Force Tracking Control of a Flexible Gripper Driven by Piezoceramic Actuators

Abstract

This paper presents a robust force tracking control of a flexible gripper driven by a piezoceramic actuator characterizing its durability and quick response time. The mathematical governing equation for the proposed system is derived by employing Hamilton’s principle and a state space control model is subsequently obtained through the modal analysis. Uncertain parameters such as frequency variation are included in the control system model. The sliding mode control theory which has inherent robustness to the system uncertainties is adopted to design a force tracking controller for the piezoceramic actuator. Using the output information from a tip force sensor, a full-order observer is constructed to estimate state variables of the system. Force tracking performances for desired trajectories represented by sinusoidal and step functions are evaluated by undertaking both simulation and experimental works. In addition, in order to illustrate practical feasibility of the proposed method, a two-fingered gripper is constructed and its performance is demonstrated by showing a capability of holding an object.