Design and Analysis of a Self-Locking Passive Transformable Wheel Mobile Robot for Enhanced Mobility

Mobile robots require high mobility, obstacle crossing ability, and terrain adaptability in unstructured environments. However, most mobile robots with passively transformable wheel lack deformation stability during motion. This work aims to design a passive transformable wheel mobile robot with enhanced stability through a self-locking mechanism, enabling stable transformation between wheel and leg modes. A gravity self-locking mechanism was designed to assist the robot in stably climbing continuous stairs in leg mode, and an electromagnetic clutch is utilized to improve the stability of wheel mode motion. The deformation and obstacle clearance processes of transformable wheel were analyzed through simulations using Adams software. A physical prototype was fabricated and tested on climbing continuous stairs and different rough terrains. The results indicate that the robot has high maneuverability as well as stability over terrains and even stairs with a height of 160 mm.