Date of Award

2008

Document Type

Thesis - Open Access

Degree Name

Master of Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Bogdan Udrea

Committee Member

Frederique J. Drullion

Committee Member

Yechiel J. Crispin

Abstract

The purpose of this study is to determine the attitude of an out of control object using a new technology called lidar (Light Ranging and Detection). As the number of spacecraft continues to grow, it is paramount to introduce a new type of autonomous on-orbit satellite inspection and repair involving docking. Traditional space vision technology is based on video systems. This method is limited by the necessity of operating when the target is illuminated by the sunlight or using its own source of illumination. The use of laser imaging technology offers an elegant solution to these challenges. This approach allows the collection of range data, while scanning the lidar field-of-view together with the transmitted laser beam across the required solid angle. A lidar simulator was implemented to generate point clouds of digital 3D models. This thesis describes methods that can be used to detect features such as edges, boundaries, surfaces and corners in the point cloud. From those features it was possible to define a reference frame and associate it to the object. Observing the evolution of this body frame, the changes in orientation can be deduced in the direction cosine matrix form. It was desired to retrieve angular rates in Euler angle form but since the conversion from rotation matrix to Euler is not a bijection, no satisfying results were obtained. The results are therefore expressed in terms of rotation matrix. It was found that depending on the orientation of the spacecraft the accuracy of the results varied. The results indicate that filtering of the direction cosine matrices might yield good data for determining attitude rates.

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