Gait design and optimization for efficient running of a direct-drive quadrupedal robot

Legged robots are capable of navigating rough terrain, but have traditionally been restrictedto slow speeds. New ro1>ot,s combine the power density necessary for rapid motions with increasingly sophisticated leg designs. Developing controllers that effectively coordinate these high-DOF legs to generate fast, agile motions is challenging. In this paper we examine a pair of control approaches to generate high-speed trotting for the direct-drive quadruped robot Minitaur. We first show that optimization of a redesigned feed-forward trajectory improves the robot's running speed by 45%, from 1.52m/s to 1.1) m/s. We then utilize a monopod version of Minitaur's 5-bar leg to directly comwire this control approach to a dywartic, model-based strategy. We find gaits with the optimized trajectory are able to achieve speeds up to 2.44m/s, but the model-based dynamic controller is able to find gaits that are more robust to parameter changes, nearly as fast, and up to 70% more efficient.