欠驱动水面船舶的非线性滑模轨迹跟踪控制

针对模型参数存在不确定性和风、浪、流时变干扰的三自由度欠驱动水面船舶动态轨迹跟踪控制问题,根据滑模控制对系统的不确定性和外界干扰具有鲁棒性的特点,提出了一种新型的非线性滑模控制律设计方法.在设计时根据欠驱动水面船舶的固有特性,船舶在横向上没有驱动,如果要同时控制船舶水平面位置和艏摇角3个自由度的运动,就需要分别引入关于纵向跟踪误差的一阶滑动平面和关于横向跟踪误差的二阶滑动平面来间接设计控制律.仿真结果表明,所设计的控制器能够使船舶跟踪虚拟船产生的参考轨迹,对参数不确定和外界扰动具有强的鲁棒性.

Nonlinear sliding mode tracking control of underatuated surface vessels

Considering the model parametric uncertainties and time-varying disturbances induced by waves,wind,and ocean-current in the trajectory tracking control of a 3 degree-of-freedom(3DOF) underactuated surface vessel,a novel nonlinear sliding mode control law was designed using sliding mode techniques,in view of the sliding mode’s robustness in anti-system uncertainties and environmental disturbances.According to the inherent characteristics of underactuated surface vessels,there were no side thrusters in the sway direction,and in order to control the ship’s 3DOF plane motion in surge,sway,and yaw directions,the control law was developed by introducing a first order sliding surface in terms of surge tracking errors and a second order sliding surface in terms of lateral motion tracking errors.Numerical simulation results show that the proposed controller is strongly robust regarding the uncertain parameters and disturbances,and can force the vessel to track a desired trajectory which is generated by a virtual ship.