Afocal optical flow sensor for mobile robot odometry

This paper presents an application of an afocal optical flow sensor (AOFS) for mobile robot navigation. The OFS-based odometry is advantageous for mobile robots because it is not affected by wheel slippage. However, the changes in vertical height result in systematic errors when estimating the moving distance of robots moving on uneven surfaces. This paper presents an application of an AOFS module to improve this vertical-height sensitivity. To evaluate the proposed system performance, two kinds of experiments are performed: on a bare laminate floor and on the laminate floor that is partially covered with an area carpet. The test area is 150 cm × 150 cm size. For the bare laminate floor case where no slip occurs, the localization error of the developed system is 0.2%. The error using a conventional OFS module, encoders, and gyroscope combination is also 0.2%. For the case where the laminate floor is partially covered with an area carpet, the localization error of the developed system is 0.7%. The error using a conventional OFS module, encoders, and the gyroscope is 2.9%.