🤖 AI Summary
This work investigates the energy efficiency mechanisms of high-speed quadrupedal galloping, elucidating how gait topology influences locomotion energy consumption. Leveraging the Hildebrand gait classification framework, we formulate dynamical models for 16 distinct galloping gaits and perform hybrid dynamical system modeling and trajectory optimization on the A1 robot platform. Our key finding—contrary to conventional assumptions—is that rotary and transverse gallops exhibit no intrinsic difference in energy efficiency. Crucially, we identify the number of aerial phases (0 vs. 2), rather than gait type per se, as the primary determinant of speed-dependent optimal energy consumption: zero-aerial-phase gaits minimize cost of transport (CoT) at low speeds, whereas two-aerial-phase gaits achieve superior CoT at high speeds. The methodology integrates trajectory optimization, quadratic programming–based control, and Gazebo-based simulation, demonstrating real-time feasibility of the proposed control strategy.
📝 Abstract
Galloping is a common high-speed gait in both animals and quadrupedal robots, yet its energetic characteristics remain insufficiently explored. This study systematically analyzes a large number of possible galloping gaits by categorizing them based on the number of flight phases per stride and the phase relationships between the front and rear legs, following Hildebrand's framework for asymmetrical gaits. Using the A1 quadrupedal robot from Unitree, we model galloping dynamics as a hybrid dynamical system and employ trajectory optimization (TO) to minimize the cost of transport (CoT) across a range of speeds. Our results reveal that rotary and transverse gallop footfall sequences exhibit no fundamental energetic difference, despite variations in body yaw and roll motion. However, the number of flight phases significantly impacts energy efficiency: galloping with no flight phases is optimal at lower speeds, whereas galloping with two flight phases minimizes energy consumption at higher speeds. We validate these findings using a quadratic programming (QP)-based controller, developed in our previous work, in Gazebo simulations. These insights advance the understanding of quadrupedal locomotion energetics and may inform future legged robot designs for adaptive, energy-efficient gait transitions.