US 12,263,961 B2
Maneuvering of satellites without rate sensors
Thomas Joseph Holmes, Rapid City, SD (US)
Assigned to Maxar Space LLC, Palo Alto, CA (US)
Filed by Maxar Space LLC, Palo Alto, CA (US)
Filed on Jun. 27, 2022, as Appl. No. 17/850,164.
Prior Publication US 2023/0415925 A1, Dec. 28, 2023
Int. Cl. B64G 1/24 (2006.01); B64G 1/26 (2006.01); B64G 1/36 (2006.01); B64G 1/28 (2006.01)
CPC B64G 1/244 (2019.05) [B64G 1/26 (2013.01); B64G 1/361 (2013.01); B64G 1/245 (2023.08); B64G 1/28 (2013.01); B64G 1/36 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An attitude control system, comprising:
a star tracker configured to receive image data from an image sensor mounted on a spacecraft and determine a sequence of attitude values for the spacecraft from the image data; and
one or more control circuits connected to receive the sequence of attitude values from the star tracker and configured to:
compare the sequence of attitude values to a set of mission attitude values;
determine a sequence of attitude adjustment values for the spacecraft from the comparing of the sequence of attitude values to the set of mission attitude values;
compare a first of the sequence of attitude adjustment values to a previous one of the sequence of attitude adjustment values;
determine an attitude adjustment rate value for the spacecraft from the comparing of the first of the sequence of attitude adjustment values to the previous one of the sequence of attitude adjustment values;
determine on time values for a set of attitude control thrusters of the spacecraft from the attitude adjustment values and the attitude adjustment rate value;
provide the on time values to the set of attitude control thrusters;
fire the set of attitude control thrusters according to the on time values;
while firing the set of attitude control thrusters according to a current set of on time values:
monitor the attitude values;
estimate an amount of change in the monitored attitude values in response to firing the set of attitude control thrusters according to the current set of on time values; and
further determine, independently of an attitude rate sensor, the current set of on time values based on the estimated amount of change in the monitored attitude values.