Design of Joint Angle Profiles for a Planar Five-Link Bipedal System

Abstract

A set of joint angle profiles for a five-link bipedal model walking on level ground is designed. One feature of the joint angle profiles is that after an impulsive energy injection at an early stage of each step, the mechanical energy of the bipedal system remains constant for the rest of the step. This feature is of special interest in the studies of energetics of bipedal walking and can be beneficial to the design of modern energy-storing prosthetic feet. The joint angle profiles also satisfy four kinematic constraints, i.e., the walking speed, stance knee bias, upright posture of the trunk and motion coordination. To obtain acceptable gait patterns, a set of parameters is carefully tuned to satisfy extra conditions (repeatable gait, no hyperextension, and no scuffing at the swing knee). This work can provide some insight into the mechanics of bipedal walking and has potential to establish a framework for estimating the optimal energy storage of modern prosthetic feet.