Research on obstacle performance and tipping stability of a novel wheel–leg deformation mechanism

Abstract. A new type of wheel–leg deformation mechanism, based on an electromagnetic clutch and gear rack transmission mechanism, is designed. This mechanism has a compact structure and simple operation, which can roll on wheels and surmount obstacles with a support leg. Firstly, the walking model is established to study the kinematics characteristics of the mechanism. The alternation of the support legs does not affect smooth obstacle crossing, but will cause the step change of the angular velocity of the centroid of the main body. Secondly, the obstacle-surmounting performance of roll-over mode and obstacle-crossing mode using support legs is analyzed. For roll-over mode, the maximum climbing height is 87.36 mm. For obstacle-crossing mode using support legs, the maximum climbing height is the maximum extension length of the support leg. According to the climbing height, the switching criteria of different climbing modes are obtained. In addition, the rolling angle of the main body has a greater impact on the support force and driving torque, while the contact angle between the legs and the ground has a small impact. Finally, the tipping stability and anti-interference ability of the wheel–leg deformation mechanism is evaluated using the stability cone method.