Underactuated UUV Three-dimensional Trajectory Tracking With Multiple Constraints

With the continuous development of China’s technology of the marine equipment,the unmanned underwater vehicle(UUV)has become an irreplaceable force in the exploration and utilization of marine resources.For UUV,the first condition to ensure that it can successfully complete the task is that UUV must be able to track the desired trajectory autonomously.In the actual tracking process of UUV,it will be affected by many factors from the marine environment and constraints from itself,such as parameter perturbation,external force interference,input time delay,actuator saturation and so on.If these interference constraints are ignored during the controller design process,not only will the tracking accuracy of the system be degraded,but also the stability of the system will be affected.Therefore,this paper studies the underactuated UUV trajectory tracking control under multi-constraint conditions.Firstly,the kinematic model of UUV is obtained by establishing a fixed coordinate system and a moving coordinate system.Then the dynamic equation of UUV is obtained by force analysis.Then,in order to facilitate the stability analysis of the time-delay system,the Lyapunov-Krasovskii stability theory,which is a tool for analyzing the stability of time-delay systems,is introduced,and the commonly used inequalities in the stability analysis of time-delay systems are also introduced at the same time.Then the difficulty of designing the underactuated UUV trajectory tracking controller is expounded.Secondly,a filter tracking error is designed for the design of underactuated UUV’s 3D trajectory tracking controller under the input time-delay constraint,which transforms the UUV model with input delay into a model without input delay.Then a trajectory tracking controller with time delay compensation is designed by using the model without time delay.A designed Lyapunov-Krasovskii functional is used to prove the stability of the system,and the relevant simulation verification of the controller.Thirdly,on the basis of dealing with the previous time-delay problem,UUV trajectory tracking control with actuator saturation constraint is also considered.By using smooth hyperbolic tangent function to limit the output,a continuous saturated time-delay tracking controller for underactuated UUV is designed.By designing appropriate Lyapunov-Krasovskii functional,the stability of the system is analyzed based on Lyapunov.The designed tracking controller is verified by simulation.Finally,in view of the input delay and parameter perturbation during the UUV navigation process,this paper evaluates the parameter perturbation items existing in the model and transforms it into a new time-delay-free model.Then further consideration is given to adding actuator saturation constraint to the previous constraints,and designing the underactuated UUV trajectory tracking controller based on it.The stability is then proved by designing a suitable Lyapunov-Krasovskii functional.The simulation results show that the underactuated UUV can achieve good tracking performance by using the designed controller.