Exclusion zone guidance method for spacecraft

• US 20090008495A1
• Filed: 03/27/2008
• Published: 01/08/2009
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Sierra Space Corporation
• Original Assignee: Spacedev Inc. (Sierra Nevada Co. LLC)
• Inventors: Koenig, Jesse D.
• Granted Patent: US 7,795,566 B2
• Time in Patent Office: Days
• US Class Current: 244/3.110
• CPC Class Codes: B64G 1/244 Spacecraft control systems
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/781 Details
• CPC Class Codes: G01S 3/786 the desired condition being maintained automatically

Abstract

Systems and methods for are adapted for automatic implementation of exclusion zone avoidance for target-tracking vehicles, such as spacecraft. The systems and methods are configured to monitor pointing commands (commanded attitude and angular rates) generated for target tracking, and modify these commands as necessary to avoid pointing a boresight into an exclusion zone.

Claims

1. A method for guiding a body that is performing a function relative to an attitude trajectory, the method comprising:

identifying a body having a body axis and a set of dynamic limits;

determining that a projection of the body axis will intersect an exclusion zone if the body follows an original desired attitude trajectory; and

modifying attitude commands to steer the projection of the body axis around the exclusion zone, wherein the attitude commands are modified in such a way that associated rates and accelerations are within dynamic limits of the body and wherein the attitude commands are modified in such a way as to minimize the amount of time for which an original desired attitude trajectory of the body is modified.

2. A method as in claim 1, wherein the body is a spacecraft.

3. A method as in claim 1, wherein the function is to track a target object by maintaining the body axis pointing at the target object.

4. A method as in claim 1, wherein the body axis is the boresight of a sensing instrument.

5. A method as in claim 1, wherein the attitude trajectory comprises a profile of attitudes over time.

6. A method as in claim 1, wherein the attitude commands are modified a minimum amount to steer the projection of the body axis around the exclusion zone.

7. A method as in claim 1, wherein the attitude commands are modified to steer the projection of the body axis around a predetermined pad around the exclusion zone.

8. A method as in claim 1, wherein the method begins modifying the attitude commands based on a cross-boresight rate of the body.

9. A method as in claim 8, wherein the method begins modifying the pointing commands a certain distance from the exclusion zone based on the cross-boresight rate of the body.

10. A method as in claim 9, wherein a higher cross-boresight rate results in the method beginning modification of the pointing commands earlier than a lower cross-boresight rate.