基于干扰观测器的输入受限非线性系统鲁棒控制

Robust control of nonlinear systems with input constraint based on disturbance observer

针对一类单输入单输出非线性系统,提出了一种有效处理输入饱和及未知外部干扰的控制方法,并应用于近空间飞行器的控制设计。利用双曲正切函数及Nussbaum函数的特殊性质对输入饱和进行处理。通过干扰观测器实现对复合扰动的有效逼近。考虑到反步控制中存在的计算膨胀和虚拟控制信号光滑性的问题,结合反步法和动态面法设计了相应的控制器。通过Lyapunov分析证明了所设计的控制律可以使闭环系统所有信号半全局最终一致有界,且跟踪误差和干扰逼近误差最终有界。仿真结果证明了该方法的有效性。

An effective control method in the control design for a near space vehicle （NSV）is proposed to deal with the input saturation and unknown external disturbance for a class of single-input and single-output （SISO）nonlinear system. The special properties of a hyperbolic tangent function and a Nussbaum function are used to handle the input saturation. A disturbance observer is designed to approximate the composite disturbance. Considering the problems of the calculation of ex- pansion and the smoothness of virtual control signals, a corresponding controller is designed combining the backstepping approach and the dynamic surface method. It is proved with the Lyapunov analysis that the proposed control scheme can guarantee that all signals of the closed-loop system are semiglobally, uniformly and ultimately bounded. The tracking error and observer error are ultimately bounded. Simulation results show the effectiveness of the method proposed here.