Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and th...Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and the target. To overcome such a problem, a novel ContinuumManipulator Space Robot(CMSR) for performing on-orbit servicing missions is proposed in this paper. Compared with rigid-manipulator space robots, CMSRs are able to perform compliant operations and avoid rigid-body collisions with a target. The CMSR consists of two kinds of flexible components, including solar arrays and continuum manipulators. The elastic vibrations of these flexible components disturb the position and attitude of CMSRs. The beating phenomenon introduced by the energy transfer among these flexible components can cause damage to solar arrays.The complicated dynamic coupling poses enormous challenges in dynamic modeling and vibration analysis. The dynamic model for CMSRs is derived and the mechanism of the beating phenomenon is analyzed in this paper. Simulation results show that an obvious beating phenomenon occurs and the amplitude of the solar arrays increases significantly when the natural frequencies of two kinds of flexible components are close. A method is provided to avoid the beating phenomenon.展开更多
Continuum manipulators have important applications in the human–machine interaction fields.The kinematics,dynamics,and control issues of the continuum manipulators are rather different from a conventional rigid-link ...Continuum manipulators have important applications in the human–machine interaction fields.The kinematics,dynamics,and control issues of the continuum manipulators are rather different from a conventional rigid-link manipulator.By the aid of Lie groups theory and exponential coordinate representations,the kinematics of the continuum manipulators with piecewise constant curvatures and actuated by tendons is investigated in this paper.On the basis of differential kinematics analysis,the complete Jacobian of the continuum manipulators is derived analytically,and then a new motion planning approach,named as“dynamic coordination method”is presented for the multisegments continuum manipulators,which is a class of superredundant manipulators.The novel motion planning approach is featured by some appealing properties,and the feasibility of the modeling and the motion planning method is demonstrated by some numerical simulations.展开更多
Tendon-driven continuum manipulators can perform tasks in confined environments due to their flexibility and curvilinearity,especially in minimally invasive surgeries.However,the friction along tendons and tendon slac...Tendon-driven continuum manipulators can perform tasks in confined environments due to their flexibility and curvilinearity,especially in minimally invasive surgeries.However,the friction along tendons and tendon slack present challenges to their motion control.This work proposes a trajectory tracking controller based on adaptive fuzzy sliding mode control(AFSMC)for the tendon-driven continuum manipulators.It consists of a sliding mode control(SMC)law with two groups of adaptive fuzzy subcontrollers.The first one is utilized to estimate and compensate for friction forces along tendons.The second one adapts the switching terms of SMC to alleviate the chattering phenomenon and enhance control robustness.To prevent tendon slack,an antagonistic strategy along with the AFSMC controller is adopted to allocate driving forces.Simulation and experiment studies have been conducted to investigate the efficacy of the proposed controller.In free space experiments,the AFSMC controller generates an average root-mean-square error(RMSE)of 0.42%compared with 0.90%of the SMC controller.In the case of a 50 g load,the proposed controller reduces the average RMSE to 1.47%compared with 4.29%of the SMC controller.These experimental results demonstrate that the proposed AFSMC controller has high control accuracy,robustness,and reduced chattering.展开更多
By combining the investigation of the biomechanics and behavior of elephant trunk in the performance of a wide range of dexterous manipulations,a novel approach in the design and kinematics modeling of a fruit harvest...By combining the investigation of the biomechanics and behavior of elephant trunk in the performance of a wide range of dexterous manipulations,a novel approach in the design and kinematics modeling of a fruit harvesting continuum manipulator was proposed.By comparing the structure of two different species of elephant trunk,a new continuum structure which matched the key features of elephant trunk was designed.Based on analysis of the underlying elephant trunk’s grasping mode,a novel kinematics model was proposed.Contrast to traditional robot kinematics which focused on end effector’s position and posture,the proposed continuum manipulator kinematics focus on the center of manipulator’s position and posture,which is more effective when trunk robot realizing grasp and establishes the foundation for its application.Finally,three typical grasping experiments were implemented.The experiment results showed that the manipulator could conduct wrap/pinch manipulations effectively for both small objects and bigger ones.展开更多
Robotics has aroused huge attention since the 1950s.Irrespective of the uniqueness that industrial applications exhibit,conventional rigid robots have displayed noticeable limitations,particularly in safe cooperation ...Robotics has aroused huge attention since the 1950s.Irrespective of the uniqueness that industrial applications exhibit,conventional rigid robots have displayed noticeable limitations,particularly in safe cooperation as well as with environmental adaption.Accordingly,scientists have shifted their focus on soft robotics to apply this type of robots more effectively in unstructured environments.For decades,they have been committed to exploring sub-fields of soft robotics(e.g.,cutting-edge techniques in design and fabrication,accurate modeling,as well as advanced control algorithms).Although scientists have made many different efforts,they share the common goal of enhancing applicability.The presented paper aims to brief the progress of soft robotic research for readers interested in this field,and clarify how an appropriate control algorithm can be produced for soft robots with specific morphologies.This paper,instead of enumerating existing modeling or control methods of a certain soft robot prototype,interprets for the relationship between morphology and morphology-dependent motion strategy,attempts to delve into the common issues in a particular class of soft robots,and elucidates a generic solution to enhance their performance.展开更多
