Measuring the effective mechanical advantage of the plantarflexors during heel-toe walking and voluntary toe-walking: A comparison of two methods

The estimation of joint angle ratios for healthy and afflicted subjects in characterizing the human gait has great significance in the development of limb prosthetics. The two dimensional analysis of human gait was performed and the ratio of hip to knee, knee to ankle, hip to ankle as well as the time taken for achieving a gait were determined. The percentage of affliction was computed based on the joint angle ratios and comparison was made with healthy gait. The joint ratios were fed as input to the driving system which comprises of six DC motors for the positioning of knee, hip and ankle during gait. Then different control strategies like P, PI and PID were tested. The t-test and ANOVA analysis were conducted between healthy, afflicted and PID controller to determine the significant difference between their joint angle ratios. The estimation of joint angle ratio improved the accuracy of the control system drive (desired position of knee, hip and ankle motors). The presence of oscillations in the output response was reduced for P and PI controllers. The implementation of PID controller eliminated the presence of peak overshoot and more settling time. Thus the joint angle ratio provides the best possible assistance to the disabled persons by appropriately compensating the affliction.