针对欠驱动船舶的模型参数不确定和外界风浪流干扰问题,为实现水平面的航迹跟踪控制,提出了一种基于上下界的滑模控制方法.首先利用反步法将控制器的设计分解为运动学回路和动力学回路.其次,在运动学回路中为实现位置跟踪误差的收敛,根据期望航迹与当前位置信息,设计船舶的纵向与侧移参考速度,并视为镇定位置误差的虚拟控制律;在动力学回路中,将虚拟控制律作为新的跟踪目标,利用滑模方法设计实际控制律实现对参考速度的跟踪控制,最终实现了欠驱动船舶的跟踪控制.最后对有无干扰下的欠驱动船模分别进行了仿真实验,仿真结果证明了控制律的有效性.
This paper studies the robust tracking control problem of an underactuated surface vessel with parameter uncertainties and external disturbances, and a sliding-mode methodology is proposed. The controller is divided by back- stepping method into the kinetic loop and the dynamic loop. In the kinetic loop, the desired position and the current position are used to determine the reference surge and sway velocities which are employed as the virtual control law in stabilizing the position errors. In the dynamic loop, the virtual control law is considered the new tracking target, and the real control law is designed by the sliding-mode method to realize the tracking control of the reference velocities. Eventually, the tracking control for the underactuated surface vessel is achieved. Simulations of the tracking control for the underactuated surface vessel with disturbances or without disturbances are performed. Results validate the effectiveness of the proposed method.