大型天文望远镜摩擦传动系统低速特性的研究

Ultra-low speed research on friction drive for astronomical telescope

研究了大型天文望远镜摩擦传动系统的运行原理和特性,并进行了实验。结果表明,影响摩擦传动低速稳定运行的因素很多,主要有:编码器的测量误差,环境变化引起的误差,摩擦力矩和电机波动力矩等引起的误差,以及加工制造和安装引起的误差。另外在整个传动链中其它部分的摩擦力矩也不可能是一个定值,也存在力矩波动。结果还表明,利用非线性PID控制算法增益参数非线性变化的特性,可以使得控制系统既能达到响应速度快,无超调的目的,又能增强抵抗影响摩擦传动低速稳定运行因素的能力。实验中,低速可以达到0.2″/s,位置精度为0.032″(RMS),证明了这种方法是行之有效的。

The theory and characteristics of friction drive for a large astronomical telescope were presented. The results of experiment indicate that there are many factors influencing on the stability of low speed of friction drive. The main factors include： measuring error of encoder ;error of environment variance;errors of friction torque and motor fluctuating torque and error of manufacturing and installing. In addition, the friction torque of total drive chain is fluctuation also. The results of experiments also indicate that the nonlinear characteristic of increment parameter of nonlinear PID control algorithm can achieve prompt response and non-overshooting of the control system. The nonlinear PID also enhances the stability to resist the influence of friction drive low speed. In this experiment, the low speed is 0.2＂/s and position precision is 0. 032＂（RMS） ,which proved that this method is effective.