Simulating muscle-reflex dynamics in a simple hopping robot

Abstract

In legged systems, springy legs facilitate gaits with subsequent
contact and flight phases. Here, we test whether electrical motors
can generate leg behaviors suitable for stable hopping. We built a vertically
operating sledge actuated by a motor-driven leg. The motor torque
simulates either a linear leg spring or a muscle-reflex system. For stable
hopping significant energy supply was required after midstance. This was
achieved by enhancing leg stiffness or by continuously applying positive
force feedback to the simulated muscle. The muscle properties combined
with positive force feedback result in spring-like behavior which enables
stable hopping with adjustable hopping height.