Analysis method of climbing stairs with the rocker-bogie mechanism

An analysis method to make the rocker bogie mechanism can climb up a stair is achieved in this paper. To verify whether the rocker bogie, with certain lengths of the linkages and radii of the wheels, could climb up a target stair or not, a kinematic analysis and its posture are determined. The trace of the center of mass of the rocker bogie was considered and the situation that three wheels contact the front side of the stair is analyzed. With this two analyses, the stair climbability graph (SCG) determined with the length and the height of a stair was drawn. The SCG shows the climbable stair group for the rocker bogie with certain size. Two prototypes of rocker bogie which has different lengths of linkages were designed and tested on two different stairs. As same result of the SCG, the first prototype rocker bogie with small rocker linkage can climb up the stair (length 450 mm and height 150 mm) but cannot climb up the other stair (length 300 mm and height 175 mm). The second prototype rocker bogie with large rocker linkage can climb up both stairs.