根据永磁同步电机驱动的大型望远镜转台对指向精度与低速跟踪精度的要求, 设计了基于摩擦模型的反演滑模控制器。建立了基于摩擦模型与外部扰动的系统模型; 然后, 按照反演设计方法, 设计了离控制输入最远的子系统, 在设计过程中加入滑模控制, 从而减小非线性摩擦因素与外部风载等对指向精度与跟踪精度的影响。通过理论仿真和实验研究验证了该方法的有效性。结果显示: 所设计的反演滑模控制器具有较好的动态响应, 对扰动等不确定性因素具有较强的鲁棒性, 当位置阶跃指令为4.6″时, 稳态误差为0.048 51″, 比传统的PI控制算法减小21.4%; 当输入斜率为5 (″)/s的位置斜坡指令时, 稳态跟踪误差为0.031 26″, 比传统的PI控制算法减小30.1%。结果表明提出的方法能够提高望远镜控制系统的指向精度和低速跟踪精度。

According to the requirement of a large telescope driven by a permanent magnet synchronous motor( PMSM) for pointing precision and following precision, a sliding mode position controller was designed based on a friction model with backstepping approach. Firstly , the system model was established based on LuGre friction model and external disturbance. Then, a subsystem which is the furthest away from the control input was designed by inversion method. In the design process, the sliding mode control law was induced into each step of backstepping approach to attenuate the influence of nonlinearity friction and external disturbance on the pointing precision and following precision of the large telescope. The effectiveness of the proposed method was verified by theoretical simulation and experimental test. The experimental results demonstrate that the system has a good dynamic performance and is insensitive to the uncertainty factors such as disturbance. The stable pointing error is 0.048 51″ when the position command is 4.6″, which decreases 21.4% than that of the traditional PI controller. The stable following error is 0.031 26″ when the ramp position command 5 (″)/s, which decreases 30.1% than that of the traditional PI controller. The proposed controller improves the pointing precision and following precision of large telescopes successfully.