Research On The Design And Key Technology Of Prosthetic Knee Joint Based On Micro-Nano Magnetorheological Damper

With the frequent occurrence of traffic accidents,accidents,industrial injuries,natural disasters and bone and joint diseases of the elderly,the number of amputees has increased sharply.Today’s medical technology can’t regenerate the amputees’ limbs,and prosthesis has become the only way to help the amputees recover their normal life.Because of the advantages of fast response,low energy consumption and controllable damping,micro-nano MR damping prosthetic knee joint has become a research hotspot in the field of prosthetic knee joint application.Therefore,the research of prosthetic knee joint with excellent performance,high cost performance,small and light structure has important academic value and social significance.In this paper,the properties of magnetorheological fluid(MRF)are analyzed,and a new type of micro-nano MRF is developed by adding different proportion of nano magnetic particles into the micro MRF.Based on the working principle of MRF,a device for testing the mechanical properties of MRF was built,and the relationship between shear torque,normal stress and applied current of micro-nano MRF was experimentally studied.Combined with the structural design principle and working mode of MR damper,the structure and parameters of micro-nano MR damper are designed.In order to satisfy the motion law of instantaneous center trajectory of micro-nano MR damper prosthesis knee joint,the motion of prosthesis knee joint in working state is simplified as double rocker mechanism,and its structural parameters are optimized.Through the ANSYS finite element simulation analysis,the rationality of the internal magnetic circuit design of the micro-nano MR damper is verified.The performance test platform of the micro-nano MR damper is built,and the relationship between the output damping force of the damper and the applied current and the piston speed is experimentally studied.According to the structural parameters and stress state of micro-nano MR damper prosthesis knee joint in working state,the motion model diagram of micro-nano MR damper prosthesis knee joint and lower limb prosthesis is established,and its kinematics and dynamics analysis are carried out.The motion parameters such as angle,angular velocity and acceleration of each member of double rocker mechanism are obtained,and the model of MR damper is established.The relationship between the output damping force and the driving torque of knee joint provides theoretical and experimental basis for the design of prosthetic knee joint with micro-nano MR damper.