US 9,809,328 B2
Attitude determination using infrared earth horizon sensors
Tam Nguyen Thuc Nguyen, Cambridge, MA (US); Kerri L. Cahoy, Lexington, MA (US); and Meghan K. Quadrino, Cambridge, MA (US)
Assigned to Massachusetts Institute of Technology, Cambridge, MA (US)
Filed by Massachusetts Institute of Technology, Cambridge, MA (US)
Filed on Mar. 11, 2015, as Appl. No. 14/644,425.
Claims priority of provisional application 61/982,414, filed on Apr. 22, 2014.
Prior Publication US 2015/0298827 A1, Oct. 22, 2015
Int. Cl. B64G 1/36 (2006.01); B64G 1/24 (2006.01); B64G 1/26 (2006.01); B64G 1/28 (2006.01); B64G 1/32 (2006.01); B64G 1/34 (2006.01); B64G 1/40 (2006.01)
CPC B64G 1/365 (2013.01) [B64G 1/26 (2013.01); B64G 1/281 (2013.01); B64G 1/283 (2013.01); B64G 1/285 (2013.01); B64G 1/286 (2013.01); B64G 1/288 (2013.01); B64G 1/32 (2013.01); B64G 1/34 (2013.01); B64G 1/36 (2013.01); B64G 1/363 (2013.01); B64G 1/366 (2013.01); B64G 1/407 (2013.01); B64G 2001/245 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A system for spacecraft attitude determination, the system comprising:
a plurality of horizon sensors, each of the plurality of horizon sensors having a respective field-of-view (FOV), each of the plurality of horizon sensors having a sensitivity to the portion of the respective FOV obscured by Earth;
an attitude determination module coupled to the plurality of horizon sensors, the attitude determination module configured to:
obtain horizon sensor readings from the horizon sensors;
determine an Earth disk radius in a spacecraft's body frame;
convert the horizon sensor readings to nadir angles using a Gaussian approximation including dividing the horizon sensor FOV into a plurality of constant sensitivity regions each having a Gaussian approximation coefficient; and
estimate a nadir vector using the nadir angles and the Earth disk radius.