Conventional manipulators with rigid structures and sti ness actuators have poor flexibility,limited obstacle avoidance capability,and constrained workspace.Some developed flexible or soft manipulators in recent years...Conventional manipulators with rigid structures and sti ness actuators have poor flexibility,limited obstacle avoidance capability,and constrained workspace.Some developed flexible or soft manipulators in recent years have the characteristics of infinite degrees of freedom,high flexibility,environmental adaptability,and extended manipulation capability.However,these existing manipulators still cannot achieve the shrinking motion and independent control of specified segments like the animals,which hinders their applications.In this paper,a flexible bio-tensegrity manipulator,inspired by the longitudinal and transversal muscles of octopus tentacles,was proposed to mimic the shrinking behavior and achieve the variable motion patterns of each segment.Such proposed manipulator uses the elastic spring as the backbone,which is driven by four cables and has one variable structure mechanism in each segment to achieve the independent control of each segment.The variable structure mechanism innovatively contains seven lock-release states to independently control the bending and shrinking motion of each segment.After the kinematic modeling and analysis,one prototype of such bionic flexible manipulator was built and the open-loop control method was proposed.Some proof-of-concept experiments,including the shrinking motion,bending motion,and variable structure motion,were carried out by controlling the length of four cables and changing the lock-release states of the variable structure mechanism,which validate the feasibility and validity of our proposed prototype.Meanwhile,the experimental results show the flexible manipulator can accomplish the bending and shrinking motion with the relative error less than 6.8%through the simple independent control of each segment using the variable structure mechanism.This proposed manipulator has the features of controllable degree-of-freedom in each segment,which extend their environmental adaptability,and manipulation capability.展开更多
Although flexible manipulators own many potential advantages, one of their major disadvantages is the deterioration of the end-effector accuracy due to the flexibility. Therefore, how to reduce vibration is a signific...Although flexible manipulators own many potential advantages, one of their major disadvantages is the deterioration of the end-effector accuracy due to the flexibility. Therefore, how to reduce vibration is a significant problem. Inspired by the observation on the motion behaviors of animals, a new idea of decreasing motion deflection of the flexible manipulator is suggested. The concept of controllable local degrees of freedom is proposed and analyzed. By way of optimizing local motion provided by the controllable local degrees of freedom, the end-effector deflection of the flexible manipulator can be effectively decreased through dynamic coupling. The corresponding optimal method for vibration control of the flexible manipulator is put forward. The kinematic simulation is carried ant on a three-link flexible manipulator The corresponding results verify the feasibility of this method.展开更多
The requirements and features of virtual assembly movement navigator areanalyzed to help operators flexibly manipulate virtual objects, precisely locate or assemble virtualparts in virtual environment. With the degree...The requirements and features of virtual assembly movement navigator areanalyzed to help operators flexibly manipulate virtual objects, precisely locate or assemble virtualparts in virtual environment. With the degree-of-freedom analysis, the assembly constrainthierarchical model is constructed and the system's constraints are built dynamically. Thus, allobjects in virtual environment can be located reasonally by the navigator. Moreover, the assemblyconstraint recognition in the process of assembly and movement correction is also discussed.展开更多
The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this p...The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this problem,cascade control method with an inner/outer-loop control structure is used,which masks the hydraulic dynamics with the inner-loop so that the designed controller takes into account of both the mechanical dynamics and the hydraulic dynamics of the manipulator.Furthermore,a cross-coupling control approach is introduced to the synchronous tracking control of the manipulator.The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent ones based on the synchronous goal.Then,with the feedback of both position error and synchronization error,the tracking is proven to guarantee that both the position errors and synchronization errors asymptotically converge to zero.Moreover,the effectiveness of the proposed approach is verified by the experimental results performed with a 6-DOF hydraulic parallel manipulator.展开更多
