Application of wide-field integration of optic flow to proximity operations and landing for space exploration missions

New advances in vision-based navigation for micro air vehicles (MAVs) have been inspired by the biological systems of flying insects and the use of optic flow. These biologically-inspired optical sensor systems for MAVs are computationally efficient and have low mass and low power consumption, which makes them attractive for small spacecraft. This study explores the applicability of the wide-field integration (WFI) of optic flow to a spacecraft operating in close proximity to an asteroid. In contrast with past WFI work, this study uses an asteroid-relative reference trajectory and known a priori environment model such that the optimal sensitivity functions are recalculated onboard the vehicle at each time step. Numerical simulations with computer-generated images of the asteroid surface are used to estimate the vehicle's translational and angular velocities. Although the accuracy of these state estimates are reasonable considering the noise in the optic flow measurements, the onboard recalculation of the sensitivity functions for this time-varying scenario add computational burden which negates the main advantage of the WFI method. Hence, future applications to time-invariant scenarios for small-body missions are also discussed.