Capability of a Time-of-Flight Camera as a Hazard Detection and Avoidance Sensor for a Moon Exploration Microrover

This paper describes the specific principles for the implementation of a time-of-flight (ToF) camera in the Google Lunar XPRIZE competition rover as a hazard detection and avoidance sensor. Each frame from the ToF camera provides a 3D point cloud of the environment. It is calculated by precisely measuring the round-trip time that light takes to travel from the near-infrared emitter, to objects in the scene and back to the imager. First, we investigate the suitability of the camera system to withstand the launch and space environment and report the results of qualification tests: a vibration test, thermal vacuum test, and radiation test. Second, we focus on the critical optical performance under lunar illumination conditions for which we conducted several experiments. We present the rationale and implementation of the first improvement made to the commercial version of the sensor to better suit strong illumination conditions. The optical tests are necessary to verify that the quality of the 3D point cloud is sufficiently reliable for input into the hazard detection and avoidance algorithm and that this novel ToF technology is suitable for the mission requirements. Through this research, a terrestrial sensor is qualified and customized to provide the data quality capable of autonomous hazard detection and avoidance on the lunar surface.