Research On Motion Control Of Underwater Unmanned Vehicle With Input Time-Delay

Among the key technologies of Unmanned Underwater Vehicles(UUVs),motion control technology is one of the key technologies to ensure UUVs perform survey and reconnaissance tasks successfully.Time-delay factors and model uncertainty factors are common in underactuated UUV motion control systems.By analyzing the existing research results of marine robots motion control at home and abroad,it is concluded that in the current research results of underactuated UUV motion control,in order to simplify the design of underactuated UUV motion controller,the input delay introduced by the actuator is usually ignored.However,even small input delays can have significant negative impacts on the underactuated UUV motion control system which requires high real time performance.Therefore,this paper will consider the influence of time-delay,and study the problem of stabilization and trajectory tracking control under the constraint of uncertainties and external disturbances of underactuated UUVs.Firstly,the 6-DOF motion modeling of the underactuated UUV is established by analyzing the stress of underactuated UUV.The influence of time-delay on the system control performance is introduced in detail.And the Lyapunov-krasovskii stability theory,which is the basis of time-delay system control theory,is proposed.Then,the tools used in controller design of time-delay systems are introduced: linear matrix inequalities and common inequalities for dealing with time-delay terms.The constraints that must be considered in the design of underactuated UUV motion controllers with time-delay are summarized.Secondly,for the underactuated UUV three-dimensional stabilization control constrainted by input time-delay,a kind of state feedback controller is designed to make it easier to implement.By introducing the free weight matrix,Moon inequality and Jensen inequality to reduce the conservativeness introduced by the Lyapunov-Krasovskii functional.And then the stable condition of the LMI form is exported.The robustness of the proposed control law to the input delay of actuators is proved by comparing the simulation results.Then,a kind of time-delay state feedback stabilization controller is designed for the underactuated UUV three-dimensional stabilization control constrainted by input time-delay and model parameter uncertainty.By analyzing the sources of the underactuated UUV parameter uncertainty,the uncertainty of underactuated UUV's inertia matrix coefficient is mainly considered.Under this condition,the state feedback controller with time-delay is improved,and the state feedback control law that can guarantee the system to be uniformly asymptotically stable is given.And the feedback gain of the state feedback controller is solved by the LMI method.A simulation experiment of time-delay stabilization control with bounded parameter perturbation norm is designed.The results show that the proposed control law is robust to parameter perturbation.Finally,a kind of integral sliding mode controller is designed for underactuated UUV trajectory tracking control problem under the constraints of input time-delay,model parameter uncertainty and external disturbance.In order to facilitate discussion,the underactuated UUV input time-delay model was simplified.The system was divided into a cascade system consisting of a kinematics subsystem and a dynamics subsystem.And the trajectory tracking position and velocity error equation are established.Then,based on the control idea of the cascade system,the integral time-delay sliding mode control law is designed for the trajectory tracking position and velocity error respectively.By constructing a suitable form of Lyqpunov-Krasovskii functional,the subsystem stability is analyzed and the global stability conclusion of LMI form is given.Simulation results show that the proposed control law achieves fast and smooth tracking of the desired trajectory by the underactuated UUV.