This study presents a novel multimodal heterogeneous perception cross-fusion framework for intelligent vehicles that combines data from millimeter-wave radar and camera to enhance target tracking accuracy and handle system uncertainties. The framework employs a multimodal interaction strategy to predict target motion more accurately and an improved joint probability data association method to match measurement data with targets. An adaptive root-mean-square cubature Kalman filter is used to estimate the statistical characteristics of noise under complex traffic scenarios with varying process and measurement noise. Experiments conducted on a real vehicle platform demonstrate that the proposed framework improves reliability and robustness in challenging environments. It overcomes the challenges of insufficient data fusion utilization, frequent leakage, and misjudgment of dangerous obstructions around vehicles, and inaccurate prediction of collision risks. The proposed framework has the potential to advance the state of the art in target tracking and perception for intelligent vehicles. Multi-source information fusion is a useful technique for processing and integrating data information from multiple information source components ,2. It inFor object recognition and tracking, multi-source information fusion encompasses a range of processes such as raw data acquisition, information interconnectivity, data association, state estimation, and information fusion. To optimize the use of each sensor’s sensing characteristics and exploit the advantages of different principle sensors while mitigating the possibility of system safety issues resulting from common cause failures, an approach relying on heterogeneous sensors is often seen as desirable for information fusion .For intelligent collision avoidance systems, relying solely on the single sensor is limited in ensuring accurate and robust perception in complex road traffic environments ,6. VisuaTo improve the reliability of the system and the robustness of the perception module, it is necessary to consider the limitations of perception sensors in complex and dynamic road traffic environments. In such conditions, certain sources of perception may be unusable or have high levels of uncertainty, or they may be outside the sensing range of a particular sensor while another perception sensor can still provide useful information. Information fusion can mitigate these challenges and enable the system to continue working without interruptions, further enhancing the reliability of the perception module.To improve measurement accuracy and enhance target detection capabilities, it is essential to utilize the complementary characteristics of different sensors in a fused system. This approach can effectively improve the accuracy of target recognition and measurement precision.To increase perception reliability and reduce uncertainty, it is necessary to use joint perception information from multiple sensors. This approach can enhance the credibility of detecting targets, increase the redundancy of the perception component, expand the perception coverage, and improve the spatial resolution of perception.For intelligent collision avoidance systems, the key to improving system reliability is how to fully utilize and explore multi-source heterogeneous perception data to reduce the uncertainty of perception and cognition in complex environments.In this study, we focus on object-level multi-sensor fusion, and the purposed method is based on understanding the spatial synchronization of radar and camera sensor fusion. In particular, we focus on collision avoidance system development using radar–camera sensor fusion. The paper is organized as follows: Vehicle sensing plays a crucial role in the development of advanced driver-assistance systems (ADASs). The method and performance of varied sensor fusion differs significantly and the architecture decides the perception performance . In realLots of state-of-the-art methods have been proposed for vehicle sensor fusion . The resData association is another key step for the sensor fusion process. Zhao uses the nearest neighbor method in multi-source data fusion to perform data association . The neaOverall, multimodal information fusion needs to coordinate the different information data from the different sensor measurements for data fusion. During the filtering process, it is important to establish motion models that match the target’s movement as closely as possible. Data association needs to take into account the uncertainty of heterogeneous sensory data for effective information matching. For target state estimation, it is necessary to consider the statistical characteristics of system noise to improve tracking accuracy, while minimizing algorithm complexity and ensuring real-time computation.In this study, a novel sensor fusion algorithm is proposed based on radar and camera. This presents a novel data match and target management approach that can consider the target existence uncertainty. To improve the measurement accuracy, the optimization method is introduced to reduce the fusion target state error. To make the motion model more closely match real target motion processes, the improved adaptive interactive multimode cubature Kalman filter is purposed, which can adjust the motion model probability dynamically. To reduce the computational cost and improve real time, the adaptive gate based on vehicle motion is purposed to reduce unnecessary data association. Additionally, tests are conducted in different scenarios for the quantitative assessment of the performance of the proposed sensor fusion algorithm.To ensure the safety of autonomous vehicles, it is fundamental to perform stable and accurate tracking of the surrounding traffic participants, which serves as the basis for subsequent decision-making, trajectory planning, and control operations. For this purpose, a robust tracking system is required that can accurately track targets as soon as they enter the sensor’s perception range, providing accurate information on the target’s position and velocity, and promptly terminate the tracking of invalid targets as soon as they leave the sensor perception range, ensuring the stability and efficiency of the tracking system. The tracking system should also handle issues such as false alarms and missed detections in sensor data that can lead to tracking instability. The proposed multimodal heterogeneous perception cross-fusion framework is designed to improve the obstacle perception and cognition system by data fusion algorithms, tracking filters, and improved data association.As shown in During the target tracking process, the returned detections and established track are associated through the fused information to get more accurate target information. The primary objective of information fusion in track is to reduce uncertainty. The Joint Probabilistic Data Association (JPDA) method is extensively used to exploit the uncertainty obtained from data association and associate multimodal fusion measurement data with the existing confirmed track. In the track management process, the existence probability of the track is calculated using the integrated JPDA method.The filtering process is the important step for data fusion and object tracking. In the framework of Bayesian theory, the posterior estimation of a system is iteratively calculated based on the actual measurement likelihood and prior probability estimation. In practical applications, nonlinearity is commonly observed in the system and the statistical properties of noise are often uncertain. The cubature Kalman filter (CKF) algorithm is a well-known method for nonlinear filtering problems, but the algorithm’s covariance matrix may lose positive definiteness during the iteration process, leading to a divergence issue. The key of the CKF is the spherical–radial cubature rule, which makes it possible to numerically compute multivariate moment integrals encountered in the nonlinear Bayesian filter. To address this problem, Arasaratnam  proposedConsidering the following nonlinear systems with additive Gaussian noisek. The procedure of the CKF for the nonlinear system can be summarized as:According to Bayes’ theorem, the posterior distribution of a system state provides complete state statistical information, involving two main steps: time update and measurement update. Firstly, the system state is predicted based on the system model, followed by updating the posterior distribution of the system state with newly obtained measurement information at time (1)Assume that Time Updatek−1 and (2)Estimate the cubature pointsn cubature points set .(3)Estimate the propagated cubature points and the predicted state(4)Estimate the posterior state covariance(5)Estimate the cubature points(6)Estimate the predicted measurement and the square root of the corresponding error covariance(7)Estimate the cross-covariance matrix(8)Estimate the Kalman gain(9)Estimate the updated state and the square root of the corresponding error covarianceMeasurement UpdateIn the derivation of the root-mean-square algorithm, the statistical characteristics of the process noise and measurement noise are assumed as known constants. However, in real-world scenarios, the noise characteristics are subject to time-varying uncertainties and these uncertainties can significantly impact posterior state estimation. To address this challenge, this study proposes a method that combines maximum likelihood estimation and maximum expectation to estimate noise characteristics. To ensure real-time performance, rolling-time domain estimation is employed to reduce computational complexity. Specifically, an adaptive cubature Kalman filter is proposed to estimate the unknown parameters of the process and measurement noise online. This approach can effectively improve the accuracy of the system state estimation, making it particularly useful in complex and dynamic applications where noise characteristics are highly variable.kx−1, kP−1, and the noise statistical characteristics kθ−1 = {kR−1, kQ−1}. At time k+1, kx and Pk are iteratively computed using time and measurement updates, while the unknown noise characteristics are estimated in a sliding time domain using maximum likelihood estimation and maximum expectation methods. Assuming that kθ = {kR, kQ} indicates the estimated statistical characteristics of the process and measurement noises, the parameters can be estimated based on the maximum likelihood criterion formula.θ.As depicted in kx is unknown, it is not possible to directly solve and calculate the likelihood function. Therefore, the maximum expectation method is used to estimate it. In addition, in order to reduce the computational complexity, the iterative process adopts rolling time domain for iterative computation.However, since the system state N > 1, For a fixed time domain System state transition can be viewed as a first-order Markov process and the likelihood function can be expressed as follows:The maximum expectation (Max-Expect) method mainly includes two steps: expectation calculation and maximum likelihood estimation.