Precision Motion Control for Piezo-Driven Microgrippers Using Adaptive Sliding Mode Control and Hysteresis Compensation by Yulong Zhang Thesis Supervisor: Prof. Qingsong Xu This thesis tackles with the problem of position control in the presence of disturbance and uncertainty parameters with application in microgrippers driven by piezoelectric stack actuators. Microgripper driven by piezoelectric actuators has been widely applied in various fields owing to its high accuracy. However, achieving higher precision is always a challenging task due to the presence of hysteresis and disturbances. In chapter 1, some typical applications of microgripper are introduced and issues in microsystem are also presented. In addition, an adaptive control approach based on sliding mode control is presented to obtain a precise position through compensating hysteresis and resisting external disturbance. This proposed control algorithm first estimates the unknown parameters online and the sliding mode control will work then using the estimated values to minimize output error. The adaptive law and control law are designed based on sliding mode control strategy to attenuate the influence of the unknown and unmodeled parts. The stability of the control system is proved by resorting to Lyapunov theorem. Chapter 2 introduces the basic mathematical preliminaries, theory and concept used in the thesis, while the process of designing controller is proposed in chapter 5. Furthermore, several feedforward control strategies are employed to compensate for hysteresis based on different hysteresis mathematical models. In chapter 3, the properties of hysteresis and mathematical model of hysteresis model are briefly introduced, while the hysteresis compensation methods used in the thesis are generalized in chapter 4. The effectiveness of the proposed control approach is verified by experimental investigations on two different types of prototype microgrippers, and comparison of the proposed compensating methods are also compared. Finally, a typical application for autonomous cell injection system is introduced