Pneumatic artificial muscles(PAMs)can generate multimodal movements,e.g.,linear contraction/extension,spiral torsion,and bending motions.Among these motions,contraction and extension movements can be achieved using li...Pneumatic artificial muscles(PAMs)can generate multimodal movements,e.g.,linear contraction/extension,spiral torsion,and bending motions.Among these motions,contraction and extension movements can be achieved using linear PAMs(LPAMs)designed to mimic human skeletal muscle.LPAMs have considerable potential for wearable applications and can be integrated into soft wearable robotic systems.Due to their inherent compliance,excellent human-robot interaction,safety,and low cost,LPAMs are considered potential alternatives as actuator components in the construction of wearable robots.This review presents a comprehensive overview of the bio-inspired design of LPAMs and their wearable applications.The biomechanics of human skeletal muscle,including anatomy,morphology,and biomechanical characterization,is analyzed to provide design inspirations for LPAMs and determine the assistance requirements of LPAM-based wearable robots.Herein,LPAMs are classified into four categories based on their structural shapes,including cylindrical-shaped muscles,flat-shaped muscles,fold-shaped muscles,and muscles with other shapes.In addition,this review provides an overview of the diverse physical interfaces utilized in wearable robots and presents a comparative analysis of the actuation characteristics of LPAMs and the assistance performance of LPAM-based wearable robots.This analysis was conducted in consideration of several key metrics,including the contraction ratio,maximum force,specific force,response frequency,assistive torque/bodyweight,and net metabolic cost.Finally,this review summarizes the ongoing challenges and future research directions.展开更多
Force feedback dataglove is an important interface of human-machine interaction between manipulator and virtual assembly system, which is in charge of the bidirectional transmission of movement and force information b...Force feedback dataglove is an important interface of human-machine interaction between manipulator and virtual assembly system, which is in charge of the bidirectional transmission of movement and force information between computer and operator. The exoskeleton force feedback dataglove is designed taking the pneumatic artificial muscle as actuator, meanwhile, its structure and work principle are introduced, and the force control problem is analyzed and researched by experiment. The mathematic model of grasping rigid object for finger is established. Considering the friction of tendon-sheath system and finger deformation, the closed-loop force control for a single joint, a single finger and multi-fingers are studied respectively by the feedforward proportional-integral（PI） control method with variable arguments. On the premise of the force smoothness, the control error of the force exerted on the finger joint is in the range of ±0.25 N, which meets the requirement of force feedback. By experimental analysis, the reason of force fluctuation is that the finger joint has a small amplitude quiver, and the consistent change tendency of the force between proximal interphalangeal（PIP） joint and distal interphalangeal（DIP） joint results from their angle coupling relationship.展开更多
An exoskeleton force feedback dataglove is developed,which uses the pneumatic artificial muscles as actuators.On the basis of the simplified hand model,the motion equation is deduced according to the theory of Denavit...An exoskeleton force feedback dataglove is developed,which uses the pneumatic artificial muscles as actuators.On the basis of the simplified hand model,the motion equation is deduced according to the theory of Denavit-Hartenberg.The model of the equivalent contact forces exerted by the object on the finger is proposed.By the principle of virtual work,the static equilibrium of finger is established.The force Jacobian matrix of finger is calculated,and then the joint torques of the finger when grasping objects are obtained.The theory and structure of the force feedback datagolve are introduced.Based on the theory of motion stabilization of four-bar linkage,the flexion angles of joints are measured.The torques on finger joints caused by the output forces of pneumatic artificial muscles are calculated.The output forces of pneumatic artificial muscle,whose values are controlled by its inner pressure,can be calculated by the joint torques of the finger when grasping objects.The arms of force,driving torques and the needed output forces of pneumatic muscle are calculated for each joint of the index finger.The criterion of output force of pneumatic muscle is given.展开更多
Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumat...Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumatic Artificial Muscle(MBPAM)that can bend in eight directions by changing the pressurized chambers.The maximum bending angle and output force are 151°and 0.643 N under the pressure of 100 kPa,respectively.Additionally,the Finite Element Model(FEM)is established to further investigate the performance.The experimental and numerical results demonstrate the nonlinear relationship between the pressure and the bending angle and output force.Moreover,the effects of parameters on the performance are studied with the validated FEM.The results reveal that the amplitude of waves and the thickness of the base layer can be optimized.Thus,multi-objective optimization is performed to improve the bending performance of the MBPAM.The optimization results indicate that the output force can be increased by 7.8%with the identical bending angle of the initial design,while the bending angle can be improved by 8.6%with the same output force.Finally,the grasp tests demonstrate the grip capability of the soft four-finger gripper and display the application prospect of the MBPAM in soft robots.展开更多
