Abstract
The Six-Degree Motion Measuring Device (MMD) is based on the Stewart platform mechanism and provides six measuring degrees of freedom. The pose of the manipulator can be directly measured by the MMD and be fed back for the servo motion control, when the upper plate of the MMD is mounted on the end of the manipulator and the base is fixed on the workpiece side. This research proposes a Direct Pose Feedback Control (DPFC) for a six-axis manipulator. During its motion control, the MMD is used to measure the pose of the tool. The actual machine coordinates are calculated after the ideal backward kinematic transform. The differences between actual machine coordinates and the machine coordinates measured by joint encoders are resulted from link errors of the manipulator. Feeding them back to the servo control loop of motors, the link errors not observable by the joint encoders can be eliminated. Presented by this thesis, the direct pose feedback control of the six-axis manipulator consists of the servo control of each motor and link errors compensation control of the six-axis manipulator. Since this method keeps the original servo control loop intact, therefore, it is easy to integrate the method in the existing control system. Additionally, The Twin-Setting-Points Motion Control (TPMC) for the six-axis manipulator is also implemented in this thesis. Together with the direct pose feedback control, the positioning and contour accuracy of the six-axis manipulator are dramatically improved.