(1)Expectation calculationBased on the likelihood ratio function and the conditional probability characteristics, it can be described as follows.During the iteration process, Calculating expectation(2)Maximum likelihood estimationThis step aims to estimate parameters by solving for the maximum value of the logarithmic likelihood function.Furthermorek. Thus, the estimated system noise characteristics are as follows.Traditional maximum likelihood algorithms also require smoothing filtering in the rolling time domain. In order to further reduce computational effort, the estimation of system noise characteristics is directly replaced by the estimated value at time During the time update process of the Kalman filter, it is necessary to predict the target motion state. For traffic objects, constant velocity, constant acceleration, and constant speed motion are common motion models.The steady-state motion model represents the target moving at a constant speed along a straight line, considering only planar motion for simplification of calculation. The discrete motion equation for this model is shown in the formula.The steady-state acceleration motion model represents the target moving along a straight line with uniform acceleration. The discrete motion equation for this model is shown as follows.The steady-state uniform circular motion represents the target moving at a constant speed in a circular path and the discrete motion equation for this model is shown as follows.The above three models have corresponding physical processes and, when the actual motion of the target matches the process model, it can predict the motion state well. However, due to the complexity and randomness of target motion, a single model cannot accurately update the target state over time. Unlike single-model algorithms, multiple-model interaction algorithms assume that the target motion process is composed of several motion models at each moment. When the target motion state changes in real time, the multiple-model interaction algorithm adjusts the model probability through a Markov chain to adapt to the current target motion state.As shown in k−1.Model interaction: the model conditions such as system state and covariance can be obtained from all filters at the previous time j at time k−1, i to model j at time k−1.i at time k−1, i to model j, and the Markov transition probability matrix is defined as follows.The transition between motion models follows a first-order Markov chain; 2.Model matched prediction update: based on the mixed initial state estimation and measurements, motion prediction state and covariance are calculated for each motion model.3.Model probability update: the likelihood for each model can be calculated using the error covariance and the mean error. Assuming it follows the Gaussian distribution, then the likelihood function of model j is shown as follows.The likelihood function describes the probability of observing a set of data given a certain set of unknown parameters; The model probability is updated using the estimation model probability and likelihood function.4.Posterior state estimationIn the multi-mode interaction algorithm, the model switching follows a first-order Markov process. In the process of state transition, the probability matrix of state transition is crucial for system mode selection and switching. Usually, the state transition probability matrix is pre-set based on experience and cannot be updated online in real time. In order to adapt more accurately to the target’s real motion process, the state transition probability matrix is online-corrected in the transition process.k; thus, the probability can be described as follows.Considering the independence of measurement sampling, Taking the tracking process of the target vehicle’s lane-changing as an example for simulation analysis, the vehicle initially moves at a constant speed in a straight line, then changes lane using a fifth-order polynomial curve and, after the lane change, it decelerates. The simulation measurement sensor is located at the coordinate origin point and the sampling time for the measurement data is 10 ms. The distance measurement error is 0.2 m and the angle measurement error is 0.1 rad. The proposed AIMM-ASRCKF algorithm and the IMM-CKF algorithm are both subjected to 100 Monte Carlo simulations. M is the number of Monte Carlo simulations, x is the true value.To further quantify the filtering effect, the root mean square error (RMSE) is used to measure the effectiveness of different filtering algorithms. The key to multi-object tracking algorithms is associating measurement information with targets. The JPDA algorithm achieves data association by computing the probability of each measurement–target association event. However, with increasing numbers of targets, the traditional JPDA algorithm exhibits exponential growth in association events, leading to the combinatorial explosion phenomenon. Furthermore, the JPDA algorithm assumes a constant value for target detection probability. In practical complex environments, the target detection probability varies with changes in the external environment. Due to the characteristics of sensors, real targets may disappear temporarily or false targets may appear intermittently, making it difficult for the traditional JPDA algorithm to manage target tracks dynamically. To address the aforementioned issues, this study proposes an improved JPDA algorithm suitable for multi-sensor information perception. The purposed algorithm corrects the probability of association events based on the confidence of measurement information matching results. Additionally, an adaptive gating is applied to determine effective association events and posterior estimation is carried out through the establishment of a unified uncertain information measurement model.The success of multi-object tracking algorithms relies heavily on the association of measured data with targets. The JPDA algorithm achieves data association by computing the probability of each measurement–target association event. However, as the number of targets grows, the traditional JPDA algorithm results in exponential increases in association events, leading to a combinatorial explosion phenomenon. Furthermore, the JPDA algorithm assumes a constant value for target detection probability. In real complex environments, the target detection probability varies with changes in the external environment. Due to the characteristics of sensors, real targets may disappear temporarily or false targets may appear intermittently, making it difficult for the traditional JPDA algorithm to manage target trajectories dynamically.The flowchart of the proposed improved JPDA algorithm is shown in j falls within the association gate domain for target t and j does not fall within the association gate domain for target t.The set of association events can be defined as follows.(1)Each measurement can only originate from a unique true target or is not associated with any existing track.(2)Each target can correspond to at most one measurement. Thus, a large number of association events occur during the process of associating measurements with true targets. As the number of measurements and true targets increases, calculating the conditional probability of association events exponentially grows. The proposed algorithm addresses this issue by using an adaptive gating technique to filter out unlikely association events, thereby ensuring real-time processing.When calculating the conditional probability of association events, the following assumptions are made:(1)Create the association event confirmation matrix based on the current measurement information and the key matching pairs of the previous measurement.(2)N targets within the tracking field of view, where the target tracking gate can be established at the predicted positions of N targets at time k. Among them, m measurement results fall within the target tracking gate field.Calculate the conditional probability of association events, assuming there are When calculating the probability of data correlations, it mainly includes the following steps:k) represents the Mahalanobis distance between the measurement value t.The conditional probability of association events can be defined as follows.k in the Kalman filter process. If the dimension of the measurement state is nz, the variable z degrees of freedom.In order to reduce the computational burden of data association, an association gate is usually set to determine whether the measurement information falls within the predicted region of the relevant target. The measurements that fall within the association gate are considered as valid associated measurements.GP can be calculated as follows.The probability The parameter Perform Cholesky decomposition on Adaptive association gate boundary parameter (3)Correction of associated event probabilitiesλ that characterizes this uncertainty and use it to adjust our association probabilities. We assign the highest confidence level to the fusion measurement results that match both the visual sensor and millimeter-wave radar sources, while visual-only observation is considered at a relatively high confidence level, and millimeter-wave radar-only observation is considered at a lower confidence level. The lowest confidence level is assigned to sets of measurements that cannot be matched. The adjusted correlation event probability is then computed based on these calibration factors. The corrected associate event probability can be defined as follows.To address the uncertainty in data association arising from fusion of multisource information, we introduce a correction factor (4)Normalization processing(5)Object state estimationk, where m ≤ n, the GOSPA is defined as follows.cd represents the truncation distance, p represents sensitivity to outliers in the localization component, and i to the ground truth object ix. When α = 2, GOSPA can be decomposed into state error, missed detection error, and false alarm error. GOSPA can be simplified as:In order to evaluate the accuracy of tracking algorithms, the GOSPA evaluation metric is introduced. Assuming there are m ground truth objects and n tracks at time In the process of heterogeneous sensor target-level information fusion, it is necessary to send data from different types of sensors to the fusion center. As the detection processes of each sensor are independent and non-interacting, it is necessary to align the asynchronous data in terms of time and unify them in space.Time alignment refers to synchronizing the measurement information of the same target detected by heterogeneous sensors to the same moment. Since the working principles of heterogeneous sensors are different and their measurement processes are independent of each other, the reporting cycles to the fusion center for target information are different. Before information fusion, it is necessary to align the asynchronous sensor measurement information to the same moment. The cycle period of millimeter-wave radar data is approximately 16 ms, with a relatively short and stable interval. The cycle period of visual sensors is longer and can fluctuate with an increase in the number of targets in the scene. The millimeter-wave radar timestamp is selected as the standard for time alignment and the visual sensor perception information is converted into time series. For visual perception information, the least-squares cubic spline curve is used for fitting the interpolation calculation. That is to say, the data measured n+1 times by the camera output in the time range  is fitted to obtain the function S(x). Then, the sampling time of the millimeter-wave radar data is used as the independent variable to input into the fitting function to obtain the visual sensor data information corresponding to the corresponding moment. After obtaining the target output information of the millimeter-wave radar and the visual sensor at the same moment, spatial transformation is performed to place the measurement results in the same spatial coordinate system.Due to the different installation positions of camera and millimeter-wave radars on the vehicle, they detect targets in their respective coordinate systems. Before data fusion, it is necessary to unify the target information detected by each sensor in the same spatial coordinate system. As shown in After spatio-temporal unification of camera and millimeter-wave radars, the matched target information needs to be fused and estimated. As shown in CM and RM, respectively, and the likelihood function L(tM) is the likelihood function of the estimated quantity x. P(CM) and P(RM) are the distribution functions of the