压电倾斜镜的高压驱动及高速控制

由于压电倾斜镜的机械谐振会降低自适应光学伺服控制系统的校正带宽,本文研究了补偿压电倾斜镜谐振特性的方法。根据压电倾斜镜机械谐振频率特性的动态模型和实测数据,提出了利用压电倾斜镜高压驱动器中现有的可编程逻辑门阵列(FPGA)设计多阶双二次型数字滤波器来优化系统的动态频率响应特性。基于多阶双二次型数字滤波器,高压驱动器能实时补偿驱动对象的频率特性,完成压电倾斜镜的正谐振和反谐振的同时补偿。将其与压电倾斜镜作为一体,可实现平坦的幅频特性,从而避免机械谐振,提高伺服控制带宽。实验结果表明:相对于传统的高带宽高压驱动器,提出的具有频率特性补偿功能的高带宽高压驱动器可在同样超调量下使系统误差带宽从56 Hz提高到了80 Hz,并且低频抑制能力也得到提高。实验显示提出的具有频率特性补偿功能的高带宽高压驱动器更适合压电倾斜镜的高速动态应用。

High-voltage drive and control for piezoelectric fast steering mirror

As the mechanic resonance of Piezoelectric Fast Steering Mirror (PFSM) degrades the correction width of an adaptive optics servo loop, this paper explores the method to improve the performance of the fast steering mirror in high-speed applications. On the basis of the dynamic model and measured data of the PFSM, a multi-order two-second digital filter was embedded in the Field Programmable Gate Array (FPGA) of the high-voltage driver. The digital filter could suppress or compensate the resonance point and the anti-resonance point at the same time. As a whole with the PFSM, the optimized frequency response of the high-voltage driver flattens the magnitude response,avoids undesired resonance behavior and improves the control bandwidth. As compared with that of traditional high-voltage drivers, experimental results with the proposed high-voltage driver show that the control bandwidth of the system is effectively improved from 56 Hz to 80 Hz at the same overshot, and also the error rejection at low frequency is enhanced. The high bandwidth high-voltage driver with a plant characteristic compensator is more attractive to drive the PFSM in high-speed applications.