Several methods of sensor fusion for vision tracking in mobile robots

This paper presents several different sensor-fusion methods for vision tracking, to keep a camera´s line of sight on a target. The data-fusion methods in this paper use several combinations of vision and motion information. The vision information is acquired through a vision processing ASIC (Application-Specific Integrated Circuit), which has an ODR (Output Data Rate) of 27 Hz. The motion information is acquired through one or more sensors, comprising a 3-axis accelerometer, a 3-axis gyroscope, and robot wheel encoders, which have the ODR of 100Hz, 100Hz, and 50 Hz, respectively. Several data-fusion scenarios are tested with these different sensors. An extended kalman filter and an appropriate data-fusion method are applied to each method. Also tested for comparison is a vision-only scenario with a slower ODR of 6.75 Hz. The vision-only method with the fast ODR of 27 Hz performs reasonably well. However, the slower case with the ODR of 6.75 Hz does not provide an adequate performance. The sensor-fusion method that uses all three motion sensors and a vision sensor greatly improves the target tracking performance, regardless of the vision sensor ODR. The motion sensors used are very low cost mass production sensors, found commonly in mobile phones. The proposed method presents a viable solution for target tracking in mobile robots.