| Locking failure joint after the robot's joint fails, a simple and reliable way, is increasingly paid more attention to by scholars. Locking failure joint may cause a series of affection on robot's kinematical performance. In this dissertation, an experiment platform for redundant robots is designed, and some experiments on redundant robot are performed on this platform.Firstly, the kinematic constraint equation for two coordinating redundant robots is established, the fault tolerant index is constructed, and the fault tolerance, which consists of the moment of failure and after the failure, is researched. And the definition of the sudden change in joint velocity is given. Then we adopt the trajectory-planning algorithm as follow: on condition that the reduced manipulability is maximal and the end-effector trajectory is within the fault tolerant workspace, determine a position, where the sum of the sudden change for the joint velocity of the master and slave robots is minimal.Secondly, the hardware and software of the devices, PowerCube modular robots and Optotrak3020, which are used in the platform, are introduced. Two 4R redundant robots are assembled for experiments. Based on the D-H coordinates, the links'parameters are given and the kinematical analytical resolution for 4R redundant robot is got. When the failed joint is locked, all the joints'velocity of the robot will change suddenly, which will have an affect on the end-effector's trajectory. After analyzing, we draw the conclusion that the initial position of the robots has an important effect on the sudden change of the joints'velocity.At last, experiments are performed on the platform. Experiments for joint two and joint three, which fails and is locked at different time, are performed separately. The co-operatings of the robots, which start from the optimum position, are simulated with the software ADAMS. The results prove that the numerical analysis is correct. |
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