Autonomous formation flying sensor

• US 6,072,433 A
• Filed: 07/31/1997
• Issued: 06/06/2000
• Est. Priority Date: 07/31/1996
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Lau, Kenneth H., Tien, Jeffrey Y., Haines, Bruce J., Dunn, Charles E., Young, Lawrence E., Lichten, Stephen M.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/999,828
• Time in Patent Office: 1,041 Days
• Field of Search: 364/460, 343/113, 455/13, 342/357.08, 342/357.11, 342/450, 342/386, 701/300
• US Class Current: 342/386
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 19/53 Determining attitude
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems

Abstract

An autonomous formation flying sensor for precise autonomous determination and control of the relative position and attitude for a formation of moving objects.

Claims

1. A formation sensing system for a formation having a plurality of formation members, comprising:

a plurality of antennas disposed on each formation member to receive and transmit transmission signals with other formation members that are indicative of relative positioning and attitude information of the formation members; and

a transceiver located on each formation member and connected to said antennas, said transceiver having a down-conversion assembly operable to demodulate received transmission signals from other formation members, a signal processor operable to process the received signals and generate data indicative of the relative positioning and attitude information without reference to an external signal outside the formation members, and an up-conversion assembly operable to use a ranging code to produce a transmission signal to other formation members,

wherein transceivers of any two communicating formation members are configured to process respective transmission signals from each other to determine a clock offset and a distance between the two transceivers, without synchronization to a clock signal.

2. A system as in claim 1, wherein said ranging code comprises a GPS ranging code and signal processor is operable to generate the data indicative of the relative positioning and attitude information in absence of GPS signals from GPS satellites.

3. A system as in claim 1, wherein said ranging code comprises a non-GPS ranging code.

4. A system as in claim 3, wherein said non-GPS ranging code is generated based on a pseudo-random noise code.

5. A system as in claim 3, wherein said non-GPS ranging code is generated based on a spaced ranging tone scheme.

6. A system as in claim 1, wherein said signal processor is configured to superimpose additional information onto said transmission signal, said additional information including at least one of the group consisting of telemetry, control commands, scientific and engineering data.

7. A system as in claim 1, wherein said antennas are arranged to form a three dimensional antenna array which has a field-of-view of about 4π

steradian.

8. A system as in claim 1, wherein said down-conversion assembly includes a signal mixer, a low-pass filter, and a signal amplifier.

9. A system as in claim 1, wherein said up-conversion assembly includes a first signal mixer that encodes said data from said signal processor according to said ranging code and a second signal mixer to superimpose said data onto a high-frequency signal carrier.

10. A system as in claim 8, further comprising a reference oscillator producing a frequency reference signal and wherein said high-frequency signal has a frequency offset with respect to said frequency reference signal.

11. A system as in claim 1, wherein said signal processor comprises a GPS receiver processor.

12. A system as in claim 1, wherein said signal processor includes a CPU that produces said data and a plurality of application-specific integrated circuits with at least one of which being configured to produce said ranging code.

13. A method of initiating and autonomously maintaining a formation of a plurality formation members, comprising:

adjusting orientation of each formation member to establish initial communication links among formation members;

using coded ranging radio signals to exchange phase and range data among formation members;

determining a clock offset between any two communicating formation in absence of a synchronization signal to compute a distance therebetween;

producing a measured formation configuration by computing relative positioning and orientation of the formation according to said phase and range data without a reference to an external reference signal outside the formation; and

comparing said measured formation configuration with a desired formation configuration to determine a difference therebetween.

14. A method as in claim 13, wherein said phase and range data are indicative of a GPS model.

15. A method as in claim 13, wherein said phase and range data are generated based on a non-GPS split spectrum scheme.

16. A method as in claim 13, further comprising repeating the exchange of the phase and range data from one formation member to others to monitor and maintain a formation configuration according to the desired formation configuration.

17. A method as in claim 13, further comprising repeating said adjusting orientation of each formation member to establish said initial communication links when the formation configuration is disrupted.

18. A method as in claim 13, further comprising generating maneuver instructions operable to minimize said difference by maneuvering at least one formation member.

19. A method of maintaining a formation having at least two formation members, comprising:

using at least two antennas in one formation member to receive transmision signals from another formation member to determine an attitude of the one formation member relative to the other formation member without a reference external to the formation;

processing a transmission signal from the one formation member to the other in a relation with another transmission signal from the other formation member to the one formation member to determine a clock offset between the two formation members based on a ranging code in the transmission signals without a synchronization clock signal; and

using the clock offset to determine a distance between the two formation members according to a time delay of signal transmission between the two formation members.

20. A method as in claim 19, wherein the ranging code comprises pulses of a temporal sequence and is used to determine a distance between two formation members.

21. A method as in claim 19, wherein the ranging code includes a pseudo-randon noise code which is used to determine a distance between two formation members.

22. A method as in claim 19, wherein the ranging code includes tones at different frequencies and is used to determine a distance between two formation members.

23. A method as in claim 19, further comprising:

comparing relative positioning and attitude of the two formation members to desired relative positioning and attitude to determine a deviation therebetween; and

adjusting at least one formation member to reduce the deviation.