The space manipulator is always designed to have 7 degrees of freedom(Dofs)with the consideration of energy limitation,as well as the flexible moving possibility.Therefore,how to plan the trajectory is important to ...The space manipulator is always designed to have 7 degrees of freedom(Dofs)with the consideration of energy limitation,as well as the flexible moving possibility.Therefore,how to plan the trajectory is important to improve the performance of the manipulator.In this paper,the speed of the end effector is configured as a projecting parameter,when a constant acceleration is applied to adjust the velocity.To implement this trajectory planning strategy,an optimization algorithm through the pseudo inverse of Jacobin matrix is designed,which adjusts the weight functions of joints.According to the functional theory,this algorithm is analyzed and the optimal solution is found in numerous sets of planning.A MATLAB simulation platform is established and the results verity the effectiveness of the algorithm.展开更多
由于六自由度机器人在装配序列规划中存在顶角叶片重力矩差难以保证、叶片重力矩分布不够均衡的问题,以至于避障过程中出现碰撞。为此,提出工业机器人六自由度装配序列规划下避障研究。通过分析六自由度机器人装配序列中,顶角叶片重力...由于六自由度机器人在装配序列规划中存在顶角叶片重力矩差难以保证、叶片重力矩分布不够均衡的问题,以至于避障过程中出现碰撞。为此,提出工业机器人六自由度装配序列规划下避障研究。通过分析六自由度机器人装配序列中,顶角叶片重力矩差和叶片重力矩分布产生的干涉关系,将装配平稳性、方向调整次数及更换装配工具的频次作为约束条件,设置干涉关系矩阵和适应度函数,以判断装配序列方案是否达到最佳;在装配方案达到最佳后,通过离散化萤火虫算法获取六自由度机器人装配序列最优解;根据该结果检测六自由度机器人碰撞结果,并采用优化随机树节点扩展控制及扩展能力检测的改进快速搜索随机树算法(Rapidly-exploring Random Tree,RRT*)来对所得装配序列进行调整修正,实现工业机器人六自由度装配序列规划下避障研究。实验结果证明:该方法可获取装配效率高、成本小的六自由度机器人装配序列;可以快速规划出最佳六自由度机器人避障路径,有效地避开障碍物,且精度较高、误差较小、实用性较强。展开更多
When performing operation tasks, the interaction between a flexible manipulator and a grasped object usually results in an impact. In this paper, a new way is suggested to alleviate impact vibration of a flexible mani...When performing operation tasks, the interaction between a flexible manipulator and a grasped object usually results in an impact. In this paper, a new way is suggested to alleviate impact vibration of a flexible manipulator via its structural characteristic when capturing a moving object. Controllable local degrees of freedom are introduced to the topological structure of the flexible manipulator, and used as an effective tool to combat impact vibration through dynamic coupling. A corresponding method is put forward to reduce impact vibration responses of the flexible manip- ulator via the controllable local degrees of freedom. By planning motion of the controllable local degrees of freedom, appropriate control force can be constructed to increase the modal damping and stiffness and eliminate the exciting force simultaneously, thereby reducing impact vibration responses of the flexible manipulator. Simulations are conducted and results are shown to prove the presented method.展开更多
Parameter optimization of the controllable local degree of freedom is studied for reducing vibration of the flexible manipulator at the lowest possible cost. The controllable local degrees of freedom are suggested and...Parameter optimization of the controllable local degree of freedom is studied for reducing vibration of the flexible manipulator at the lowest possible cost. The controllable local degrees of freedom are suggested and introduced to the topological structure of the flexible manipulator, and used as an effective way to alleviate vibration through dynamic coupling. Parameters introduced by the controllable local degrees of freedom are analyzed and their influences on vibration reduction are investigated. A strategy to optimize these parameters is put forward and the corresponding optimization method is suggested based on Particle Swarm Optimization (PSO). Simulations are conducted and results of case studies confirm that the proposed optimization method is effective in reducing vibration of the flexible manipulator at the lowest possible cost.展开更多
The structure and motion principle of a hinged synchronous universal joint (HSUJ) is introduced, also whose kinematics is theoretically analyzed. As a result, a few kinematic characters of the HSUJ are obtained,which ...The structure and motion principle of a hinged synchronous universal joint (HSUJ) is introduced, also whose kinematics is theoretically analyzed. As a result, a few kinematic characters of the HSUJ are obtained,which establish the foundation of its application for snake-like manipulator. Making use of the HSUJ ss actuating mechauism, the developed snake-like manipulator has the merits of small curve radius, fewer actuator, and small volume etc.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51705066,51805128)Sichuan Science and Technology Program(Grant No.2019YFG0343)Fundamental Research Funds for the Central Universities of China(Grant Nos.ZYGX2019J041,ZYGX2016KYQD137).
