Adaptive control with unknown parameters estimation for motion tracking of piezo-driven micromanipulator

The microgripper actuated by piezoelectric actuator (PEA) is a typical micromanipulator. In order to control it to attain exact position, a good adaptiveness and robustness against disturbance should be guaranteed. However, because of the nonlinear hysteresis in the PEA and other disturbance such as drift, it is not an easy assignment to get an accurate position control. Another difficulty lies in the changes of mass, damping or stiffness. This paper proposes a solution to tackle these difficulties using sliding mode control with an adaptive law. The designed controller can guarantee the stability of micromanipulator. It also enables the system enough feasibility and robustness to resist the disturbance and the variation of uncertain parameters.