On Prismatic and Torsional Actuation for Running Legged Robots

Among the challenges faced when developing dynamic, legged platforms are the manner and mechanisms utilized to modulate system energy. A great deal of success has been demonstrated by low degree of freedom platforms that rely on either pure torsion or thrusting to provide the requisite locomotive power. However, means of synergizing these approaches and the potential benefits thereof are not well understood. In this study, the effects of torsional and prismatic energy addition on running performance are investigated, both in isolation and as a hybrid approach. By allowing both mechanisms to be used in tandem, improvements to speed, stability and efficiency are noted. Additionally, these results suggest that rather than utilizing prismatic and torsional actuation to provide an even distribution of power, in homogenous power generation may lead to futher performance benefits. This study not only examines the degree of actuator hybridization that leads to improved running, but also identifies the fundamental mechanisms by which these two approaches affect performance. These insights, in turn, provide physical intuition for the design of future legged platforms of more complex morphologies.