Identification of dynamic and friction parameters of a parallel manipulator with actuation redundancy

The dynamic model is formulated in the joint space for a parallel manipulator with actuation redundancy. The established model is expressed in its linear matrix form with respect to the dynamic and friction parameters, and then the Weighted Least Square (WLS) method is applied to estimate the parameters. In order to get satisfying estimated results, the filters of joint angle and actuated torque are designed for the parallel manipulator. A simple and effective method is presented to design the excitation trajectory by analyzing the mechanism structure characteristics of the actual parallel manipulator. Another type of trajectory which is different from the excitation trajectory is adopted to verify the estimated parameters. The dynamic control experiments based on the identified model with the estimated parameters are implemented on an actual 2-DOF parallel manipulator with actuation redundancy, and the tracking accuracy of the identified model is compared with the result of the so-called nominal model.