110m大射电望远镜的两自由度复合控制器设计

The design of two degree of freedom compound controller for 110m radio telescope

针对110m大射电望远镜结构柔性大、固有频率低的特点,本文在传统伺服控制的基础上进一步考虑副反射面支撑结构对指向精度的影响,提出了一种两自由度复合控制器.该控制器由内外两环构成,外环是基于广义比例积分(Generalized Proportional Integral,GPI)的鲁棒控制器,其以副反射面支撑结构的振动量为输入,确定伺服的参考指令;内环利用线性二次型高斯(Linear Quadratic Gaussian,LQG)控制器以外环输出为参考,对天线伺服驱动部分进行控制.与目前已有的大口径天线控制方法相比,该控制器既可以有效抑制驱动部分的柔性振动,又能抑制副反射面的振动,进而提高大口径天线的指向精度.本文以等效天线模型为控制对象.通过数值仿真验证了该方法的可行性.

Considering that the 110 m large radio telescope has the characteristics of big structural flexibility and low fundamental frequency, a two degree of freedom compound controller is proposed basing on the traditional servo control and considering the influence of subreflector＇s support structure for pointing accuracy. The controller consists of both inner and outer loop. The outer loop is based on the GPI （Generalized Proportional Integral） robust controller to determine the servo reference instruction by the vibration of subreflector; the inner loop uses the output of outer loop as its reference to control the drive part through the LQG controller. With this scheme, the flexible vibration of the drive part and the subreflector＇s support structure can be effectively suppressed simultaneously, thus improving the antenna＇s pointing accuracy. The validity of proposed algorithm is verified by numerical simulation on the equivalent antenna model.