On Stabilization Mechanism of a Hopping Robot Utilizing Weakness of Actuator

Abstract

This paper is concerned with nonlinear analysis of a 1-d.o.f. vertical hopping robot, composed of its body, foot and a DC motor with crank mechanism. We show that its hopping motion under a constant voltage converges into a stable limit cycle, through physical experiments and numerical simulations. We then clarify this stabilization mechanism based on a simplified mathematical model, by showing that the negative torque-velocity correlation (weakness) of DC motors plays as a feedback law for stabilization. We also show that the limit cycles exhibit period-doubling bifurcation as the applied voltage increases, and the corresponding bifurcation diagram is affected by the weakness parameter of the DC motor. CPG 7) 8) 9) 10)12) compliant oscillator compliant oscillator 1 12) 12) DC