Dynamics, Sensing, and Control of a Thin-Film Piezoelectric Vertical Micro-Stage

A novel thin-film piezoelectric vertical actuator with integrated strain gage position sensor is described, with sensor performance in simulated sliding mode control examined. The actuator utilizes four bending-beam thin-film lead-zirconate-titanate (PZT) legs to generate net translational out-of-plane motion of almost 100 μm, with higher speed and lower voltages than most MEMS vertical actuators. In addition, a portion of the top platinum electrode on the piezoelectric thin-film is used to perform position sensing, and shown to have good sensitivity during experimental operation of the actuator. A dynamic model of the stage based on a hysteresis model derived to fit experimental piezoelectric strain coefficient behavior is presented, and used to predict stage performance during sliding mode control using the integrated strain gage.