A simplified skid-steering model for torque and power analysis of tracked small unmanned ground vehicles

The ability to predict the torque and power consumption of a tracked robot, a.k.a., small unmanned ground vehicle (SUGV) is important for its design. Accurate torque and power consumption prediction enables motion planning that does not exceed the torque and power limitations of the propulsion system or the terrain. Due to the fact that skid steering may consume a large percentage of the propulsion power of tracked SUGVs, it must be included in any accurate power analysis. Modeling of skid steering of tracks is difficult on soft soils because of the track-soil interaction and the distributed nature of shear stress along the contact area. This study begins with a general theory of skid steering track-soil interaction at steady state. A fast yet accurate 2-D simplified model is then developed, which is solved with pre-calculated skid steering resistance coefficient maps. Subsequently a quadratic equation for internal power consumption is obtained experimentally. The simplified model is verified using the experimental data obtained from an iRobot Packbot driving on dry sand.