控制方向未知的时变非线性系统鲁棒控制

针对一类具有未知时变控制方向、不确定时变参数以及未知时变有界干扰的严反馈非线性系统,给出一种带有死区修正算法的鲁棒控制方法.在控制系数符号未知的情况下,通过在反步法中引入Nussbaum增益和死区修正技术,得到一种修正的鲁棒反步设计方法.该方法不需要未知时变控制系数的上下界先验知识以及不确定参数和外界干扰的上界信息.算法保证了闭环系统所有信号的有界性,同时使得跟踪误差收敛于零的任意小邻域内.

Robust Control of Time-varying Nonlinear Systems with Unknown Control Directions

A robust control approach with a dead zone modification is proposed for a class of time-varying uncertain strict feedback nonlinear systems with completely unknown time-varying control directions, uncertain time-varying parameters and tmknown time-varying bounded disturbances. Nussbaum gains and dead zone modification are introduced in the backstepping design to obtain robust controller for systems without a priori knowledge of the signs of the control directions. The modified robust backstepping control design method need not require knowledge of the bounds of the uncertain time-varying control coefficients, the upper bounds of the uncertain parameters and the bounds of unknown time-varying disturbances. It is proved that under the proposed control, all the closed-loop signals are bounded and the tracking error converges to any prescribed small interval around zero.