摩擦传动的压电定位台高精度跟踪控制

High Accuracy Tracking Control of Piezoelectric Positioning Stage Using Friction Drive

针对选用的摩擦传动的压电定位台控制系统,首先根据其物理机理建立了近似的时域数学模型,通过开环实验,采用最小二乘法进行了参数辨识,所得模型与实际系统对输入的脉宽信号与三角波信号具有较为一致的输出;然后根据该模型的形式,采用其逆系统补偿加滑模变结构控制的方案,并讨论了该控制算法的稳定性及其参数的选择依据;最后进行了信号跟踪的实验测试,得到了微米级(最大跟踪误差为0.010 95 mm)的控制精度。作为对比,采用PI控制方法跟踪同一信号,结果表明,本文所用控制算法的控制精度远优于常规的PI控制方法。

With the development of science and technology, there is an urgent need to develop micrometer positioning technology in the fields of the precision manufacturing. The traditional electromagnetic motors are difficult to meet this demand as they are characterized by high speed and low torque. Piezoelectric actuator uses piezoelectric ceramics as transducers, and utilizes the inverse piezoelectric effect of piezoelectric ceramics to convert the electrical energy to the mechanical energy,which can masterly utilize certain structural forms to transfer motions and motive forces. In addition,due to the compact structure of piezoelectric actuator,the rotor inertia is small,and fast in response to braking, the load can be directly driven, and has good controllability for positioning and speed,therefore,piezoelectric actuator is widely used in equipment drive and control with high performance for precision manufacturing. For the selected piezoelectric positioning stage system using friction drive,an approximate time-domain mathematical model was established according to its physical mechanism. The parameters were identified by the open-loop experiment with the least squares method. The model output of the pulse width signal and the triangular wave signal were consistent with that of the actual system.Then,according to the form of the model,inverse system compensation plus sliding mode variable structure control scheme was designed. The stability of the control algorithm and its control parameters were discussed. The PI control method and the control algorithm proposed were used to track the same signal. The results showed that the control precision of the control algorithm used was much better than that of the PI control method,the maximum tracking error by using the proposed control algorithm was0. 010 95 mm. So it had good practical value in the drive and control of precision instruments and equipment.