Configuration And Dimension Synthesis Of Redundant Manipulators Based On Fault-tolerant Workspace

Redundant manipulator is the frontier of robotics. Regular manipulator’sjoint-dimension equals to task-dimension. That means once a failure occurs to a joint,the given task will be badly performed or must be canceled. While redundantmanipulator has more joint-dimension than task-dimension, it gains an ability of faulttolerance. When several joints meet failure, as long as the remained joint-dimension isno less than task-dimension, there is a probability that the given task can still be wellperformed. Thus, the design and operation of fault-tolerant manipulators is critical forapplications in remote and/or hazardous environments where routine maintenance andrepair are not possible. Example applications include space exploration, underwaterexploration, and nuclear waste remediation.Solutions of redundant manipulator’s fault tolerance include two aspects. The firstis considering the best configuration and dimension for fault tolerance. The second israpid detection and identification of failure and taking in new control strategy for themanipulator. The first is mainly a mechanical design and kinematics problem whilethe second is mainly a dynamics and control problem.This dissertation studies the problem related to kinematics. That’s the configurationand dimension synthesis of redundant manipulators based on fault-tolerant workspace(FTW). An index named "Fault-Tolerant Ratio"(FTR) is proposed to evaluate therelative size of FTW. For the purpose of maximizing FTR, the synthesis of threetypical redundant manipulators is performed in this dissertation.First, the existence disciplines of workspace and single-joint FTW of planar3Rmanipulator are studied. Combined rasterization method and flood-fill operation inmathematics morphology, fast computing method (FCM) is proposed for thecomputations of workspace and single-joint FTW of planar3R manipulator.Then, the existence disciplines of dexterous workspace (DW) and single-jointfault-tolerant dexterous workspace (FTDW) of planar4R manipulator are studied.Adding erosion in mathematics morphology, FCM is proposed for the computationsof DW and single-joint FTDW of planar4R manipulator.After that, this dissertation studies the workspace and single-joint FTW of spatial4R manipulator. Combined rasterization method and dilation in mathematicsmorphology, FCM is proposed for the computations of workspace and1stjoint’s FTWof spatial4R manipulator. A conception named "Equivalent Cross Section"(ECS) is proposed for the computations of other joints’ FTW.In the end, the synthesis of these three typical redundant manipulators is performedto maximizing FTR with the help of Genetic Algorithm Toolbox (GAT) of MATLAB.In further research based on results of planar4R manipulator, two kinds of fixed-pointplanar linkage mechanism with one degree of freedom (DOF) are designed.