Design And Experimental Research On 3-DOF Mechanical Joint Actuated By Water Hydraulic Artificial Muscles

Nowadays the capacity of deep-sea operation is enhanced and the equipment of deep-sea exploration is improved due to the great needs of the country.Underwater manipulator becomes the key technology of the equipment for exploration,search and salvage under the sea therefore designing an excellent actuator to drive mechanical arm and a high degree of freedom mechanical joint are becoming the research hot point for scholars.Because the water hydraulic artificial muscle pertains to the application in underwater manipulators widely used in ocean development,with high force-to-weight ratio,good flexibility and good bio-imitability,this new green actuator has ideal prospect of application in ocean engineering.Referencing the shoulder joint of human body,a three DOFs mechanical joint actuated by water hydraulic artificial muscles is designed innovatively in this thesis.The mathematical model of joint system is builted in simulation.The joint system is set up and static experiments and dynamic experiments are conducted.Dynamic and static characteristics of the joint system are studied.A good control performance is obtained by using PID control method.The contents of this thesis are as follows:(1)The movement mechanism and the movement parameters of the shoulder joint of human body are investigated.The movement parameters of the mechanical joint are designed.The range of rotation around the X,Y axis is ±30° and around the Z axis is 90°.The range of torque around the X,Y axis is 200 Nm and around the Z axis is 100 Nm.The structure scheme of the mechanical joint of three degrees of freedom is designed.The parameter specification of the water hydraulic artificial muscles which drive the mechanical joint is calculated.(2)Mathematical model of water hydraulic artificial muscles,hydraulic pressure control system and mechanical joint is builted.The mechanical joint system is simulated in MATLAB and the dynamic and static drive characteristics of the joint system are analyzed.(3)The water hydraulic artificial muscles used in the joint are manufactured.The driving characteristics are analyzed and mathematical expressions and theoretical correction formula are investigated in experiments.(4)The mechanical joint and the joint system are set up.Finally,static control experiments and dynamic control experiments are done.The range of rotation around the the Z axis is 52° and around X,Y axis is ±23°.The system frequency response characteristic is analyzed and transfer function is calculated.The error of joint system is analyzed and the improvement plan is proposed.