Bionic Architecture Design and Robust Rough-Terrain Locomotion for a High-Payload Quadrupedal Robot*

In this work, an electrically actuated quadrupedal robot with bionic architecture, Pegasus, is reported. With investigating the anatomical skeleton of medium-sized dog, its movement mechanism, and dog’s joints, we conclude that the architecture design of quadrupedal robots can benefit from bionics research. There is an optimization for structural parameters, geometrical relationship, and motion range of each joint according to the findings in bionics. The bionic structure design is verified by analyzing mechanical performance and motion ability of the robot. The bionic architecture allows COG trajectory not to follow the terrain profile and COG fluctuations are significantly suppressed when going through rough terrains. In order to generate a stable COG trajectory with fewer pose fluctuations, the step sequence and four footholds in each step follow the typical biological gait pattern for dynamic walking over rough terrains while the robot can keep robust postures in efficient workspace for each leg. Moreover, "Virtual Muscle" model is realized for each leg’s compliance control with two sets of virtual spring and damper, in order to absorb feet impacts on the ground.