Abstract: To address the challenge of traditional wheeled mobile robots adapting to curved surfaces with variable curvatures, a reconfigurable wheeled mobile robot with the ability to adapt to variable-curvature surfaces by leveraging the advantage of reconfigurable mechanisms in having multiple motion modes is proposed. Firstly, the motion plane of the robot’s wheel-leg branch chain is defined, and the mapping relationship between the motion of the reconfigurable trunk and the attitude of the magnetic wheels is established. Furthermore, based on the normal vector of the motion plane of the wheel-leg branch chain, an attitude ruled surface in four-dimensional space is constructed. The Gaussian mapping is used to characterize the angle change of the normal vector of the magnetic wheels, revealing the variation law between the normal vector angle and the surface curvature, thus theoretically verifying the robot’s ability to adapt to variable curvatures. Moreover, based on the finite displacement screw theory, the motion screws of the reconfigurable trunk and the wheel-leg branch chain are established respectively. Combined with the rolling constraint model of the magnetic wheels on the curved surface, a constrained kinematic model of the robot in the curved surface environment is constructed. Finally, experiments on the physical prototype show that the robot can move flexibly on variable-curvature surfaces by adjusting the attitude of the reconfigurable trunk, verifying its surface adaptability and the rationality of the kinematic model.

Key words: variable curvature surface, reconfigurable mechanism, mobile robot, finite displacement screw, kinematic modeling