Measurement-Limited Multi-Agent, Relative Pose Estimation for On-Orbit Inspection

Relative navigation methods are a critical enabling technology for the next generation of autonomous spacecraft conducting close proximity operations. This is especially true for multi-agent inspection operations in which safety including intra-agent or agent-target collisions are a serious concern. Additionally, in an on-orbit servicing operation various failure modes of the target may result in unreliable a-priori knowledge or cooperation from the target. The main contribution of this work is the demonstration of a method for multi-agent, relative pose estimation that is robust to A) sensor blinding and B) dynamic uncertainty. This objective is accomplished leveraging GTSAM, an existing toolbox for the formulation of factor graphs, along with an algorithm for the efficient, real-time so- lution of such factor graphs, iSAM2. This estimation method is demonstrated in an example scenario with uncertain dynamics and sensor blinding due to sun position. Results revealed that the iSAM2-based method is capable of handling sensor blinding through leveraging an inter-agent range measurement, despite a dynamically uncertain environment.