An Adaptive PI Control Method Considering Large Inertia for Multi-DoF Forming Robot

Abstract

In order to realize the process of thin wall part with high efficiency, a multi-DoF forming robot (MDFR) with high moving weight (20 kN) is developed. The time-varying large inertia force and Coriolis force lead to poor control performance using traditional control method. To solve this problem, this paper proposes an adaptive PI control method to compensate the large inertia. Firstly, the electromechanical coupling dynamic model (ECDM) of MDFR, in which the inertia force and Coriolis force are represented by equivalent mass and equivalent damping, is established. Then, the inertia force and Coriolis force are revealed to influence the control precision greatly. Thus, an adaptive identification method of equivalent mass and damping is proposed, in which the adaptive factor is determined based on the changing rate of identification result. Further, the relation between the PI parameters, equivalent mass and damping is established based on the stability condition, so that realization of adaptive PI adjustment. On such basis, an adaptive PI control method considering large inertia for MDFR is proposed. Compared with traditional PI method, the experimental control errors reduce 34.62 % under a velocity of 60 r/min, showing a better performance of the proposed method under high velocity.