According to the deficiency of the present model of pneumatic artificialmuscles (PAM), a serial model is built up based on the PAM's essential working principle with theelastic theory, it is validated by the quasi...According to the deficiency of the present model of pneumatic artificialmuscles (PAM), a serial model is built up based on the PAM's essential working principle with theelastic theory, it is validated by the quasi-static and dynamic experiment results, which are gainedfrom two experiment systems. The experiment results and the simulation results illustrate that theserial model has made a great success compared with Chou's model, which can describe the forcecharacteristics of PAM more precisely. A compensation item considering the braid's elasticity andthe coulomb damp is attached to the serial model based on the analysis of the experiment results.The dynamic experiment proves that the viscous damp of the PAM could be ignored in order to simplifythe model of PAM. Finally, an improved serial model of PAM is obtained.展开更多
In this paper, the practicality and feasibility of Active Force Control （AFC） integrated with Fuzzy Logic（AFCAFL） applied to a two link planar arm actuated by a pair of Pneumatic Artificial Muscle （PAM） is inves...In this paper, the practicality and feasibility of Active Force Control （AFC） integrated with Fuzzy Logic（AFCAFL） applied to a two link planar arm actuated by a pair of Pneumatic Artificial Muscle （PAM） is investigated. The study emphasizes on the application and control of PAM actuators which may be considered as the new generation of actuators comprising fluidic muscle that has high-tension force, high power to weight ratio and high strength in spite of its drawbacks in the form of high nonlinearity behaviour, high hysteresis and time varying parameters. Fuzzy Logic （FL） is used as a technique to estimate the best value of the inertia matrix of robot arm essential for the AFC mechanism that is complemented with a conventional Propor- tional-Integral-Derivative （PID） control at the outermost loop. A simulation study was first performed followed by an experi- mental investigation for validation. The experimental study was based on the independent joint tracking control and coordinated motion control of the arm in Cartesian or task space. In the former, the PAM actuated arm is commanded to track the prescribed trajectories due to harmonic excitations at the joints for a given frequency, whereas for the latter, two sets of trajectories with different loadings were considered. A practical rig utilizing a Hardware-In-The-Loop Simulation （HILS） configuration was developed and a number of experiments were carried out. The results of the experiment and the simulation works were in good agreement, which verified the effectiveness and robustness of the proposed AFCAFL scheme actuated by PAM.展开更多
This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching time and chattering r...This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching time and chattering reduction.The proposed method dynamically adapts to the variation of the switching function,which is based on an exponential term and a power rate term of the sliding surface.Thus,the controlled system can achieve high tracking performance while still obtain chattering-free control.Moreover,the effectiveness of the proposed method is validated through multiple experimental tests,focused on a dual pneumatic artificial muscle system.Finally,experimental results show the effectiveness of the proposed approach in this paper.展开更多
A variable camber wing driven by pneumatic artificial muscles is developed in this paper. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed and the relations...A variable camber wing driven by pneumatic artificial muscles is developed in this paper. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed and the relationship between the static output force and the air pressure is investigated. Experimental results show that the static output force of pneumatic artificial muscle decreases nonlinearly with the increase of contraction ratio. Secondly, the model of variable camber wing driven by pneumatic artificial muscles is manufactured to validate the variable camber concept. Finally, wind tunnel tests are conducted in the low speed wind tunnel. It is found that the wing camber increases with the increase of air pressure. When the air pressure of PAMs is 0.4 MPa and 0.5 MPa, the tip displacement of the trailing-edge is 3 mm and 5 mm, respectively. The lift of aerofoil with flexible trailing-edge increases by 87% at AOA of 5°.展开更多
The bionic legs are generally driven by motors which have the disadvantages of large size and heavy weight.In contrast,the bionic legs driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,go...The bionic legs are generally driven by motors which have the disadvantages of large size and heavy weight.In contrast,the bionic legs driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,good bionics and flexibility.A kind of bionic leg driven by PAMs is designed.The proportional-integral-derivative(PID)algorithm and radial basis function neural network(RBFNN)algorithm are combined to design RBFNN-PID controller,and a low-pass filter is added to the control system,which can effectively improve the jitter phenomenon of the joint during the experiment.It is verified by simulation that the RBFNN-PID algorithm is better than traditional PID algorithm,the response time of joint is improved from 0.15 s to 0.07 s,and the precision of joint position control is improved from 0.75°to 0.001°.The experimental results show that the amplitude of the change in error is reduced from 0.5°to 0.2°.It is verified by jumping experiment that the mechanism can realize jumping action under control,and can achieve the horizontal displacement of 500 mm and the vertical displacement of 250 mm.展开更多
