Friction Identification and Compensation of Modular Joints Based on Whale Optimization Algorithm

Accurate identification of friction parameters is important to control modular joints. In this paper, an offline parameter identification method and a feedforward friction compensation algorithm were proposed. First, a self-developed modular joint was introduced, including its structure, control system, and mathematical model. Second, the LuGre model was used to describe the friction characteristics of the joint, and friction parameters were identified using the modified whale optimization algorithm (WOA). Finally, a friction compensation algorithm was proposed and verified. Experimental results show that after friction compensation, the velocity error was reduced by 36.9% and the bandwidth of the velocity loop was increased by 41.6%. The proposed method has high accuracy, and can effectively improve the performance of the joint control system.