Stellar Positioning System Part II: Overcoming Error During Implementation

Stellar Positioning System (Part I): An Autonomous Position Determination Solution

“…Comparing this result to the normalized local position vector, l, using Dy ¼ cos 21 (ĝ Á l, maximum angular error between the two vectors, Dy, is 1.3 arcsec. When multiplied by the equatorial radius, this error translates to approximately 40.40 m. Given this order of error, it seems reasonable to conclude that the assumption of l ¼ 2g/kgk is valid with respect to the current level of accuracy achieved in implementation [13]. This approximation may be sufficient for SPS validation on Earth, but a full investigation and development of a gravity model will be necessary for extraterrestrial deployment.…”

“…Estimation of the relative positions of these hardware components must be performed a priori and relies on the accuracy of calibration instrumentation, such as GPS. Accuracy of the time system clock and inclinometer readings, as well as the quality of the images also contribute to error uncertainty, as discussed in the companion paper [13].…”

“…Refinements to the initial Earth model, assumed to be spherical, will then be described. Finally, a brief overview of implementation obstacles is provided, though a full discussion of hardware and data processing solutions is beyond the scope of this paper [12,13].…”

A Survey on Star Identification Algorithms

“…His key to reducing the recursive mode time was to speed the selection of stars that ought to be visible given some other visible stars. He presented two methods, one which used the Mortari's Spherical Polygon-Search (SP-Search) [30,31], which in turn used his k-vector, and the second which used a pre-built catalog of stars that should be visible if another star is visible, the Star Neighborhood Approach (SNA). The SP-Search uses a k-vectorattitude estimate to search for the presence of these predicted stars in the set of the camera's observed stars.…”

“…Positioning System. If carried on a planet or moon, it could be used to estimate its position on the body when combined with a clock and two inclinometers [30,31].…”