This paper presents a method for the length-pressure hysteresis modeling of pneumatic artificial muscles(PAMs)by using a modified generalized Prandtl-Ishlinskii(GPI)model.Different from the approaches for establishing...This paper presents a method for the length-pressure hysteresis modeling of pneumatic artificial muscles(PAMs)by using a modified generalized Prandtl-Ishlinskii(GPI)model.Different from the approaches for establishing the GPI models by replacing the linear envelope functions of operators with hyperbolic tangent and exponential envelop functions,the proposed model is derived by modifying the envelope functions of operators into arc tangent functions,which shows an improvement in the modeling accuracy.The effectiveness of the proposed model is verified by the experimental data of a PAM.Furthermore,its capacity in capturing the hysteresis relationship between length and pressure is testified by giving different input pressure signals.With regard to the computational efficiency,the influence of the number of operators on the modeling accuracy is discussed.Furthermore,the inversion of the GPI model is derived.Its capability of compensating the hysteresis nonlinearities is confirmed via the simulation and experimental study.展开更多
Pneumatic artificial muscles(PAMs)usually exhibit strong hysteresis nonlinearity and time-varying features that bring PAMs modeling and control difficulties.To characterize the hysteresis relation between PAMs’displa...Pneumatic artificial muscles(PAMs)usually exhibit strong hysteresis nonlinearity and time-varying features that bring PAMs modeling and control difficulties.To characterize the hysteresis relation between PAMs’displacement and fluid pressure,a long short term memory(LSTM)neural network model and an adaptive Takagi-Sugeno(T-S)fuzzy model are proposed.Experiments show that both models perform well under the load free conditions,and the adaptive T-S Fuzzy model can furtherly adapt to the change of load with the online adaptation ability.With the concise expression and satisfactory performance of the adaptive T-S Fuzzy model,a model predictive controller is designed and tested.Experiments show that the model predictive controller has a good performance on tracking the given references.展开更多
Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-poll...Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-polluting characteristic, and environmental adaptability provide pneumatic soft robots an important position in the field of soft robots. In this paper, a soft robot with 10 soft modules, comprising three uniformly distributed endoskeleton pneumatic artificial muscles, was developed. The robot can achieve flexible motion in 3D space. A novel kinematic modeling method for variable-curvature soft robots based on the minimum energy method was investigated, which can accurately and efficiently analyze forward and inverse kinematics. Experiments show that the robot can be controlled to move to the desired position based on the proposed model. The prototype and modeling method can provide a new perspective for soft robot design, modeling, and control.展开更多
The aim of this article is to provide a survey on the most popular modeling approaches for PMAs （pneumatic muscle actuators）. PMAs are highly non-linear pneumatic actuators where their elongation is proportional to ...The aim of this article is to provide a survey on the most popular modeling approaches for PMAs （pneumatic muscle actuators）. PMAs are highly non-linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been an increase in the industrial and scientific utilization of PMAs, due to their advantages such as high strength and small weight, while various types of PMAs with different technical characteristics have appeared in the literature. This article will： （a） analyse the PMA＇s operation from a mathematical modeling perspective; （b） present their merits and drawbacks of the most common PMAs; and （c） establish the fundamental basis for developing industrial applications and conducting research in this field.展开更多
Continuum robots have been a hot topic in recent years due to their intrinsic features of agility,flexibility,and safety.To successfully deploy continuum robots in practical applications,further enhancements in variab...Continuum robots have been a hot topic in recent years due to their intrinsic features of agility,flexibility,and safety.To successfully deploy continuum robots in practical applications,further enhancements in variable stiffness,decoupled motion,and embedded sensing are highly desirable.Since continuum robots are usually composed of multiple joints assembled in series,their mechanical properties and performance will certainly rely on the connected joints.This paper proposes a motion-decoupled variable stiffness-decoupled pneumatic rigid-flexible hybrid joint(RFHJ),which is modular designed and integrated with a rigid hinge,a stiffness-tuning module,and soft actuators.The soft pneumatic muscle actuators are pre-stretched during assembly,ensuring the stable initial state of RFHJ.A novel musculature-mounting configuration is also presented,which