A paper describes a method devised to increase the robustness and accuracy of tracking of targets by means of three stereoscopic pairs of video cameras on a Mars-rover-type exploratory robotic vehicle. Two of the camera pairs are mounted on a mast that can be adjusted in pan and tilt; the third camera pair is mounted on the main vehicle body. Elements of the method include a mast calibration, a camera-pointing algorithm, and a purely geometric technique for handing off tracking between different camera pairs at critical distances as the rover approaches a target of interest.

The mast calibration is an extension of camera calibration in which the camera images of calibration targets at known positions are collected at various pan and tilt angles. In the camerapointing algorithm, pan and tilt angles are computed by a closed-form, noniterative solution of inverse kinematics of the mast combined with mathematical models of the cameras. The purely geometric camera-handoff technique involves the use of stereoscopic views of a target of interest in conjunction with the mast calibration.

This work was done by Won Kim, Adnan Ansar, and Robert Steele of Caltech for NASA's Jet Propulsion Laboratory.

NASA Tech Briefs Magazine

This article first appeared in the December, 2007 issue of NASA Tech Briefs Magazine.

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