Design And Realization Of A High Speed Unmanned Underwater Vehicle Motion Control System

Unmanned underwater vehicles(UUV)are vehicles that can operate via remote control or autonomous underwater navigation using built-in batteries.UUVs have strong operational capabilities,good maneuverability and wide range of motions.Therefore,UUVs play important roles in marine development and research nowadays.Good motion control and path tracking capabilities are the basic technical prerequisites for UUVs to complete various underwater operations,which makes UUVs motion control one of the key research interests in UUVs area.With the expansion of UUVs missions,attention has begun to be paid to UUV with both low speed cruising and high speed navigation capabilities.Compared with medium/low speed UUVs,high-speed UUVs are prone to cause larger tracking error,which also brings higher requirements to its motion control system and algorithm.Therefore,the well-designed high-speed UUV motion control system is the basic premise of improving its tracking ability and ensuring its operation capability at high speed,which has important practical significance.In this study,a motion control system is designed based on a high-speed UUV(with a maximum speed of more than 20 knots).The auto-navigation task for 3D path consisting of several target points is decomposed into horizontal plane path tracking and vertical plane depth task,and the control algorithms are proposed respectively.The main work is as follows:Firstly,the UUV software and hardware system are designed.According to the design task,the whole control system is divided into a shipboard end and a vehicle end.The hardware system is built and then the software program is developed.The UUV combines the functions of signal acquisition,data processing,information storage and graphic interface display together.Two motion modes of shipboard,manual remote control and UUV autonomous navigation,are realized.The reliability of the hardware platform and the correctness of the software program is proved by UUV remote control experiment.Secondly,the UUV motion control models are established.According to the actual situation and combined with the motion characteristics of UUV,the 6-DOF motion model is decoupled into horizontal motion control model and vertical plane motion control model,the maneuverability simulation analysis is carried out,and the results verify the accuracy of the control model.Finally,the UUV motion control strategies are designed.A tracking algorithm based on lineof-sight(LOS)guidance with time-varying foresight distance is adopted for the horizontal plane straight-line path tracking problem and a double closed-loop PID control algorithm for distance deviation is proposed for high-speed navigation,which suppresses the large steering error at high speed.The simulation results show that the algorithm can reduce the tracking error and improve path tracking effect.Aiming at the vertical plane tracking problem,a cascade PID controller is designed to ensure safety and stability requirements.The simulation results show that the designed controller enables the UUV to accomplish the vertical plane tracking task.