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针对带有谐波减速器的双框架控制力矩陀螺框架伺服系统中的非线性摩擦问题,提出了非线性摩擦建模及补偿方法。首先,根据框架伺服系统数学模型导出摩擦力矩与角加速度和电机电流的关系;然后,通过光电码盘测得的角位置计算角速率并设计估计器来估计电机端和负载端的角加速度,利用采样电流和估计的角加速度计算摩擦力矩,建立库伦+粘滞+Stribeck摩擦模型;最后,设计基于摩擦模型的前馈补偿控制器抑制非线性摩擦以提高系统控制精度。实验结果显示,与传统PID控制方法相比,伺服系统加入基于摩擦模型的前馈补偿之后,角速率误差曲线峰峰值减小28.2%,角速率误差均方值减小25.7%;表明通过基于摩擦模型的前馈补偿可以有效抑制非线性摩擦引起的角速率误差,提高伺服系统的控制精度。
Aiming at the problem of nonlinear friction in a two-frame control moment gyro frame servo system with harmonic reducer, a nonlinear friction modeling and compensation method is proposed. Firstly, the relationship between the friction torque and the angular acceleration and the motor current is deduced according to the mathematical model of the frame servo system. Then, the angular velocity is calculated from the angular position measured by the photoelectric encoder and the estimator is designed to estimate the angular acceleration of the motor end and the load end. Current and estimated angular acceleration, the coulomb + viscous + Stribeck friction model is established. Finally, the feedforward compensation controller based on the friction model is designed to suppress nonlinear friction to improve the system control accuracy. Experimental results show that, compared with the traditional PID control method, after the feedforward compensation based on the friction model is added to the servo system, the peak-to-peak error of the angular rate error decreases by 28.2% and the mean square error decreases by 25.7% The model feedforward compensation can effectively suppress the angular rate error caused by nonlinear friction and improve the control accuracy of the servo system.