Design of electronically controlled hydraulic damper for prosthetic knee / 中国组织工程研究

ABSTRACT

OBJECTIVE: To design an electronically controlled hydraulic damper cylinder as a key part of the computer-controlled intelligent knee joint.METHODS: According to the characteristics of hydraulic fluids and processing technology, new type of micro-structure of the digital throttle and unique structure of the two-cylinder piston had been applied to the damper. It could control extension and flexion of the knee joint in two-way automatically, which improved the gait symmetry of artificial limb. Finally, a special self-made testing device was used to evaluate the performance of the hydraulic damper. The damping force adjustment was simulated in test by controlling the two needle valves with micro-computer. The kinematics speed was detected under different state of simulating the driving moment of hip joint and the damping moment of knee joint. The testing results indirectly built the dynamics relationship among the inertial force, damping force and the swing speed of the knee joint. RESULTS: When the position value X of the needle valve was reduced by the step motor driving, the resistance of the hydraulic cylinder was increased which resulted in faster speed of the cylinder rod. The sensitivity of the speed to the driving force decreased with the opening of needle valve increasing. When the stepping motor controlled the needle valve closer, the damping moment increased which led to a faster swing speed.CONCLUSION: The design of hydraulic damper cylinder meets the requirements of prosthetic knee dynamics control.