状态测量不确定和动力学未知的无人艇固定时间容错控制

Fixed-time Fault-tolerance Control of an Unmanned Surface Vehicle With Uncertain Measurements and Unknown Dynamics

针对含有推进器故障和状态测量不确定的无人艇(Unmanned surface vehicle, USV)系统,提出一种基于双扰动观测器的固定时间容错跟踪控制(Double disturbance observer-based fixed-time fault-tolerance control, DDO-FxFC)方法.设计两个固定时间扰动观测器,分别估计状态测量不确定性产生的非匹配干扰和包含推进器故障的集总非线性,同时自适应实时补偿未知观测误差;采用测量位姿跟踪误差及其动态,设计快速非奇异终端滑模面,构建DDO-FxFC框架;理论分析证明DDO-FxFC方法能够确保跟踪误差固定时间收敛,其中收敛时间的上界独立于系统初始状态;针对原型USV的仿真结果和综合对比验证所提出DDO-FxFC技术的有效性和优越性.

In this paper,a double disturbance observer-based fixed-time fault-tolerance control(DDO-FxFC)scheme is developed for an unmanned surface vehicle(USV)in the presence of thruster faults and measurement uncertainties.To be specific,two fixed-time disturbance observers are devised to estimate the mismatching disturbances generated by measurement uncertainties and the lumped nonlinearities including thruster faults,respectively,while unknown estimation errors are compensated in an adaptively real-time manner.Furthermore,a fast nonsingular terminal sliding-mode using measurement tracking errors and their dynamics is deployed to build up the DDO-FxFC framework.Theoretical analysis proves that the DDO-FxFC scheme can ensure fixed-time convergence of tracking errors,whereby the upper bound of convergence time is independent of initial states.Simulation results and comprehensive comparisons on a prototype USV demonstrate the remarkable effectiveness and superiority of the proposed DDO-FxFC scheme.