Novel Experimental Technique for Visualizing and Analyzing Robot-Soil Interactions

A novel experimentation and analysis technique has been developed to enable detailed investigation of robot interactions with granular regolith. This technique, the Shear Interface Imaging Analysis Tool, provides visualization and analysis capability of soil shearing and flow as it is influenced by a wheel or excavation tool. The method places an implement (wheel, excavation bucket, etc.) in granular soil up against a transparent sidewall. During controlled motion of the implement, images are taken of the sub-surface soil, and are processed with optical flow software. Analysis of the resulting displacement field identifies clusters of soil motion and shear interfaces. The Shear Interface Imaging Analysis Tool enables analysis of robot-soil interactions in richer detail than possible before. Prior art relied on longexposure images that provided only qualitative insight, while the new processing technique identifies sub-millimeter gradations in motion and can do so even for high frequency changes in motion (several Hz). Results are presented for various wheel types and locomotion modes: small/large diameter, rigid/compliant, with/without grousers, and rolling/inching. Results are also presented for an excavation bucket horizontally cutting granular soil.