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Research Seminars

May 17, 2018 at 1:30 PM

Location:3124 Mackenzie

Speaker: Jian-Feng Shi, PhD Candidate

Abstract: This presentation presents a level-set and image pixel probability-based method to compute pose estimation of satellites. The level-set segmentation technique elevates the two-dimensional image contours to a third dimension allowing easy handling of topology changes. The investigated method allows efficient feedback in the pose estimation process by combining level-set segmentation with pixel likelihood prior generated by a 3D model projection. This investigation provides an original matrix formulation of the energy partial derivative with respect to the pose parameters accounting for the pixel skew factor. Enhancement of the posterior map is provided using Otsu’s thresholding and a flood-fill sequence. Results show the improvement reduces the degradation of the pixel probability and level-set contour generation error. This method was tested using colour and monochromatic monocular spacecraft images.

Speaker: Jeffrey Hough, NSERC USRA Research Assistant

Abstract: This presentation develops stable guidance laws based on Lyapunov vector fields to perform close-proximity maneuvers of robotic spacecraft. The general case is considered, where targets are orbiting the Earth elliptically and are analyzed within rotating, three-dimensional reference frames. As a main contribution, a first of its kind strategy for employing Lyapunov vector field guidance within such reference frames is developed. Three guidance laws are proposed: one for loiter circle formation flying, one for docking to tumbling targets, and one for obstacle avoidance. Numerical simulations demonstrate robust and versatile guidance capabilities.