Visual target tracking (VTT) software has been incorporated into Release 9.2 of the Mars Exploration Rover (MER) flight software, now running aboard the rovers Spirit and Opportunity. In the VTT operation (see figure), the rover is driven in short steps between stops and, at each stop, still images are acquired by actively aimed navigation cameras (navcams) on a mast on the rover (see artistic rendition). The VTT software processes the digitized navcam images so as to track a target reliably and to make it possible to approach the target accurately to within a few centimeters over a 10-m traverse.

Artistic Rendition of MER.

The operations on the digitized images include a normalized cross-correlation algorithm along with template-image-magnification and template-image-roll-compensation algorithms. Each VTT update takes about 50 seconds. VTT has helped to make it possible to approach a target over a 10-m traverse and place an instrument on the target during a single sol, whereas previously, such approach and placement took 3 sols. Alternatively, VTT can be used to simply image a target as the rover passes it. VTT can be used in conjunction with any combination of blind driving, autonomous navigation with hazard avoidance, and/or visual odometry.

Functional Flow of VTT integrated into MER flight software. VTT module functions (square boxes) are additions to the existing MER flight software (circles).

This program was written by Won Kim, Jeffrey Biesiadecki, and Khaled Ali of Caltech for NASA's Jet Propulsion Laboratory. This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-45019.