具有未知扰动上界的气垫船全鲁棒滑模控制

Global sliding mode control for hovercraft with unknown disturbance upper bound

本文以轨迹跟踪为任务目标,针对具有未建模动态,参数不确定和未知扰动的全垫升气垫船非线性动力学模型,提出了一种新颖的全鲁棒滑模变结构控制器,并且结合一种不需要扰动上界信息的综合观测器对系统的总扰动进行前馈补偿.首先给出气垫船四自由度的运动学和动力学矢量模型,在扰动上界未知的条件下,针对系统内外不确定性的本质不同,分别设计前馈补偿,同时加入补偿项进一步减小估计误差.然后,设计了一种新颖的无趋近过程的全鲁棒滑模控制器,保证高速行驶的气垫船在未知扰动的环境中仍能够较好的完成跟踪任务,减小跟踪误差的同时消除抖振,增强气垫船控制系统的鲁棒性.通过Young’s不等式和李雅普诺夫稳定性证明整个联动系统的稳定性,仿真结果表明该方法的有效性.

In this paper,with trajectory tracking as the task goal,a novel global sliding mode controller is proposed for the nonlinear dynamic model of hovercraft with unmodeled dynamics,uncertain parameters and unknown disturbances,and combined with a comprehensive observer that does not require disturbance upper bound information,feedforward compensation for the total perturbation of the system.First,the kinematics and dynamics vector model of the hovercraft with four degrees of freedom is given.Under the condition that the upper bound of the disturbance is unknown,the feedforward compensation is designed separately according to the essence of the uncertainties inside and outside the system,and an observer’s compensation term is added to further compensate the observation error.Then,a novel global sliding mode controller with no approaching process is designed to ensure that the hovercraft traveling at high speed can still complete the tracking task well in the unknown disturbance environment,has smaller buffeting,achieves smaller tracking errors and enhances the robustness of the hovercraft control system at the same time.The stability of the entire linkage system is proved by Young’s inequality and Lyapunov stability,and the simulation results verify the effectiveness of the method.