Optimal Design of Body Profile for Stable Stair Climbing Via Tri-wheels

In this paper, we propose a mobile robot platform that is an improved form of LEVO. The LEVO uses a regular wheel and curved spoke triwheel(CSTW) system to drive flat terrain and stair climbs. However, this robot has problems when climbing stairs: it’s bottom profile collides with the stairs, resulting in huge jerk. To solve this problem, in this study, attempts to reduce the jerk value by applying a blade using a B-spline to the bottom profiles where the robot collides with the stairs. At this time, by reducing jerk, it can contribute to extending the life of the robot and improving driving stability. This study involved two steps. First, simulation was performed by adjusting the number and position of control points of the curve (B-spline). In this process, the orthogonal arrangement was applied among the optimal design techniques to finally reduce the jerk value by 92% and the driving torque needed to climb the stairs by 9.5%. At this time B-spline has one control point and the position is (300, 15). This simulation result was verified experimentally using a test bench and a prototype robot. As a result, it was confirmed that the jerk was reduced by 66.7%. Simulations and experimental verification based on them have shown that the proposed method is sufficiently effective in real environment.