Accuracy improvement of Shadow Range Finder: SRF for 3D surface measurement

In planetary exploration, when collecting a rock, it is important how to get information of the surface around a sample. Usually, surface information is brought by a special sensor such as laser range finder and stereo camera. These sensors, however, need more weight and power consumption and are used for only one function such as the surface measurement. And furthermore, there are some difficulties to use those sensors in some situation, for example, a high brightness environment. In this research, we apply Shadow Range Finder: SRF, which can make good use of a shadow for the measurement of surface information under the direct sunlight. SRF is robust for above-mentioned environment, and a shadow would be recognized in the case of a halation. The measurement by SRF uses a single camera installed on a manipulator, and a link of a manipulator, which produce its shadow. The principle of SRF is same as laser range finder, and a shadow is used for scanning slit instead of a laser. In this paper, experimental results of actual objects are shown, and we discusses about accuracy improvement for measurement data, considering an umbra and a penumbra caused by surface light source. Finally, we apply this method to tele-sampling by a manipulator on a rover system.