基于扰动观测器的超螺旋终端滑模天线伺服控制方法研究
Research on Antenna Servo Control Method Based on Super Twisting Terminal Sliding Mode of Disturbance Observer
-
摘要: 指向精度是评价射电望远镜天线性能的重要指标, 而天线的伺服控制方法是影响该指标的关键因素. 研究提出了一种基于扰动观测器的超螺旋终端滑模控制方法, 实现了天线伺服系统的全局鲁棒有限时间稳定, 并利用Lyapunov稳定性理论分 析了系统的收敛时间. 所提出方法中的滑模变量采用和状态相关的变指数系数, 固定了最大滑动时间提高了系统的鲁棒性. 扰动观测器可准确获取伺服系统的干扰, 结合2阶结构的变增益超螺旋算法的控制率, 能有效缓解抖振现象, 实现天线的鲁棒控制. 仿真结果显示, 系统能在0.55 s左右快速跟踪信号, 跟踪误差小且抖振抑制效果明显. 提出的控制策略能够更快、更简单、更有效地跟踪参考信号抑制天线伺服系统的干扰.Abstract: Pointing accuracy is an important index to evaluate the performance of radio telescope antenna, and the servo control method of antenna is the key factor to affect the index. A new sliding mode control method based on disturbances observer is proposed to achieve global robust fixed-time stability of antenna servo system. The settling time is analyzed by using Lyapunov theory. The sliding mode variable in the proposed method adopts the variable exponential coefficient related to the state, which calculate the maximum sliding time in advance and improves the robustness of the system. The use of disturbance observer can accurately obtain and compensate the servo system interference, combined with the control input of the 2 order variable gain super twisting algorithm, which effectively alleviates the chattering phenomenon, and realizes the robustness control of the antenna. The simulation results show that the system can track the signal quickly at about 0.55 s, the tracking error is small, and the inhibition effect of chattering is obvious. The proposed control strategy can track the reference signal faster, simpler and more effectively to suppress the interference of the antenna servo system.