基于非奇异快速终端滑模的多水面船固定时间协同控制

Fixed-time cooperative control for multiple surface vessels based on nonsingular fast terminal sliding mode

针对多水面船协同控制过程中存在的时变海洋环境干扰、模型参数不确定性、速度测量值未知和输入饱和的问题,提出一种基于非奇异快速终端滑模的固定时间分布式协同控制方案,该方案可保证协同控制系统的全局固定时间稳定性.首先,设计一个固定时间扩张状态观测器,用于估计速度和集总干扰(包括时变海洋环境干扰和模型参数不确定性);其次,设计一种新型的固定时间辅助动态系统处理输入饱和;再次,基于固定时间非奇异快速终端滑模面提出一种分布式抗饱和的滑模控制器,消除系统的奇异性,并且使得收敛时间上界独立于系统的初始状态;最后,为了避免在编队控制律中使用邻船的加速度,设计一种改进的一致鲁棒精确微分器估计邻船的加速度信息.仿真结果验证了所提方案的有效性.

This paper presents a fixed-time distributed cooperative control scheme based on non-singular fast terminal sliding mode to solve the problems of time-varying marine environment disturbances,model parameter uncertainties,unavailable velocity measurements and input saturation in the cooperative control process for multiple surface vessels.The scheme ensures the global fixed time stability of the cooperative control system.Firstly,a fixed-time extended state observer is designed to estimate the velocities and lumped disturbances,including time-varying marine environmental disturbances and model parameter uncertainties.Secondly,a novel fixed-time auxiliary dynamic system is designed to deal with input saturation.Thirdly,a distributed anti-saturation sliding mode controller is proposed based on the fixedtime non-singular fast terminal sliding mode manifold to eliminate the singularity of the system,and make the upper bound of convergence time independent of the initial state of the system.Finally,in order to avoid using the acceleration for the adjacent vessel in the formation control law,an improved uniform robust exact differentiator is designed to estimate the acceleration information.The simulation results show that the proposed scheme is effective.