Interference Force Analysis And Control Research Of AUV Underwater Docking

As underwater unmanned work equipment,the autonomous underwater vehicle(AUV)has been paid more and more attention under the current upsurge of unmanned and intelligent.The research and application of AUV is a systematic project,among which the docking technology is the key technology to realize AUV continuous operation.Underwater docking is similar to the process of space/sky docking by using the fixed or mobile recovery device of AUV The AUV can accomplish a series of actions such as returning,approaching,docking,locking,etc.;it has a broad prospect of development.In this paper,the mother ship carries the recovery device,and completes the docking with the AUV to recover the AUV The design of recovery scheme,maneuverability simulation,interference force analysis,trajectory tracking of underactuated AUV,semi-physical simulation and visual simulation are completed.Firstly,the AUV underwater siting dynamic docking scheme,which is the basis of the full-text research,was established.The back of the sports mother-vehicle is equipped with a docking device as the recovery end,and the AUV is used as the control carrier.The whole recycling process is divided into three stages:homing,adjusting and siting.Finally,the AUV enters the docking device under the guidance of the acoustic and optical vision system.And lock to complete the recycling.In order to analyze the motion characteristics of AUV,a mathematical model of AUV was established to simulate and predict the maneuvering performance in a still water environment,including stability verification,speed and acceleration characteristics,swing performance and space motion capability,laid the foundation for the study of the design of the control systemSecondly,for the tracking control problem of the homing segment AUV,the control characteristics of the under-actuated AUV are analyzed firstly,and the controllability of the system is proved.Then,based on the influence mechanism of ocean currents,the motion model is modified.Based on this,the response and maneuverability of AUV under ocean current are studied,and the maneuver forecast is completed.The recovery of the homing segment can be transformed into the AUV trajectory tracking control problem.This paper proposes to combine the cascading backstepping method with the model predictive control theory to improve the dynamic performance and anti-interference ability of the control system through the rolling optimization process.And with the explicit constraint processing capability unique to the model predictive control,the control output and control parameters of the AUV are constrained.Finally,the trajectory tracking ability of AUV under ocean current disturbance and parameter perturbation is verified by simulation experiments.Furthermore,considering that the two-body hydrodynamic interference force due to the existence of the mother-vehicle may affect the AUV recovery,a hydrodynamic simulation experiment is carried out based on the studied object.By analyzing the flow field above the mother-vehicle,the superiority from the middle of the mother-vehicle is proved.According to the simulation data,the double-body interference of the siting segment is obtained.The two-body interference additional force is obtained by two Aitken interpolations,and then the AUV dynamic equation is modified to obtain the non-infinite static wide-water environment in the presence of the mother-vehicle,which improves the simulation accuracy.By optimizing the control strategy to suppress the influence of the two-body interference,on the one hand,by arranging the transition process to suppress the vertical position overshoot,on the other hand,by optimizing the thrust distribution strategy,the AUV’s ability to control the trimming motion is enhanced,and effectively improve the AUV’s ability to cope with double-body interference in the sitting segment.Finally,in order to show the whole docking process more intuitively,a 3D visual simulation system is designed,including model design,scene construction and rendering.Then based on the established semi-physical simulation platform,the simulation scene is driven by secondary development of the Vega program under the MFC framework.Finally,the 3D scene of the AUV underwater docking process was demonstrated.