enables RFHJs to achieve independent motions in two orthogonal planes.Furthermore,the variable stiffness module is embedded in the RFHJ’s structure to offer real-time and independent stiffness tunability across multiple scales in two perpendicular directions.The proposed RFHJ makes most of the advantages of soft continuum robots and conventional rigid serial robots by introducing a hybrid structure to provide both safe human-robot interaction(HRI),accurate control and reliable stiffness variation,presenting promising potentials for robotic systems,which have been theoretically proved and experimentally verified on the physical prototype.The experimental results also indicate that the developed RFHJ can work with variable stiffness ranging in[1.2,49.9]N·m/rad.A variable stiffness rigid-flexible hybrid continuum arm(RFHA)is designed with three RFHJs in series.Primary tests on the developed RFHA prototype demonstrate that it has the characteristics of decoupled driving,bidirectional stiffness tunability and self-stability.展开更多
Bionic robots are generally driven by motors.As robots driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,good bionics and flexibility,more and more researchers have adopted PAMs to drive ...Bionic robots are generally driven by motors.As robots driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,good bionics and flexibility,more and more researchers have adopted PAMs to drive bionic robots.A kind of bionic leg driven by PAMs for hopping is proposed in this work.A 3-DOF bionic leg driven by 4 PAMs is designed by analyzing the biological structure and movement principles of frog legs,and 3 kinds of leg configuration with different PAMs arrangement is proposed.One biarticular muscle is used to increase the joint rotating range.The bracket pulley and PAMs for driving joint can effectively increase its rotating range.The rotating range of hip and knee joint driven by a biarticular muscle is simulated.The simulation results show that the biarticular muscle can transfer the movement of the hip joint to the knee joint and increase the rotating range of the knee joint.The greater the contraction of PAM,the greater the rotating range of joint.The bionic leg can perform planned step distance and step height of hopping.展开更多
Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a b...Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a bellows woven sleeve.The maximal extension can be conveniently regulated by just adjusting the wrinkles’initial angle of the bellows woven sleeve.The kinematics of US2A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated.Based on the principle of virtual work,the actuating models have been established:the pressure-elongation model and the pressure-force model.These models reflect the influence of the silicone tube’s shell thickness and material properties on the pneumatic muscle’s performance,which facilitates the optimal design of US2A for various working conditions.The experimental results showed that the maximum elongation of the US2A prototype is 257%,and the effective elongation could be variably regulated in the range of 0 and 257%.The proposed models were also verified by pressure-elongation and pressure-force experiments,with an average error of 5%and 2.5%,respectively.Finally,based on the US2A,we designed a pneumatic rehabilitation glove,soft arm robot,and rigid-soft coupling continuous robot,which further verified the feasibility of US2A as a soft driving component.展开更多
The pivot turning function of quadruped bionic robots can improve their mobility in unstructured environment.A kind of bionic flexible body mechanism for quadruped robot was proposed in this paper,which is composed of...The pivot turning function of quadruped bionic robots can improve their mobility in unstructured environment.A kind of bionic flexible body mechanism for quadruped robot was proposed in this paper,which is composed of one bionic spine and four pneumatic artificial muscles(PAMs).The coordinated movement of the bionic flexible body and the leg mechanism can achieve pivot turning gait.First,the pivot turning gait planning of quadruped robot was analyzed,and the coordinated movement sequence chart of pivot turning was presented.Then the kinematics modeling of leg side swing and body bending for pivot turning was derived,which should meet the condition of the coordinated movement between bionic flexible body and leg mechanism.The PAM experiment was conducted to analyze its contraction characteristic.The study on pivot turning of the quadruped robot will lay a theoretical foundation for the further research on dynamic walking stability of the quadruped robot in unstructured environment.展开更多
As the pneumatic artificial muscle （PAM） has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in...As the pneumatic artificial muscle （PAM） has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in robotics. In this paper, a kind of musculoskeletal leg mechanism driven by PAMs is presented, which has three joints driven by four PAMs. The jumping movement is divided into three phases. The forward and inverse kinematics of the leg mechanism in different jumping phases is derived. Considering the ground reaction force between feet and environment, the dynamic in different jumping phases is analyzed by Lagrange method, then the relationship between PAM driving force and the joints angular displacement, angular velocity, angular acceleration during one jumping cycle is obtained, which will lay a foundatiori for the jumping experiment of the musculo- skeletal lez mechanism.展开更多
基金supported by the National Natural Science Foundation of China(No.52475067).
