Grasping force hysteresis compensation of a piezoelectric-actuated wire clamp with a modified inverse Prandtl-Ishlinskii model

This paper presents the grasping force hysteresis compensation of a piezoelectric-actuated wire clamp with a modified hysteresis model. Considering dynamic characteristics of the wire clamp, a modified inverse Prandtl-Ishlinskii (MIPI) hysteresis model is developed to improve the hysteresis modeling accuracy. The proposed MIPI model is composed of a P-I model and a dynamic model which are connected in parallel. The proposed hysteresis model has the advantage of high modeling accuracy with a concise identification process, which means the step by step identification is not needed here. Experiments on grasping force hysteresis compensation with a feedforward controller are carried out based on the developed MIPI model. The grasping force error in steady state lies in ±8.17 mN, while the maximum percentage and root mean square percentage of the grasping force error are 2.93% and 0.92%, respectively. The results show that the proposed hysteresis model is efficient and the wire clamp exhibits good performance with the feedforward controller. Therefore high frequency grasping operations can be realized based on the proposed MIPI hysteresis model.