BiCLAW‐VC: A Leg‐Wheel Robot With Four Wheels Integrating Symmetric Claws Following Variable Cycloidal Trajectories

To overcome the limitations of existing leg‐wheel robots, which require frequent locomotion mode switching according to terrain conditions and exhibit direction‐dependent obstacle‐crossing capability, this paper proposes a leg‐wheel robot with symmetric variable cycloidal claw locomotion mechanisms to improve terrain adaptability. The robot has four identical claw‐wheel mechanisms, each driven by two motors mounted on the body. One motor drives the rotation of the wheel, while the other adjusts the claw configuration relative to the wheel, thereby regulating the spatial orientation of the claw‐tip trajectory. The roots of each pair of claws are symmetrically mounted on the wheel through revolute joints, and the middle sections of the claws are connected by links to the output shaft of the claw configuration adjustment motor. The claws move along a cycloidal trajectory driven by wheel rotation. Through coordinated control of the two motors, the claw wheel can realize three locomotion modes: claw‐assisted rolling, wheel, and spoke‐wheel modes. Owing to its symmetric design, the robot exhibits identical locomotion modes and performance in both forward and backward directions, thereby achieving isotropic locomotion. This paper presents the robot design method in detail, establishes a dynamic model, and analyzes the step‐climbing capability and stability during stair climbing. A robot prototype was fabricated using three‐dimensional printing and machining, and experiments were conducted on locomotion in different modes, including step and stair climbing, pit escape, and locomotion over complex terrain. The experimental results demonstrate that the robot can stably and efficiently traverse complex environments using the three locomotion modes, climb steps up to 2.38 times the wheel radius and stairs with common daily‐life dimensions, and shows broad potential for applications such as inspection and post‐disaster search and rescue.