FORCE TRACKING CONTROL OF A FLEXIBLE GRIPPER DRIVEN BY PIEZOCERAMIC ACTUATORS

This paper presents a robust force tracking control of a flexible grip per driven by a piezoceramic actuator characterizing its durability an d quick response time. The mathematical governing equation for the pro posed system is derived by employing Hamilton's principle and a state space control model is subsequently obtained through the modal analysi s. Uncertain parameters such as frequency variation are included in th e control system model. The sliding mode control theory which has inhe rent robustness to the system uncertainties is adopted to design a for ce tracking controller for the piezoceramic actuator. Using the output information from a rip force sensor, a full-order observer is constru cted to estimate state variables of the system. Force tracking perform ances for desired trajectories represented by sinusoidal and step func tions are evaluated by undertaking both simulation and experimental wo rks. In addition, in order to illustrate practical feasibility of the proposed method a two-fingered gripper is constructed and its performa nce is demonstrated by showing a capability of holding an object.