Development And Test Of Flexible Arm Mechanical System For Underwater Operation

With the development of science and technology and the progress of society,people begin to focus on the exploitation of Marine resources.The complex and changeable underwater environment,such as low temperature,high pressure,turbulence,poor visibility and other factors,makes the crew's mission is full of dangers.Therefore,underwater manipulator with different functions has been developed for underwater operations.At present,there have been a lot of research on traditional rigid manipulator suitable for underwater operation.However,the traditional rigid mechanical arm installs the driving motor on the arm,which not only increases the weight of the arm,but also leaves an empty cavity inside the arm,and the influence of water pressure on the arm shell extrusion needs to be considered.Traditional rigid mechanical arms control the arm torso through a certain number of driving motors,but the longer arm torso makes the manipulator unable to move flexibly in a series of narrow,limited and unstructured Spaces.Therefore,in view of the shortcomings of traditional rigid underwater manipulator,this paper proposes a continuous type manipulator(Flexible Arm)driven by rope that has good flexibility and flexibility and can work in underwater environment.The details are as follows:Firstly,the whole structure of the flexible arm mechanical system is designed.Determine the type and size of arm joint suitable for this subject.To the motor output shaft and communication interface water seal design,so as to adapt to the underwater working environment.The driving system is designed to reduce the number of driving motors so as to achieve a more compact mechanism and lighter body weight.The total length of the whole mechanical system is 1332 mm,the length of the arm is 800 mm.Secondly,according to the geometric analysis method,the kinematics model suitable for this flexible arm is established.The rope holes are distributed in the same phase on the joint plane,so the kinematics model is simplified.The mapping relationship of joint space,drive space and operation space was analyzed.The position and pose of the flexible arm end were represented by homogeneous coordinate matrix,and the coupling relationship of the rope length variation of the three-stage arm segment was further considered.MATLAB is used to simulate the kinematics model,and the workspace of the flexible arm is obtained.Thirdly,the flexible arm was simulated based on virtual prototype technology,which verified the feasibility of the arm structure design as well as the kinematics model,and further optimized the arm joints in the process.Finally,the prototype of the flexible arm is manufactured,and the bending experiment,load experiment and precision experiment are carried out.Before the underwater target grabbing experiment,the air tightness experiment and water tightness experiment are carried out.The success of the underwater target grabbing experiment verifies the feasibility and reliability of the flexible arm from structure design to motion control.The research of this topic provides a certain engineering application foundation for the continuous type manipulator in the underwater field.