# US 10,501,211 B1 · Pre and post orbit maneuver pulses to reduce flexural oscillations

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- Number: US 10,501,211 B1
- Document ID: US10501211B1
- Status: Granted
- Kind: B1
- Application number: 14/972,736
- Filed: 2015-12-17
- Granted: 2019-12-10
- Earliest claimed: 2015-12-17
- Assignees: Space Systems/Loral, Inc.
- Applicants: Space Systems/Loral, LLC
- Inventors: Philip Conway Hirschberg
- Web page: https://patentgrep.com/patent/US10501211B1

## CPC

- B64G 1/38: damping of oscillations, e.g. nutation dampers
- B64G 1/24: Guiding or controlling apparatus, e.g. for attitude control
- B64G 1/242: {Orbits and trajectories}
- B64G 1/26: using jets
- B64G: COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR

## Abstract

Techniques for performing an orbital maneuver on a spacecraft by firing a thruster include executing a first double pulse, double coast firing (DPDC) sequence with the thruster prior to the orbital maneuver, firing the thruster for a duration of the orbital maneuver, and executing a second DPDC firing sequence with the thruster subsequent to the orbital maneuver.

## Claims

### Claim 1

A method for performing an orbital maneuver on a spacecraft by firing a thruster, the method comprising:
executing a first double pulse, double coast firing (DPDC) sequence with the thruster prior to the orbital maneuver;
firing the thruster for a duration of the orbital maneuver; and
executing a second DPDC firing sequence with the thruster subsequent to the orbital maneuver.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the first DPDC firing sequence includes a first pulse firing having a first duration Ta1, followed by a first coast interval having a second duration Tb1, followed by a second pulse firing for the second duration Tb1, followed by a second coast interval for the first duration Ta1; and
the second DPDC firing sequence includes a third coast interval for a third duration Ta2, followed by a third pulse firing for a fourth duration Tb2, followed by a fourth coast interval for the fourth duration Tb2 followed by a fourth pulse firing for the third duration Ta2.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the spacecraft includes, in an on-orbit configuration, a deployed appendage, mechanically coupled with the spacecraft and has a characteristic dynamic response period of oscillation (‘T’); and
each of Ta1, Tb1, Ta2, andTb2 is selected as a respective particular fraction of the characteristic dynamic response period.

### Claim 4 (depends on 3)

The method of claim 3, wherein Ta1 and Ta2 are selected to be within the approximate range of 0.06 T to 0.1 T and Tb1 and Tb2 are selected to be within the approximate range of 0.1 T to 0.3 T.

### Claim 5 (depends on 3)

The method of claim 3, wherein Ta1 and Ta2 are selected to be approximately equal to 0.08 T and Tb1 and Tb2 are selected to approximately equal 0.21 T.

### Claim 6 (depends on 3)

The method of claim 3, wherein Ta1 and Ta2 are selected to be approximately equal to 0.09 T and Tb1 and Tb2 are selected to be approximately equal 0.28 T.

### Claim 7 (depends on 3)

The method of claim 3, wherein Ta1=Ta2 and Tb1=Tb2.

### Claim 8 (depends on 3)

The method of claim 3, wherein the appendage is a solar array or a payload element.

### Claim 9

A spacecraft comprising a spacecraft controller and a thruster, the spacecraft controller configured to cause the spacecraft to execute an orbital maneuver by firing a thruster, wherein the spacecraft controller:
executes a first double pulse, double coast firing (DPDC) sequence with the thruster prior to the orbital maneuver;
fires the thruster for a duration of the orbital maneuver; and
executes a second DPDC firing sequence with the thruster subsequent to the orbital maneuver.

### Claim 10 (depends on 9)

The spacecraft of claim 9, wherein:
the first DPDC firing sequence includes a first pulse firing having a first duration Ta1, followed by a first coast interval having a second duration Tb1, followed by a second pulse firing for the second duration Tb1, followed by a second coast interval for the first duration Ta1; and
the second DPDC firing sequence includes a third coast interval for a third duration Ta2, followed by a third pulse firing for a fourth duration Tb2, followed by a fourth coast interval for the fourth duration Tb2 followed by a fourth pulse firing for the third duration Ta2.

### Claim 11 (depends on 9)

The spacecraft of claim 9, wherein:
the spacecraft includes, in an on-orbit configuration, a deployed appendage, mechanically coupled with the spacecraft and has a characteristic dynamic response period of oscillation (‘T’); and
each of Ta1, Tb1, Ta2, and Tb2 is selected as a respective particular fraction of the characteristic dynamic response period.

### Claim 12 (depends on 11)

The spacecraft of claim 11, wherein Ta1 and Ta2 are selected to be within the approximate range of 0.06 T to 0.1 T and Tb1 and Tb2 are selected to be within the approximate range of 0.1 T to 0.3 T.

### Claim 13 (depends on 11)

The spacecraft of claim 11, wherein Ta1 and Ta2 are selected to be approximately equal to 0.08 T and Tb1 and Tb2 are selected to approximately equal 0.21 T.

### Claim 14 (depends on 11)

The spacecraft of claim 11, wherein Ta1 and Ta2 are selected to be approximately equal 0.09 T and Tb1 and Tb2 are selected to approximately equal 0.28 T.

### Claim 15 (depends on 11)

The spacecraft of claim 11, wherein Ta1=Ta2 and Tb1=Tb2.

### Claim 16 (depends on 11)

The spacecraft of claim 11, wherein the appendage is a solar array or a payload element.

### Claim 17

A non-transitory computer readable medium having software stored thereon, the software including instructions for causing a controller to:
cause a spacecraft, the spacecraft including the controller and a thruster, to execute an orbital maneuver by firing the thruster, wherein the firing the thruster includes:
executing a first double pulse, double coast firing (DPDC) sequence with the thruster prior to the orbital maneuver;
firing the thruster for a duration of the orbital maneuver; and
executing a second DPDC firing sequence with the thruster subsequent to the orbital maneuver.

### Claim 18 (depends on 17)

The computer readable medium of claim 17, wherein:
the first DPDC firing sequence includes a first pulse firing having a first duration Ta1, followed by a first coast interval having a second duration Tb1, followed by a second pulse firing for the second duration Tb1, followed by a second coast interval for the first duration Ta1; and
the second DPDC firing sequence includes a third coast interval for a third duration Ta2, followed by a third pulse firing for a fourth duration Tb2, followed by a fourth coast interval for the fourth duration Tb2 followed by a fourth pulse firing for the third duration Ta2.

### Claim 19 (depends on 17)

The computer readable medium of claim 17, wherein:
the spacecraft includes, in an on-orbit configuration, a deployed appendage, mechanically coupled with the spacecraft and has a characteristic dynamic response period of oscillation (‘T’); and
each of Ta1, Tb1, Ta2, and Tb2 is selected as a respective particular fraction of the characteristic dynamic response period.

### Claim 20 (depends on 19)

The computer readable medium of claim 19, wherein Ta1=Ta2 and Tb1=Tb2.