camera and millimeter-wave radar, respectively. Assuming that the sensor measurement data follow a Gaussian distribution, their conditional probability can be expressed as follows.By integrating the measurement characteristics of sensors, the maximum likelihood estimation principle is used to optimize target information. The measurement information of the camera and millimeter-wave radar are defined as tM represents the true value of the target state; iP is the covariance matrix, n is the number of sensors, and nM is the measured results of sensor n.The logarithmic likelihood function can be expressed as follows.By solving the logarithmic maximum likelihood function, the estimated state variables can be obtained.CP is the covariance of measurements from the visual sensor and RP is the covariance of measurements from the millimeter-wave radar.Since the information fusion in this study only involves two sensors, the millimeter-wave radar and camera, the optimized state estimation can be represented as:The experimental test vehicle platform is built as shown in As shown in The heterogeneity of sensor perception characteristics and measurement accuracy may result in differences in detection effectiveness under different scenarios, especially in extremely complex situations where one sensor may temporarily malfunction. Multimodal information fusion of heterogeneous sensors can effectively improve the system’s robustness and measurement accuracy. To demonstrate the effectiveness of the fusion algorithm, the experiment results among radar, camera, and fusion algorithm are compared in complex test scenarios. The testing scenarios include crossroads, pedestrian crossings, abnormal weather, and other situations, while GOSPA evaluation metrics are used to uniformly compare the results.(1)The crossroad scenarioThere are a large number of complex traffic participants in the crossroad and the purposed fusion algorithm is mainly validated in this scenario. As shown in (2)Pedestrian crossing scenarioTraffic accidents are more likely to occur in the pedestrian crossing scenario. The testing purpose is to examine the response speed and measurement accuracy of the fusion algorithm in such extreme scenarios. As shown in (3)Nighttime scenarioThe primary goal of the test in the dark environment is to evaluate the reliability of the fusion perception algorithm when a single sensor fails. As shown in (4)Underground parking scenarioDue to the relatively enclosed nature of the underground parking scenario, there is more reflection of echo information by the millimeter-wave radar, which makes it prone to missed detections and false detections. As depicted in Based on the comprehensive results of various scenario tests, the proposed fusion algorithm exhibits high detection performance and measurement accuracy in complex and extreme environments. In the crossroad scenario, there is a diverse range of traffic participants and targets can occlude each other, hindering their perception and detection by the perception module. In such testing environments, it is beneficial for evaluating the comprehensive performance of the perception module. The results show that the proposed algorithm can fully utilize the strengths of the heterogeneous sensors and achieve stable target detection and tracking. In the pedestrian crossing scenario, pedestrians can suddenly appear from the blind spots of the perception module. Because the fusion module can use the camera detection result immediately, the relevant detection information can be promptly transmitted to the decision-making and planning module. Also, there is some delay compared with the single camera detection in this test, because the fusion algorithm needs time to process the comprehensive detection results again. In the nighttime scenario, the camera cannot recognize targets due to low light intensity but the fusion module can use the millimeter-wave radar detection result to perceive the targets. Moreover, in order to prevent a false positive alarm of the collision avoidance system, the test was conducted in an underground parking lot with a high level of clutter. Because the proposed algorithm assigns different confidences to the detected targets based on the matching results of the heterogeneous sensors, the fusion algorithm can effectively filter out clutter targets. Among the different test results, the test result is more complex in the crossroad scenario, because it maintains more complex scenario elements such as vehicles, pedestrians, and complex road structure. In terms of target tracking accuracy, the fusion algorithm optimizes the detection accuracy based on the measurement uncertainty of each sensor. Compared with the target detection and tracking results of a single sensor, the fusion algorithm achieves comprehensive optimization. This provides a decision-making foundation for assisting driving system decisions and risk management.This study proposes a multimodal heterogeneous perception cross-fusion framework that combines millimeter-wave radar and camera data. It employs the Hungarian algorithm for matching and optimal estimation. To improve the estimation accuracy, the adaptive root-mean-square cubature Kalman filter is used to estimate noise characteristics and the adaptive multimodal interaction approach is introduced to improve target motion prediction. The improved joint probability data association handles multi-source perception uncertainty. Experimental results demonstrate the purposed fusion framework can enhance target tracking accuracy and robustness in complex traffic scenarios. The research has significant implications for collision avoidance systems, offering potential for more efficient fusion algorithms. Furthermore, more efficient and effective solutions for improving the fusion algorithm could be developed by considering the scenario understanding in the future study.


The aim of this review was to 1) discuss the specifics of experimental design and interpretation of data obtained by myography and 2) highlight the importance of the combined use of myography with various complementary techniques necessary for a deep understanding of vascular physiology.The study of the mechanisms of regulation of vascular tone is an urgent task of modern science, since diseases of the cardiovascular system remain the main cause of reduction in the quality of life and mortality of the population. Myography (isometric and isobaric) of isolated blood vessels is one of the most physiologically relevant approaches to study the function of cells in the vessel wall. On the one hand, cell-cell interactions as well as mechanical stretch of the vessel wall remain preserved in myography studies, in contrast to studies on isolated cells, e.g., cell culture. On the other hand,  Diseases of the circulatory system like hypertension, diabetes and atherosclerosis are still accompanied by high morbidity and mortality. Therefore, the function of the cells of the vascular wall, i.e., endothelial cells, smooth muscle cells (SMCs) and also adipocytes as well as other cells of the adventitia is continuously in the focus of contemporary research. As far as the main function of the circulatory system, the distribution of blood according to local demand, is concerned, a variety of methods is employed to study the mechanisms governing the control of blood vessel tone.in vivo. SMCs, for example, alter their phenotype (conversion from the contractile to the synthetic phenotype). Thus, data obtained on single cells, in particular in cell culture, have to be verified in more physiological systems like intact isolated blood vessels or ultimately the intact circulatory system in order to extrapolate them to the in vivo situation.Basic functions of the cells of the vascular wall can be addressed by applying a large array of molecular, biochemical, and physical methods on single cells, most often in cell culture. However, in cell culture cell-cell interactions inside the particular organ studied as well as interactions between different organs are lost. Moreover, cells in cell culture change gene expression quickly because they are kept in a growth promoting environment that has limited relevance for the physiological situation Methods have been developed to study the contractility of isolated blood vessels from the largest vessel in the organism, the aorta, down to arterioles with a diameter of just a few micrometers. The basic principles of these methods (isometric and isobaric myography) have been described long ago . Howeve effects .100). Thereafter, tension is reduced by decreasing internal circumference by a certain degree, often by 10%, as at this decreased internal circumference optimal contractility has been observed  as calculated by the law of Laplace. Based on the relationship between the internal circumference of the vessel and vessel tension, first the circumference of the vessel is determined, that corresponds to a pressure of 100 mmHg  solution deprived of calcium ions . Unfortu100. Unfortunately, the transmural pressure in small arteries of awake animals has not been studied systematically. In small mesenteric arteries of awake rats a transmural pressure of about 65 mmHg has been determined  has been published previously .Initial Experiments on isolated vessels, whether isobaric or isometric preparations, often begin with a so-called starting procedure. During this procedure the vessel is challenged repetitively by contractile agonists after the potentially damaging vessel isolation and mounting procedure until a stable contractile response is achieved. In addition, a test to prove the existence/absence of a functional endothelium should be performed. Furthermore, in isometric preparations the starting procedure frequently includes the determination of maximum active tension as contractile responses often are normalized to this value.• recover contractile responses until sufficient and stable reactions are obtained; determine maximum active tension (cave: maximum active tension is sensitive to vessel damage)• test the existence of sufficient reactions upon endothelial stimulation or their absence in endothelium-denuded preparationsStarting procedure.Importantly, knowledge of maximum active tension is required when contractility has to be determined in absolute terms . This may be required for the comparison of the contractility of, e.g., vessels from different vascular beds or of vessels from wild-type subjects and subjects deficient for certain molecules suggested to be important for vessel contractility. However, maximum active tension is heavily influenced by the vessel isolation and mounting procedures that are potentially damaging. Thus, whenever differences in maximum active tension are observed, this can be due to either real differences in the structure of the vascular wall , or differences in contractile mechanisms on the cellular level, or damage induced during the vessel isolation and mounting procedure. The latter effect should be excluded by performing a number of control experiments in order to get evidence for a biological cause of possible differences in maximum active tension. For example, observing a thinner vascular wall will be consistent with a smaller maximum active tension and will provide evidence against the hypothesis that damage was the cause of the smaller active tension. Vessel wall thickness (better media thickness) can be estimated histologically or, which is easier, by light microscopy in mounted vessel segments . In addiOften, contractile responses of vessels, whether isobaric or isometric preparations, exposed to two or more conditions are compared. For example, vessels may be studied in the absence/presence of an ion channel or protein kinase inhibitor. Here, appropriate control experiments have to be performed and reported. Unfortunately, at least the latter is not done routinely.Two protocols are