Synchronous Fault Tolerant Planning For Redundant Manipulators And Coordinating Redundant Manipulators

In this dissertation,fault tolerant planning of kinematical redundant manipulators for locked joint failures is discussed. The synchronous fault tolerant planning at failure moment and after failure moment for redundant manipulators is systemically investigated. Besides, the preliminary research of fault tolerance for coordinating manipulators is done.Firstly, by means of analyzing the previous literatures, it is indicated that locked joint failure as a simple and reliable mode is increasingly paid attention to by scholars home and overseas. On the basis of probing into the theory about kinematical optimization for redundant manipulators, the optimized index----reduced manipulability is determined according to the kinematical property of redundant manipulators for locked joint failures. Further the optimization algorithm and the related optimization ability and parameter are analyzed, and then the grads projection algorithm is adopted in this dissertation.Secondly, the new physical intuition into reduced manipulability is given by means of decomposing reduced manipulability into arm length index and rotation angle index. The center index that expresses the positional relation between fault tolerant workspace and end-effector's motion is proposed. Planning the end-effector's motion by utilizing reduced manipulability and center index can guarantee higher dexterity ability for redundant manipulators at failure moment. Since in advance the end-effector's motion is in the corresponding center of fault tolerant workspace, it is guaranteed that the reduced manipulator can accomplish the unfinished task after the failure and can constantly keep higher dexterity ability during the post-failure operation.Thirdly, fault tolerant planning is researched through simulation examples for a planar 3R manipulator and a spatial 4R manipulator. Research results show that synchronous fault tolerant planning of joint motion and end-effector's motion for redundant manipulator is valid. The relationship between reduced manipulability index and center index is in-depth discussed. Finally, fault tolerant planning for two coordinating manipulators isinvestigated. The kinematical model for coordinating manipulators is constructed and research is done through simulation examples for two coordinating manipulators holding one object. Research results show that for the fault tolerant planning of two coordinating manipulators multi-joint indexes should be utilized as much as possible while single joint index should be avoided. That is one of the radical differences between the fault tolerant planning for one single manipulator and that for two coordinating manipulators.