Analysis of Inching for Planetary Rover Exploration

Abstract

Inching, also called push-rolling, is method of moving for vehicles that can change the position of their wheels relative to their body. Like an inchworm, it is possible to hold some wheels stationary while advancing the others and the body. In this research a test apparatus capable to independently controlling wheel speed and body-relative position was designed, built, and used to measure and understand inching, particularly as it applies to traction, climbing, and sinkage for planetary rovers. Inching is shown to produce dramatically better performance than nominal mobility methods in loose soil at slip values above 20%. Tractive performance is shown to be related to wheel slip, even when inching. Therefore Inching can induce wheel slip, even when there is little vehicle slip, to increase tractive performance. Inching, as a method of mobility, shows great promise as a way to climb steeper hills safely with planetary rovers.