Continuum manipulators have been applied in different surgical scenarios due to their dexterity and multi-DoF(degree of freedom)design compactness.To improve surgery safety,it is preferable to enable active compliance...Continuum manipulators have been applied in different surgical scenarios due to their dexterity and multi-DoF(degree of freedom)design compactness.To improve surgery safety,it is preferable to enable active compliance and force sensing abilities for a continuum manipulator.Existing works on active compliance and force sensing often rely on force sensors at the proximal or the distal ends,which inevitably increases the system complexity.In this paper,a shape reconstruction algorithm,a compliant motion controller,and a force estimation method are proposed successively based on the manipulator's tip pose via visual feedback.Four support vector regression(SVR)trainers are constructed and trained to compensate for the actuation residues,which are the differences between the actual actuation lengths outputs at the actuators and the ideal actuation lengths calculated from the estimated shape using the kinematics model,under no-load condition.Then,a compliant motion controller and a force estimation method are realized based on the current actuation residues,compared with the actuation residues under the no-load condition.In this way,no additional sensors are needed as an endoscopic camera is often available in a laparoscopic or endoscopic surgical system.The experiments were conducted on aφ3 mm-continuum manipulator to demonstrate the effectiveness of the proposed algorithms.展开更多
Continuum manipulators can conform to curvilinear paths and manipulate objects in complex environments,which makes it emerging to be applied in minimally invasive surgery(MIS).However,different and controllable operat...Continuum manipulators can conform to curvilinear paths and manipulate objects in complex environments,which makes it emerging to be applied in minimally invasive surgery(MIS).However,different and controllable operating stiffness of the continuum manipulator is required during different stages of surgery to achieve safe access or stable and precise operation.This work proposes an operating stiffness controller(OSC)for the typical tendon-driven continuum manipulator based on the variable impedance control method with Lagrangian dynamic modeling.This controller can adjust the operating stiffness by modifying the driving forces along the driving tendons of the continuum manipulator without changing its material or structure.The proposed OSC converts the damping and stiffness matrices of the impedance control into variable parameters.This merit allows it to dynamically adjust the operating stiffness of the continuum manipulator according to the desired constant or time-varying stiffness.Furthermore,the OSC stability can be proven based on a Lyapunov function,and its stiffness control performances have been analyzed and evaluated in both simulations and experiments.The OSC controller generated average relevant error values of 7.82%and 3.09%for the operating stiffness control experiments with constant and time-varying desired stiffness,respectively.These experimental results indicate that the OSC has high accuracy,stability,and strong robustness in the operating stiffness control tasks.展开更多
The friction between the joints of the continuum manipulator with discrete joints brings great difficulties to kinematic modeling.The traditional driving wire arrangement limits the load capacity of the manipulator.A ...The friction between the joints of the continuum manipulator with discrete joints brings great difficulties to kinematic modeling.The traditional driving wire arrangement limits the load capacity of the manipulator.A cable-stayed notch manipulator for transluminal endoscopic surgery is proposed,and a driving force coupling kinematic mode is established.The manipulator is fabricated from a superelastic Nitinol tube with bilaterally cut rectangular notches and is actuated by a stay cable.By applying the comprehensive elliptic integral solution(CEIS)for large deformation beams,the bending angle of each elastic beam is obtained,and the kinematics from the driving space to the joint space is formed.According to the bending angle of each elastic beam,the expression of the manipulator in Cartesian space can be obtained by geometric analysis.The kinematics from the joint space to the Cartesian space is established.The outer diameter of the manipulator is only 3.5 mm,and the inner diameter can reach 2 mm,allowing instruments to pass through.The maximum error of the manipulator movement is less than 5%.The load capacity of the manipulator has been verified through the stiffness experiments,and the maximum load of the manipulator can reach 400 g.The cable-stayed notch manipulator can be accurately modeled on the base of CEIS,and its motion accuracy can meet the needs of engineering applications.The compact size and excellent load capacity of the manipulator make it potential for application in transluminal endoscopic surgical robots.展开更多
基金supported by the National Natural Science Foundation of China(Nos.91748203,11922203,11772074)。
文摘Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and the target. To overcome such a problem, a novel ContinuumManipulator Space Robot(CMSR) for performing on-orbit servicing missions is proposed in this paper. Compared with rigid-manipulator space robots, CMSRs are able to perform compliant operations and avoid rigid-body collisions with a target. The CMSR consists of two kinds of flexible components, including solar arrays and continuum manipulators. The elastic vibrations of these flexible components disturb the position and attitude of CMSRs. The beating phenomenon introduced by the energy transfer among these flexible components can cause damage to solar arrays.The complicated dynamic coupling poses enormous challenges in dynamic modeling and vibration analysis. The dynamic model for CMSRs is derived and the mechanism of the beating phenomenon is analyzed in this paper. Simulation results show that an obvious beating phenomenon occurs and the amplitude of the solar arrays increases significantly when the natural frequencies of two kinds of flexible components are close. A method is provided to avoid the beating phenomenon.
