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Design of a Large-scale Electrically-actuated Quadruped Robot and Locomotion Control for the Narrow Passage

With the gradual maturity of the software and hardware of quadruped robots, the application scenarios of quadruped robots are increasing, such as security, rescue, exploration and other tasks. Quadruped robots are flexible and adaptive to challenging or complex environment. This study presents a large-scale quadruped robot, Pegasus II, which is a new version upgraded from the previous quadruped robot, Pegasus [1]. System design of Pegasus II is introduced, including mechanical and electronic design. Locomotion control for a special scene, L-shaped narrow corner, in which a large-scale quadruped robot is not able to traverse in a common quadrupedal mode, is demonstrated. The long body length of a large-scale quadruped robot, such as Pegasus II, incurs difficulty in traversing freely in such a narrow passage. Motivated by this issue, this study proposes an experimental implementation to realize the transition from quadrupedal mode to bipedal mode. The control framework is presented, which mainly includes trajectory optimization, whole-body control, compliance control, and joint torque estimator. Simulations and experiments are conducted to validate the performance, including gait transition, compliance control.