Research On Position Detection Control Method Of Underwater Propulsion System Based On Sliding Mode Observer

With the continuous expansion of China's marine industry and the shortage of land resources,there is a higher demand for the exploration and exploitation of marine resources.The Remotely Operated Vehicle(ROV)has the advantages of strong environmental adaptability,convenient control and strong endurance.The underwater propulsion system is the power core module of the underwater robot.To achieve stable operation in an unknown environment,it must rely on a safe and reliable underwater propulsion system,including a system structure with good sealing and pressure resistance.Run a stable drive control algorithm.In this paper,a high-power,small-volume underwater propulsion system is developed for the deep-sea operation of underwater auxiliary oil recovery robots.Based on this,a new algorithm based on sliding mode observer for position sensorless drive control is developed.It is applied to an improved underwater propulsion direct torque control system.The main research contents are as follows:Firstly,on the basis of expounding the overall design scheme of underwater auxiliary oil recovery operation robot,the paper focuses on designing and developing the underwater propulsion system of underwater auxiliary production robot.The underwater propulsion system includes navigation cabin,control cabin,power cabin and underwater propeller.The paper completes the structural design of the underwater propeller and the design,fabrication and commissioning of the underwater propulsion system software and hardware.Then,the method of position sensorless control based on sliding mode observer is studied.A new method of direct torque control of underwater propulsion system based on new sliding mode observer position detection is proposed.The method introduces the hyperbolic tangent function into the line back-EMF sliding mode observer and applies the sliding mode observer to the traditional underwater propulsion direct torque control system.Simulation experiments show that the new sliding mode observer designed in this paper can estimate the line back EMF value better than the traditional sliding mode observer.Secondly,based on the design of the back-potential observation of the new sliding mode observer,the traditional direct torque control method is improved,so that the drive control system can perform sector discrimination and torque estimation by observing the line back EMF.Thereby six commutating switch signals are obtained,enabling improved direct torque control of the underwater propulsion system without position sensor detection.The propeller load characteristics of the underwater propulsion system are analyzed,and the parameters are fitted.The mathematical model of the propeller load characteristics is constructed and introduced as a load module into the improved underwater propulsion direct torque control system.The simulation experiments show that the new sliding mode observer designed in this paper can be used in the improved underwater propulsion direct torque control system under the propeller load characteristics,which can better perform sector discrimination and torque observation,and has a good closed loop.Control characteristics and effects,torque ripple is greatly improved.Finally,through the on-the-spot debugging of the navigation cabin,control cabin and power cabin,the real-time and accuracy of the data transmitted by each electronic cabin are verified.At the same time,the underwater propulsion is tested on land and underwater experiments.The designed speed,thrust and power of the underwater propeller meet the design requirements.Finally,the underwater propulsion system developed is systematically adjusted to verify the stability and practicability of the underwater propulsion system developed in this paper.