Research On UUV Near-Bottom Terrain Tracking Strategy And Control Method

Unmanned Underwater Vehicle(UUV)is an autonomous underwater vehicle,which is widely used in military,scientific and economic fields,it can complete tasks such as intelligence gathering,topographic surveys,shipwreck salvage,seabed search and rescue.It is performing these tasks,especially for seabed topography surveys,in order to get accurate information,UUV should maintain a stable height from the sea floor,in other words,near bottom following.However,the seabed is unknown and rugged in the actual marine environment,it is difficult for UUV to achieve near bottom following Therefore,it is of great theoretical significance and practical value to study the near-bottom terrain tracking problem of UUV in the unknown environment.In this paper,a tracking strategy based on seabed feature guidance is proposed for UUV's terrain tracking problem in the unknown environment.Firstly,the analysis of the tracking problem of the near-bottom terrain tracking is proposed,and three single-beam detection sonar detection infrastructures for seabed topography are designed.Secondly,the seafloor topographic feature extraction is performed based on the ranging fusion information of the single beam ranging sonar.Finally,a terrain tracking strategy based on terrain features to determine the UUV navigation altitude command is proposed.Aiming at the problem of three-dimensional unknown terrain tracking,this paper proposes a near-bottom terrain tracking control architecture for UUV.It transforms 3D terrain-tracking into joint control of horizontal and vertical planes.That is,UUV tracks the desired two-dimensional horizontal plane track points on a horizontal plane.Designing a height controller using backstepping method to control the sailing altitude of UUV based on the in-situ bottom-following strategy in the vertical plane,which enables UUV to track real-time 3D terrain.This paper uses MATLAB software to verify the above control strategies and methods.First,four typical two-dimensional seabed terrain models,namely uphill terrain,downhill terrain,convex terrain and concave terrain,were established.Verify the real-time and effectiveness of control methods by tracking four terrains.Then,the terrain-tracking simulation experiments of UUV with different sonar installation angles and different speeds were carried out.Finally,a complex three-dimensional seabed topography was established,and the proposed control architecture,tracking strategy and control method were verified.In a conclusion,the proposed algorithm and method for tracking and controlling the near bottom following can not only accurately track the gentle terrain,but also effectively and safely track the rugged terrain,which is easy to implement and has good practical value.