirectional link between cognition and affect; the affective state of an individual influences cognitive processing and alters how information from the environment is perceived and interpreted , 17. UsiMaccaca mulatta) showed that they reduced their attention towards aggressive faces when subjected to stressful procedures , unless stated otherwise. Assumptions of normal distribution and homoscedasticity were assessed by graphical analysis of the residuals, and data were log-transformed  or square root-transformed  if necessary, after which assumptions were met. Data was analysed in R using package lme4 for generalized linear mixed effect models .We used an information criterion based approach for model selection that measures the strength of evidence for each model within a given set of models . The adva priori and used the Akaike Information Criterion adjusted for small sample sizes (AICc) to select the most appropriate model based on Δi  and wi (AICc weight), the probability of the model being the expected optimal model for the situation considered  kg and the control group 35.6  kg. One week after completion of the treatment the chronic stress group weighed 33.8  kg and the control group 34.4  kg.There was weak evidence for a slightly greater decrease in body weight in the chronic stress group than in the control group  with no evidence for a treatment effect on the cortisol responses , and we only found weak evidence for an effect of treatment .The cortisol responses to the combined CRH/AVP challenge were best explained by the time course of the experiment . The optimal model for the AUC of ACTH was the intercept only model , with only weak evidence for an effect of treatment .The chronic stress group’s ACTH response to the combined CRH/AVP challenge  was loweThe total duration of vigilance behaviour was lower and the frequency of transitions between vigilant and non-vigilant behaviour was higher in the chronic stress group . These vIn the pre-shearing test, the majority of sheep approached the P locations, except for one sheep in the chronic stress treatment and two sheep in the control treatment .i = 0, wi = 0.52). However, the evidence that sheep from the chronic stress group were more likely to approach the locations was only slightly weaker . The optimal model for the AUC for cortisol fitted the intercept only , with only weak evidence for a main effect of treatment .Plasma cortisol concentrations in response to shearing over time were more affected in the chronic stress group . The AUC for the ACTH responses was also higher in the chronic stress group  than in the control group .Plasma ACTH responses to shearing were higher in the chronic stress group  and we only found weak evidence for an effect of treatment . The maximum increase in body temperature was higher in the chronic stress group  than in the control group .The body temperature responses to the shearing challenge  were besIn the post-shearing test, the majority of sheep approached the P locations, except for one sheep in the chronic stress treatment .i = 0, wi = 0.60, i = 2.11, wi = 0.21, Spatial location was also the main factor influencing the decision to approach a location or not  but also positive  stimuli, which suggest that it mostly reflects physiological arousal and that HPA-axis activation in itself is not necessarily an indication of bad welfare . HoweverWe found some signs of HPA-axis dysregulation in our chronic stress group: ACTH responses to the CRH/AVP challenge were reduced in the chronic stress group. However, ACTH responses were increased in the chronic stress group following the shearing challenge. It is possible that the ACTH response between the CRH/AVP and shearing challenges differed because the shearing challenge had to be psychologically perceived in order to activate the HPA-axis. The increase in ACTH responding to the shearing challenge, however, is a classic sign of down-regulation of the HPA-axis during chronic stress while maintaining responsivity to novel challenges , 48–50. The chronic stress group also showed reduced vigilance behaviour and was faster to approach the food, suggesting reduced attention towards a potential predator threat. General activity was unchanged in the attention bias test, so the quicker approach to the food is unlikely to be explained by a general increase in activity. We also found some evidence that the chronic stress group had a more optimistic judgement bias in the pre-shearing test compared to the control group, as shown by a slightly shifted curve while the steepness of the curve was not affected. This evidence, however, was relatively weak because our data could not fully differentiate between a model fitting the main effect of location only and a model fitting the main effects of treatment and location. The reduced vigilance behaviour and the seemingly more ‘optimistic’ judgement bias are contradictory to our hypothesis. Our results, however, are in agreement with other studies showing optimistic judgement biases following shearing and restraint challenges in sheep , 53, andThere are, however, alternative explanations for the reduced vigilance behaviour in the chronic stress group. In humans, it has been found that a challenge (competitive computer task) results in a rapid disengagement of attention towards negatively valenced words, but not neutral or positive words . This atAlternatively, long-term challenges can lead to a general increase in motivational behaviours for rewarding stimuli, which in turn leads to increased consumption of highly palatable foods and drugs of abuse . The conWe had also expected that sheep in the chronic stress group would have had a different judgement bias compared to the control group after shearing. There are different explanations possible for the lack of additional change in judgement bias in the chronic stress group following an acute challenge. It is possible that 1) animals either did not perceive the additional challenge as particular challenging, or that (2) our judgement bias test was not sufficiently sensitive to detect subtle differences in the affective state, that (3) their affective state had changed to the maximum and no further change was possible or that (4) animals had learned that the ambiguous locations were not reinforced in the post-shearing challenge . The chr animals The housing and handling of the control group could also have impacted our results. For example, the animals in the control group were group housed and handled more positively in order to make the control animal’s environment as pleasant as possible. These differences in the human-animal relationship could potentially have affected the behaviour of the sheep –70. On tThe negative reinforcer in our judgement bias test was a dog that was present throughout training and testing. We cannot exclude the possibility that the presence of olfactory cues during testing could have affected the responses of the sheep. The presence of reinforcers in test sessions has attracted discussion in the literature with no clear conclusion being reached as to whether reinforces should or should not be present during testing , 76. ManOn the other hand, the perception of the dog’s olfactory cues itself may also have been influenced by the chronic stress treatment. It has been shown that the affective state can influence the perception of sensory information, called affective realism. For example, a negative mood results in increased perception of loudness  while unThere was also a high number of animals that did not reach the learning criteria for the judgement bias test (28 out of 60). We adapted the test by removing the bucket from the experiment, because it was too attractive for some animals, and this improved learning the no-go response. However, some other animals were scared of having to put their head through an open door to get their food reward, so this reduced the go responses in these animals. It is possible that we have selected animals with a certain temperament or personality  and it has been shown that personality can affect performance in a judgement bias task in hens . FurtherIn conclusion, lying disruption combined with individual housing led to reduced plasma ACTH responses during the CRH/AVP challenge but increased ACTH responses following shearing. These changes in HPA-axis functioning are consistent with a chronic stress state. Furthermore, the chronic stress group was unable to mount a cortisol response to the shearing challenge reflective of the additional stress experienced. The chronic stress group also expressed a slightly more optimistic judgement bias compared to the control group (pre-shearing test) and approached the food quicker and showed reduced vigilance behaviour in the attention bias test. These cognitive biases are most likely due to an increased attention, expectation or motivation for rewarding stimuli induced by chronic stress. Despite nine days of exposure to challenges, judgement bias responses to the shearing challenge were similar in the chronic stress and the control groups. This lack of behavioural adaptation in the chronic stress group to the shearing challenge may be indicative of an increased allostatic load, and may increase the risk of compromised welfare in these animals.S1 File(PDF)Click here for additional data file.S2 File(XLSX)Click here for additional data file.S3 File(XLSX)Click here for additional data file.