一类非最小相位系统未知频率正弦干扰的观测器设计

近年来,前馈补偿技术得到广泛研究,其可以提高系统的控制精度.对于非最小相位系统,很难给出干扰和可测信息的直接关系,此外,频率的不确定性以及估计值之间的耦合会导致大量冗余参数的运算.现有的自适应方法存在估计值之间的耦合,会增加干扰估计误差收敛性能分析难度.而基于干扰观测器控制(DOBC)通过调节控制器和观测器参数,可以同时对多源不确定进行补偿和抑制.基于此,提出一种分步式观测器设计方法.首先设计一种辅助滤波器和观测器对未知频率正弦干扰参数进行估计,同时给出干扰的等效形式;然后利用估计值构造观测器得到输入干扰状态,从而将这类非线性系统的干扰抵消问题转换为线性系统的观测器设计问题;最后通过李雅普诺夫定理和数值仿真验证所提出方法的有效性.

Observer design of unknown frequency sinusoidal disturbance for a class of nonminimum phase

In recent years, feedforward compensation technology has been widely studied which can improve the system control accuracy. For non-minimum phase systems, it is difficult to give the direct relationship between disturbance and measurable information. In addition, the frequency uncertainty and the coupling between the estimated values will add the parameter calculation burden inevitable. The coupling between the estimated values in existing adaptive methods makes it difficult to analyze the convergence performance of disturbance estimation errors. At present, disturbance observer based control(DOBC) can compensate and reject multi-source uncertainty simultaneously by adjusting controller and observer parameters. Therefore, a separate observer design method is presented in this paper. Firstly, the special auxiliary filter and observer are designed to estimate the sinusoidal disturbance parameters of unknown frequency, meanwhile, the equivalent form of disturbance is reformulated. Then, the observer is designed to obtain the input disturbance state. With above, the nonlinear non-minimum disturbance rejection problem can be simplified to the observer design problem for the linear system. Finally, the effectiveness of the proposed method is demonstrated using the Lyapunov theorem by numerical simulation.