文摘Pneumatic artificial muscles(PAMs)can generate multimodal movements,e.g.,linear contraction/extension,spiral torsion,and bending motions.Among these motions,contraction and extension movements can be achieved using linear PAMs(LPAMs)designed to mimic human skeletal muscle.LPAMs have considerable potential for wearable applications and can be integrated into soft wearable robotic systems.Due to their inherent compliance,excellent human-robot interaction,safety,and low cost,LPAMs are considered potential alternatives as actuator components in the construction of wearable robots.This review presents a comprehensive overview of the bio-inspired design of LPAMs and their wearable applications.The biomechanics of human skeletal muscle,including anatomy,morphology,and biomechanical characterization,is analyzed to provide design inspirations for LPAMs and determine the assistance requirements of LPAM-based wearable robots.Herein,LPAMs are classified into four categories based on their structural shapes,including cylindrical-shaped muscles,flat-shaped muscles,fold-shaped muscles,and muscles with other shapes.In addition,this review provides an overview of the diverse physical interfaces utilized in wearable robots and presents a comparative analysis of the actuation characteristics of LPAMs and the assistance performance of LPAM-based wearable robots.This analysis was conducted in consideration of several key metrics,including the contraction ratio,maximum force,specific force,response frequency,assistive torque/bodyweight,and net metabolic cost.Finally,this review summarizes the ongoing challenges and future research directions.
基金supported by National Natural Science Foundation of China (Grant No. 50375034)Research Foundation for the Doctoral Program of Higher Education of China (Grant No. 200802881002)
文摘Force feedback dataglove is an important interface of human-machine interaction between manipulator and virtual assembly system, which is in charge of the bidirectional transmission of movement and force information between computer and operator. The exoskeleton force feedback dataglove is designed taking the pneumatic artificial muscle as actuator, meanwhile, its structure and work principle are introduced, and the force control problem is analyzed and researched by experiment. The mathematic model of grasping rigid object for finger is established. Considering the friction of tendon-sheath system and finger deformation, the closed-loop force control for a single joint, a single finger and multi-fingers are studied respectively by the feedforward proportional-integral（PI） control method with variable arguments. On the premise of the force smoothness, the control error of the force exerted on the finger joint is in the range of ±0.25 N, which meets the requirement of force feedback. By experimental analysis, the reason of force fluctuation is that the finger joint has a small amplitude quiver, and the consistent change tendency of the force between proximal interphalangeal（PIP） joint and distal interphalangeal（DIP） joint results from their angle coupling relationship.
基金This project is supported by National Natural Science Foundation of China(No.50375034).
文摘An exoskeleton force feedback dataglove is developed,which uses the pneumatic artificial muscles as actuators.On the basis of the simplified hand model,the motion equation is deduced according to the theory of Denavit-Hartenberg.The model of the equivalent contact forces exerted by the object on the finger is proposed.By the principle of virtual work,the static equilibrium of finger is established.The force Jacobian matrix of finger is calculated,and then the joint torques of the finger when grasping objects are obtained.The theory and structure of the force feedback datagolve are introduced.Based on the theory of motion stabilization of four-bar linkage,the flexion angles of joints are measured.The torques on finger joints caused by the output forces of pneumatic artificial muscles are calculated.The output forces of pneumatic artificial muscle,whose values are controlled by its inner pressure,can be calculated by the joint torques of the finger when grasping objects.The arms of force,driving torques and the needed output forces of pneumatic muscle are calculated for each joint of the index finger.The criterion of output force of pneumatic muscle is given.
基金the National Natural Science Foundation of China(11872178,51621004)are gratefully acknowledged。
文摘Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumatic Artificial Muscle(MBPAM)that can bend in eight directions by changing the pressurized chambers.The maximum bending angle and output force are 151°and 0.643 N under the pressure of 100 kPa,respectively.Additionally,the Finite Element Model(FEM)is established to further investigate the performance.The experimental and numerical results demonstrate the nonlinear relationship between the pressure and the bending angle and output force.Moreover,the effects of parameters on the performance are studied with the validated FEM.The results reveal that the amplitude of waves and the thickness of the base layer can be optimized.Thus,multi-objective optimization is performed to improve the bending performance of the MBPAM.The optimization results indicate that the output force can be increased by 7.8%with the identical bending angle of the initial design,while the bending angle can be improved by 8.6%with the same output force.Finally,the grasp tests demonstrate the grip capability of the soft four-finger gripper and display the application prospect of the MBPAM in soft robots.
