Abstract:
Small celestial bodies such as asteroids and comets are abundantly present in
the Solar System, yet their surfaces remain largely unexplored. Achieving regular
access to these surfaces would have a major impact on capabilities such as
planetary defence and in situ resource utilisation and lead to significant scientific
insights. However, missions close to small celestial objects remain challenging in at least
two aspects: technically, due to weak gravity fields, complex operational
environments and latency from long communication times, and commercially,
with the applications still being few and cost-ineffective. A potential solution to reducing development and operational costs and obtaining
robust, scalable operations, could be using small, camera-only spacecraft with
an elevated degree of autonomy. Enabling a camera-based autonomy requires
building appropriate computer vision pipelines. All computer vision pipelines start
with the detection of features - salient patterns within the scene. This thesis
presents multiple methods and tools enabling the appropriate selection and
management of different features for autonomous navigation in proximity to
asteroids. To that end, relevant contributions developed during this work consist of:
The development of a software toolbox for prototyping and testing optical
navigation technologies through a parametrisable synthetic 3D visual
environment;
An analysis of the response of feature detectors to internal factors (e.g.,
feature model) and external factors (e.g., illumination). This response,
once known, can be used for designing the system or to obtain situational
awareness
An assessment of the response of template matching methods when the
template (model) does not perfectly match the observed target (asteroid,
with illumination). Through the above contributions, it was shown that considering environmental
cues and the perception model helps in achieving robust camera-only navigation
processes.
This capability could lead to small satellites autonomously exploring hundreds or
thousands of small celestial objects or be employed on more powerful spacecraft
for redundancy.