principally possible. In the first, the sequential design, a vessel will be exposed to different conditions sequentially, e.g., the application of a contractile agonist initially in the absence and later in the presence of an ion channel blocker. Using this protocol, the contribution of the targeted ion channel to the effect of the contractile agonist can be studied. Of note, when more than one intervention is desired to be performed in the sequential design , appropriate control experiments should verify that the first intervention does neither facilitate nor impede  the second intervention. For example, the effect of the BK channel blocker iberiotoxin is not fully reversible, thus any further intervention will be performed with at least partially blocked BK channels.More importantly, it should be considered that contractile responses of vessels, whether isobaric or isometric preparations, are not stable over time, as was shortly mentioned in . Therefo2 or Δ area under the curve) and the resulting values be compared  of potentially involved signaling pathways are often used. Notably, these inhibitors may affect contractility even before the addition of the contractile agonist because of a basal activity of the signaling pathway studied.In isobaric vessel preparations possessing a myogenic tone at a physiologically relevant transmural pressure such basal activity is easily detected by a change in vessel diameter upon addition of the inhibitor. If such an effect is observed, an altered effect of the tested agonist in the presence of the inhibitor may be caused non-specifically due to the alteration of basal vessel tone induced by the inhibitor. Hence, appropriate controls have to be included to prove that the inhibitor specifically affects the action of the tested agonist.Such control experiments may include, for example, the demonstration that another inhibitor targeting a synergistic signaling pathway  does not change the effect of the tested agonist. For example, Alternatively, it can be shown that the effect of another agonist targeting a similar, parallel signaling pathway  compared to the initially studied agonist is not modified by the tested inhibitor.In addition, the cited study  contains• consider possible effects of inhibitors/activators on basal activity of signaling pathways and perform appropriate control experiments• consider masking effects of synergistic signaling pathwaysAnalysis and interpretation of experimental myography data, preparations with spontaneous tone.These considerations in no way imply that all control experiments discussed have to be performed. Depending on the specific experimental conditions, the appropriate control experiments should be selected.• consider possible effects of inhibitors/activators on basal activity of signaling pathways masked because they are occurring below the threshold of active tone development and perform appropriate control experiments by measuring additional parameters• consider masking effects of synergistic signaling pathwaysAnalysis and interpretation of experimental myography data, preparations without spontaneous tone.The basal activity of a tested signaling pathway as discussed in the previous paragraph is more difficult to detect in isometric vessel preparations, particularly when the inhibitor has a relaxing effect and is applied to the vessel without agonist- or stretch-induced basal tone. Of note, this is true also for instances where larger vessels or some rare smaller arteries not able to develop pressure-induced tone are studied under isobaric conditions. In these cases, it should be considered that contraction has a certain threshold, i.e., that a minimum concentration of an agonist has to be applied to evoke contraction above passive basal tone. Of note, it has been observed that, e.g., membrane potential often has a lower threshold ; the same may be true for the intracellular calcium concentration. This means that these parameters may increase already at lower contractile agonist concentrations compared to vessel tension indicating that certain signaling pathways are active below the threshold for tone development, i.e., at basal tone. For example, if an inhibitor of a calcium signaling pathway is given to a vessel not possessing basal tone, tone will not change (decrease). If the subsequently added contractile agonist is observed to have a decreased effect, this is usually interpreted as a suppressive effect of the inhibitor on a calcium signaling pathway activated by the agonist assuming that the agonist increases the intracellular calcium concentration. However, at basal tone the inhibitor may have decreased the intracellular calcium concentration if the latter has a lower threshold than active tone. Let’s suppose that the contractile agonist in fact does not increase the intracellular calcium concentration but strengthens calcium sensitivity. Of note, pathways affecting calcium sensitivity and pathways altering the intracellular calcium concentration often interact. Thus, the inhibitor mentioned above, by producing a decrease of the intracellular calcium concentration, may have reduced the activity of the calcium sensitivity pathway as well. Consequently, the effect of the agonist acting through the calcium sensitivity pathway will be reduced. Thus, without measuring the intracellular calcium concentration, the reduced effect of the agonist can be misinterpreted as described above to indicate that the agonist increases the intracellular calcium concentration. Only having measured the intracellular calcium concentration would provide the correct interpretation that the effect of the agonist is mediated by a calcium sensitivity pathway. Consequently, whenever possible the measurement of additional parameters along with vessel tone or vessel diameter should be considered. Otherwise, the interpretation of the data should be done with great caution considering alternative explanations.When working with isometric vessel preparations or with isobaric preparations without pressure-induced tone, there is a special issue in experiments addressing the mechanisms of action of relaxing agonists. Here, a certain level of contraction, the so-called pre-contraction, has to be established by a contractile agonist. The effect of a relaxing agonist is often characterized by constructing concentration-response relationships. Since the application of a sufficient number of concentrations for a full concentration-response relationship requires quite some time, the pre-contraction has to be rather stable. However, often this is not the case see , challen–5 M produced full relaxation when applied at a moderate pre-contraction level (panel b) but only about 50% relaxation when applied at a somewhat stronger pre-contraction level (panel c). Let’s suppose, for example, that such a stronger pre-contraction was the result of the addition of an inhibitor of a certain signaling pathway. A smaller relaxing response in the presence of the inhibitor could be interpreted to indicate the involvement of the signaling pathway in the action of the relaxing agonist. However, in reality this difference was just the result of a functional antagonism, where the relaxing agonist had to “work” against much stronger contractile pathways. This misinterpretation can easily be avoided. There are two options. If the relaxing response is calculated using the pre-contraction level as baseline, the pre-contraction level itself should be reported as percent of maximum contraction. When two (or more) experimental groups will be studied, the respective pre-contraction levels should be shown to be equal . A more comprehensive way to present data of the effect of relaxing agonists is to calculate all effects in percent of maximum contraction (together with the pre-contraction level)  without the BK channel inhibitor iberiotoxin (IBTX) and a second vessel was exposed to the same concentration of MX in the presence of IBTX. Both pre-contraction levels were quite similar  without the BK channel inhibitor IBTX but the second vessel was exposed to a smaller concentration of MX in the presence of IBTX. Because at this smaller MX concentration IBTX had a considerable contractile effect, both pre-contraction levels were also quite similar  at higher concentrations of MX compared to its effect at smaller concentrations of MX . It was • test different conditions of pre-contraction as they may affect the dominating pathway mediating vessel relaxationAnalysis and interpretation of experimental myography data, study of the mechanism of action of relaxing agonists after pre-contraction in preparations without spontaneous tone.The finding that different pathways of vessel relaxation may dominate depending on the conditions used for pre-contraction should also be considered when comparing data from isometric and isobaric vessel preparations. As discussed in the previous comprehensive review , pre-conThe investigation of the mechanisms of arterial contractile/vasodilator responses may require the use of additional methods targeted at, for example, the determination of the content of proteins or mRNA of interest in the vascular tissue. Additionally, it might be of interest to determine the degree of activation of the corresponding protein based on the level of its phosphorylation using phospho-specific antibodies. While the determination of the relative content of proteins or mRNA in arterial tissue does not raise questions , the determination of the content of the phosphorylated protein often requires its preceding activation using vasoactive substances. This section will describe how a wire myograph can be used for the preparation of arterial tissue for further analysis by Western blotting using phospho-specific antibodies, as well as the preparation of endothelium-denuded arterial tissue for this purpose. Of note, a commercially produced pressure myograph for rapid freezing or fixing of intact, pressurized vessels is available. Its special chamber is made of special inert material to withstand low temperatures and fixatives.In some cases, it may be desired to determine protein phosphorylation levels under certain conditions, for example, following the action of a vasoconstrictor or a specific inhibitor. Since continuous measurements of protein phosphorylation, similar to vessel tension or vessel diameter measurements, are not possible, the level of protein phosphorylation should be determined at those moments that correspond to the most relevant time points according to the experimental protocol . In suchOf note, when using a standard wire myograph, the length of an arterial segment in the myograph chamber will be 2 mm at maximum. In some cases this is not enough to obtain a sufficient amount of protein. Thus, either several preparations must be combined into one sample. Alternatively, to increase the length of arterial segments, we developed a custom analogue of the myograph with wider heads to increase segment length up to 10 mm . This wiIn some cases, it is desirable to carry out PCR and/or Western blotting on vessels without endothelium. This is necessary, for example, to determine the localization of certain genes and/or proteins in SMCs or endothelial cells. One possible approach here is the mechanical removal of the endothelium in vascular ring segments using the wire myograph system, followed by rapid tissue processing . To do tetc.) should be determined simultaneously in endothelium-intact and endothelium-denuded samples. The expression level of mRNAs or proteins  should be several times lower in samples without endothelium than in samples with endothelium  should be compared in endothelium-denuded and endothelium-intact samples in order to confirm the success of endothelium removal• in case of denudation of the endothelium, mRNA or protein expression specific for endothelial cells  in order to penetrate a small cell without damaging