文摘According to the deficiency of the present model of pneumatic artificialmuscles (PAM), a serial model is built up based on the PAM's essential working principle with theelastic theory, it is validated by the quasi-static and dynamic experiment results, which are gainedfrom two experiment systems. The experiment results and the simulation results illustrate that theserial model has made a great success compared with Chou's model, which can describe the forcecharacteristics of PAM more precisely. A compensation item considering the braid's elasticity andthe coulomb damp is attached to the serial model based on the analysis of the experiment results.The dynamic experiment proves that the viscous damp of the PAM could be ignored in order to simplifythe model of PAM. Finally, an improved serial model of PAM is obtained.
文摘In this paper, the practicality and feasibility of Active Force Control （AFC） integrated with Fuzzy Logic（AFCAFL） applied to a two link planar arm actuated by a pair of Pneumatic Artificial Muscle （PAM） is investigated. The study emphasizes on the application and control of PAM actuators which may be considered as the new generation of actuators comprising fluidic muscle that has high-tension force, high power to weight ratio and high strength in spite of its drawbacks in the form of high nonlinearity behaviour, high hysteresis and time varying parameters. Fuzzy Logic （FL） is used as a technique to estimate the best value of the inertia matrix of robot arm essential for the AFC mechanism that is complemented with a conventional Propor- tional-Integral-Derivative （PID） control at the outermost loop. A simulation study was first performed followed by an experi- mental investigation for validation. The experimental study was based on the independent joint tracking control and coordinated motion control of the arm in Cartesian or task space. In the former, the PAM actuated arm is commanded to track the prescribed trajectories due to harmonic excitations at the joints for a given frequency, whereas for the latter, two sets of trajectories with different loadings were considered. A practical rig utilizing a Hardware-In-The-Loop Simulation （HILS） configuration was developed and a number of experiments were carried out. The results of the experiment and the simulation works were in good agreement, which verified the effectiveness and robustness of the proposed AFCAFL scheme actuated by PAM.
文摘This paper develops a discrete-time sliding mode controller with a power rate exponential reaching law approach to enhance the performance of a pneumatic artificial muscle system in both reaching time and chattering reduction.The proposed method dynamically adapts to the variation of the switching function,which is based on an exponential term and a power rate term of the sliding surface.Thus,the controlled system can achieve high tracking performance while still obtain chattering-free control.Moreover,the effectiveness of the proposed method is validated through multiple experimental tests,focused on a dual pneumatic artificial muscle system.Finally,experimental results show the effectiveness of the proposed approach in this paper.
基金Sponsored by the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20102302120032)the Open Foundation of Key Laboratory of Advanced Composites in Special Environmentsthe Natural Scientific Research Innovation Foundation in Harbin Institute of Technology(Grant No.HIT.NSRIF.2012028)
文摘A variable camber wing driven by pneumatic artificial muscles is developed in this paper. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed and the relationship between the static output force and the air pressure is investigated. Experimental results show that the static output force of pneumatic artificial muscle decreases nonlinearly with the increase of contraction ratio. Secondly, the model of variable camber wing driven by pneumatic artificial muscles is manufactured to validate the variable camber concept. Finally, wind tunnel tests are conducted in the low speed wind tunnel. It is found that the wing camber increases with the increase of air pressure. When the air pressure of PAMs is 0.4 MPa and 0.5 MPa, the tip displacement of the trailing-edge is 3 mm and 5 mm, respectively. The lift of aerofoil with flexible trailing-edge increases by 87% at AOA of 5°.
基金Supported by the National Natural Science Foundation of China(No.51775323).
文摘The bionic legs are generally driven by motors which have the disadvantages of large size and heavy weight.In contrast,the bionic legs driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,good bionics and flexibility.A kind of bionic leg driven by PAMs is designed.The proportional-integral-derivative(PID)algorithm and radial basis function neural network(RBFNN)algorithm are combined to design RBFNN-PID controller,and a low-pass filter is added to the control system,which can effectively improve the jitter phenomenon of the joint during the experiment.It is verified by simulation that the RBFNN-PID algorithm is better than traditional PID algorithm,the response time of joint is improved from 0.15 s to 0.07 s,and the precision of joint position control is improved from 0.75°to 0.001°.The experimental results show that the amplitude of the change in error is reduced from 0.5°to 0.2°.It is verified by jumping experiment that the mechanism can realize jumping action under control,and can achieve the horizontal displacement of 500 mm and the vertical displacement of 250 mm.
