Toward benchmarking locomotion economy across design configurations on the modular robot: AMBER-3M

Abstract

Making conclusive performance comparisons of bipedal locomotion behaviors can be difficult when working with different robots. This is particularly true in the case of comparing energy economy, which is highly dependent on mechanical, electrical and control components. As a means of limiting these disparities in methodical testing, we built a modular bipedal robot platform, AMBER-3M. Three leg configurations were designed for this purpose: actuated flat foot, rigid point-foot, and compliant point-foot. As a proof of concept for the mechanical, electrical, and algorithmic modularity, we present walking experiments with all three AMBER-3M configurations, using the same control methods and experimental procedures. As a pilot study for investigating locomotion economy, we performed further systematic experiments of point-foot walking with the purpose of examining the effects of speed on the cost of transport (COT). We optimized 36 walking gaits for maximum locomotion economy at various transport velocities. Walking performance data was collected from these gaits spanning a speed range of 0.34 to 0.94m/s. An apparent Pareto-optimal frontier was observed in the data, showing that mechanical cost of transport increases with speed; ranging from 0.22 up to 0.36. Conversely, the electrical cost of transport decreased at higher walking speeds.