基于扰动力矩观测器的大口径望远镜低速控制

为了增强大口径望远镜跟踪架伺服控制系统的抗扰动性能,提高其低速跟踪精度,提出了基于扰动力矩观测器的力矩补偿方法。该方法采用改进的加减速法控制转台的加减速时间,使得望远镜转台微震;通过测量电机的速度和电流响应曲线,辨识获得望远镜转台的转动惯量。然后,设计了望远镜转台的加速度估计器,根据编码器位置反馈数据,采用双积分和PD控制的方法,估计出当前系统的加速度。最后,基于转动惯量辨识和加速度估计,设计了扰动力矩观测器,根据电机的电流和转台的加速度,计算出外部的扰动力矩,并将扰动前馈补偿到电流控制器的输入端,以修正电流输入参考值。在2m望远镜控制系统中对扰动观测器的性能进行了实验验证,结果表明,加入扰动力矩观测器补偿后,在跟踪斜率为0.36(″)/s的位置斜坡时,跟踪误差值(RMS)由0.012 7″减小到0.007 3″;相比未加入扰动力矩观测器的补偿方法,望远镜的低速跟踪抖动明显减小,提高了伺服系统的低速跟踪精度,实现了对目标的平滑、稳定跟踪。

Low-speed control of large telescope based on disturbance torque observer

To improve the anti-disturbance performance and following tracking accuracy for the servo system in a large telescope ,a torque compensation method based on a disturbance observer was pro-posed .With the method ,the revised acceleration/deceleration control method was adopt to guide the telescope turntable oscillating in a little angle .Through measuring the velocity and current of a mo-tor ,the rotation inertia of the telescope turntable was indentified .Then ,an acceleration estimator was designed to estimate the low-acceleration based on encoder feedback data by using the double inte-gration and PD control method .Finally ,based on the inertia identification and acceleration estima-tion ,a disturbance observer was designed to estimate the external torque according to the motor cur-rent and turntable acceleration .Furthermore ,the estimated disturbance torque was used to compen-sate the current input to correct reference currents .Experiment results demonstrate that after the ob-server is added ,the following error RMS is reduced from 0 .0127″to 0 .0073″at the sloop position of servo system to be 0 .36 (″)/s .Compared with that without the disturbance torque observer ,the fol-lowing tracking jitter is reduced and the tracking accuracy is improved .