推进器饱和/故障下的无人艇固定时间指定性能容错控制

Fixed-time specified performance fault-tolerance control of an unmanned surface vehicle with thruster saturations/faults

针对系统动态未知的无人艇(USV)在推进器故障与饱和约束下轨迹跟踪问题,本文提出一种基于固定时间扩张状态观测器的积分滑模容错控制方法.首先,构造固定时间扩张状态观测器,实现未知速度信息、集总未知非线性的准确估计.进而,通过引入一种新型设定时间性能函数,约束位姿跟踪误差,并利用误差转换函数将其转化为无约束误差动态系统.在此基础上,结合固定时间积分滑动模态与饱和补偿动态系统,设计固定时间控制策略,保证系统实际固定时间稳定且位姿跟踪误差严格位于指定范围内.最后,仿真验证所提出控制方法的有效性与优越性.

In this paper,an integral sliding-mode fault-tolerance control scheme based on the fixed-time extended state observer(FxESO-ISMFC)scheme is proposed for trajectory tracking of an unmanned surface vehicle(USV)with unknown system dynamics and thruster saturations/faults.First,a fixed-time extended state observer is constructed to achieve accurate estimation of unknown velocity information and the lumped nonlinearity,simultaneously.Furthermore,a setting-time performance function is introduced to constrain the position tracking error,such that the tracking error constraints can be transformed into the unconstrained error dynamic system through a conversion function.On this basis,a fixed-time tracking control scheme is designed by combining the integral sliding-mode with the saturation compensation system,which can ensure that the system is practical fixed-time stable.While position tracking errors are strictly within the specified ranges.Simulation results demonstrate the effectiveness and superiority of the proposed FxESO-ISMFC strategy.