Research On Trajectory Racking Algorithm For Underwater Vehicles Based On High Order Sliding Mode Control

With the increasingly prominent strategic position of ocean development in the country,there is an increasing demand for ocean exploration by humans,and underwater robots are increasingly widely used for tasks such as resource exploration,observation,and ocean research.Among them,ROV has attracted increasing attention due to its higher real-time performance and flexibility,playing an irreplaceable role in the military and civilian fields.However,there are many technical challenges in the actual motion control of ROV,and trajectory tracking control technology,as a necessary extension and supplement to ROV control technology,has important research value.Due to the complex ocean environment,hydrodynamic coefficient disturbances,and unpredictable external disturbances that constantly affect the underwater motion of ROVs,the underwater velocity of ROVs is often difficult to measure.These issues make the implementation of precise trajectory tracking control for ROV very challenging.This article investigates the trajectory tracking control of ROV by designing a controller and observer based on high-order sliding mode theory.The main research work of this article includes the following aspects.Firstly,considering the problem of time-varying ocean current interference on ROV during underwater motion,a mathematical model of the ROV motion control system was established.According to the conversion relationship between inertial coordinate system and body coordinate system,a simplified four degree of freedom motion model of ROV is established.In order to reduce the chattering problem in traditional Sliding mode control,an adaptive super torque terminal Sliding mode control(ASTNTSMC)method is designed.Secondly,in response to the problem of difficult measurement of velocity information and uncertainty of model parameters in ROV control,a high-order sliding mode observer(HOSMO)is designed by standardizing the ROV model and centralizing the processing of uncertainty and external disturbances.The speed of the ROV can be estimated based on known external position information,Full state feedback controllers can be designed without speed sensors and effectively reduce the impact of model uncertainty on the design of robot trajectory tracking controllers.The simulation results demonstrate that the designed controller can achieve closed-loop control of the robot by estimating information,which not only responds faster,but also has higher accuracy and robustness.Finally,based on the robot architecture and control model parameters studied,the physical system and software of the ROV were designed.The functionality of the robot system was tested in a laboratory pool environment.The depth and attitude control control experiments of ROV are carried out.It has been proven that the designed ROV can effectively complete underwater tasks.