| Piezoceramic actuators are increasingly used in high precision position control applications because of their nanometer displacement resolution, high stiffness and fast frequency response. However, piezoceramic actuators have the disadvantage of hysteresis and creep behaviors, which severely limits performance of the positioning system, such as giving rise to undesirable inaccuracy or oscillations, even leading to instability in some closed-loop control systems. Hysteresis in piezoceramic material is a form of non-linearity with memory; thus, the piezoceramic expansion depends not only on the current voltage excitation but also on the history of excitation. Modeling and compensation of hysteresis in piezoceramic actuators are the key way to achieve high precision positioning.A brief introduction on hysteresis in piezoceramic actuators is presented and a lot of studies on hysteresis modeling and compensation are discussed. The classical Preisach model is able to represent the non-local memory, which has been shown to exist in piezoceramics and has been shown to be suitable for describing hysteresis in piezoceramics. For the convenience of real-time implementation, a discrete-time Preisach model presented in a recursive form is developed using C language. A hysteresis compensation scheme based on the developed discrete-time Preisach model is also developed.To experimentally verify the performance of hysteresis compensation schemes based on Preisach model, an experimental system is designed and developed. Experimental results demonstrate that the linear voltage-to-displacement relationship is greatly improved with feedforward compensation based on the Preisach model. The maximum width of the hysteresis curve is reduced to 0.6μm, while the width is 3.2μm before compensation. The positioning precision is noticeably improved by adding the feedforward compensation based on the Preisach model with a feedback PID controller. The maximum error is 106nm at the stroke of 20μm.
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