Research On Motion Control Method Of Variable Load Underwater Unmanned Platform

With the situation that less and less resources available on land,the exploitation and utilization of marine resources is particularly urgent.Marine development requires advanced technologies and equipment,and underwater unmanned platforms have obvious advantages over common submersibles in solving long-term detentions and diversification of operational tasks,which has attracted the attention of various countries.Because of requirements of casting mission load at the target location,add with the complicated underwater environment,therefore the dynamic performance of the underwater unmanned platform is time-variable and strongly non-linear,which will impact the posture and fixed-point control accuracy of underwater unmanned platforms.Therefore,it has important research significance and practical value to study the motion control method of underwater unmanned platforms.This paper develops an underwater unmanned platform which provides experimental carriers for its control technology research.In order to acquire posture information of an underwater unmanned platform,corresponding sensors are selected and installed;a software and hardware control system are designed.In order to achieve accurate control of the underwater unmanned platform,based on the establishment of underwater unmanned platform thruster dynamic model,an underwater unmanned platform dynamic model that based on floating-base multi-rigid body system assumption is established and identified off-line by pool experiment performed.In order to verify the accuracy of the identified dynamic model,a confirmatory experiment is performed to identify the Yawing dynamic of The underwater unmanned platform.This paper develops a buoyancy regulation system that can precisely adjust the water volume of the ballast tank.After task load of unmanned platform is released,a part of the weight will be lost,resulting in a change in the re-buoyancy vector of the experimental carrier,which resulting in a change in the pitch posture of the experimental platform.According to the mission requirements,in order to ensure the balance of the heavy buoyancy of the carrier while the pitch posture is basically stable,this paper develops a hydraulic buoyancy regulation system.After the task load isreleased,for using the buoyancy adjustment system to balance the carrier's re-buoy force while controlling the t pitch posture.A single-neuron-based adaptive PID controller is designed to control the water volume of the front and rear ballast tanks and use Simulink to simulate on ballast tank water volume control.Aiming at the problem that the upper bound of total system uncertainty is difficult to determine and the control accuracy caused by the system's highly time-varying and strongly nonlinear dynamic characteristics by use general inversion sliding mode control method,when posture control is performed on an underwater unmanned platform.This paper designs a self-adaptive inversion sliding mode controller that introduces the state quantities ? of the system,the ordinary inversion slidingmode control method,to verify the validity of method in this paper.Aiming at the problem of steady-state deviation caused by adaptive inversion of sliding mode control method due to lack of estimation ability of total system uncertainty,this paper designs a self-adaptive inversion sliding mode controller based on RBF neural network,and simulates with the matching model before and after the task load is released by the Simulink module,and compares it with the adaptive inversion sliding mode control method above,to verify the effectiveness of the improved method.In order to compare the control performance of the improved control algorithm designed in this paper,a lateral contrast simulation experiment was conducted with an adaptive inversion sliding mode control method that uses the RBF network to directly approach the total system uncertainty.In order to verify the practical effect of the single neuron adaptive PID water controller designed in this paper,the buoyancy control system developed in this paper is used to carry out the water volume control experiment.In order to verify that the adaptive inversion sliding mode designed in this paper is better than the control effect of ordinary inversion sliding mode,the underwater unmanned platform experimental carrier developed in this paper is used to perform different amplitude step and composite sine wave trajectory tracking pool verification experiments.In order to verify the control effect that adaptive inversion sliding mode controller based on RBF network designed in this paper,can effectively reduce the steady-state deviation compare to perform different amplitude step and composite sine wave trajectorytracking pool verification experiments.In order to verify the truly control effect that adaptive inversion sliding mode controller based on RBF network designed in this paper,A composite sinusoidal trajectory tracking and pool verification experiment was carried out by using the RBF network to directly approximate the total uncertainty of the system.