it. In this regard, microelectrodes in electrophysiological studies of arterial smooth muscle have a relatively high resistance - at least 30 MΩ, e.g., . ImportaRecording of the membrane potential should be carried out on an antivibration table to prevent the possible escape of the microelectrode from the impaled cell in case of any mechanical disturbances. The position of the microelectrode in relation to the studied artery should be controlled in two stages. In the first stage of “rough” adjustment, the microelectrode is manually moved using a manipulator macro-screw to a position where the tip of the electrode is close to the vessel but does not touch it yet. In the next stage, just before and during the impalement, a more subtle way of changing the position of the microelectrode is required. For this purpose, for example, a Piezo micromanipulator should be used, which allows to move the electrode over several micrometers.The thin and long tip of the microelectrode can easily be clogged with fragments of connective tissue or bent on contact with the vessel wall. This will lead to the appearance of artifacts , which the experimenter may mistake for the impaling of a cell. Therefore, it is important to control the input resistance of the microelectrode tip throughout the experiment by applying subthreshold (short and low-amplitude) current pulses (may be except of periods used to record example traces for illustration). A sharp increase in the amplitude of these pulses will indicate that the tip of the microelectrode rests against the vessel wall, is bent, or is contaminated. When the tip of the microelectrode has penetrated the cell successfully, the amplitude of the responses to the current pulses should be small since the total resistance of the microelectrode tip and the smooth muscle syncytium is low . Special2 (30 µM) or AVE1231 (1 µM), respectively) depolarized arterial smooth muscle by about 10 mV, while it did not induce the development of a contractile reaction  . While td <1 μM, useful for the determination of the cytosolic calcium concentration) to low affinity ones . Detailed descriptions of the general methodological background of these methods can be found elsewhere, e.g., . For this purpose, FURA-2 has often been used because it allows ratiometric measurements . This dyetc. , #3/4. Oetc. . Therefoetc., are rather critical. Especially movement artefacts have to be avoided. This can be achieved either by strongly immobilizing the vessel preparation, which is non-physiological, or by techniques to correct for motion artifacts .The loading of synthetic calcium dyes into the cells of isolated vessel preparations is quite straightforward. Commonly, these dyes are polycarboxylate anions and therefore are not able to cross the lipid bilayer. For better membrane permeability these dyes are usually modified to acetoxymethyl esters. They are dissolved in an appropriate solvent, most often DMSO, and the vessel preparation is incubated with the dye for an appropriate time. Dye loading can be facilitated using dispersing agents like Pluronic F-127 or Cremophor EL. In some cells this loading procedure can produce dye concentrations in the cytosol of hundreds of µM with just several µM in the loading medium . This isSeveral additional critical points should be considered regarding the loading procedure. The acetoxymethyl moiety does not only facilitate dye crossing of the cytoplasmic membrane, but also the crossing of intracellular membranes. This leads to a compartmentalization of the dyes into intracellular organelles , #5. In • dye loss• photobleaching• dye precipitates stick to the adventitia adding a strong calcium-insensitive signal• compartmentalization of dyes• screening or scatter of fluorescence by connective tissuePitfalls to be considered in studies with synthetic calcium dyes.The ability to obtain fluorescence from dyes to estimate the intracellular calcium concentration depends not only on successful loading of the dye. Another critical point is the connective tissue surrounding all vessels to a larger or smaller extend. Sometimes this connective tissue is able to screen or scatter the fluorescence from successfully loaded dyes quite strongly , #6. In d of the dye and of the fluorescence in the absence of calcium (Fmin) and the presence of saturating calcium (Fmax) for non-ratiometric dyes or of the fluorescence ratio in the absence of calcium (Rmin) and in the presence or saturating calcium (Rmax) for ratiometric dyes. For the measurement of the latter factors, an equilibrium should be established between the calcium concentration in the external bath solution and in the cytosol, usually by the addition of an ionophore such as ionomycin. For FURA-2 this is usually done in a 3-step procedure. 1) Incubation in bath solution containing ionomycin and EGTA to reduce the calcium concentration and to get Rmin; 2) Incubation in bath solution containing ionomycin and a high calcium concentration to get Rmax; and 3) addition of Mn2+ quenching FURA fluorescence to get background fluorescence  difficult due to the division by a very small number.Although this seems to be a straightforward approach, it is not. Thus, especially for non-ratiometric dyes the determination of minimum and maximum fluorescence is often impossible due to non-avoidable dye leakage from the preparations and photobleaching of the dye during the course of an experiment. For ratiometric dyes, other limitations make the determination of these factors difficult. Because ionomycin is not very effective in an environment with a low calcium concentration, determination of Rd should be known. However, the binding of calcium to a fluorescent dye is highly dependent on a number of conditions, including pH, ionic strength, the presence of other ions that also bind to the dye, and other substances that directly influence the dye. Since the intracellular values of many of these factors are not known, the Kd of a fluorescent dye determined outside the cell of interest in vitro is not a good estimate of the real Kd value  remain in the vessel wall after it is isolated. They stay functional (capable of storing and secreting neurotransmitters) for several hours, and with proper storage even for several days after vessel isolation from the body (Studies the body .1), P2X (predominantly P2X1) receptors and Y1 receptors, respectively. In addition, noradrenaline can induce vasorelaxation by activating β-adrenoceptors. Direct effects of NPY are hardly observed in vitro, but it can considerably potentiate the effects of noradrenaline and ATP , substance P, neurokinins, and, presumably, anandamide . CGRP-ere.g., CS100, Danish Myo Technology). The electrodes can be either wires (about 1-mm thick)  are placed 1–3 mm from each side of the vessel without touching it. Thus, the nerves are excited by the electric field passing through the physiological salt solution  . Stimulam thick)  or platem thick) . In the m thick) . It is bv) channels of nerve fibers and hence the neurogenic vasomotor responses , which blocks voltage-gated sodium  should be plotted in the absence and in the presence of TTX for the studied vessel type . The parv channels .The endothelium can modulate neurogenic responses of isolated vessels through various mechanisms. Firstly, neurotransmitters released from intramural nerves may diffuse to the endothelium and activate it. For example, activation of the endothelium by neuronal acetylcholine was shown in guinea-pig basilar arteries . CholineNext, the endothelium may be activated secondarily to the activation of SMCs. Such a mechanism of endothelium-dependent suppression of EFS-induced constrictor responses was demonstrated in isobarically pressurized third-order mouse mesenteric arteries . The autv channels in vascular endothelial cells  before testing the sensitivity of EFS-induced reactions to TTX, capsaicin or other appropriate pharmacological tools that will be discussed in the next section.• in most cases, the neurogenic response is blocked by TTXv channels can be eliminated by capsaicin• the effects of sensory nerves containing TTX-insensitive Na• vascular endothelium can modulate vascular responses to stimulation of sympathetic, sensory and parasympathetic nerves• high-current stimulation can induce vasorelaxation due to the formation of chlorine gas or reactive oxygen species potentially damaging to vascular wall cellsElectrical field stimulation of intramural nerves:Therefore, when performing EFS in experiments on isolated arteries, it is extremely important to ensure the neurogenic origin of the response. Notably, with correctly selected parameters, the scavenging of free radicals did not affect EFS-induced vessel responses . Since nThe next task when studying neuroeffector mechanism is to understand what type of nerve fibers is activated upon EFS and what neurotransmitter induced the vasomotor response. This can be done using pharmacological tools that disrupt i) the secretion of transmitters from nerve fibers or ii) the interaction of neurotransmitters with their receptors (receptor antagonists). In the first case, it is important to verify the selective presynaptic action of secretion disruptors (the absence of their effects on vascular smooth muscle). In the second case, it is necessary to prove the blockade by stimulating the receptors  against the background of antagonist action. The agonist should be applied at a submaximal concentration, or at least at a concentration that causes a vasomotor effect comparable in amplitude to the neurogenic response. Care should also be taken in choosing the concentration of the antagonist because at high concentrations antagonists may have undesirable side effects.in vitro sympathectomy  and guanethidine. Incubation of isolated vessels with 6-OHDA provides thectomy . An undoperiment . 6-OHDA periment . Importaperiment . Howeverperiment .Guanethidine blocks adrenergic transmission by two mechanisms that are also associated with its uptake by sympathetic fibers . First, 1-adrenoceptor antagonist prazosin  channels which are a hallmark of C-type sensory nerve fibers and, therefore, it is an excitotoxin for these fibers  (ω-nitro-L-arginine methyl ester (L-NAME)   or Nω-ni(L-NAME) . In some(L-NAME) .Notably, NO is a key vasodilator neurotransmitter in the parasympathetic control of vascular tone, with the other transmitters, including acetylcholine, acting as presynaptic modulators of NO release . In addi• neurotransmitter secretion from sympathetic and sensory nerve fibers can be disrupted using 6-OHDA/guanethidine and capsaicin, respectively• postjunctional effects of the neurotransmitters can be blocked with the use of appropriate receptor antagonists; the blockade must be confirmed by applying respective agonists• at high or even moderate concentrations receptor antagonists may have undesirable side effectsPharmacological analysis of activated nerve fiber types and their postjunctional effects:Importantly, the effective concentrations of all pharmacological tools affecting sympathetic, sensory, and parasympathetic intramural nerves may vary in arteries and veins from different species as well as in vessels from different organs. To get more information on this topic, we refer readers to the above-cited articles, as well as to the following reviews .PharmacoWhen vascular responses to EFS of intramural nerves are studied by wire myography, the common procedures of normalization and activation of the preparation are performed at the beginning of each experiment. Notably, high-potassium physiological salt solution should not be used for activation of vascular smooth muscle since it also depolarizes nerve fibers and can deplete them of neurotransmitters. This is especially important in relation to peptide transmitters, whose reserves cannot be replenished by synthesis in varicosities of nerve fibers. For activation of the contractile