Grid-Based Estimation of Surface Traversability Applied to Local Terrain (GESTALT) is a software library that helps a robotic wheeled vehicle choose a safe path across nearby terrain. The input to GESTALT consists mainly of three-dimensional range measurements of the nearby terrain taken by sensors (e.g., stereoscopic cameras or a laser scanner) aboard the robot as it moves along. GESTALT groups the data into grid cells, then geometrically evaluates the cells as separate planar patches, identifying such impediments to traversability as steps, steep slopes, and excessive roughness. Both straight and curved paths from present position of the robot can be evaluated. The safest path that helps the rover move toward its goal is selected. The resulting path evaluations can be used to steer the robot.

GESTALT is an extension of a previously developed algorithm known as Morphin, incorporating additional capabilities: Diagnostic outputs in greater detail are available. Traversability can be evaluated in a direction-specific manner; for example, a hill found to be unclimbable if approached head-on might be found climbable on a sideways approach. Navigation parameters can be reset at any time. Multiple rover configurations can be evaluated in a single map.

This program was written by Mark Maimone of Caltech for NASA's Jet Propulsion Laboratory.

This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393-3425. Refer to NPO-21233.


This Brief includes a Technical Support Package (TSP).
Software for Analyzing Traversability of Terrain

(reference NPO21233) is currently available for download from the TSP library.

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This article first appeared in the December, 2001 issue of Motion Control Tech Briefs Magazine.

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