文摘Conventional manipulators with rigid structures and sti ness actuators have poor flexibility,limited obstacle avoidance capability,and constrained workspace.Some developed flexible or soft manipulators in recent years have the characteristics of infinite degrees of freedom,high flexibility,environmental adaptability,and extended manipulation capability.However,these existing manipulators still cannot achieve the shrinking motion and independent control of specified segments like the animals,which hinders their applications.In this paper,a flexible bio-tensegrity manipulator,inspired by the longitudinal and transversal muscles of octopus tentacles,was proposed to mimic the shrinking behavior and achieve the variable motion patterns of each segment.Such proposed manipulator uses the elastic spring as the backbone,which is driven by four cables and has one variable structure mechanism in each segment to achieve the independent control of each segment.The variable structure mechanism innovatively contains seven lock-release states to independently control the bending and shrinking motion of each segment.After the kinematic modeling and analysis,one prototype of such bionic flexible manipulator was built and the open-loop control method was proposed.Some proof-of-concept experiments,including the shrinking motion,bending motion,and variable structure motion,were carried out by controlling the length of four cables and changing the lock-release states of the variable structure mechanism,which validate the feasibility and validity of our proposed prototype.Meanwhile,the experimental results show the flexible manipulator can accomplish the bending and shrinking motion with the relative error less than 6.8%through the simple independent control of each segment using the variable structure mechanism.This proposed manipulator has the features of controllable degree-of-freedom in each segment,which extend their environmental adaptability,and manipulation capability.
基金Important Project of Science and Technology Research of Ministry of Education of China (No. 307005)National Hi-tech Research and Development Program of China (863 Program, No.SQ2007AA04Z231266).
文摘Although flexible manipulators own many potential advantages, one of their major disadvantages is the deterioration of the end-effector accuracy due to the flexibility. Therefore, how to reduce vibration is a significant problem. Inspired by the observation on the motion behaviors of animals, a new idea of decreasing motion deflection of the flexible manipulator is suggested. The concept of controllable local degrees of freedom is proposed and analyzed. By way of optimizing local motion provided by the controllable local degrees of freedom, the end-effector deflection of the flexible manipulator can be effectively decreased through dynamic coupling. The corresponding optimal method for vibration control of the flexible manipulator is put forward. The kinematic simulation is carried ant on a three-link flexible manipulator The corresponding results verify the feasibility of this method.
基金China 863 Hi-tech Program CIMS Topic (No.863-511-941-001) and Provincial Natural Science Foundation of Zhejiang, China (No.60008
文摘The requirements and features of virtual assembly movement navigator areanalyzed to help operators flexibly manipulate virtual objects, precisely locate or assemble virtualparts in virtual environment. With the degree-of-freedom analysis, the assembly constrainthierarchical model is constructed and the system's constraints are built dynamically. Thus, allobjects in virtual environment can be located reasonally by the navigator. Moreover, the assemblyconstraint recognition in the process of assembly and movement correction is also discussed.
基金Project(50375139) supported by the National Natural Science Foundation of ChinaProject(NCET-04-0545) supported by the New Century Excellent Talent Plan of the Ministry of Education of China
文摘The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this problem,cascade control method with an inner/outer-loop control structure is used,which masks the hydraulic dynamics with the inner-loop so that the designed controller takes into account of both the mechanical dynamics and the hydraulic dynamics of the manipulator.Furthermore,a cross-coupling control approach is introduced to the synchronous tracking control of the manipulator.The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent ones based on the synchronous goal.Then,with the feedback of both position error and synchronization error,the tracking is proven to guarantee that both the position errors and synchronization errors asymptotically converge to zero.Moreover,the effectiveness of the proposed approach is verified by the experimental results performed with a 6-DOF hydraulic parallel manipulator.
