Kinematic and error modeling of TAU parallel robot

Large motion errors of industrial robots have confined them to manufacturing processes of low accuracy requirements such as automated welding, painting, material handling, and assembly, and prevented them from precision manufacturing processes such as milling and grinding. This study focuses on the kinematic and error modeling of a new robotic configuration TAU in order to realize high precision and high stiffness with a large workspace for industrial robots.; The kinematic model and error model are established with all possible error sources considered using Jacobian matrix method. Also established is an effective Jacobian approximation method for calculating the forward kinematic problem instead of using Newton-Raphson iteration method. It denotes that a closed form solution can be obtained instead of a numerical iteration solution allowing fast error computation and compensation. Both Jacobian matrix and Jacobian approximation method are verified using simulation with micron level accuracy. The established models are used in the development of the TAU robot in the stages of system design, lab prototype calibration, and industrial prototype error compensation. A full size Jacobian matrix is used in carrying out error analysis, error budget, model parameter estimation and identification. Experimental results obtained based on both the lab prototype and industrial prototype show that the established models enabled the realization of high precision for the new class of robots.; The established models are also used in the development of other precision robotics systems. Precision robotic machining processes using existing serial robots have been realized successfully with industry partners involved. These precision processes include robotic milling of aluminum engine blocks, and belt grinding of complicated parts of curved surfaces such as engine blades, and human knee joint replacements.