Novel Mobile Mechanism Design for an Obstacle-Overcoming Robot Using Rotating Spokes

In this paper, a mechanism for overcoming high obstacles is proposed to broaden the application range of the exterior wall cleaning robot. The proposed one-degree-of-freedom wheel mechanism can overcome high obstacles by the rotation of a wheel with two different spoke lengths. To implement the inclined tilted wheel (ITW), two design variables were studied - a spoke assembly angle and a wheel shaft assembly angle. At the critical assembly angles of φ = 45° and θ = 135°, the characteristics of the generated wheel trajectory does not invade the upper and lower space of the robot. From the trajectory, the space efficiency can be secured for thrust unit cleaning device. And the same contact characteristics can get with the existing wheel on the surface. To secure the orientation stability after overcoming a high obstacle, the reaction force analysis at each caster was performed. Through the analysis results, the orientation stability was secured without the distance compensation at the gantry during or after overcoming obstacles. To verify the obstacle-overcoming ability of the ITW, a 6m - high - test bench and a 0.3m - high - obstacles was manufactured. With a scenario defining an angular position of ITW, the ability of overcoming obstacle was confirmed in the test. In addition, the scenario was supplemented for stable overcoming to avoid a collision against obstacles through additional experiments.