Colour-Gradient Redundancy for Real-time Spatial Pose Tracking in Autonomous Robot Navigation

Mobile-robot interception or rendezvous with a maneuvering target requires the target’s pose to be tracked. This paper presents a novel 6 degree-of-freedom pose tracking algorithm. This algorithm incorporates an initial-pose estimation scheme to initiate tracking, operates in real-time, and, is robust to large motions. Initial-pose estimation is performed using the on-screen position and size of the target to extract 3D position, and, Principal Component Analysis (PCA) to extract orientation. Real-time operation is achieved by using GPU-based filters and a novel data-reduction algorithm. This data reduction algorithm exploits an important property of colour images, namely, that the gradients of all colour channels are generally aligned. A processing rate of approximately 60 to 85 fps was obtained. Multi-scale optical-flow has been adapted for use in the tracker, to increase robustness to larger motions.