평면 3자유도를 갖는 전방향 자전거의 개발

This study addresses the development of a riding toy with 3 degree of freedom(DOF) motion. A typical riding toy has one input power and it is steered by a handle. However, if omnidirectional wheels are used, the riding toy can perform 3DOFs motion on a 2-dimensional plane by an appropriate combination of input powers without any additional steering means. These input powers are one foot-driven power and two hand-driven powers. In this study, an alternate wheel mechanism is selected for an omnidirectional riding toy; each rear wheel is connected to a differential gear set. This decoupling mechanism improves the intuitional operation of the omnidirectional riding toy. Ergonomics is considered into the design of the omnidirectional riding toy on the basis of accumulated data for physical condition of humans. In this study, the driving mechanism is proposed by simulating a human body as a 4-bar linkage. Each of driving torques of the omnidirectional riding toy is compared with the human strength in each direction. The simulation results show that higher input power is required for the complex motion of the omnidirectional riding toy such as rotational motion but independent motion with one direction only can be obtained by a relatively small input power and the omnidirectional riding toy can be operated at the same speed as typical riding toys with a low speed ratio. Accordingly, the omnidirectional riding toy can be used by 6-7 year-old-boys who have low physical strength.