GMA离散自适应滑模变结构位移追踪控制研究

On displacement tracking controlling of GMA with discrete adaptive sliding mode variable structure controller

超磁致伸缩作动器(GMA)有应变大、能量密度高和响应速度快的特点,在主动隔振领域具有广阔的应用前景,但是其自身材料的磁滞非线性导致其位移控制精度大大降低。为提高其控制精度,方便在实际工程中应用,提出一种前馈逆补偿和反馈控制相结合的位移追踪控制策略。首先,采用自由能磁滞模型表示GMA的磁滞非线性特性;然后,通过变步长的LMS自适应滤波器逼近自由能磁滞模型的逆算子,实现前馈逆补偿,反馈控制方面则采用离散自适应滑模变结构控制器来实现;再次,考虑到实际应用中的过程噪声和测量噪声的干扰,采用Kalman滤波器进行滤波,消除了位移跟踪控制中变结构控制量的抖振;最后,仿真试验分析了控制器的跟踪性能以及抗噪声干扰能力,验证了该控制策略的有效性和可靠性。

Giant magnetostrictive actuator(GMA)has a wide application prospect in active vibration isolation due to its large strain,high energy density and fast response.However,its displacement control accuracy is greatly reduced because of the hysteresis nonlinearity of GMA's materials.In order to improve the control accuracy and convenience of application,a displacement tracking control strategy based on feed-forward inverse compensation and feedback was proposed.Firstly,a free-energy hyste-resis model was used to represent the hysteresis nonlinear characteristics of GMA,and then the inverse operator was approximated by a variable step LMS adaptive filter to realize feed-forward and inverse compensation.The feedback control was realized by discrete adaptive sliding mode variable structure controller.Considering the interference of process noise and measurement noise in practical application,Kalman filter was used to eliminate chattering of variable structure control variables in displacement tracking control.Finally,the tracking performance and anti-noise ability of the controller were analyzed through simulation test,and the effectiveness and reliability of the control strategy are verified.