基金Supported by the National High Technology Research of China(2015AA043101,2015BAF10B02)Basic Scientific Research(B2220133017)National Natural Science Foundation of China(61503029,61573063)
文摘The space manipulator is always designed to have 7 degrees of freedom(Dofs)with the consideration of energy limitation,as well as the flexible moving possibility.Therefore,how to plan the trajectory is important to improve the performance of the manipulator.In this paper,the speed of the end effector is configured as a projecting parameter,when a constant acceleration is applied to adjust the velocity.To implement this trajectory planning strategy,an optimization algorithm through the pseudo inverse of Jacobin matrix is designed,which adjusts the weight functions of joints.According to the functional theory,this algorithm is analyzed and the optimal solution is found in numerous sets of planning.A MATLAB simulation platform is established and the results verity the effectiveness of the algorithm.
文摘由于六自由度机器人在装配序列规划中存在顶角叶片重力矩差难以保证、叶片重力矩分布不够均衡的问题,以至于避障过程中出现碰撞。为此,提出工业机器人六自由度装配序列规划下避障研究。通过分析六自由度机器人装配序列中,顶角叶片重力矩差和叶片重力矩分布产生的干涉关系,将装配平稳性、方向调整次数及更换装配工具的频次作为约束条件,设置干涉关系矩阵和适应度函数,以判断装配序列方案是否达到最佳;在装配方案达到最佳后,通过离散化萤火虫算法获取六自由度机器人装配序列最优解;根据该结果检测六自由度机器人碰撞结果,并采用优化随机树节点扩展控制及扩展能力检测的改进快速搜索随机树算法(Rapidly-exploring Random Tree,RRT*)来对所得装配序列进行调整修正,实现工业机器人六自由度装配序列规划下避障研究。实验结果证明:该方法可获取装配效率高、成本小的六自由度机器人装配序列;可以快速规划出最佳六自由度机器人避障路径,有效地避开障碍物,且精度较高、误差较小、实用性较强。
基金co-supported by the National Natural Science Foundation of China (Nos.51105015 and 51075013)Beijing Natural Science Foundation (No.4102035)National Key Technology R&D Program of China (No.2011BAF04B00)
文摘When performing operation tasks, the interaction between a flexible manipulator and a grasped object usually results in an impact. In this paper, a new way is suggested to alleviate impact vibration of a flexible manipulator via its structural characteristic when capturing a moving object. Controllable local degrees of freedom are introduced to the topological structure of the flexible manipulator, and used as an effective tool to combat impact vibration through dynamic coupling. A corresponding method is put forward to reduce impact vibration responses of the flexible manip- ulator via the controllable local degrees of freedom. By planning motion of the controllable local degrees of freedom, appropriate control force can be constructed to increase the modal damping and stiffness and eliminate the exciting force simultaneously, thereby reducing impact vibration responses of the flexible manipulator. Simulations are conducted and results are shown to prove the presented method.
基金the National Natural Science Foundation of China (Nos. 51105015,51075013)Beijing Natural Science Foundation (No.4102035)+2 种基金The Fundamental Research Funds for the Central Universities (Nos. YWF-10-01-A09, YWF-11-03-Q-275)State Key Laboratory of Robotics and System (HIT)National Key Technology R&D Program (No. 2011BAF04B00)
文摘Parameter optimization of the controllable local degree of freedom is studied for reducing vibration of the flexible manipulator at the lowest possible cost. The controllable local degrees of freedom are suggested and introduced to the topological structure of the flexible manipulator, and used as an effective way to alleviate vibration through dynamic coupling. Parameters introduced by the controllable local degrees of freedom are analyzed and their influences on vibration reduction are investigated. A strategy to optimize these parameters is put forward and the corresponding optimization method is suggested based on Particle Swarm Optimization (PSO). Simulations are conducted and results of case studies confirm that the proposed optimization method is effective in reducing vibration of the flexible manipulator at the lowest possible cost.
基金Robotics LaboratoryChinese Academy of Sciences foundation(RL200105)+1 种基金Shanghai Civic Department of ScienceTechnology(985511057)
文摘The structure and motion principle of a hinged synchronous universal joint (HSUJ) is introduced, also whose kinematics is theoretically analyzed. As a result, a few kinematic characters of the HSUJ are obtained,which establish the foundation of its application for snake-like manipulator. Making use of the HSUJ ss actuating mechauism, the developed snake-like manipulator has the merits of small curve radius, fewer actuator, and small volume etc.