Biomimetic Transition Gait for Quadruped Robot Creeping From Level to Slope Surfaces

ABSTRACT Wheeled rovers have been widely used to conduct surface exploration on the Moon or Mars. However, these rovers struggle to traverse granular steep slopes, thereby limiting potential exploration sites. Biomimetic legged robots offer superior mobility compared to wheeled rovers and are expected to enhance surface exploration capabilities. Nevertheless, current biomimetic robots exhibit limited climbing ability on steep slopes. Inspired by desert lizards that move efficiently on granular sand, this study proposes a biomimetic transition gait to enable a quadruped robot to creep from the ground onto slope surfaces. When ascending a slope, the robot elevates its trunk above the incline while ensuring that all feet maintain contact with the sand. During leg swings, the trunk remains attached to the slope to prevent slippage. Combined with active attitude adjustments, the robot can stably move from ground to slope on a Martian soil analog testbed. In experiments on level ground to 32° of Mars slope analog, the robot demonstrated a transition speed of 2.83 mm/s, thereby advancing the capability of quadruped robots to explore uneven terrain on the Moon or Mars.