Motion Control Study of a Two Wheel-Leg Robot with Terrain Adaptation Capability

As a typical floating base robot, the two wheel-leg robot faces challenges such as instability, nonlinearity, and underactuation, making it prone to tip-ping over and instability when moving on complex terrains. To enhance the stability of the two wheel-leg robot when traversing complex terrains, this paper completes the full-body dynamic modeling of the robot through a dis-tributed modeling approach, preserving its dynamic characteristics. The active driving force at the end of the wheel-legs is used to eliminate linearly related passive driving forces, establishing a complete mapping relationship between the resultant force on the torso and the driving force of the wheel-legs. A virtual actuation force distribution constraint based on the attitude angle constraint of the wheel-legs is constructed, and a layered controller for uneven terrain is built. To further improve the terrain adaptability of two wheel-leg robot, a wheel-leg torque solver with the end output force as the control target is constructed based on the distributed full-body dynamic model, achieving a complete mapping between the end output force and the joint torque. An adaptive planning method for the longitudinal trajectory of the torso during jumping motion is proposed, and a full-body torque jumping controller for two wheel-leg robot is established to achieve the jumping motion. Finally, multiple simulation experiments and prototype tests verify the effectiveness of the proposed method.