Dynamic modeling and feedforward control of TAU parallel robot.

摘要

This study concerns the research and development of a new parallel-serial industry robot with strong competencies in certain industry applications. For this newly invented TAU parallel robot configuration, its closed-loop analytical kinematics is given in this study for the first time. Explicit expressed rigid body inverse dynamics derived in this study and its control implementation are the key components in the development.; Based on the review of serial and parallel configurations currently adopted by industry robots and the analyses of demands from various industry applications, the requirements for a new type of robots have been outlined. Using the link clustering design approach, a new design, namely the TAU parallel robot, combining the advantages of serial and parallel robots has been proposed. The objective of this study is to establish the knowledge base for building the next generation industrial robot with a high accuracy, high stiffness, large workspace and outstanding flexibility.; In current the flexible automation, when dealing with applications requiring a high accuracy and/or high stiffness application, a serial robot performs poorly while CNC machines or parallel-configured robots are limited by its small workspace and a lack of flexibility. With the increasing demands for new solutions to satisfy such a kind of applications, the TAU parallel configuration as an innovative mechanism, addresses effectively the challenge by fundamentally improving the accuracy and stiffness of the robot itself without sacrificing its workspace and flexibility. The rigid body dynamic model will further help to enhance its dynamic performance.; In the study, a rigid body dynamic model for the TAU robot is presented as well as all the necessary kinematics. The model is established based on the virtual work principle. Jacobian matrices are used to transfer the computed-torque from Cartesian coordinates into joint space. Explicit separation format for the rigid body dynamic model is obtained as well. The contributions from coupling, Coriolis, centrifugal and gravity can be separated and their effects on the dynamic performance can be studied separately.; As the result of this work, an accurate and explicit separated dynamic model is obtained and used in the control loop. An improved dynamic performance is achieved. Also a friction model and a kinematic error model are introduced as efforts to improve the dynamic and kinematic accuracies.