带非线性观测器的欠驱动船舶自适应动态面输出反馈轨迹跟踪控制

Adaptive dynamic surface output feedback trajectory tracking control for underactuated ships with nonlinear observer

针对船速与艏摇角速度均不可测的三自由度欠驱动船舶轨迹跟踪问题,考虑在海洋环境扰动未知,提出一种带非线性观测器的动态面自适应输出反馈控制方法。该方法通过对系统模型进行坐标变换,设计非线性观测器估计船舶的速度向量;采用动态面技术可处理反演法对虚拟控制量求导导致的"微分膨胀"问题,减少计算量;同时采用自适应律估计海洋环境干扰的界值,从而防止参数漂移。利用Lyapunov函数证明该控制律可保证船舶轨迹跟踪误差的一致最终有界性,仿真结果证明了所提出控制方法的有效性。

To solve the problem of underactuated ship trajectory tracking with immeasurable states, an adaptive dynamic surfaceoutput feedback control approach is proposed in the presence of unknown environmental disturbances. The nonlinear observer is designed to estimate the velocity state variables by coordinate transformation of the system. The dynamic surface control technology is introduced to eliminate the “differential explosion” problem of traditional back-stepping methods on the direct derivative of virtual control, which can reduce the computational burden. An adaptive control law incorporated with σmodification is used to estimate the bound of the unknown environmental disturbances, which can prevent parameters from drifting. Application of Lyapunov function analysis proves that the trajectory tracking error is uniformly ultimate bounded. Finally, numerical simulation results demonstrate the validity of the proposed strategy.