mechanisms, vessel segments can be exposed several times to the maximal concentration of noradrenaline separated by washout intervals long enough for relaxation . To actiThe general characteristics of responses to sympathetic nerve stimulation can be obtained from cumulative frequency–response relationships , maintaining each frequency until a stable tension level is reached . Notably50 value, which is the frequency corresponding to the half-maximum response. The magnitude of neurogenic vasorelaxation can be expressed as a percentage of the pre-contraction level (for more detail see the section “Study of the mechanism of action of contractile or relaxing agonists in isometric vessel preparations”).To compare the magnitude of neurogenic contraction of different vessels, responses to nerve stimulation are expressed as a percentage of the maximum contraction in response to noradrenaline. The sensitivity of vessel segments to EFS can be assessed using an EFA non-cumulative stimulation protocol is used in experiments with antagonists of neurotransmitter receptors . The tim+ solution during start-up activation of the preparation• do not use high-K• when studying the frequency–response relationship, take into account that full response time at each frequency can vary depending on the arterial type• do not use long stimulation when studying the effects of sensory nerves, to avoid depletion of non-recovering peptide neurotransmitters• time control experiments are necessary in experiments with neurotransmitter receptor antagonists• the contribution of a particular transmitter to the neurogenic response can depend on the frequency and duration of the stimulation as well as on vessel wall stretchProtocol features in studies of neurotransmission in isolated vessels:During data analysis, the effects of the antagonist on the magnitude of neurogenic contractions are evaluated. Importantly, the contribution of the investigated transmitter to the neurogenic response often depends on the frequency of stimulation . In addiExcitation-secretion coupling in vascular nerves is regulated by a number of prejunctional receptors and local non-receptor mechanisms . A simplThe method of the electrochemical measurement of the concentration of noradrenaline in the vessel wall is based on the ability of noradrenaline to oxidize upon contact with a positively charged electrode. The recorded oxidation current amplitude is linearly related to the noradrenaline concentration . To recoAt the beginning of such studies, the measurements were performed with the use of differential pulse voltammetry  and differential pulse amperometry  . It was In most studies, the measurements of noradrenaline release were carried out in vessel segments pinned to the elastomer-covered base of the recording chamber, where the vascular wall is not distended properly . ImportaOf note, in wire myographs of conventional design it is difficult to position the electrode so that it is leaning against the vessel wall along a sufficiently long section. However, this can be realized in a wire myograph specially designed for confocal studies and equipped with plastic mounting heads with electrodes . After mounting the segment, the myograph heads can be rotated to place the segment vertically. Thereafter a carbon fiber electrode is placed alongside the segment in a gently touching position . ImportaWhen conducting a pharmacological analysis of the prejunctional mechanisms by the amperometry technique, it must be considered that some substances can affect the oxidation current of noradrenaline . It was 2+ ([Ca2+]i) is a key signal for neurotransmitter secretion  corresponding to individual varicosities are selected in the image obtained before the start of nerve stimulation . Then siarteries .Studying


Developing a human bionic manipulator to achieve certain humanoid behavioral skills is a rising problem. Enabling robots to operate the steering wheel to drive the vehicle is a challenging task. To address the problem, this work designs a novel 7-DOF (degree of freedom) humanoid manipulator based on the arm structure of human bionics. The 3-2-2 structural arrangement of the motors and the structural modifications at the wrist allow the manipulator to act more similar to a man. Meanwhile, to manipulate the steering wheel stably and compliantly, an admittance control approach is firstly applied for this case. Considering that the system parameters vary in configuration, we further introduce parameter fuzzification for admittance control. Designed simulations were carried out in Coppeliasim to verify the proposed control approach. As the result shows, the improved method could realize compliant force control under extreme configurations. It demonstrates that the humanoid manipulator can twist the steering wheel stably even in extreme configurations. It is the first exploration to operate a steering wheel similar to a human with a manipulator by using admittance control. With the development of intelligent robots, there is an increasing demand for robots with various manipulation skills. Steering, a simple but commonly used human action, has attracted the attention of many researchers . It aimsAfter our verification, due to limitations in control efficiency and machine performance, robot humanoid driving has rarely been extensively studied in previous years. In 2015, Rojas et al.  proposedIn this work, we introduce our own humanoid robotic arm design based on task requirements at the beginning. The key is to implement a lighter weight by imitating the structure of a human arm. Then, we firstly propose an admittance control method that achieves the stable steering wheel operation with a humanoid manipulator. The key first is to attempt to ensure stable interaction between the manipulator and the steering wheel. However, we found that the manipulator may often reach singularity and lose stability with the failure of the admittance controller at the near-limit operating distance. Therefore, a parameter fuzzification strategy is proposed to improve the control effect. A suitable humanoid robot platform is the first consideration for steering wheel control. Xin et al.  made a tA 7-DOF humanoid manipulator is designed with a dexterous movement space. Imitating a human’s wrist, this provides a dexterous joint. Approaching human arm weight makes the manipulator lighter. Oblique installation offers a larger workspace. It is suitable as a research platform for the manipulator’s human-like operation.An admittance control approach is first applied to solve the safe interaction with the steering wheel. Different admittance controllers were applied to the end movement of the manipulator to achieve force position hybrid control during steering wheel operation. It can realize stable and compliant manipulation of the steering wheel with the 7-DOF humanoid manipulator.An admittance controller based on parameters fuzzification is proposed, which is designed to adapt different operating configurations. Three simulation environments are set up for small, medium, and large operating distances away from the steering wheel. By fuzzifying the inertia, damping, and stiffness parameters differently, our controller performs better than classic admittance controllers.The contributions of this work are three-fold and can be summarized as follows:https://github.com/nubot-nudt/Steering_wheel_with_7Dof_arm_sim, last accessed on 17 August 2023.The rest of this paper is organized as follows. The overall process of the manipulator operating the steering wheel is a complex and challenging set of tasks. The robot needs to transport to the front of the steering wheel, after which the manipulator trajectory planning is carried out according to the vision information processing to obtain the steering wheel size and attitude information. This research focuses on the project of how the humanoid manipulator grips the steering wheel and then steadily completes the action of rotating the steering wheel. Manipulating the steering wheel with a humanoid manipulator requires the following basic considerations for its execution.Firstly, the task process of manipulating the steering wheel is a problem of maintaining trajectory tracking. The operating space of the steering wheel is usually a regular circular motion in the plane, and the end-effector needs to track this circular motion while performing self-rotation to keep the hand always facing the center of the movement during the operation of the steering wheel. Secondly, cars will take turning moments between the tires and the ground when the vehicle turns. At the end of that turn, the suspension system will reposition the wheels and the body through its inherent reversion force so that the body will automatically return to its position. The EPS (Electric Power Steering) in most cars adaptiveiy adjusts the steering wheel deflection angle to increase handling performance . While tLastly, due to the impact of the design of the carrier platform, in some more extreme cases, the robot enters the vehicle with little space left for the arm to operate the steering wheel, and the manipulator may approach the singularity. At that time, the output of the admittance controller may drive the arm to break through the stability boundary and make the arm a singularity with the unstable steering wheel operation. Thus, an improvement strategy that makes the manipulator control method suitable for different manipulating spaces is worth considering.In addition, the steering wheel manipulation task has vertical tilt, vibration interference, and manipulation rate in practical applications, which are not within the scope of the main study of this paper and are therefore not discussed further.In this paper, we adopt a self-designed 7-DOF humanoid manipulator concerning the arm of a male adult (1.7 m in height), shown in To enlarge the operating space of the robot in front, the first joint is installed oblique 45 degrees, which makes the robot arm inverse solution more difficult but it can be solved by changing the definition of the base coordinate system. In addition, for the need to carry large loads, crossed roller bearings are used at the non-flanged output of the motor to improve the stiffness of the robotic arm. Moreover, joints 5, 6 and 7 are orthogonally arranged to imitate the human wrist and achieve some actions such as the ’folding wrist’ and ’buckling wrist’. Joint 5 is set forward to the elbow to improve wrist mobility, which is different from most 7-DOF robotic arms. It makes the end motion close to human and reduces the possibility of wrist singularity in the forward working space. By combining the movements of these seven joints, this manipulator can replicate the intricate and precise movements of a human arm.As for kinematic solutions, modeling the arm’s structural body is required. Usually, the direct kinematic modeling process of the humanoid manipulator is to derive the end-effector in Cartesian space by calculating the rotation angle of each joint, while the inverse kinematics is to obtain the rotation angle of each joint by deducing the end-effector in Cartesian space in the reverse direction . The armThe inverse kinematic solution of the humanoid manipulator plays an important role in robot control. The Jacobi matrix represents the relationship between the joint rotation velocity and the end tool actuator motion velocity, while the Jacobian of a redundant manipulator is a non-square matrix, and its generalized inverse matrix is generally obtained by Singular Value Decomposition (SVD). The speed of N joints’ rotation is denoted as The Jacobi matrix of the redundant manipulator is rectangular, represented by its pseudo-inverse as p˙=J+q˙ . DependiDynamics modeling is required because of the interaction between the humanoid manipulator and the steering wheel. The kinetic equations of the humanoid manipulator are derived from the