The current motion planning approaches for redundant manipulators mainly includes two categories： improved gradient-projection method and some other efficiency numerical methods. The former is excessively sensitive t...The current motion planning approaches for redundant manipulators mainly includes two categories： improved gradient-projection method and some other efficiency numerical methods. The former is excessively sensitive to parameters, which makes adjustment difficult; and the latter treats the motion planning as general task by ignoring the particularity, which has good universal property but reduces the solving speed for on-line real-time planning. In this paper, a novel stepwise solution based on self-motion manifold is proposed for motion planning of redundant manipulators, namely, the chief tasks and secondary tasks are implemented step by step. Firstly, the posture tracking of end-effector is achieved accurately by employing the non-redundant joint. Secondly, the end-effector is set to keep stationary. Finally, self-motion of manipulator is realized via additional work on the gradient of redundant joint displacement. To verify this solution, experiments of round obstacle avoiding are carried out via the planar 3 degree-of-~eedom manipulator. And the experimental results indicate that this motion planning algorithm can effectively achieve obstacle avoiding and posture tracking of the end-effector. Compared with traditional gradient projection method, this approach can accelerate the problem-solving process, and is more applicable to obstacle avoiding and other additional work in displacement level.展开更多
For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasing...For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasingly difficult to obtain the analytic solution of its self-motion manifold in the traditional way for solving matrix equation.In this paper,we take the pose of end manipulator as the result of the joint sequential motion based on the mentality of motion equivalence,the structure and the reference velocity which correspond precisely to the points in self-motion manifold as self-motion variable.Thus an analytical solution for the self-motion manifold of the 8 degree of freedom wheeled mobile manipulator is presented by taking vector algebra as a tool,which facilitates deriving the closed solution of its self-motion manifold.In the closing part of this paper,calculating examples of self-motion manifold and mechanism self-motion simulation are proposed,which proves the validity of solution algorithm for self-motion manifold.展开更多
Accurate self-motion perception,which is critical for organisms to survive,is a process involving multiple sensory cues.The two most powerful cues are visual(optic flow)and vestibular(inertial motion).Psychophysical s...Accurate self-motion perception,which is critical for organisms to survive,is a process involving multiple sensory cues.The two most powerful cues are visual(optic flow)and vestibular(inertial motion).Psychophysical studies have indicated that humans and nonhuman primates integrate the two cues to improve the estimation of self-motion direction,often in a statistically Bayesian-optimal way.In the last decade,single-unit recordings in awake,behaving animals have provided valuable neurophysiological data with a high spatial and temporal resolution,giving insight into possible neural mechanisms underlying multisensory self-motion perception.Here,we review these findings,along with new evidence from the most recent studies focusing on the temporal dynamics of signals in different modalities.We show that,in light of new data,conventional thoughts about the cortical mechanisms underlying visuo-vestibular integration for linear self-motion are challenged.We propose that different temporal component signals may mediate different functions,a possibility that requires future studies.展开更多
为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉...为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉冲型地震动作用下的失效概率.为了对比分析,同时选取60条远场无脉冲型地震动记录对附加SCEB桥墩结构进行了易损性分析.结果表明:在小震作用下,SCEB仅为桥墩结构提供刚度和承载力,在大震作用下还可提供耗能能力,同时可以提供良好的自复位能力;附加SCEB可有效降低桥墩结构在近场脉冲型地震动作用下的失效概率(最大侧移率和残余侧移率),特别是残余侧移率;附加SCEB桥墩结构在近场脉冲型地震动作用下的失效概率大于远场无脉冲型地震动作用下的失效概率.自复位耗能支撑可有效减小桥墩结构的失效概率,提高桥墩结构的抗震性能.展开更多
基金supported by National Hi-tech Research and Develop- ment Program of China (863 Program, Grant No. 2005AA404291)
文摘The current motion planning approaches for redundant manipulators mainly includes two categories： improved gradient-projection method and some other efficiency numerical methods. The former is excessively sensitive to parameters, which makes adjustment difficult; and the latter treats the motion planning as general task by ignoring the particularity, which has good universal property but reduces the solving speed for on-line real-time planning. In this paper, a novel stepwise solution based on self-motion manifold is proposed for motion planning of redundant manipulators, namely, the chief tasks and secondary tasks are implemented step by step. Firstly, the posture tracking of end-effector is achieved accurately by employing the non-redundant joint. Secondly, the end-effector is set to keep stationary. Finally, self-motion of manipulator is realized via additional work on the gradient of redundant joint displacement. To verify this solution, experiments of round obstacle avoiding are carried out via the planar 3 degree-of-~eedom manipulator. And the experimental results indicate that this motion planning algorithm can effectively achieve obstacle avoiding and posture tracking of the end-effector. Compared with traditional gradient projection method, this approach can accelerate the problem-solving process, and is more applicable to obstacle avoiding and other additional work in displacement level.
文摘For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasingly difficult to obtain the analytic solution of its self-motion manifold in the traditional way for solving matrix equation.In this paper,we take the pose of end manipulator as the result of the joint sequential motion based on the mentality of motion equivalence,the structure and the reference velocity which correspond precisely to the points in self-motion manifold as self-motion variable.Thus an analytical solution for the self-motion manifold of the 8 degree of freedom wheeled mobile manipulator is presented by taking vector algebra as a tool,which facilitates deriving the closed solution of its self-motion manifold.In the closing part of this paper,calculating examples of self-motion manifold and mechanism self-motion simulation are proposed,which proves the validity of solution algorithm for self-motion manifold.
基金supported by grants from the National Science and Technology Innovation 2030 Major Program(2022ZD0205000)the Strategic Priority Research Program of CAS(XDB32070000)+1 种基金the Shanghai Municipal Science and Technology Major Project(2018SHZDZX05)the Shanghai Academic Research Leader Program(21XD1404000).
文摘Accurate self-motion perception,which is critical for organisms to survive,is a process involving multiple sensory cues.The two most powerful cues are visual(optic flow)and vestibular(inertial motion).Psychophysical studies have indicated that humans and nonhuman primates integrate the two cues to improve the estimation of self-motion direction,often in a statistically Bayesian-optimal way.In the last decade,single-unit recordings in awake,behaving animals have provided valuable neurophysiological data with a high spatial and temporal resolution,giving insight into possible neural mechanisms underlying multisensory self-motion perception.Here,we review these findings,along with new evidence from the most recent studies focusing on the temporal dynamics of signals in different modalities.We show that,in light of new data,conventional thoughts about the cortical mechanisms underlying visuo-vestibular integration for linear self-motion are challenged.We propose that different temporal component signals may mediate different functions,a possibility that requires future studies.
文摘为了研究桥墩结构的震后功能可恢复性,针对附加自复位耗能支撑(self-centering energy dissipation braces,SCEB)双柱式桥墩结构进行基于增量动力分析方法的地震易损性分析,采用最大侧移率和残余侧移率作为性能指标,系统探讨其在近场脉冲型地震动作用下的失效概率.为了对比分析,同时选取60条远场无脉冲型地震动记录对附加SCEB桥墩结构进行了易损性分析.结果表明:在小震作用下,SCEB仅为桥墩结构提供刚度和承载力,在大震作用下还可提供耗能能力,同时可以提供良好的自复位能力;附加SCEB可有效降低桥墩结构在近场脉冲型地震动作用下的失效概率(最大侧移率和残余侧移率),特别是残余侧移率;附加SCEB桥墩结构在近场脉冲型地震动作用下的失效概率大于远场无脉冲型地震动作用下的失效概率.自复位耗能支撑可有效减小桥墩结构的失效概率,提高桥墩结构的抗震性能.
