Trajectory Tracking And Formation Control Of Autonomous Underwater Vehicles

As complex systems,integrated with artificial intelligence,sensor network,advanced material,new technology,autonomous planning,autonomous navigation,environmental perception,target detection,Autonomous Underwater Vehicle(AUV)is widely used in military and civil fields.This thesis addresses the trajectory tracking and formation control of AUVs in the presence of time-varying disturbances,model parameter uncertainties,input saturation,without velocity measurement,etc.A series of studies is carried out by the command filtered technology,the auxiliary dynamic system,fixed-time control theory,the radial basis function neural networks and adaptive technology.The main research work is as follows.(1)For the trajectory tracking control problem of AUV subject to unknown time-varying disturbances and input saturation,the trajectory tracking control law is designed using auxiliary dynamic system,disturbance observer,error compensation system and command filtered technique.Here,the command filter avoids the differential operation of the intermediate virtual control function,which makes the controller design simple and improved tracking performance.Furthermore,considering the thruster dynamics and model parameter uncertainties of AUV,a disturbance observer is first designed to estimate the compound disturbances induced by model parameter uncertainties and unknown disturbances,then based the observer,command filter and the auxiliary dynamic system,a tracking control law is designed,and the global fixed-time stability of the closed-loop system is guaranteed.(2)For the formation control problem of AUVs in the presence of model parameter uncertainties,and a formation control law is designed using the radial basis function neural networks and adaptive technique.The AUV uncertain dynamics is approximated by the adaptive radial basis function neural networks,which improves the formation accuracy.Further,under without leader's velocity,unknown time-varying disturbances and LOS range andangle constraints,a state observer is designed to estimate the velocity of leader within settling time,and the formation control law which only depend on position and heading of leader AUV,is designed combining the command filtered technique,error compensation system,In-type barrier Lyapunov function(BLF)method,the radial basis function neural networks and the adaptive technique.Here,the command filter simplifies the controller design,the filter error is compensated and the In-type BLF guarantees that the LOS range and angle satisfy the time-varying constraint requirements.(3)For the formation control problem of AUV based on fixed-time theory,firstly,under the model parameter uncertainties and time-varying disturbance,a fixed-time based disturbance observer is designed to estimate the unknown disturbance,based on the observer,the formation control law is designed combining command filtered technique,and the global fixed-time stability of the closed-loop formation control system is guaranteed,too.Secondly,under without velocity measurement,a state observer is designed to estimate the velocity of AUV within settling time,and the formation control law,which depend on estimated velocity and measured position,is designed combining command filtered technique,error compensation system,the radial basis function neural networks and adaptive technique.The control law is simple to computer due to introducing the command filter,the filter errors are compensated by compensation system,the uncertain dynamics is approximated by the adaptive radial basis function neural networks,the upper boundary of the interference is estimated by adaptive technique,and practical fixed-time stability of control system is guaranteed.Finally,under continuous communication mode,an event-triggered intermittent communication is designed and switching between the continuous communication mode and the periodic communication mode is realized.In order to avoid the Zeno phenomenon and ensure that the formation is realized within the sampling period,the formation control law is designed and the global fixed-time stability of the closed-loop system is guaranteed.(4)The numerical simulations under the above designed trajectory tracking control laws and formation control laws are carried out using the Matlab/Simulink toolbox,respectively.The simulation results show that the designed trajectory tracking control laws make the AUV to the desired trajectory and achieve the trajectory tracking of AUV in the presence of time-varying disturbance,model parameter uncertainties,input saturation and thruster dynamics.In addition,the simulation results show that the designed formation control laws make the follower AUV track the leader AUV at the desired configuration and achieve the formation control of AUV with time-varying disturbance,model parameter uncertainties,LOS range and angle constraints as well as unmeasured AUV velocities.