Newton-Euler equation as follows, where ipulator (3)M(q)qF acting on the actuators at the end of the humanoid manipulator and the torque The relationship between the force This section focuses on the task of steering wheel operation by proposing an admittance controller based on parameters fuzzification, which consists of a trajectory tracking strategy to maintain circular motion through velocity control in Cartesian space . An admiFor the first question in the previous section, the end-effector is required to rotate while being able to accurately track a circular motion trajectory to always keep one axis pointing to the center of the circular motion, and this motion constraint x and For the second question, it is necessary to design the admittance controller to realize the active compliance of the humanoid manipulator. Impedance/admittance control was first proposed by HOGAN  in 1985,ectively . As mentThe velocity deviation Combining the external force The flow chart of the humanoid manipulator compliant control is shown in To improve adaptability at different operating distances , the Mm, experts . Figure X contains membership functions as zero (Z), positive small (PS), positive medium (PM) and positive big (PB). Y contains membership functions as negative big (NB), negative small (NS), zero (Z), positive small (PS), and positive big (PB). The fuzzy control output includes parameters of the admittance controller, which contain membership functions as low (L), medium (M), and high (H). The construction of a Fuzzy Inference System (FIS) is based on the Takagi-Sugeno model . The chaThe farther away the manipulator is from the steering wheel, the closer it reaches the limit attitude of the manipulator, and the more likely it becomes a singularity. In this case, the system will be unstable if the admittance controller produces the output due to vibration or steering wheel slewing torque that pulls the end-effector to the limit state . It can The computer device used is a Lenovo Blade 7000 K with Inter core i7-11700F CPU, 32 GB of RAM, 1.5 TB of storage and NVIDIA RTX-3060Ti GPU. The simulation software used is Coppeliasim in version 4.1, which is also called Vrep in older versions. The physics engine of simulation is Bullet 2.78, and the simulation step is set to 10 ms. The operating system used is Ubuntu18.04 based on Linux for an easy coding and debugging. A Robot Operating System  is used to communicate with the Coppeliasim and the ROS message release frequency is set to 100 Hz. The model is imported through an urdf file to ensure the accuracy, the humanoid manipulator is installed on the left side of the stand, and the steering wheel (radius is 0.23 m) is placed in front of the bracket, facing the operation direction of the humanoid manipulator. The end coordinate system and the base coordinate system are shown in The simulation sets the initial angle On the one hand these data prove the correctness of the kinematic inverse solution, on the other hand they show that the task cannot be accomplished using motion control alone. In comparison, the left figure in According to the range of parameter fuzzification, we set the initial angle Firstly, we started the simulation with an initial condition of small operating distances. As is shown in Then, we started the simulation with an initial condition of medium operating distances. As is shown in Finally, we started the simulation with an initial condition of large operating distances. As is shown in With all the data above organized, a comparative table has been completed as This paper proposes an admittance control method with parameters fuzzification to achieve compliant steering wheel operation with a self-designed humanoid manipulator. Firstly, the challenges of operating the steering wheel by a humanoid manipulator are analyzed, including the problem of unstable interaction and the problem of operation at a near-limit distance. Secondly, the kinematic and dynamic modeling of the self-designed humanoid manipulator is introduced. Furthermore, a kind of admittance controller is designed, whose inertia, damping, and stiffness coefficients are fuzzified according to the operating distance of the steering wheel. After that, simulation results provide intuitive data to verify the effectiveness and reliability of this control method, which can complete the steering wheel operation at a near-limit operating distance.The biomimetic design of redundant manipulators will contribute to achieving flexibility similar to human arms. Much biology research on human body structure, such as muscle group movement and scapulohumeral rhythm, can help design high-performance robotic arms. Meanwhile, studying the humanoid skills of robots can help understand human action mechanisms and behavioral patterns. However, learning humanoid driving skills is a challenging task which requires domain knowledge in many engineering fields, such as mechanical design, adaptive control, multi-sensor fusion, and trajectory tracking, etc. The experiment results demonstrate the effectiveness of admittance control during the steering wheel operation with a redundant manipulator. As far as we know, this is the first publicly available exploration for robots to operate a steering wheel like humans with the help of control theory.It is noteworthy that the proposed method is based on the ground-truth state as the input signal. However, it is difficult to measure the state precisely during the interaction between the steering wheel and the manipulator. The initial parameters need to be adjusted appropriately to achieve good control effect. What is more, our method relies on linearization functions with parameters fuzzification, which may be difficult to adapt to complex unknown environments. In future work, the development of humanoid skills in robots will be an important research direction. We will demonstrate more convincing experiments on our designed real platform. Adding damping systems is an efficient approach to improve the performance of the current controller. Latifinavid  designed


This article scrutinizes blood circulation through an artery having magnetized hybrid nanoparticles (silver and gold) with multiple stenoses at the outer walls and erratic thrombus of different radii at the center. In the realm of biomedical innovation, magnetized hybrid nanoparticles emerge as a captivating frontier. These nanoparticles, amalgamating diverse materials, exhibit magnetic properties that engender novel prospects for targeted drug delivery, medical imaging enhancement, and therapeutic interventions. The study was carried out employing modern bio-fluid dynamics (BFD) software. In this iterative procedure, a second-order finite difference approach is used to solve the governing equations with 0.005 tolerance. The experiment is performed on a blood conduit with mild stenosis assumptions, and expressions of temperature, resistance impedance to flow, velocity, wall shear stress, and pressure gradient are generated by employing related boundary conditions. No one has ever attempted to acquire the remedial impact of an induced magnetic field and hybrid nanoparticles on the bloodstream in a tapering artery containing multiple stenoses on the outside walls and multi-thrombus at the center using 3-D bio-fluid simulation. Furthermore, the study's findings are unique, and these computational discoveries were not previously published by any researcher. The findings suggest that hybrid nanoparticles can be used as medication carriers to reduce the impact of thrombosis and stenosis-induced resistance to blood flow or coagulation-related factors. A condition known as atherosclerosis occurs when fatty compounds build up on the arterial walls and harden them. Plaques are the common name for these fatty accumulations. Plaques that plug inside the arteries signal the presence of a dangerous illness known as arterial atherosclerosis. When a blood vessel or more structures like a tube narrows abnormally, it is referred to as stenosis in medicine. The slow accumulation of plaque, which is mostly made of cholesterol, fat, and cellular debris, on the inner walls of arteries is referred to as atherosclerosis. On the other hand, stenosis is the narrowing or constriction of an artery as a result of a variety of circumstances, such as the buildup of atherosclerotic plaque. In essence, stenosis can result from atherosclerosis when plaque formation narrows the artery lumen, obstructing blood flow and perhaps hurting health. There are essentially two tube-like structures in the spine. The narrowing of one or more areas within your spine is known as spinal stenosis. When your spine is compressed, the nerves and spinal cord that emerge from it have less room to travel. Young2 was the first to investigate stenosis; the author says that relatively minor growths cause moderate blockages. Mandal and Chakravarthy4 examine a non-Newtonian model of blood flow in a truncated overlapped confinement. Several biological systems do not have linear vessels, and some may have proclivity. Nadeem et al.5 used varying viscosity to theoretically describe the movement of nanotubes over an artery containing multiple stenoses. The effects of proclivity on the flow of blood via perfused arteries are investigated by many researchers8.According to research, the blood flow from and to the heart is a factor in more than 80% of deaths caused by heart disease9. An arterial thrombus is a blood clot in the artery that can be deadly because it prevents blood from reaching vital organs. Several academics have recently focused on studying of bloodstream through arteries with thrombus in the center. Such blood clots (thrombus) grow more commonly in sick arteries with tapering walls. As a result, the artery with severe stenosis seems to be more likely to develop a thrombus. This is a life-threatening case that almost limits the flow of blood and it has catastrophic implications. In this case, catheter insertion improves flow once again. This thin, empty pipe can be inserted into such problematic arteries to improve the flow. Doffin et al.10 investigated the flow issue with both scenarios (stenosis and thrombus) both analytically and experimentally.Another common kind of cardiovascular illness that can emerge as a consequence of stenosis worsening is thrombosis, which results from the establishment of a clot, which also barricades blood flow in the veins. Its progression can result in a variety of illnesses and ailments, including infarction, strokes, malignancy, and infections11 discovered bio-magnetic fluid dynamics. Biological fluids are Ferro-fluids, which are magnetic fluids that do not carry electricity. Ferro-fluids are used in a variety of applications, including pharmaceuticals, and anti-tumor drug haulers. Magneto-therapy is a complementary medical treatment in which magnets are utilized to address pain and multi-health concerns in people with cardiovascular disease12. Researchers are interested in investigating basic bio-magnetic hydrodynamics flow problems because of the innumerable major applications in biomedical engineering and biological sciences, like the advancement of magnetic materials for cell parting, targeted therapies transfer employing magnetic nanoparticles as medication delivery transporters, magnetic help combat and cancer therapy instigating magnetic hypoglycemia, minimizing blood loss during surgical treatment, and incitement of occlusive disease. Another notable implementation of these liquids is in chemotherapy. The medicine is coated with magnetized nanoparticles and administered adjacent to the malignance in the treatment. The drug is immersed by the malignant tumor using an extravagant magnetic field focused around the tumor’s midpoint. This method diminishes the adverse effects of anticancer drugs. This approach has primarily been tested on tiny animals. Recently, several studies