Wheeled robot with movable center of mass for traversing over rough terrain

Abstract

Planetary exploration requires rovers to perform a variety of challenging tasks autonomously. In order to complete relevant scientific mission, these rovers need to overcome difficulty for rough terrain traversing by "online methods". This paper discusses an idea that utilizes a rover mobile center of mass in order to aid in traversing rough terrain. According to vehicle pitch angle and contact angles, the rover recalculates the optimal position for the center of mass to minimize the indicator defined by two factors : the wheel driving force over the wheel normal force (adhesion coefficient) and tip-over stability angle (stability coefficient). Two innovative approaches are developed in this paper. The first one is that the authors defines easily comprehensible two factors, adhesion and stability coefficients for traversability indicator and proposes a method to calculate optimal center of mass position. The second one is that in the case of four-wheels drive, the relation between the front wheel and the rear wheel adhesion coefficient is easily solved and the best case for giving the driving forces can be solved as force making the front and the rear wheel adhesion coefficient equal. The authors call this "optimal force distribution method". Finally, this paper shows some simulation results for traversing rough terrain that compute the optimal center of mass while traversing the terrain.

Wheeled-Robot Navigation With Velocity Updating on Rough Terrains

“…There are works that model the vehicles driving with differential equations (Nakamura et al, 2007), (Kim et al, 2008), (Ward and Iagnemma, 2008). But this approach is difficult because, in general, differential equations are nonlinear, and their solution is hard to obtain.…”

Slide-Down Prevention for Wheeled Mobile Robots on Slopes

“…where F iz is the normal force of the wheel on the inclined plane (Thibodeau et al, 2006) (Nakamura et al, 2007).…”

Surmounting obstacles by arm maneuver for unmanned power shovel

“…Ref. [8] has proposed a wheeled robot with a movable center of mass (CoM) to ease the traverse over rough terrain. The proposed system also considers change of CoM, indirectly, by maneuvering its arm; however, the main focus is on getting the reaction force at the bucket as a support to lift the power shovel crawler.…”