一种新型微操作平台的精确运动控制
Precision Motion Control of a Novel Micro-manipulation Stage

设计一种具有2级放大的高精度微操作平台,建立压电陶瓷驱动的平台动态模型,采用PID控制策略综合平衡其性能。采用杠杆原理设计的2级放大机构,将平台设计为对称结构,提高了其运动精度。采用有限元法和振型截断法建立平台的传递函数,它可等效为一质量-阻尼-弹簧系统。将压电陶瓷驱动器的电气特性等效为RC电路,力学特性等效为具有一定柔度的器件,建立整个系统的开环传递函数和闭环传递函数。以综合平衡系统的动态性能和稳定性为目的设计PID控制器。结果表明,在PID控制器作用下,系统的相位裕度和幅值裕度均增大,提高了系统的稳态性能,但剪切频率减小,降低了系统的快速响应性。同时,系统的调节时间和超调量减小,提高了系统的平稳性。驱动器时间常数对微操作平台动态性能有较大的影响,时间常数选择于0.2 ms附近可以得到较小的调节时间和合适的超调量。
A high-precision micro-manipulation stage with two-level amplifer was presented, which dynamic model was driven by PZT actuator, and PID control strategy was adopted to trade off its characteristics. With two-level amplification mechanism, the stage is designed into a symmetrical structure in order to improve the motion accuracy. The finite element method and the modal truncation method are used to build the transfer function of the stage which can be modeled as a mass-spring-damper system. The electrical properties of PZT actuator is equivalent to the RC circuit, and the mechanical properties is equivalent to the device with a certain flexibility. Thus, the open-loop and closed-loop transfers of the whole system can be obtained. The PID controller is designed for the purpose of balancing the dynamic performance and stability of the system. The analysis results showed that the phase and gain margin of the system can increase, and the steady performance can be improved under the PID controller. But the cut-off frequency decreases, and the rapid response is slowed down. Meanwhile, the settling time and overshoot of the system can be reduced to improve the system stability. The time constant of the actuator has a great effect on the dynamic performance of the micro-manipulation stage, and when the time constant is around 0.2 ms, the smaller settling time and suitable overshoot can be obtained