Laser Ranger based Hazard Detection

Abstract

This technical report outlines the laser ranger based hazard detection developed for the Lunar Rover project. Even though it is designed with a specific vehicle in mind the concept can be applied to a wide variety of mobile robots. The laser system falls into two parts: the data acquisition section and an interpretation section. In the acquisition part it is described how the integrity of the laser system is checked, how level problems are corrected and unreliable data is removed. It is also assessed whether the remaining data is sufficient for the interpretation section to function properly. The interpretation section tests for three physical hazards: Step, drop and belly hazards. The signal from the acquisition and the interpretation section are fused to reach an emergency stop signal controlling the rover at low level. The different tests are heuristic metrics to reach a high processing speed. Also in appendix is provided information regarding various practical aspects such as calculating the optimal number of samples per scan, the optimal motor speed, 3D resolution obtainable and necessary, possible positions of the laser scanner on a given vehicle at a given speed and estimates of the maximum tilt angles allowing proper laser operation.