Research Of Velocity Servo System For Towed Underwater Vehicle

The towed underwater vehicle can simulate the deep-sea-scene on land,which is an effective means to verify the function and performance of inflatable liferaft.The main work of this paper is to develop a speed servo system for the towed underwater vehicle,so the functional and performance requirements for simulating the uniform motion of deep-sea vehicles under automated conditions are guaranteed.In order to meet the requirements of underwater test,the vehicle needs to be dragged by the towing winch and the reset winch.After three-stage motion of acceleration,uniform motion and deceleration,it will reach the specified test position in the specified speed within the required time to release the inflatable liferaft.It has harsh requirements for the rapidity and accuracy of controller,however,there are many constraints on space and force.For example,the length of the underwater track is limited;the system can only pressure terminate tensile force;the length of the wire rope brings stability problems.Therefore,practical control strategies and algorithms are needed to solve the contradiction between the rapidity,accuracy,stability and constraints of space and force,developmenting such an actual control system is the key issue to be solved in this paper.In the first,motion characteristics of the towed underwater vehicle are analyzed,which is helpful to define the requirements for the performance of speed servo system.Then the mathematical model of the control object is established,and a twin-winch control strategy is proposed considering that the underwater aircraft has large inertia,variable load and insufficient system stiffness.The nonlinear auto disturbance rejection algorithm is used to control the speed of the underwater vehicle;the rotor flux linkage vector control method is used to control the two inverter motors which provide power for the whole vehicle.Digital simulation of the entire system is producted with Simulink.Subsequently,the engineering development of the speed servo system was carried out,including scheme design,hardware selection,software development,on-site hardware integration and software debugging work.The control effect of motor in bottom layer and even the whole vehicle was verified through field test.After the field test,we can find that the system we designed and developed can meet its functional requirements and indicators of capability.Its functions are complete and reliable,and the proposed control strategy and algorithm can be used to control the the motion of underwater vehicle which is heavy and dragged by steel cable.This work provides a solution to the key technical issue actually,which has made the servo control system behave as well as we expected and safe enough during the operation.This is a contribution to theoretical research and engineering.