Design and terrainability analysis of a novel mobile robot with variable-diameter wheels

Mobile robots are usually demanded to enter into unstructured terrain. Thus, terrainability of a robot is specially important in cluttered environments. A novel mobile robot with variable-diameter wheels is designed here. This robot can adjust its attitude by variable wheel diameters to improve its terrainability. For terrainability, stability and obstacle-surmounting capability of the robot are studied. Furthermore, variable wheel diameters' effects on these performances were researched. For lateral and longitudinal stabilities, parametric relationships between the maximum slope that the robot can climb and stability requirements were obtained. To avoid stability failures, appropriate failure criterions were proposed. Stability of the robot can be enhanced by changing wheel diameters. The obstacle-surmounting performances of front and rear wheels were analyzed by building two quasi-static models. The results showed that increased wheel diameters enhanced the obstacle-surmounting height. The analytical calculations and the simulations were compared. The simulations verified the reliability of the theoretical calculations. Based on tip-over failure criterions, appropriate strategies can be used to enhance the stability. These analysis presented also can provide theoretical basis for performance optimization design of the robot.