Design And Dynamics Simulation Of Active-passive Hybrid Drive Prosthetic Knee Joint

Wars,diseases and traffic accidents,as well as natural disasters,have led to an increasing number of people having to undergo limb resection,especially the removal of the knee joint,which has a huge impact on the patient's daily walking.A suitable prosthesis can help the amputee return to normal walking and return to normal life and work.With the advancement of science and technology and the improvement of the economic level,amputees have put forward new requirements for artificial limbs.Currently,prosthetic products on the market can no longer meet people's needs.Based on the above situation,a active-passive hybrid drive prosthetic knee joint mechanism was designed to help the knee amputation patient to regain normal walking ability.In this paper,the PhaseSpace three-dimensional motion capture system is used to collect the motion information of healthy people in the process of advancing,retreating and going up and down the stairs.Through the data processing,the hip,knee and ankle angles of the lower limbs were obtained,and the coordinated movement and gait realization of each joint under different walking modes were analyzed,which in theory to guide the design of prosthetic knee joint.A prosthetic knee joint with active and passive hybrid drive was designed.The direct current motor provided the driving torque and the hydraulic damping system provided the resistance torque.The dimensions of the major rods within the prosthetic structure are determined.The kinematics and dynamics model of the lower limbs of the human body was established to solve the knee joint torque and power,which is used to select the parameters and models of the direct current motor.The damping force is obtained from the pressure loss generated by the fluid flowing from the hydraulic cylinder through the flow passage and the throttle valve.The dimensions of the various parts of the hydraulic cylinder are designed,and the diameter of the pipe was determined according to the minimum resistance moment of the knee joint.A kind of throttle valve with rotating structure was designed,and the change rule of throttle area was studied.The output damping force of the throttle valve of the hydraulic damper system in full open state is solved by using the simulation software,which shows that the designed system meets the maximum damping force requirement.Finally,the mathematical model between the output damping force and the velocity of the hydraulic damper system and the throttle area is established.The three-dimensional model of the prosthetic wearer was established by Solidworks,and the virtual prototype was built in ADAMS.Kinematics simulation was used to simulate the movement process of human body moving forward,backward and up and down stairs,and to solve the required moment of prosthetic knee joint in support and swing phases under ideal gait.Direct current motor can provide ideal driving moment,and the hydraulic damping system still output damping force when the throttle valve is fully open,that is,the damping moment can not be infinitely small,which is not consistent with the ideal damping moment.The actual moment curve of the prosthetic knee joint was input into the wearer's virtual prototype model,and the rest of the hip and ankle joints were driven by ideal motion curve.The difference between the actual prosthetic knee joint angle and the normal knee joint angle during walking was compared to verify the rationality of the designed prosthetic limb.