Hysteresis Compensation Of Shape Memory Alloy Activators

Shape Memory Alloy is one kinds of metal alloys, which exhibit shape memory effect. The unique properties make them the perfect choice for many applications. In the last decade, some of the successful application of SMA actuators has emerged. However these applications only require on-off actuation. In many potential applications, such as muscle wires, position actuator, more precise actuation of SMA is required. Due to the complex tree-dimension hysteresis of SMA actuators, position control poses a significant challenge. This research will concentrate on precision control of SMA actuators.In recent years, several methods to control hysteresis actuators have emerged. Most of them adopt inverse control and propose kinds of algorithm to compute the inversion of the Preisach model. The purpose is minimizing the actual position s\and reference position. In this paper, the Preisach model is used to capture the essential characteristics of hysteresis in SMA.This dissertation presents a new compensation algorithm of hysteresis based on the inversion of numerical implementation of the Preisach model in order to eliminate the non-linearity hysteresis. This algorithm can avoid the double integration and will be executed more accurately, which is highly desirable feature for real-time control. Furthermore, the identification of the inversion hysteresis model only requires first-order descending curves of hysteresis.A novel memory matrix (input memory matrix MU and output memory matrix MF) are introduced for the investigation of the Preisach model and its inversion. The simulation and experimental results demonstrate performance of the control strategy. Investigations of three-dimensional hysteresis model have been developed. All the factors which could affect the generation of the hysteresis loops are extracted into three parameters. This model is a temperature-dependent model and could be seen as a generation of the Preisach model. At the April of 2004, the simulation and control system has passed the acceptance check in LPMM of "Ecole National Superieure d'Art et Metiers" in France. And it obtains good appraisements of the engineer in the laboratory.