含有非匹配干扰和未知动态的非仿射系统滑模控制算法

针对含有非匹配干扰和未知动态的非仿射系统控制问题,提出了一种基于扩张状态观测器(ESO)的改进滑模控制(SMC)方案.本文首先利用扩张状态观测器,将原系统转变为一个包含干扰的二阶积分级联系统,使含有未知动态的非仿射系统控制器设计问题转化为二阶积分级联系统的控制器设计问题,从而使得控制器在设计过程中不需要对对象模型完全已知.为了改善ESO的瞬态性能,提出了一种含有预设性能函数(PPF)的改进ESO,利用PPF对估计误差进行约束,抑制ESO收敛过程中的振荡和超调.其次,提出了一种带有修正项的改进滑模面,在降低ESO估计误差所带来的非匹配干扰影响的同时,也提高控制系统的收敛速度和跟踪精度.仿真算例表明,所提的改进ESO能够更快收敛,振荡次数显著减少,改进的滑模控制能够处理非匹配干扰的影响,并获得更快的收敛速度以及更高的跟踪精度.

Sliding mode control for unknown non-affine system with mismatched disturbances

A sliding mode control (SMC) scheme based on the extended state observer (ESO) is proposed for unknown non-affine systems with mismatched disturbances. By using the extended state observer, the original system is transformed into a second-order integral series system with disturbance, and the problem of control design for the non-affine system with unknown dynamics and disturbances is transformed into that of an integral series system. Therefore, it is not necessary to completely know the model during the control design. Firstly, a modication with the prescribed performance function (PPF) is introduced into ESO design for improving the transient performance of the ESO. In the design, the PPF guarantees the bound of the estimation error and suppresses the oscillation and overshoot in the response process. Then, a sliding surface with a correction term is proposed to reduce the influence of mismatched disturbances caused by ESO estimation error, and improve the tracking speed and accuracy of the control scheme. Finally, the simulation results show that the proposed ESO converges faster and the oscillations are significantly suppressed. The improved SMC can deal with mismatched disturbances and has a faster convergence speed and higher tracking accuracy.