Step Climbing of Mecanum Wheeled Robot

Abstract

An omnidirectional mobile vehicle created with Mecanum wheels does not easily negotiate stepped terrain, because the small slanted freely moving wheels in the Mecanum wheel rotate at the step edge and cannot obtain a grip sufficient for climbing. We developed two types of driving wheel mechanisms based on the Mecanum wheel. One is a hybrid that combines a larger grouser wheel with a smaller Mecanum wheel with a synchronized peripheral velocity and vertically adjustable central shaft. The other comprises a split Mecanum wheel where the halves shift back and forth. The radius of the grouser wheel hybrid must be carefully designed so that the grouser can produce an adequate grip at a low position for reliable transition to the frictional grip of the Mecanum wheel. Similarly, for the split Mecanum wheel, the horizontal shift distance must be carefully determined so that the grip of the edge of one half is maintained until an adequate grip can be obtained by the other half of the wheel. Experimental robots were built with Mecanum wheels 152mm in diameter to demonstrate both wheel types. These robots showed good performance by negotiating a 100mm step (grouser type) and a 70mm step (split type).