An optimization algorithm has been developed to design the artificial above-knee prosthetic device. With this algorithm three types of the prevalent single axis A/K mechanism are compared with respect to the functional and cosmetic aspects. Those mechanisms are linear damper spring mechanism, hydraulic damper spring mechanism, and conventional constant friction component mechanism.
Firstly optimization is implemented during each phase, stance and swing phase, to investigate the knee characteristics for each knee component with the design variables such as damping and spring coefficients or friction factor. The constant friction component system describes best the dynamic characteristics of the knee during stance phase and the linear damper spring system during swing phase.
Finally the design of prosthetic device is performed for real design parameters such as damping and spring coefficients and intertial properties of the lower prosthetic limb. The linear damper spring system is the best among them under the specified design strategy-minimization of the square sum of the gait angle and velocity deviations from the normal.