基金supported by the National Key R&D Program of China under Grant 2019YFB1309603the Natural Science Foundation of China under Grants 51775002 and 11702294+2 种基金the Natural Science Foundation of Beijing under Grants L172001,4204097,3172009,and 3194047the Joint Program of Beijing Municipal Foundation and Education Commission under Grant KZ202010009015the Scientific Research Foundation of North China University of Technology.
文摘Continuum manipulators have important applications in the human–machine interaction fields.The kinematics,dynamics,and control issues of the continuum manipulators are rather different from a conventional rigid-link manipulator.By the aid of Lie groups theory and exponential coordinate representations,the kinematics of the continuum manipulators with piecewise constant curvatures and actuated by tendons is investigated in this paper.On the basis of differential kinematics analysis,the complete Jacobian of the continuum manipulators is derived analytically,and then a new motion planning approach,named as“dynamic coordination method”is presented for the multisegments continuum manipulators,which is a class of superredundant manipulators.The novel motion planning approach is featured by some appealing properties,and the feasibility of the modeling and the motion planning method is demonstrated by some numerical simulations.
基金supported by the National Natural Science Foundation of China(92148201,52475029)supported by International Institute for Innovative Design and Intelligent Manufacturing of Tianjin University in Zhejiang,Shaoxing 312000,China.
文摘Tendon-driven continuum manipulators can perform tasks in confined environments due to their flexibility and curvilinearity,especially in minimally invasive surgeries.However,the friction along tendons and tendon slack present challenges to their motion control.This work proposes a trajectory tracking controller based on adaptive fuzzy sliding mode control(AFSMC)for the tendon-driven continuum manipulators.It consists of a sliding mode control(SMC)law with two groups of adaptive fuzzy subcontrollers.The first one is utilized to estimate and compensate for friction forces along tendons.The second one adapts the switching terms of SMC to alleviate the chattering phenomenon and enhance control robustness.To prevent tendon slack,an antagonistic strategy along with the AFSMC controller is adopted to allocate driving forces.Simulation and experiment studies have been conducted to investigate the efficacy of the proposed controller.In free space experiments,the AFSMC controller generates an average root-mean-square error(RMSE)of 0.42%compared with 0.90%of the SMC controller.In the case of a 50 g load,the proposed controller reduces the average RMSE to 1.47%compared with 4.29%of the SMC controller.These experimental results demonstrate that the proposed AFSMC controller has high control accuracy,robustness,and reduced chattering.
基金supported by National Natural Science Foundation of China(Grant No.51075363)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY12E05022).
文摘By combining the investigation of the biomechanics and behavior of elephant trunk in the performance of a wide range of dexterous manipulations,a novel approach in the design and kinematics modeling of a fruit harvesting continuum manipulator was proposed.By comparing the structure of two different species of elephant trunk,a new continuum structure which matched the key features of elephant trunk was designed.Based on analysis of the underlying elephant trunk’s grasping mode,a novel kinematics model was proposed.Contrast to traditional robot kinematics which focused on end effector’s position and posture,the proposed continuum manipulator kinematics focus on the center of manipulator’s position and posture,which is more effective when trunk robot realizing grasp and establishes the foundation for its application.Finally,three typical grasping experiments were implemented.The experiment results showed that the manipulator could conduct wrap/pinch manipulations effectively for both small objects and bigger ones.