基金supported by the National Key Technologies Research&Development Program of China(Grant No.2018YFB2101000)the National Natural Science Foundation of China(Grant No.51622508).
文摘This paper presents a method for the length-pressure hysteresis modeling of pneumatic artificial muscles(PAMs)by using a modified generalized Prandtl-Ishlinskii(GPI)model.Different from the approaches for establishing the GPI models by replacing the linear envelope functions of operators with hyperbolic tangent and exponential envelop functions,the proposed model is derived by modifying the envelope functions of operators into arc tangent functions,which shows an improvement in the modeling accuracy.The effectiveness of the proposed model is verified by the experimental data of a PAM.Furthermore,its capacity in capturing the hysteresis relationship between length and pressure is testified by giving different input pressure signals.With regard to the computational efficiency,the influence of the number of operators on the modeling accuracy is discussed.Furthermore,the inversion of the GPI model is derived.Its capability of compensating the hysteresis nonlinearities is confirmed via the simulation and experimental study.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.61873268,62025307 and U1913209)the Beijing Natural Science Foundation(Grant No.JQ19020).
文摘Pneumatic artificial muscles(PAMs)usually exhibit strong hysteresis nonlinearity and time-varying features that bring PAMs modeling and control difficulties.To characterize the hysteresis relation between PAMs’displacement and fluid pressure,a long short term memory(LSTM)neural network model and an adaptive Takagi-Sugeno(T-S)fuzzy model are proposed.Experiments show that both models perform well under the load free conditions,and the adaptive T-S Fuzzy model can furtherly adapt to the change of load with the online adaptation ability.With the concise expression and satisfactory performance of the adaptive T-S Fuzzy model,a model predictive controller is designed and tested.Experiments show that the model predictive controller has a good performance on tracking the given references.
基金the National Natural Science Foundation of China(Grant Nos.51975566,61821005,and U1908214)the Key Research Program of Frontier Sciences,CAS,China(Grant No.ZDBS-LY-JSC011).
文摘Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-polluting characteristic, and environmental adaptability provide pneumatic soft robots an important position in the field of soft robots. In this paper, a soft robot with 10 soft modules, comprising three uniformly distributed endoskeleton pneumatic artificial muscles, was developed. The robot can achieve flexible motion in 3D space. A novel kinematic modeling method for variable-curvature soft robots based on the minimum energy method was investigated, which can accurately and efficiently analyze forward and inverse kinematics. Experiments show that the robot can be controlled to move to the desired position based on the proposed model. The prototype and modeling method can provide a new perspective for soft robot design, modeling, and control.
文摘The aim of this article is to provide a survey on the most popular modeling approaches for PMAs （pneumatic muscle actuators）. PMAs are highly non-linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been an increase in the industrial and scientific utilization of PMAs, due to their advantages such as high strength and small weight, while various types of PMAs with different technical characteristics have appeared in the literature. This article will： （a） analyse the PMA＇s operation from a mathematical modeling perspective; （b） present their merits and drawbacks of the most common PMAs; and （c） establish the fundamental basis for developing industrial applications and conducting research in this field.
基金Supported by Shenzhen Municipal Natural Science Foundation of China(Grant No.U2013212)National Key R&D Program of China(Grant No.2020YFB1313001)National Natural Science Foundation of China(Grant No.U23 A20328).
文摘Continuum robots have been a hot topic in recent years due to their intrinsic features of agility,flexibility,and safety.To successfully deploy continuum robots in practical applications,further enhancements in variable stiffness,decoupled motion,and embedded sensing are highly desirable.Since continuum robots are usually composed of multiple joints assembled in series,their mechanical properties and performance will certainly rely on the connected joints.This paper proposes a motion-decoupled variable stiffness-decoupled pneumatic rigid-flexible hybrid joint(RFHJ),which is modular designed and integrated with a rigid hinge,a stiffness-tuning module,and soft actuators.The soft pneumatic muscle actuators are pre-stretched during assembly,ensuring the stable initial state of RFHJ.A novel musculature-mounting configuration is also presented,which enables RFHJs to achieve independent motions in two orthogonal planes.Furthermore,the variable stiffness module is embedded in the RFHJ’s structure to offer real-time and independent stiffness tunability across multiple scales in two perpendicular directions.The proposed RFHJ makes most of the advantages of soft continuum robots and conventional rigid serial robots by introducing a hybrid structure to provide both safe human-robot interaction(HRI),accurate control and reliable stiffness variation,presenting promising potentials for robotic systems,which have been theoretically proved and experimentally verified on the physical prototype.The experimental results also indicate that the developed RFHJ can work with variable stiffness ranging in[1.2,49.9]N·m/rad.A variable stiffness rigid-flexible hybrid continuum arm(RFHA)is designed with three RFHJs in series.Primary tests on the developed RFHA prototype demonstrate that it has the characteristics of decoupled driving,bidirectional stiffness tunability and self-stability.
基金Supported by the National Natural Science Foundation of China(No.51775323,51375289)
文摘Bionic robots are generally driven by motors.As robots driven by pneumatic artificial muscles(PAMs)have the advantages of light weight,good bionics and flexibility,more and more researchers have adopted PAMs to drive bionic robots.A kind of bionic leg driven by PAMs for hopping is proposed in this work.A 3-DOF bionic leg driven by 4 PAMs is designed by analyzing the biological structure and movement principles of frog legs,and 3 kinds of leg configuration with different PAMs arrangement is proposed.One biarticular muscle is used to increase the joint rotating range.The bracket pulley and PAMs for driving joint can effectively increase its rotating range.The rotating range of hip and knee joint driven by a biarticular muscle is simulated.The simulation results show that the biarticular muscle can transfer the movement of the hip joint to the knee joint and increase the rotating range of the knee joint.The greater the contraction of PAM,the greater the rotating range of joint.The bionic leg can perform planned step distance and step height of hopping.
基金National Natural Science Foundation of China(Grant No.U2013212)Key Research and Development Program of Zhejiang(Grant No.2021C04015)Fundamental Research Funds for the Provincial Universities of Zhejiang(Grant No.RF-C2019004)。
文摘Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a bellows woven sleeve.The maximal extension can be conveniently regulated by just adjusting the wrinkles’initial angle of the bellows woven sleeve.The kinematics of US2A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated.Based on the principle of virtual work,the actuating models have been established:the pressure-elongation model and the pressure-force model.These models reflect the influence of the silicone tube’s shell thickness and material properties on the pneumatic muscle’s performance,which facilitates the optimal design of US2A for various working conditions.The experimental results showed that the maximum elongation of the US2A prototype is 257%,and the effective elongation could be variably regulated in the range of 0 and 257%.The proposed models were also verified by pressure-elongation and pressure-force experiments,with an average error of 5%and 2.5%,respectively.Finally,based on the US2A,we designed a pneumatic rehabilitation glove,soft arm robot,and rigid-soft coupling continuous robot,which further verified the feasibility of US2A as a soft driving component.
基金Supported by the National Natural Science Foundation of China(No.51375289)Shanghai Municipal National Natural Science Foundation of China(No.13ZR1415500)the Innovation Fund of Shanghai Education Commission(No.13YZ020)
文摘The pivot turning function of quadruped bionic robots can improve their mobility in unstructured environment.A kind of bionic flexible body mechanism for quadruped robot was proposed in this paper,which is composed of one bionic spine and four pneumatic artificial muscles(PAMs).The coordinated movement of the bionic flexible body and the leg mechanism can achieve pivot turning gait.First,the pivot turning gait planning of quadruped robot was analyzed,and the coordinated movement sequence chart of pivot turning was presented.Then the kinematics modeling of leg side swing and body bending for pivot turning was derived,which should meet the condition of the coordinated movement between bionic flexible body and leg mechanism.The PAM experiment was conducted to analyze its contraction characteristic.The study on pivot turning of the quadruped robot will lay a theoretical foundation for the further research on dynamic walking stability of the quadruped robot in unstructured environment.
基金Supported by the National Natural Science Foundation of China(No.51375289)Shanghai Municipal National Natural Science Foundation of China(No.13ZR1415500)Innovation Fund of Shanghai Education Commission(No.13YZ020)
文摘As the pneumatic artificial muscle （PAM） has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in robotics. In this paper, a kind of musculoskeletal leg mechanism driven by PAMs is presented, which has three joints driven by four PAMs. The jumping movement is divided into three phases. The forward and inverse kinematics of the leg mechanism in different jumping phases is derived. Considering the ground reaction force between feet and environment, the dynamic in different jumping phases is analyzed by Lagrange method, then the relationship between PAM driving force and the joints angular displacement, angular velocity, angular acceleration during one jumping cycle is obtained, which will lay a foundatiori for the jumping experiment of the musculo- skeletal lez mechanism.
