Research On Underwater Water-hydraulic Manipulator System And Position Measuring Technology

Autonomous Underwater Vehicle(AUV: autonomous underwater vehicle)is a powerful equipment for marine environment investigation and resource exploration,which has the advantages of flexible movement and wide working range.Generally,AUV equips with small electric manipulator which operating range and load capacity are far less than the hydraulic manipulator of ROV.So it is unable to meet the actual needs of the operation,especially for complex,narrow space,dangerous,extreme environment of underwater high precision work task,the manipulator not only to ensure the storage of small volume AUV to reduce the sailing resistance,but also meet the large operating range and higher working precision to ensure the safety and reliability of operation.Therefore,it has important theoretical research significance and practical application value to study the AUV's hydraulic manipulator system with large operating range,miniaturization,high flexibility and high precision.The paper focuses on the research of five DOF underwater water-hydraulic manipulator system,mainly studies the water-hydraulic manipulator system and spatial measuring device.According to the main characteristics of functions of the underwater manipulator,the paper analysis the current development of underwater manipulator used by AUV and water-hydraulic manipulator at home and abroad from the point of view of structure and driving mode which finding the research direction of underwater water hydraulic manipulator structure that is suitable for small AUV.Meanwhile,the paper analyzes the research status of the accuracy measurement and the methods of underwater manipulator control,and provides the technical basis for the design of the spatial position measuring device and the improvement of the hydraulic manipulator precision.Aiming at the design ideas of lightweight,modular,a large expansion length and small back volume,the paper analyzes the overall design of underwater manipulator and designs the module division of manipulator mechanical structure.In order to improve the mechanical structural strength,stiffness,reduces vibration frequency and increases the reliability of mechanical structure,the paper optimizes manipulator joint linkage and analyzes the modal of manipulator.To realize high precision control of the manipulator and in accordance with the need of the small flow control about manipulator joints,this chapter designs a set of small flow hydraulic drive system and analyses the pressure loss of hydraulic system,friction characteristics and water medium,the equivalent bulk modulus of the hydraulic hose.The paper studies the forward kinematics of the manipulator based on the D-H method,and also studies the underwater manipulator's inverse kinematics and inverse kinematics equations based on the inverse transformation method.Because of the compressibility of water hydraulic medium and connecting hose,it makes the manipulator control system have dead zone,the manipulator's response to the hydraulic control system command is slow and the adjusting time is long.For this phenomenon,a segment PID control method is put forward,based on segment PID control for manipulator's single joint and normal PID control experiment,through the contrast experiment to verify the effectiveness of the proposed method.The paper simulation analysis the end error of the manipulator,and analysis the influence of various error factors on the end position;In order to detect the actual working precision of manipulator,spatial position measuring device is developing.This paper uses the method of extension cord increasing stroke to improve,and analyses measuring device itself errors.The detection strategy of the static,dynamic and the angle precision of the end of the manipulator is given in this paper,and the device also is tested.In order to improve the accuracy of manipulator end,for the control error and testing error,this paper respectively proposes compensation methods.The paper does related experimental studies according to 5-DOF water-hydraulic manipulator system and spatial position measuring device.To verify manipulator gripper shear's requirement,the paper do the test by making pressure to gripper cylinder and controls the robot gripper crawling in real work.On the basis of segment PID control of single joint,the segment PID is applied to the manipulator's four joint.To verify the underwater manipulator's static accuracy can meet the technical indicators,this paper uses the spatial position measuring device to carried out the experimental study.In order to improve the end static precision of the manipulator,in the experiment this paper uses arm's elbow joint,wrist swing joint to compensating error and validates the compensation method is effective.