Modeling and Robust Control Strategy for a Control-Optimized Piezoelectric Microgripper

In this paper, modeling and robust control strategy for a new control-optimized piezoelectric microgripper are presented. The device to be controlled is a piezoelectric flexible mechanism dedicated to micromanipulation. It has been previously designed with an emphasis to control strategy, using a new topological optimization method, by considering innovative frequency-based criteria. A complete nonlinear model relating the voltage and the resulting deflection is established, taking into account hysteresis as a plurilinear model subjected to uncertainties. The approach used for controlling the actuator tip is based on a mixed high authority control (HAC)/low authority control (LAC) strategy for designing a wideband regulator. It consists of a positive position feedback damping controller approach combined with a low-frequency integral controller, which is shown to have robustness performances as good as a RST-based robust pole placement approach for the microgripper. The rejection of the vibrations, naturally induced by the flexible structure, and the control of the tip displacement have been successfully performed. Because we had taken into account frequency-based criteria from the first designing step of our device, we demonstrate that the tuning of the HAC/LAC can be easily performed and leads to low-regulator order.