保证闭环系统鲁棒稳定性的干扰观测器系统性设计方法

研究带有干扰观测器(Disturbance observer,DOB)的反馈控制系统对模型不确定性鲁棒稳定的充分条件,在此基础上,选取满足此充分条件的加权函数,使得标准H∞干扰观测器设计方法保证对受控对象参数变化的鲁棒稳定性.提出了在H∞干扰观测器设计中兼顾鲁棒性设计指标和结构约束的频率加权函数的选取方法.利用加权函数选取的自由度,在干扰观测器低通滤波器设计中,实现Q—滤波器在截止频率上的高峰幅度与干扰抑制性能之间的最佳折中,使得干扰观测器在满足其幅度指标的条件下,具有最优干扰抑制性能.实验结果表明该方法保证了闭环反馈系统的鲁棒稳定性,同时,具有实现其他设计指标的自由度.

Systematic Design Method of Disturbance Observer Guaranteeing Closed-loop System's Robust Stability

The sufficient condition on the robust stability against model uncertainties in the feedback system with disturbance observer(DOB) is studied.Weighting functions satisfying this condition are consequently selected such that robust stability to plant s parameters variation is guaranteed by the disturbance observer designed with standard H∞ disturbance observer design method.Selection methods of frequency weighting functions are proposed concerning about the robustness design specifications and structural restrictions in designing the H∞ DOB.Trade-off between peek magnitude in cut-off frequency of Q-filter and disturbance depressing performance is optimized in designing low-pass filter of disturbance observer via selections of the weighting functions.Therefore,the resultant disturbance observer has the optimal disturbance rejection performance with satisfactory peak magnitude.Experimental results show the proposed method could guarantee robust stability of closed-loop system while providing design freedom for other available design specifications.