Mixed pixels removal of a Laser Rangefinder for mobile robot 3-D terrain mapping

This paper presents an in-depth characterization of a direct time-of-flight laser rangefinder (LRF). It investigates several important characteristics of the LRF, such as the relationship between the intensity of the received signal and the range, the distribution and limited range effect of mixed pixels, and the evolution of the mixed pixelpsilas range and intensity when a laser beam traverses the edge of an object. A method based on the discontinuity of the range and intensity is proposed to identify and remove the mixed pixels. An Extended Kalman Filter is designed to segment the range data and detect the range discontinuity. The proposed method is integrated with a terrain mapping and navigation system and tested in outdoor environments with a real mobile robot.