Passive Dynamic Walking of Combined Rimless Wheel and Its Efficiency Analysis

—Speeding-up by Adjustment of Phase Difference between Fore and Rear Legs—

Abstract

This paper investigates passive dynamic walking and its efficiency of a combined rimless wheel (CRW) that consists of two identical 8-legged rimless wheels. First, we introduce a mathematical model of the CRW and develop the system equations. We then numerically show that stable passive-dynamic gaits can be generated regardless of the phase difference between the fore and rear legs. Second, we show that the walking speed is maximized when the phase difference is nearly equal to the half inter-leg angle through numerical analysis, and experimentally verify the validity using our prototype CRW machine. Furthermore, we discuss the inherent speeding-up mechanism from the potential barrier point of view.