Development of a Biologically Inspired Hopping Robot - "Kenken"

A b s t r a c t m As many biomechanists indicate~ tendon plays important role for running or jumping motion. It stores the kinetic energy as a potential energy during stance and also absorbs the impulse at touch down. Inspired by such biomechanical studies~ we propose a new simple mechanical model for hindlimb of a dog to realize a robot that imitates dog running~ and the hardware design of one-legged running robot, "Kenken' . The robot has an articulated leg and uses two hydraulic actuators as muscles and a tensile spring as a tendon. The spring being attached like gastrocnemius or plantaris enables the robot to produce sufficient propulsion force by virtue of the "energy transfer" from the knee, even if there is no actuator at the ankle joint. Using an empirical controller based on the characteristic dynamics of the model~ the robot has succeeded in planar onelegged hopping. Although the problem related to the stability at the higer speed remains~ the experimental results demonstrate that the proposed hindlimb mechanism is effective for legged running. K e y w o r d s H o p p i n g robot~ Running robot~ Legged locomotion, Biomechanics, Tendon.