Design of energy efficient joint profiles for a planar five-link biped robot

Joint profiles for a five-link biped, walking on a horizontal surface, are determined using five constraint functions. These constraint functions are designed to constrain the walking speed, support knee bias angle, and coordinate the motion of the legs, upright posture of the upper body and energy conservation of the bipedal system. It is shown that if only the initial potential energy is given, additional energy must be provided at the beginning of each step in order to synthesize the joint profiles. This type of energy addition has biological basis and is provided by the strain energy release from the deformable foot as in human walking. Also, it is shown that depending on the walking speed, a second energy input may be required during each step. Joint profiles for three walking speeds have been obtained, but only one of them is presented. The potential impact of this work on the development of bipedal robots and the design of prosthetic feet is also discussed.