Determining Robot Egomotion from Motion Parallax Observed by an Active Camera

In order to control the motion of a mobile robot, it is necessary to have accurate egomotion parameters. In addition, egomotion parameters are useful in determining environmental depth and structure. We present a computationally inexpensive method that rapidly and robustly determines both the translational vector and rotational component of robot motion through the use of an active camera. We employ gaze control consisting of two types of camera motion. First, the camera fixates on an item in the environment, while measuring motion parallax. Based on the measured motion parallax, the camera then rapidly saccades to a different fixation point. The algorithm iteratively seeks out fixation points that are closer to the translational direction of motion, rapidly converging so that the active camera will always point in the instantaneous direction of motion. At that point, the tracking motion of the camera is equal but opposite in sign to the robot's rotational component of motion. Experiments are carried out both in simulation and in the real world, giving results that are close to the actual motion parameters of the robot