INS/ST/Optical Sensor Integrated Algorithm With Weighted Multi Observation

Abstract

This research focuses on demonstrating the navigation system which can improve robustness and accuracy without prior information in approaching phase of planet. Craters are targeted landmarks for optical sensor since the success of Near Earth Asteroid Rendezvous (NEAR) mission during the approaching phase to the asteroid Eros 433. If circle is lying on plane, normal vector of the plane can be calculated from coefficient matrix of the circle. Despite of craters are known to be ellipse-shaped landmarks that exist on the surface of the planets, approximately 5% of all kilometre-sized craters formed on Mars, Venus, and the Moon have elliptical shapes. So the approaching phase, normal vector can be obtained from craters and it is integrated with star tracker measurement. The integrated measurement includes horizontal information of absolute position. To mitigate the error from elliptical crater, quality value of each measurement is calculated with parity vector which is often used in Fault Detection and Isolation(FDI). The elliptical craters are considered as fault that its error level is quantized via p-value test using parity vector. Finally, the performance of the proposed method is verified through numerical simulation. To verify that how well the algorithm estimates horizontal position and performance is compared with and without quality value.