Development of noncircular wheel "TFW" for traveling over a single step only by rotational movement

Wheeled vehicles are used daily because they have high movement efficiency, simple structures and low cost. However, their travel ranges may be limited due to the low traveling performance of wheels when they encounter a step. Various movement mechanisms have been developed to solve this issue, but they have become complicated and heavy in attempts to meet each design condition, so they are hard to use daily in some cases. The authors therefore devised a simple, low cost movement mechanism the TFW (Transformable Flexible Wheel) that can travel over a step without special controls. This is a noncircular wheel that can travel over a step without slipping by denting the outer circumference of the wheel when it comes into contact with a step and catching the step with the internal mechanism of the TFW. In this paper, the outline of the structure and movement of the TFW is discussed. In addition, its effectiveness is verified through the creation of two vehicles, the simple prototype SRIDERzero and the experimental model SRIDER, to prove that the traveling performance of the TFW over a step is superior to that of conventional wheels and to demonstrate the basic movements of the TFW.