Multi-degree-of-freedom joint nonlinear motion control with considering the friction effect

Friction effect between joints needs to be considered in the fast changeover process of the dulcimer robot which is oriented to precise position control. A complete nonlinear dynamic equation with coulomb friction model for a six-degree-of-freedom robot is proposed. Based on Solidworks and Matlab SimMechanics dynamics model, the transformation and simulation of the above dynamic equations are completed, and the joint motion parameter recognition for the end positions is obtained. The results show that with and without considering the friction, the maximum difference on the moment response of joints of the robot is 7%. In order to precisely control the movement of each joint, a track tracking method combining traditional PID control and adaptive fuzzy PID control is proposed, and the angular difference of each joint track can keep within the range below 0.08 rad. The research process and results provide a theoretical reference for improving the high-speed position accuracy and evaluating the response characteristics of the multi -degree-of-freedom dulcimer robot, and have important engineering reference for ensuring the accurate acquisition of the multi-degree-of-freedom robot's motion.