MOBILITY MODES AND CONTROL OF A PASSIVELY-ARTICULATED MULTI-SEGMENT WHEELED VEHICLE

This paper presents mobility modes and control methods for the SnoWorm, a passively-articulated multi-segment autonomous wheeled vehicle concept for use in Earth’s polar regions. SnoWorm is based on FrostyBoy, a four-wheeled GPS guided rover built for autonomous surveys across ice sheets. Data collected from FrostyBoy were used to ground-truth a ROS/Gazebo model of vehicle-terrain interaction for simulations on snow surfaces. The first mobility mode, inchworm movement, uses active prismatic joints that link the SnoWorm’s segments, and allow them to push and pull one another. This pushing and pulling of individual segments can be coordinated to allow forward motion through terrain that would immobilize a single-segment vehicle. The second mobility mode utilizes fixed links between SnoWorm’s segments and uses the tension or compression measured in these links as a variable to control wheel speeds and achieve a targeted force distributions within the multi-segment vehicle. This ability to control force distribution can be used to distribute a towed load evenly across the entire SnoWorm. Alternatively, the proportion of the load carried by individual segments can be increased or decreased as needed based on each segment’s available drawbar pull or wheel slip.