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US 12,263,961 B2Granted
Maneuvering of satellites without rate sensors
AssigneeMaxar Space LLC
InventorThomas Joseph Holmes
Life of this patent
Estimating the term…
Abstract
An attitude control system for a satellite is presented that can determine on time values for attitude control thrusters without use of attitude rate sensors, such as those based on gyros. The attitude control systems uses the attitude values from a star tracker to determine both attitude adjustment values and attitude adjustment rate values directly from the star tracker values, where the processing is performed using quaternions. From the attitude adjustment values and attitude adjustment rate values, a set of thruster on time values are determined.
Claims20
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.
12 more elements
A method, comprising:
- receiving from a star tracker a sequence of attitude values for a spacecraft;
- comparing the sequence of attitude values to a set of mission attitude values;
- determining 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;
- comparing a first of the sequence of attitude adjustment values to a previous one of the sequence of attitude adjustment values;
- determining 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;
- determining on time values for a set of attitude control thrusters of the spacecraft from the attitude adjustment values and the attitude adjustment rate value;
- providing the on time values to the set of attitude control thrusters;
- firing 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:
- monitoring the attitude values;
- estimating 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 determining, independently of an attitude rate sensor, the current set of on time values based on the estimated amount of change in the attitude values.
10 more elements
A satellite, comprising a set of attitude control thrusters responsive to on time values;
- an image sensor mounted on a body of the satellite;
- and
- an attitude control system configured to receive image data from the image sensor and to supply the on time values to the set of attitude control thrusters, the attitude control system comprising:
- a star tracker configured to receive the image data and determine a sequence of attitude values for the satellite 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 satellite 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 satellite 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 the on time values for the set of attitude control thrusters of the satellite 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 attitude values.
15 more elements
Dependencies are inferred from the claim text.