导引头稳定平台的扰动补偿及改进滑模控制

为提高导引头稳定平台抗扰性,提出了一种导引头稳定平台的扰动补偿及改进滑模控制策略。首先根据扰动特点将扰动分为摩擦力矩和"剩余扰动"两部分,基于Stribeck摩擦模型辨识摩擦参数,并进行摩擦力矩补偿;采用扩张高增益观测器对"剩余扰动"进行估计,并给出了扩张高增益观测器的收敛条件。然后设计了改进滑模控制器作为稳定回路的控制器实现伺服控制,采用Lyapunov函数证明其稳定性。最后,搭建测试系统分别进行了稳定平台性能测试和导引头性能测试,用于验证跟踪和抗扰效果。实验结果表明,跟踪1(°)/s的梯形波时,提出的控制器有效地补偿了摩擦,同时稳态精度提高了0.032 8(°)/s;给定三轴转台典型幅值和频率扰动下,采用提出的控制器时系统隔离度至少提高了0.57%。表明提出的控制器改善了系统抗扰性。

Disturbance compensation and improved sliding-mode control of stabilized platform for seekers

A control scheme consisting of a disturbance compensation method and an improved sliding mode controller was proposed to improve the disturbance rejection rate of the stabilized platform used in a seeker. Firstly, the disturbances were divided into friction torque and rest disturbances. The friction parameters based on the Stribeck friction model were identified. An extended high-gain observer was designed to estimate the rest disturbances in the system dynamics, and the convergence condition of the estimation error was set. Meanwhile, the peaking phenomenon of the observer was reduced by saturating the estimates. Then, an improved sliding mode controller was chosen to control the servo system, and a Lyapunov-based analytical method was employed to ensure the convergence of the tracking error. Lastly, experiments on the stabilized platform and the seeker were carried out to validate the control scheme. By using the proposed control scheme, the dead zone at low angular velocity caused by friction was eliminated, and the steady precision was increased by 0.032 8 (°)/s, when tracking a trapezoidal wave of 1 (°)/s. In addition, the disturbance rejection rate was increased by a minimum of 0.57%, when the three-axis turntable was disturbed by typical disturbance conditions. It can be concluded that the control scheme can improve disturbance rejection.