reported the use of such a technology for human therapy in cases when the tumor is close to the skin13.Bio-magnetic hydrodynamics is a novel field of fluid mechanics that studies the fluid dynamics of bio-fluids in the existence of magnetic fields. Several scientists are eager to learn more about the impact of magnetic flux on blood flow. The magnetic field significantly impacts bodily fluid dynamics, which has ramifications for biotechnology and medical equipment. As a result, the magnetic fields may affect the blood flow. Magnetic field applications associated with health disciplines are demonstrated in several contexts, including illness treatment. Nevertheless, Haik et al.14 was the first who invented nano-fluids. These are manipulated colloids constituted of nanoparticles and the base fluid. The nanoparticles are composed of metals, oxides and carbon nanotubes. These nanoparticles contain thermal conductivity and have a magnitude greater than the base fluid. Also, the sizes of nanoparticles are lesser than 100 nm. Nanotechnology is a new discipline of research that involves the formation and advancement of different nanomaterials. The nanoparticles have broad applications in medical like as bio-medicines, because of how nanoparticles collaborate with matter15. The characteristics of nanoparticles like surface chemistry, shape, and size can be handled to increase their objectives in human circulatory systems. This article offers a moving through a perfused area to determine how hybridized could assist to improve blood flow. Nanoparticles may be utilized in the investigation, like mediators in optical, photoacoustic, in the delivery of drugs, as shippers capable to enhance cancer disclosure to a therapeutic assistant, developing treatment fallout by continuance circulation times, preserving transported drugs from deterioration and increasing tumor assimilation. The blood-mediated nanoparticles consignment is the expanded and latest area in the progression of therapeutics and diagnostics.Choi16 studied the presence of minor stenosis plaques in the presence of several types of nanoparticles including copper (Cu), aluminum (Al2O3), and titanium dioxide (TiO2). Lubna et al.17 examined the impact of nano-fluids on a stenotic damaged artery. Zeeshan et al.18 investigated the effects of nanoparticle morphologies on mixed convective steady flow across a revolving disc. Copper nanoparticles of various sizes in disc, cylindrical, and spherical forms, as well as water as the base fluid, are studied for nanofluids. Nadeem19 investigated nanofluid flow in a curved duct with flexible walls. Mekheimer et al.21 investigated the effects of copper (Cu) nanoparticles on blood flow through a stenotic conduit in the presence of a magnetic field.Hybrid nano-fluids are relatively novel forms of nanofluid that may be created by suspending distinct types (two or more) of nanoparticles in the base fluid, and hybrid (compound) nanoparticles in the base fluid. A hybrid constituent is a substance that blends the physical and biochemical properties of many substances at the same time and delivers the properties in a uniform phase. The physicochemical characteristics of synthesized hybrid nanostructures are exceptional since they do not present in the separate components. Ahmed and NadeemWe looked over the existing research publications, and this data unambiguously reveals that no one has numerically and visually examined the blood flow within a vessel with multiple stenosis and multi-thrombosis with a varying radius in the presence of an induced magnetic field through three-dimensional computational simulation. Our study's goal is to fill up this significant research gap by venturing into unknown terrain and using the nonlinear Navier–Stokes equations to thoroughly examine the intricate fluid dynamics at work. To improve blood flow, our strategy also involves injecting hybrid nanoparticles into the body. By highlighting the possibility of creative approaches to improving blood circulation in situations characterized by numerous stenoses and multi-thrombosis, this research increases the practical value of our work. The precise results are further clarified by the inclusion of graphical representations, making this work helpful for theoretical insights as well as for guiding possible clinical applications and treatment approaches.22. As illustrated in Fig. Let us look into the computational simulation for the unsteady, incompressible, two-dimensional, and laminar blood flow across a circular artery of finite length L, containing hybrid nanoparticles (silver and gold) which are injected in the artery as a drug, passing through a thrombus (blood clot) of various radii developed at the center of the stenosed artery. A uniform magnetic field is applied to examine its effect on blood flow. The electrical conductivity of the blood is taken as 0.70 S/m and its relative permittivity is mentclass2pt{minim23:The dimensions of time-dependent stenosis in the arterial wall The expression for the time-dependent parameter is where 24:Correspondingly, the equations of an unsteady, viscous, and incompressible, hybrid nano-fluid along a stenotic artery having thrombosis and applying a magnetic field are given asThe underlying relationships comprise the Eq. 7\documenThe equations of the functional magnetic field are given as:mentclass2pt{minim25.Following are the specified boundary conditions of the given modelAt the inlet of the artery, blood velocity is zero. The speed at the intake and the inflow could regulate the arterial pressure.The boundary condition equation at the inlet was given by the equation:To give the simulations a much more authentic look, we provided the blood supply model's pressure at the outflow. The outlet is on the opposite side of the inlet boundary. The outlet equation is given below:Because of the viscous nature of the blood, it cannot pass through the walls and adheres to it instead. No slip condition is considered here. So the equation at the wall was as follows:All the boundaries of the geometry are thermally insulated. The equation of thermal insulation is given below:2 is supplied to the inlet of the cylinder. The main equation of heat flux is specified as:A general inward heat flux of 1200 WmThe equation of magnetic insulation is given byThe governing equations for mass, momentum, and energy for the specified velocity field,For a compressible flow, the dissipation function in cylindrical coordinates is denoted by:After applying the velocity vector U = [where 26:The following are the thermo-physical characteristics of hybrid nanoparticlesAmong the key components of computational fluid dynamics is mesh. The mesh's efficiency can be used to gauge the number of iterations and the solution's precision.Represents the geometryRepresents the solution fieldFinite element mesh serves two purposes:The finite element discretization of the geometry follows the same principles as the discretization of the system's mathematical model, the result is approximated as continuous across each couple of points in the mesh. A mesh with finer components creates more precise outcomes and offers superior functionality. It is noted that the mesh is extra rectified in the stenotic section, as can be observed by the stenotic area, and less rectified while far distant from the stenosis, as seen in Fig. The influence of induced magnetic field and hybrid nanoparticles (silver and gold) on blood flow in defective arteries with multiple stenoses on the outer layers and erratic thrombus (clots) of different radii via the inner part of the artery is deliberated in this study using 3-D computational simulation. The experiment is performed on a blood conduit with mild stenosis assumptions, and expressions of temperature, resistance impedance to flow, velocity, wall shear stress, and pressure gradient are generated by employing related boundary conditions. According to the outcomes, the form of stenosis and thrombus at the center of an artery is the primary source of higher shear rates at the arterial walls. The findings support the cardiovascular properties of arteries with stenosis and thrombosis. The addition of hybridized nanoparticles modified the physical characteristics of blood, such as density, ability to conduct heat, electrical conductivity, and dynamic viscosity, influencing the simulation findings. We took a cut plane down the length of the artery in the XZ direction at Y = 0 and discussed it at various intervals.−1 and the minimum velocity is 0 m s−1. For 0 s there is no change in velocity along the artery's length. Figure Figures Figures mentclasspt{minimaAnother important characteristic controlled by hybrid nanoparticles and the induced magnetic field is temperature. When nanoparticles are subjected to an alternating magnetic field, they create heat via mechanisms such as hysteresis losses and magnetic relaxation. The temperature of the surrounding blood and tissue can be raised as a result of this localized heating. To avoid any negative effects on healthy tissues and to achieve the intended therapeutic outcomes, the temperature is carefully monitored and controlled by specific hybrid nanoparticles volume fraction. Figures The line graph depicts the behavior of blood flow and temperature all along the artery.−1. Hence we conclude that as time increases velocity along the x-axis also increases. So line graph of the velocity profile shows that the velocity is maximum for elliptical stenosis and is minimum for trapezoidal-shaped stenosis. The legend shows the change in velocity concerning time. Figure Figure In Fig. Figure The laminar flow experiment revealed that blood flow velocity fluctuates all along the model due to erratic thrombus and arterial plaque.The induced magnetic field causes an increase in arterial pressure decrease, which is most visible at the ideal flow rate.The magnetic field is observed to resist fluid mobility in the center of the artery, but the nanoparticle volume fraction increases motility.The induced magnetic increased the impedance to the flow, however, the nanoparticle volume fraction decreased it.The increase in the volume percentage of nanoparticles lowers the temperature profile.Temperature elevation varied according to the concentration and dispersion of the nanoparticles, as well as the strength and duration of the applied magnetic field.Higher nanoparticle concentrations and higher magnetic fields resulted in greater temperature rises.The temperature of the fluid decreases as the stenosis form parameter and depth of stenosis rise, resulting in a drop in blood flow in the artery.The inclusion of nanoparticles changed the flow patterns and resistance inside the pipes, resulting in pressure drop differences as compared to baseline circumstances.The variations in wall shear stress and pressure drop observed revealed the effect of hybrid nanoparticles on the overall hemodynamics of stenosed and thrombosed arteries.A mathematical and computational model was developed in this work to investigate the characteristics of blood flow inoculating silver and gold hybrid nanoparticles and generated magnetic fields in numerous stenosed arteries with irregular thrombosis. Newtonian characteristics of blood were calculated computationally using the second-order finite element method (FEM). It is imperative to remember that in certain situations, induced magnetic fields can be generated for magnetic medication aiming. The injection of hybrid nanoparticles into the circulation, in conjunction with the application of an external magnetic field, has been studied as a way of improving targeted medication delivery and thermal treatment. A generated magnetic field can direct nanoparticles to specific target areas, increasing their accumulation and therapeutic efficiency. The following are some of the important findings of the current inquiry, as indicated via graphical analysis: