Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of hi...Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.展开更多
Cable-driven parallel robots(CDPRs)use cables instead of the rigid limbs of traditional parallel robots,thus processing a large potential workspace,easy to assemble and disassemble characteristics,and with application...Cable-driven parallel robots(CDPRs)use cables instead of the rigid limbs of traditional parallel robots,thus processing a large potential workspace,easy to assemble and disassemble characteristics,and with applications in numerous fields.However,owing to the influence of cable flexibility and nonlinear friction,model uncertainties are di cult to eliminate from the control design.Hence,in this study,the model uncertainties of CDPRs are first analyzed based on a brief introduction to related research.Control strategies for CDPRs with model uncertainties are then reviewed.The advantages and disadvantages of several control strategies for CDPRS are discussed through traditional control strategies with kinematic and dynamic uncertainties.Compared with these traditional control strategies,deep reinforcement learning and model predictive control have received widespread attention in recent years owing to their model independence and recursive feasibility with constraint limits.A comprehensive review and brief analysis of current advances in these two control strategies for CDPRs with model uncertainties are presented,concluding with discussions regarding development directions.展开更多
Cable-driven soft robots exhibit complex deformations,making state estimation challenging.Hence,this paper develops a multi-sensor fusion approach using a gradient descent strategy to estimate the weighting coefficien...Cable-driven soft robots exhibit complex deformations,making state estimation challenging.Hence,this paper develops a multi-sensor fusion approach using a gradient descent strategy to estimate the weighting coefficients.These coefficients combine measurements from proprioceptive sensors,such as resistive flex sensors,to determine the bending angle.Additionally,the fusion strategy adopted provides robust state estimates,overcoming mismatches between the flex sensors and soft robot dimensions.Furthermore,a nonlinear differentiator is introduced to filter the differentiated sensor signals to address noise and irrational values generated by the Analog-to-Digital Converter.A rational polynomial equation is also introduced to compensate for temperature drift exhibited by the resistive flex sensors,which affect the accuracy of state estimation and control.The processed multi-sensor data is then utilized in an improved PD controller for closed-loop control of the soft robot.The controller incorporates the nonlinear differentiator and drift compensation,enhancing tracking performance.Experimental results validate the effectiveness of the integrated approach,demonstrating improved tracking accuracy and robustness compared to traditional PD controllers.展开更多
Birds in nature exhibit excellent long-distance flight capabilities through formation flight,which could reduce energy consumption and improve flight efficiency.Inspired by the biological habits of birds,this paper pr...Birds in nature exhibit excellent long-distance flight capabilities through formation flight,which could reduce energy consumption and improve flight efficiency.Inspired by the biological habits of birds,this paper proposes an autonomous formation flight control method for Large-sized Flapping-Wing Flying Robots(LFWFRs),which can enhance their search range and flight efficiency.First,the kinematics model for LFWFRs is established.Then,an autonomous flight controller based on this model is designed,which has multiple flight control modes,including attitude stabilization,course keeping,hovering,and so on.Second,a formation flight control method is proposed based on the leader–follower strategy and periodic characteristics of flapping-wing flight.The up and down fluctuation of the fuselage of each LFWFR during wing flapping is considered in the control algorithm to keep the relative distance,which overcomes the trajectory divergence caused by sensor delay and fuselage fluctuation.Third,typical formation flight modes are realized,including straight formation,circular formation,and switching formation.Finally,the outdoor formation flight experiment is carried out,and the proposed autonomous formation flight control method is verified in real environment.展开更多
Cable-driven parallel robots(CDPRs) are categorized as a type of parallel manipulators. In CDPRs, flexible cables are used to take the place of rigid links. The particular property of cables provides CDPRs several adv...Cable-driven parallel robots(CDPRs) are categorized as a type of parallel manipulators. In CDPRs, flexible cables are used to take the place of rigid links. The particular property of cables provides CDPRs several advantages, including larger workspaces, higher payload-to-weight ratio and lower manufacturing costs rather than rigid-link robots. In this paper, the history of the development of CDPRs is introduced and several successful latest application cases of CDPRs are presented. The theory development of CDPRs is introduced focusing on design, performance analysis and control theory. Research on CDPRs gains wide attention and is highly motivated by the modern engineering demand for large load capacity and workspace. A number of exciting advances in CDPRs are summarized in this paper since it is proposed in the 1980 s, which points to a fruitful future both in theory and application. In order to meet the increasing requirements of robot in different areas, future steps foresee more in-depth research and extension applications of CDPRs including intelligent control, composite materials, integrated and reconfigurable design.展开更多
This article introduces a cable-driven lower limb rehabilitation robot with movable distal anchor points(M-CDLR).The traditional cable-driven parallel robots(CDPRs)control the moving platform by changing the length of...This article introduces a cable-driven lower limb rehabilitation robot with movable distal anchor points(M-CDLR).The traditional cable-driven parallel robots(CDPRs)control the moving platform by changing the length of cables,M-CDLR can also adjust the position of the distal anchor point when the moving platform moves.The M-CDLR this article proposed has gait and single-leg training modes,which correspond to the plane and space motion of the moving platform,respectively.After introducing the system structure configuration,the generalized kinematics and dynamics of M-CDLR are established.The fully constrained CDPRs can provide more stable rehabilitation training than the under-constrained one but requires more cables.Therefore,a motion planning method for the movable distal anchor point of M-CDLR is proposed to realize the theoretically fully constrained with fewer cables.Then the expected trajectory of the moving platform is obtained from the motion capture experiment,and the motion planning of M-CDLR under two training modes is simulated.The simulation results verify the effectiveness of the proposed motion planning method.This study serves as a basic theoretical study of the structure optimization and control strategy of M-CDLR.展开更多
An assessment of the human motion repeatability for three selected Activities of Daily Living(ADL)is performed in this paper.These exercises were prescribed by an occupational therapist for the upper limb rehabilitati...An assessment of the human motion repeatability for three selected Activities of Daily Living(ADL)is performed in this paper.These exercises were prescribed by an occupational therapist for the upper limb rehabilitation.The movement patterns of five participants,recorded using a Qualisys motion capture system,are compared based on the Analysis of Variance(ANOVA)method.This survey is motivated by the need to find the appropriate task workspace of a 6-degrees of freedom cable-driven parallel robot for upper limb rehabilitation,which is able to reproduce the three selected exercises.This comparison is performed to justify,whether or not,there is enough similarity between the participants’gestures,and so a single reference trajectory can be adopted as the robot-prescribed workspace.Using the results of the comparative study,an optimization process of the sought robot design is carried out,where the structure size and the cable tensions simultaneously minimized.展开更多
Swarm intelligence embodied by many species such as ants and bees has inspired scholars in swarm robotic researches. This paper presents a novel autonomous self-assembly distributed swarm flying robot-DSFR, which can ...Swarm intelligence embodied by many species such as ants and bees has inspired scholars in swarm robotic researches. This paper presents a novel autonomous self-assembly distributed swarm flying robot-DSFR, which can drive on the ground, autonomously accomplish self-assembly and then fly in the air coordinately. Mechanical and electrical designs of a DSFR module, as well as the kinematics and dynamics analysis, are specifically investigated. Meanwhile, this paper brings forward a generalized adjacency matrix to describe configurations of DSFR structures. Also, the distributed flight control model is established for vertical taking-off and horizontal hovering, which can be applied to control of DSFR systems with arbitrary configurations. Finally, some experiments are carried out to testify and validate the DSFR design, the autonomous self-assembly strategy and the distributed flight control laws.展开更多
In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target ...In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target satellite. This developed approach combines the dynamics of both systems in one structure along with holonomic and nonholonomic constraints in a single framework. Furthermore, this modeling allows consid-ering the generalized contact forces between the space robot end-effecter and the target satellite as internal forces rather than external forces. As a result of this approach, linear and angular momentum will form holonomic and nonholonomic constraints, respectively. Meanwhile, restricting the motion of the space robot end-effector on the surface of the target satellite will impose geometric constraints. The proposed momentum of the combined system under consideration is a generalization of the momentum model of a free-flying space robot. Based on this unified model, three reduced models are developed. The first reduced dynamics can be considered as a generalization of a free-flying robot without contact with a target satellite. In this re-duced model it is found that the Jacobian and inertia matrices can be considered as an extension of those of a free-flying space robot. Since control of the base attitude rather than its translation is preferred in certain cases, a second reduced model is obtained by eliminating the base linear motion dynamics. For the purpose of the controller development, a third reduced-order dynamical model is then obtained by finding a common solution of all constraints using the concept of orthogonal projection matrices. The objective of this approach is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the con-tact force during the robotic operation. Moreover, Inverse dynamics and adaptive inverse dynamics control-lers are designed to achieve the control objectives. Both controllers are found to be effective to meet the specifications and to overcome the un-actuation of the target satellite. Finally, simulation is demonstrated by to verify the analytical results.展开更多
Rehabilitation is the most effective way to reduce motor impairments in post-stroke patients.This process demands several hours with a specialized therapist.Given resources and personnel shortages,the literature repor...Rehabilitation is the most effective way to reduce motor impairments in post-stroke patients.This process demands several hours with a specialized therapist.Given resources and personnel shortages,the literature reports a high interest in robotic assisted rehabilitation solutions.Recently,cable-driven robotic architectures are attracting significant research interest for post-stroke rehabilitation.However,the existing cable-driven robots are mostly unilateral devices allowing the rehabilitation only of the most affected limb.This leaves unaddressed the rehabilitation of bimanual activities,which are predominant within the common Activities of Daily Living(ADL).Thus,this paper presents a specific novel design to achieve bimanual rehabilitation tasks that has been named as BiCAR robot.Specifically,this paper provides a full insight on the BiCAR system as well as on its dedicated developed software BiEval.In particular,BiEval software has been developed as based on a serious game strategy and a virtual reality environment to track the patient exercising duration,motion ranges,speeds,and forces over time for achieving a quantitative assessment of the rehabilitation progress.Finally,the paper presents the BiCAR/BiEval capabilities by referring to a pilot Randomized Controlled Trial(RCT).The clinical trials have been used to validate the BiCAR/BiEval in terms of engineering feasibility and user acceptance to achieve an innovative cost-oriented integrated hardware/software device for the bimanual assistive rehabilitation of post-stroke patients.展开更多
The use of space robots(SRs)for on-orbit services(OOSs)has been a hot research topic in recent years.However,the space unstructured environment(i.e.:confined spaces,multiple obstacles,and strong radiation interference...The use of space robots(SRs)for on-orbit services(OOSs)has been a hot research topic in recent years.However,the space unstructured environment(i.e.:confined spaces,multiple obstacles,and strong radiation interference)has greatly restricted the application of SRs.The coupled active-passive multilink cable-driven space robot(CAP-MCDSR)has the characteristics of slim body,flexible movement,and electromechanical separation,which is very suitable for extreme space environments.However,the dynamic and stiffness modeling of CAP-MCDSRs is challenging,due to the complex coupling among the active cables,passive cables,joints,and the end-effector.To deal with these problems,this paper proposes a workspace,stiffness analysis and design optimization method for such type of MCDSRs.Firstly,the multi-coupling kinematics relationships among the joint,cables and the end-effector are established.Based on hybrid series-parallel characteristics,the improved coupled active–passive(CAP)dynamic equation is derived.Then,the maximum workspace,the maximum stiffness,and the minimum cable tension are resolved,among them,the overall stiffness is the superposition of the stiffness produced by the active and the passive cable.Furthermore,the workspace,the stiffness,and the cable tension are analyzed by using the nonlinear optimization method(NOPM).Finally,an 8-DOF CAP-MCDSR experiment system is built to verify the proposed modeling and trajectory tracking methods.The proposed modeling and analysis results are very useful for practical space applications,such as designing a new CAP-MCDSR,or utilizing an existing CAP-MCDSR system.展开更多
Torque control algorithm and its simulation of capturing a moving target for Free Flying Space Robots(FFSR) are discussed in this paper. The efficient recursive algorithm of joint driven torque for FFSR is developed. ...Torque control algorithm and its simulation of capturing a moving target for Free Flying Space Robots(FFSR) are discussed in this paper. The efficient recursive algorithm of joint driven torque for FFSR is developed. The torque control algorithm combined with Resolved Motion Rate Contro(RMRC) based on Generalized Jacobian Matrix(GJM) for capturing a moving target is proposed. The computer simulation verifies the effectiveness of the proposed algorithm.展开更多
Reaction wheel or reaction thruster is employed to maintain the attitude of the base of space robot fixed in attitude control of free flying space robot. However, in this method, a large amount of fuel will be consume...Reaction wheel or reaction thruster is employed to maintain the attitude of the base of space robot fixed in attitude control of free flying space robot. However, in this method, a large amount of fuel will be consumed, and it will shorten the on orbit life span of space robot, it also vibrate the system and make the system unsteady. The restricted minimum disturbance map (RMDM) based algorithm of attitude control is presented to keep the attitude of the base fixed during the movement of the manipulator. In this method it is realized by planning motion trajectory of the end effector of manipulator without using reaction wheel or reaction thruster. In order to verify the feasibility and effectiveness of the algorithm attitude control presented in this paper, computer simulation experiments have been made and the experimental results demonstrate that this algorithm is feasible.展开更多
The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Gene...The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Generalized Jacobian Matrix of a multi arm FFSR is proposed to enable the coordinated motion of all the other arms while one arm is tracing a given path so that there is no disturbance on the body, and the problem of attitude disturbance with an operating multi arm FFSR is thereby better resolved. The simulation run with a dual arm FFSR system verifies the effectiveness of this algorithm.展开更多
A new method of dynamic optimization for the flying trajectory of a free flying space robot based on its flying motion characteristics is presented. The continuous flying trajectory is broken into a number of segment ...A new method of dynamic optimization for the flying trajectory of a free flying space robot based on its flying motion characteristics is presented. The continuous flying trajectory is broken into a number of segment and the control efforts and the duration of the segment are chosen as the optimization parameters. The objective function is made by using the weighted sum of the fuel used and the time spent, and the constraint equations are selected. Finally, the internal point punishment function method is adopted in the optimization program, and the results of computer simulation are given.展开更多
This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of t...This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of the center of gravity, controller design and implementation, etc. Physical components are also briefly discussed in this paper. Attitude dynamics of the system is inherently unstable. It is stabilized by a regulator. In addition, an observer is designed and utilized to estimate the unmeasured states. Thrust force generated by the propulsion unit is estimated by using the identified mathematical model of the unit. An experimental setup is employed to identify the mathematical model that expresses the relation between the applied input voltage to the propulsion unit and thrust produced by the propeller. Mathematical model for the attitude dynamics of Toruk is built. Then controllability and observability analysis are carried out for the system. Dynamic compensator composed of a state observer and a regulator, is designed on the mathematical model. Physical implementation on the system will be performed.展开更多
文摘Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed movement.Concretely,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal parameters.Afterward,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance capability.Furthermore,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was employed.Lastly,the proposed method was successfully verified by simulations and experiments.The experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.
基金Supported by National Natural Science Foundation of China(Grant No.51525504)。
文摘Cable-driven parallel robots(CDPRs)use cables instead of the rigid limbs of traditional parallel robots,thus processing a large potential workspace,easy to assemble and disassemble characteristics,and with applications in numerous fields.However,owing to the influence of cable flexibility and nonlinear friction,model uncertainties are di cult to eliminate from the control design.Hence,in this study,the model uncertainties of CDPRs are first analyzed based on a brief introduction to related research.Control strategies for CDPRs with model uncertainties are then reviewed.The advantages and disadvantages of several control strategies for CDPRS are discussed through traditional control strategies with kinematic and dynamic uncertainties.Compared with these traditional control strategies,deep reinforcement learning and model predictive control have received widespread attention in recent years owing to their model independence and recursive feasibility with constraint limits.A comprehensive review and brief analysis of current advances in these two control strategies for CDPRs with model uncertainties are presented,concluding with discussions regarding development directions.
基金financial support from the National Natural Science Foundation of China(62103039,62073030)the Joint Fund of Ministry of Education for Equipment Pre-Research(8091B03032303).
文摘Cable-driven soft robots exhibit complex deformations,making state estimation challenging.Hence,this paper develops a multi-sensor fusion approach using a gradient descent strategy to estimate the weighting coefficients.These coefficients combine measurements from proprioceptive sensors,such as resistive flex sensors,to determine the bending angle.Additionally,the fusion strategy adopted provides robust state estimates,overcoming mismatches between the flex sensors and soft robot dimensions.Furthermore,a nonlinear differentiator is introduced to filter the differentiated sensor signals to address noise and irrational values generated by the Analog-to-Digital Converter.A rational polynomial equation is also introduced to compensate for temperature drift exhibited by the resistive flex sensors,which affect the accuracy of state estimation and control.The processed multi-sensor data is then utilized in an improved PD controller for closed-loop control of the soft robot.The controller incorporates the nonlinear differentiator and drift compensation,enhancing tracking performance.Experimental results validate the effectiveness of the integrated approach,demonstrating improved tracking accuracy and robustness compared to traditional PD controllers.
基金This work was supported in part by the National Natural Science Foundation of China(Grant No.62233001)Shenzhen excellent scientific and technological innovation talent training project(Grant No.RCJC20200714114436040)the Basic Research Program of Shenzhen(Grant No.JCYJ20190806142816524).
文摘Birds in nature exhibit excellent long-distance flight capabilities through formation flight,which could reduce energy consumption and improve flight efficiency.Inspired by the biological habits of birds,this paper proposes an autonomous formation flight control method for Large-sized Flapping-Wing Flying Robots(LFWFRs),which can enhance their search range and flight efficiency.First,the kinematics model for LFWFRs is established.Then,an autonomous flight controller based on this model is designed,which has multiple flight control modes,including attitude stabilization,course keeping,hovering,and so on.Second,a formation flight control method is proposed based on the leader–follower strategy and periodic characteristics of flapping-wing flight.The up and down fluctuation of the fuselage of each LFWFR during wing flapping is considered in the control algorithm to keep the relative distance,which overcomes the trajectory divergence caused by sensor delay and fuselage fluctuation.Third,typical formation flight modes are realized,including straight formation,circular formation,and switching formation.Finally,the outdoor formation flight experiment is carried out,and the proposed autonomous formation flight control method is verified in real environment.
基金Supported by National Natural Science Foundation of China(Grant Nos.51605126,51575150,91748109)
文摘Cable-driven parallel robots(CDPRs) are categorized as a type of parallel manipulators. In CDPRs, flexible cables are used to take the place of rigid links. The particular property of cables provides CDPRs several advantages, including larger workspaces, higher payload-to-weight ratio and lower manufacturing costs rather than rigid-link robots. In this paper, the history of the development of CDPRs is introduced and several successful latest application cases of CDPRs are presented. The theory development of CDPRs is introduced focusing on design, performance analysis and control theory. Research on CDPRs gains wide attention and is highly motivated by the modern engineering demand for large load capacity and workspace. A number of exciting advances in CDPRs are summarized in this paper since it is proposed in the 1980 s, which points to a fruitful future both in theory and application. In order to meet the increasing requirements of robot in different areas, future steps foresee more in-depth research and extension applications of CDPRs including intelligent control, composite materials, integrated and reconfigurable design.
基金funded by the National Natural Science Foundation of China,Grant Number:52175006.
文摘This article introduces a cable-driven lower limb rehabilitation robot with movable distal anchor points(M-CDLR).The traditional cable-driven parallel robots(CDPRs)control the moving platform by changing the length of cables,M-CDLR can also adjust the position of the distal anchor point when the moving platform moves.The M-CDLR this article proposed has gait and single-leg training modes,which correspond to the plane and space motion of the moving platform,respectively.After introducing the system structure configuration,the generalized kinematics and dynamics of M-CDLR are established.The fully constrained CDPRs can provide more stable rehabilitation training than the under-constrained one but requires more cables.Therefore,a motion planning method for the movable distal anchor point of M-CDLR is proposed to realize the theoretically fully constrained with fewer cables.Then the expected trajectory of the moving platform is obtained from the motion capture experiment,and the motion planning of M-CDLR under two training modes is simulated.The simulation results verify the effectiveness of the proposed motion planning method.This study serves as a basic theoretical study of the structure optimization and control strategy of M-CDLR.
基金supported by the"PHC Utiquc"program of the French Ministry of Foreign Affairs and Ministry of Higher Education,Research and Innovation and the Tunisian Ministry of Higher Education and Scientific Research.P.n°19G1121the support of the Erasmus+KA 107 program.
文摘An assessment of the human motion repeatability for three selected Activities of Daily Living(ADL)is performed in this paper.These exercises were prescribed by an occupational therapist for the upper limb rehabilitation.The movement patterns of five participants,recorded using a Qualisys motion capture system,are compared based on the Analysis of Variance(ANOVA)method.This survey is motivated by the need to find the appropriate task workspace of a 6-degrees of freedom cable-driven parallel robot for upper limb rehabilitation,which is able to reproduce the three selected exercises.This comparison is performed to justify,whether or not,there is enough similarity between the participants’gestures,and so a single reference trajectory can be adopted as the robot-prescribed workspace.Using the results of the comparative study,an optimization process of the sought robot design is carried out,where the structure size and the cable tensions simultaneously minimized.
基金the National High-tech Research and Development Program of China(''863''Program)(No.2012AA041402)National Natural Science Foundation of China(Nos.61175079and51105012)Fundamental Research Funds for the Central Universities (No.YWF-11-02-215)
文摘Swarm intelligence embodied by many species such as ants and bees has inspired scholars in swarm robotic researches. This paper presents a novel autonomous self-assembly distributed swarm flying robot-DSFR, which can drive on the ground, autonomously accomplish self-assembly and then fly in the air coordinately. Mechanical and electrical designs of a DSFR module, as well as the kinematics and dynamics analysis, are specifically investigated. Meanwhile, this paper brings forward a generalized adjacency matrix to describe configurations of DSFR structures. Also, the distributed flight control model is established for vertical taking-off and horizontal hovering, which can be applied to control of DSFR systems with arbitrary configurations. Finally, some experiments are carried out to testify and validate the DSFR design, the autonomous self-assembly strategy and the distributed flight control laws.
文摘In this paper a unified control-oriented modeling approach is proposed to deal with the kinematics, linear and angular momentum, contact constraints and dynamics of a free-flying space robot interacting with a target satellite. This developed approach combines the dynamics of both systems in one structure along with holonomic and nonholonomic constraints in a single framework. Furthermore, this modeling allows consid-ering the generalized contact forces between the space robot end-effecter and the target satellite as internal forces rather than external forces. As a result of this approach, linear and angular momentum will form holonomic and nonholonomic constraints, respectively. Meanwhile, restricting the motion of the space robot end-effector on the surface of the target satellite will impose geometric constraints. The proposed momentum of the combined system under consideration is a generalization of the momentum model of a free-flying space robot. Based on this unified model, three reduced models are developed. The first reduced dynamics can be considered as a generalization of a free-flying robot without contact with a target satellite. In this re-duced model it is found that the Jacobian and inertia matrices can be considered as an extension of those of a free-flying space robot. Since control of the base attitude rather than its translation is preferred in certain cases, a second reduced model is obtained by eliminating the base linear motion dynamics. For the purpose of the controller development, a third reduced-order dynamical model is then obtained by finding a common solution of all constraints using the concept of orthogonal projection matrices. The objective of this approach is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the con-tact force during the robotic operation. Moreover, Inverse dynamics and adaptive inverse dynamics control-lers are designed to achieve the control objectives. Both controllers are found to be effective to meet the specifications and to overcome the un-actuation of the target satellite. Finally, simulation is demonstrated by to verify the analytical results.
基金partially funded by UFU,FAPEMIG,CNPQ,and CAPES(Finance Code 001).
文摘Rehabilitation is the most effective way to reduce motor impairments in post-stroke patients.This process demands several hours with a specialized therapist.Given resources and personnel shortages,the literature reports a high interest in robotic assisted rehabilitation solutions.Recently,cable-driven robotic architectures are attracting significant research interest for post-stroke rehabilitation.However,the existing cable-driven robots are mostly unilateral devices allowing the rehabilitation only of the most affected limb.This leaves unaddressed the rehabilitation of bimanual activities,which are predominant within the common Activities of Daily Living(ADL).Thus,this paper presents a specific novel design to achieve bimanual rehabilitation tasks that has been named as BiCAR robot.Specifically,this paper provides a full insight on the BiCAR system as well as on its dedicated developed software BiEval.In particular,BiEval software has been developed as based on a serious game strategy and a virtual reality environment to track the patient exercising duration,motion ranges,speeds,and forces over time for achieving a quantitative assessment of the rehabilitation progress.Finally,the paper presents the BiCAR/BiEval capabilities by referring to a pilot Randomized Controlled Trial(RCT).The clinical trials have been used to validate the BiCAR/BiEval in terms of engineering feasibility and user acceptance to achieve an innovative cost-oriented integrated hardware/software device for the bimanual assistive rehabilitation of post-stroke patients.
基金supported by the National Natural Science Foundation of China(No.62103454)the Key-Area Research and Development Program of Guangdong Province(No.2020B1111010001)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110680)the Shenzhen Municipal Basic Research Project for Natural Science Foundation(No.JCYJ20190806143408992)the Fundamental Research Funds for the Central Universities(No.2021qntd08)Sun Yat-sen University。
文摘The use of space robots(SRs)for on-orbit services(OOSs)has been a hot research topic in recent years.However,the space unstructured environment(i.e.:confined spaces,multiple obstacles,and strong radiation interference)has greatly restricted the application of SRs.The coupled active-passive multilink cable-driven space robot(CAP-MCDSR)has the characteristics of slim body,flexible movement,and electromechanical separation,which is very suitable for extreme space environments.However,the dynamic and stiffness modeling of CAP-MCDSRs is challenging,due to the complex coupling among the active cables,passive cables,joints,and the end-effector.To deal with these problems,this paper proposes a workspace,stiffness analysis and design optimization method for such type of MCDSRs.Firstly,the multi-coupling kinematics relationships among the joint,cables and the end-effector are established.Based on hybrid series-parallel characteristics,the improved coupled active–passive(CAP)dynamic equation is derived.Then,the maximum workspace,the maximum stiffness,and the minimum cable tension are resolved,among them,the overall stiffness is the superposition of the stiffness produced by the active and the passive cable.Furthermore,the workspace,the stiffness,and the cable tension are analyzed by using the nonlinear optimization method(NOPM).Finally,an 8-DOF CAP-MCDSR experiment system is built to verify the proposed modeling and trajectory tracking methods.The proposed modeling and analysis results are very useful for practical space applications,such as designing a new CAP-MCDSR,or utilizing an existing CAP-MCDSR system.
文摘Torque control algorithm and its simulation of capturing a moving target for Free Flying Space Robots(FFSR) are discussed in this paper. The efficient recursive algorithm of joint driven torque for FFSR is developed. The torque control algorithm combined with Resolved Motion Rate Contro(RMRC) based on Generalized Jacobian Matrix(GJM) for capturing a moving target is proposed. The computer simulation verifies the effectiveness of the proposed algorithm.
文摘Reaction wheel or reaction thruster is employed to maintain the attitude of the base of space robot fixed in attitude control of free flying space robot. However, in this method, a large amount of fuel will be consumed, and it will shorten the on orbit life span of space robot, it also vibrate the system and make the system unsteady. The restricted minimum disturbance map (RMDM) based algorithm of attitude control is presented to keep the attitude of the base fixed during the movement of the manipulator. In this method it is realized by planning motion trajectory of the end effector of manipulator without using reaction wheel or reaction thruster. In order to verify the feasibility and effectiveness of the algorithm attitude control presented in this paper, computer simulation experiments have been made and the experimental results demonstrate that this algorithm is feasible.
文摘The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Generalized Jacobian Matrix of a multi arm FFSR is proposed to enable the coordinated motion of all the other arms while one arm is tracing a given path so that there is no disturbance on the body, and the problem of attitude disturbance with an operating multi arm FFSR is thereby better resolved. The simulation run with a dual arm FFSR system verifies the effectiveness of this algorithm.
文摘A new method of dynamic optimization for the flying trajectory of a free flying space robot based on its flying motion characteristics is presented. The continuous flying trajectory is broken into a number of segment and the control efforts and the duration of the segment are chosen as the optimization parameters. The objective function is made by using the weighted sum of the fuel used and the time spent, and the constraint equations are selected. Finally, the internal point punishment function method is adopted in the optimization program, and the results of computer simulation are given.
文摘This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of the center of gravity, controller design and implementation, etc. Physical components are also briefly discussed in this paper. Attitude dynamics of the system is inherently unstable. It is stabilized by a regulator. In addition, an observer is designed and utilized to estimate the unmeasured states. Thrust force generated by the propulsion unit is estimated by using the identified mathematical model of the unit. An experimental setup is employed to identify the mathematical model that expresses the relation between the applied input voltage to the propulsion unit and thrust produced by the propeller. Mathematical model for the attitude dynamics of Toruk is built. Then controllability and observability analysis are carried out for the system. Dynamic compensator composed of a state observer and a regulator, is designed on the mathematical model. Physical implementation on the system will be performed.
