Mechanical Upgrade and Gait Development of Re-Sizable Quadruped, HARQ

This paper presents the continued development of HARQ (Human Assistive and Robust Quadruped) which has been designed and built by ART (Assistive Robot Team) in University of Hartford since 2019. To enable the robot to deal with various obstacles with different sizes, HARQ’s mechanical design and building process was focused on the achievement of kinematic adjustability as its main technical design requirement. In this study, the mechanical design changes, which are implemented to increase the robot’s balancing capability and to prevent the slippery between end-effectors and ground, are described first. Based on the changes, the kinematic analysis is also upgraded and various walking trajectories are designed to enable HARQ to locomote with different gaits. To simplify the previous inverse kinematics process which was built based on the numerical method, the analytical equations are newly derived for HARQ. Lastly, the upgraded robot is tested and evaluated in human-centered environments which include both indoor and outdoor task spaces.