文摘Robotics has aroused huge attention since the 1950s.Irrespective of the uniqueness that industrial applications exhibit,conventional rigid robots have displayed noticeable limitations,particularly in safe cooperation as well as with environmental adaption.Accordingly,scientists have shifted their focus on soft robotics to apply this type of robots more effectively in unstructured environments.For decades,they have been committed to exploring sub-fields of soft robotics(e.g.,cutting-edge techniques in design and fabrication,accurate modeling,as well as advanced control algorithms).Although scientists have made many different efforts,they share the common goal of enhancing applicability.The presented paper aims to brief the progress of soft robotic research for readers interested in this field,and clarify how an appropriate control algorithm can be produced for soft robots with specific morphologies.This paper,instead of enumerating existing modeling or control methods of a certain soft robot prototype,interprets for the relationship between morphology and morphology-dependent motion strategy,attempts to delve into the common issues in a particular class of soft robots,and elucidates a generic solution to enhance their performance.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB4700900)the National Natural Science Foundation of China(Grant No.51722507)。
文摘Continuum manipulators have been applied in different surgical scenarios due to their dexterity and multi-DoF(degree of freedom)design compactness.To improve surgery safety,it is preferable to enable active compliance and force sensing abilities for a continuum manipulator.Existing works on active compliance and force sensing often rely on force sensors at the proximal or the distal ends,which inevitably increases the system complexity.In this paper,a shape reconstruction algorithm,a compliant motion controller,and a force estimation method are proposed successively based on the manipulator's tip pose via visual feedback.Four support vector regression(SVR)trainers are constructed and trained to compensate for the actuation residues,which are the differences between the actual actuation lengths outputs at the actuators and the ideal actuation lengths calculated from the estimated shape using the kinematics model,under no-load condition.Then,a compliant motion controller and a force estimation method are realized based on the current actuation residues,compared with the actuation residues under the no-load condition.In this way,no additional sensors are needed as an endoscopic camera is often available in a laparoscopic or endoscopic surgical system.The experiments were conducted on aφ3 mm-continuum manipulator to demonstrate the effectiveness of the proposed algorithms.
基金supported in part by Technology Program Project of Shaoxing City under grant 2023A14016the National Natural Science Foundation of China under grants 62211530111 and 92148201+1 种基金Science and Royal Society under IEC\NSFC\211360Graduate Research Innovation Project by Tianjin Education Commission under grant 2022BKY075.
文摘Continuum manipulators can conform to curvilinear paths and manipulate objects in complex environments,which makes it emerging to be applied in minimally invasive surgery(MIS).However,different and controllable operating stiffness of the continuum manipulator is required during different stages of surgery to achieve safe access or stable and precise operation.This work proposes an operating stiffness controller(OSC)for the typical tendon-driven continuum manipulator based on the variable impedance control method with Lagrangian dynamic modeling.This controller can adjust the operating stiffness by modifying the driving forces along the driving tendons of the continuum manipulator without changing its material or structure.The proposed OSC converts the damping and stiffness matrices of the impedance control into variable parameters.This merit allows it to dynamically adjust the operating stiffness of the continuum manipulator according to the desired constant or time-varying stiffness.Furthermore,the OSC stability can be proven based on a Lyapunov function,and its stiffness control performances have been analyzed and evaluated in both simulations and experiments.The OSC controller generated average relevant error values of 7.82%and 3.09%for the operating stiffness control experiments with constant and time-varying desired stiffness,respectively.These experimental results indicate that the OSC has high accuracy,stability,and strong robustness in the operating stiffness control tasks.
基金supported by the National Key Research and Development Program of China(2023YFB4705800 and 2022YFB4703000)the Key Research and Development Program of Shandong Province,China(2022CXGC010503)Shandong Provincial Postdoctoral Innovative Talents Funded Scheme,China(238226).
文摘The friction between the joints of the continuum manipulator with discrete joints brings great difficulties to kinematic modeling.The traditional driving wire arrangement limits the load capacity of the manipulator.A cable-stayed notch manipulator for transluminal endoscopic surgery is proposed,and a driving force coupling kinematic mode is established.The manipulator is fabricated from a superelastic Nitinol tube with bilaterally cut rectangular notches and is actuated by a stay cable.By applying the comprehensive elliptic integral solution(CEIS)for large deformation beams,the bending angle of each elastic beam is obtained,and the kinematics from the driving space to the joint space is formed.According to the bending angle of each elastic beam,the expression of the manipulator in Cartesian space can be obtained by geometric analysis.The kinematics from the joint space to the Cartesian space is established.The outer diameter of the manipulator is only 3.5 mm,and the inner diameter can reach 2 mm,allowing instruments to pass through.The maximum error of the manipulator movement is less than 5%.The load capacity of the manipulator has been verified through the stiffness experiments,and the maximum load of the manipulator can reach 400 g.The cable-stayed notch manipulator can be accurately modeled on the base of CEIS,and its motion accuracy can meet the needs of engineering applications.The compact size and excellent load capacity of the manipulator make it potential for application in transluminal endoscopic surgical robots.
