Motion-based visual behaviors for mobile robots
We investigate two specific visual motion behaviors that are appropriate for mobile robot applications because of their simplicity and low computational load. The first behavior determines the distance to a flat wall to the side of the moving robot. Such a measurement is essential for a wall-following behavior. The second behavior determines the projected amount of time until the robot collides with a stationary object assuming that the robot continues to move at a constant velocity. This time-to-contact estimate relies on the expansion of the optical flow field and can act as a collision-warning sensor to warn of impending obstacles. The numberical estimates given by both behaviors are expressed as simple ratios of easily measured visual quantities and do not require any elaborate calibration procedures. These behaviors use a 1D patch-wise correlation technique that was developed by Poggio and Ancona. We have further simplified the computation and show results on true image sequences.