Overcoming hysteresis in multilayered piezoceramic actuators used in adaptive optics

Piezoceramic actuators are of increasing interest within the field of adaptive optics through their ability for macro and nano positioning. However, a major drawback for their use is the inherent, non linear hysteresis that is present, which will reduce the accuracy in positioning. Typical (raw) hysteresis for multilayered piezoceramic actuators is 20% of full extension. Methods have been researched to overcome the hysteresis but they often involve complex additions to the actuators and its positioning system. This paper discusses two methods to overcome the hysteresis in a simpler approach. The first method is using capacitance measurements which correlate with the extension of the actuators and reduces hysteresis to 5%. The second method involves measuring the frequency at a specific impedance phase, which can reduce hysteresis to between 0 - 2%. Both methods provide reduction in hysteresis during extension sensing.