Flexible Motion Framework of the Six Wheel-Legged Robot: Experimental Results

In complex real-world scenarios, wheel-legged robots with maneuverability, stability, and reliability have addressed growing research attention, especially in material transportation, emergency rescue, as well as the exploration of unknown environments. How to achieve stable high-level movement with payload delivery simultaneously is the main challenge for the wheel-legged robot. In this article, a novel hierarchical framework for the flexible motion of the six wheel-legged robot is considered in experimental results. First, for the wheeled motion, the speed consensus algorithm is implemented to the six-wheeled cooperative control; for the legged motion, three gait sequences, and foot-end trajectory based on the Bezier function are designed. Furthermore, a whole-body control architecture includes the attitude controller, impedance controller, and center height controller is developed for obstacle avoidance, which can ensure the horizontal stability of the body of the robot when it passes through obstacles in different terrain. Finally, extensive experimental demonstrations using the six wheel-legged robot (BIT-6NAZA) are dedicated to the effectiveness and robustness of the developed framework, indicating that it is a superior case of a selectable flexible motion with satisfactory stable performance under the field world environment.