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US 2002/0116993 A1Published application
Method and apparatus for determining the yaw angle of a satellite
AssigneeSES Astra S.A.
InventorChristian Patouraux
Life of this patent
Estimating the term…
Abstract
The method according to the invention allows to determine the yaw angle of a satellite from the reading of two different sensors measuring the roll and/or pitch angles, provided that the reference point of the two sensors are not identical. A description is given basically for geostationary satellites but the method can be applied directly to satellites which are stationary with respect to any star. The method can be employed for circular and non-circular orbits.
Claims26
Method for determining the yaw angle of a satellite,
- wherein a fixed cartesian coordinate system is defined with regard to the satellite, having a first axis which is directed substantially tangential to the orbit of the satellite and defines a roll angle, having a second axis which is directed substantially perpendicular to the orbit plane of the satellite and defines a pitch angle, and having a third axis which is directed substantially radial to the orbit of the satellite and defines a yaw angle, comprising the steps of:
- providing a first angle sensor and a second angle sensor having different reference points and measuring the same angle about a measurement axis which is anti-parallel to the third axis,
- evaluating a first angle and a second angle about the measurement axis on the basis of the angle sensors, and
- determining the yaw angle on the basis of the first angle and the second angle.
1 more element
Method for determining the yaw angle of a satellite,
- wherein a fixed cartesian coordinate system is defined with regard to the satellite, having a first axis which is directed substantially tangential to the orbit of the satellite and defines a roll angle, having a second axis which is directed substantially perpendicular to the orbit plane of the satellite and defines a pitch angle, and having a third axis which is directed substantially radial to the orbit of the satellite and defines a yaw angle, comprising the steps of:
- providing a first angle sensor and a set of angle sensors including a second and third angle sensor, wherein the first, second and third angle sensors measure angles about different measurement axes which are anti-parallel to the third axis and wherein for the first angle sensor and for the set of angle sensors different reference points are assigned,
- evaluating measurement angles on the basis of the angle sensors, and
- determining the yaw angle on the basis of the measurement angles.
1 more element
Method for determining a calibrated value for a yaw angle of a satellite, comprising the steps of:
- storing a yaw angle profile over a quiet orbit,
- determining a sample yaw angle at a calibration time (t0),
- determining a calibrated value by subtracting the sample yaw angle with a yaw angle profile value having a time shift in the yaw angle profile corresponding to the calibration time (t0).
Method for determining a calibrated value for a yaw angle of a satellite,
- storing for each angle sensor on board of the satellite a profile over a quiet orbit,
- determining a sample value for each of the angle sensors at a calibration time (t0),
- determining calibrated values for each angle sensor by subtracting the sample values with a angle sensor profile value having a time shift in the respective angle sensor profile corresponding to the calibration time (t0),
- determining a calibrated value for a yaw angle with calibrated values for each angle sensor.
1 more element
Apparatus for determining the yaw angle of a satellite,
- wherein a fixed cartesian coordinate system is defined with regard to the satellite, having a first axis which is directed substantially tangential to the orbit of the satellite and defines a roll angle, having a second axis which is directed substantially perpendicular to the orbit plane of the satellite and defines a pitch angle, and having a third axis which is directed substantially
- radial to the orbit of the satellite and defines a yaw angle, comprising:
- a first angle sensor and a second angle sensor having different reference points,
- means for measuring the same angle about a measurement axis which is anti-parallel to the third axis,
- means for evaluating a first angle and a second angle about the measurement axis on the basis of the angle sensors, and
- means for determining the yaw angle on the basis of the first angle and the second angle.
3 more elements
Apparatus for determining the yaw of a satellite,
- wherein a fixed cartesian coordinate system is defined with regard to the satellite, having a first axis which is directed substantially tangential to the orbit of the satellite and defines a roll angle, having a second axis which is directed substantially perpendicular to the orbit plane of the satellite and defines a pitch angle, and having a third axis which is directed substantially radial to the orbit of the satellite and defines a yaw angle, comprising:
- a first angle sensor and a set of angle sensors including a second and third angle sensor,
- means for measuring by the first, second and third angle sensors angles about different measurement axes which are anti-parallel to the third axis, wherein for the first angle sensor and for the set of angle sensors different reference points are assigned,
- means for evaluating measurement angles on the basis of the angle sensors, and
- means for determining the yaw angle on the basis of the measurement angles.
2 more elements
Apparatus for determining a calibrated value for a yaw angle of a satellite, comprising:
- means for storing a yaw angle profile over a quiet orbit,
- means for determining a sample yaw angle at a calibration time (t0),
- means for determining a calibrated value by subtracting the sample yaw angle with a yaw angle profile value having a time shift in the yaw angle profile corresponding to the calibration time (t0).
Apparatus for determining a calibrated value for a yaw angle of a satellite,
- means for storing for each angle sensor on board of the satellite a profile over a quiet orbit,
- means for determining a sample value for each of the angle sensors at a calibration time (t0),
- means for determining calibrated values for each angle sensor by subtracting the sample values with a angle sensor profile value having a time shift in the respective angle sensor profile corresponding to the calibration time (t0),
- means for determining a calibrated value for a yaw angle with calibrated values for each angle sensor.
1 more element
Dependencies are inferred from the claim text.