Local area positioning system

• US 6,445,344 B1
• Filed: 11/13/2000
• Issued: 09/03/2002
• Est. Priority Date: 11/16/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Wise, Carl D., Powell, Norman F., Iny, David R., Moulds, Clinton W.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US09/709,299
• Time in Patent Office: 659 Days
• Field of Search: 342/450, 342/457, 342/458, 342/431, 342/462, 342/463, 342/357.08, 342/357.09, 342/357.1
• US Class Current: 342/458
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 2205/07 Military
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems
• CPC Class Codes: G01S 5/0264 at least one of the systems being a non-radio wave positioning system
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

A local area positioning system which includes a plurality of platforms or nodes consisting of airborne and/or ground based vehicles that are coupled in a platform-to-platform local area network. The platforms themselves establish a spatial reference system for location and communication between platforms is accomplished using directive millimeter wave beams, and where measurements and communicated estimates of node locations, in a local inertial reference frame, are processed via Kalman tracking filters to generate updated estimates of position and velocity vectors associated with each node.

Claims

1. A local area positioning system for providing vehicular navigation within a common spatial reference system, comprising:

a plurality of networked platforms including air, space and/or ground vehicles communicating with one another by means of directed beams of electromagnetic energy; and

,

wherein each of the platforms includes an identical tracking system which is responsive to on-board range and range rate measurements of predetermined operational parameters, the measurements being not only used by the respective platform, but also communicated to a selected number of other platforms of said plurality of platforms, said platform in return receiving like measurements from said other platforms for calculating and updating a respective navigation state of the respective platform relative to the other platforms.

2. The local area positioning system according to claim 1 wherein said identical type tracking system comprises a Kalman filter tracking system which generates updated estimates of respective platform position, velocity and attitude within said navigation coordinate frame.

3. The local area positioning system according to claim 2 wherein said Kalman filter tracking system includes:

a set of state integrators for generating state vector estimates of position and velocity of the respective platform in response to inputs from an inertial measurement unit;

a Kalman filter section for updating the state vector estimates generated by the set of state integrators of the respective platform in response to range and range rate measurements, as well as state vector estimates of position and velocity received from said selected number of other platforms;

a communications link for coupling state vector estimates, range and range rate measurements between said platforms; and

,

another set of state integrators which receive and update state vector estimates of position and velocity of the respective platform as well as the state vector estimates of position and velocity of said selected number of other platforms for controlling the pointing of said beams of electromagnetic energy to said selected number of other platforms.

4. The local area positioning system according to claim 3 and additionally including a frequency and time reference section for adding a clock bias to the state vector estimates.

5. The local area positioning system according to claim 2 wherein said plurality of platforms operate in a pairwise mode as node pairs by transferring state and covariance estimates to each other when respective on-board measurements are made.

6. The local area positioning system according to claim 5 where the Kalman filter tracking system of each of said platforms or nodes includes a Kalman filter, first and second sets of state integrators for each platform, and a communications link coupling said pair of said platforms whenever pairwise measurements are made, and

wherein the first set of state integrators has inputs of F and {dot over (θ

)} from a respective inertial measurement unit and an input of K[y_k+1−

HΦ

{circumflex over (x)}_k] from the Kalman filter, said first set of state integrators generating an output of Φ

{circumflex over (x)}_k of the respective, platform of said pair of platforms which is coupled to the communications link,

wherein the Kalman filter receives inputs of del(t)/del(f), Φ

{circumflex over (x)}_k and P generated by the tracking system of the other platform of said pair of platforms and coupled thereto via the communication link,

the Kalman filter additionally providing an output of P of the respective platform which is fed to the communications link for coupling to said other platform,

wherein the communications link additionally receiving inputs of Φ

{circumflex over (x)}_k and P from said other platform while coupling outputs of del(t)/del(f), Φ

{circumflex over (x)}_k and P of the respective platform to said other platform,

wherein the communications link further couples Φ

{circumflex over (x)}_k of at least said one platform and said other platform to the second set of state integrators for generating control signals for controlling the pointing of a beam of electromagnetic energy from said one platform to said other platform, and

where F is a measurement of specific force on the platform, {dot over (θ

)} is a measurement of attitude rate of the platform, K represents a matrix of Kalman gains, y_k+1 represents measurements of range and rate between said pair of platforms at time k+1, H is an observation matrix expressing the relationship between y and {circumflex over (x)}_k, where {circumflex over (x)}_k corresponds to state vector estimates of position, velocity and attitude of a particular platform at time k, Φ

is a state transition matrix used to extrapolate the state estimate {circumflex over (x)}_k, Φ

{circumflex over (x)}_k is the extrapolated state estimate, del(t) corresponds to range, del(f) corresponds to range rate, and P represents a state covariance matrix.

7. The local area positioning system according to claim 6 and additionally including a frequency and time reference section for adding a clock bias to the state vector estimates and receiving del(t) and del(f inputs from the Kalman filter section for updating and providing corrections to time and frequency standard therein.

8. The local area positioning system according to claim 2 wherein said plurality of platforms operate in a fully coupled mode wherein data is passed between all networked platforms so as to achieve greater accuracy, and wherein respective estimates of platform position, velocity and attitude of all nodes within the common spatial reference system are jointly updated.

9. The local area positioning system according to claim 8 wherein the Kalman filter tracking system of each of said platforms or nodes includes a Kalman filter, first and second sets of state integrators, said first set of state integrators forming a portion of the Kalman filter, and a communications link for mutually coupling all of said platforms together, and

wherein the first set of state integrators has inputs of F and {dot over (θ

)} from a respective inertial measurement unit and an input of K[y_k+1−

HΦ

{circumflex over (x)}_k] from the respective Kalman filter, said first set of state integrators generating outputs of Φ and

{circumflex over (x)}_k which are coupled to the other node of said node pair as well as all other platforms via the communications link,

the Kalman filter receiving inputs via the respective communications link of del(t)/del(f), Φ

generated in the Kalman tracking section of all of the other platforms, and {circumflex over (x)}_k from the other node of said node pair,

the communications link receiving additional inputs of Φ

from all the other platforms or nodes including the other node of said node pair, and {circumflex over (x)}_k from the other node of said node pair, and coupling outputs of del(t)/del(f), Φ and

{circumflex over (x)}_k to all nodes including {circumflex over (x)}_k of said one node of the node pair to the other node thereof,

the communications link further coupling Φ

{circumflex over (x)}_k, of a predetermined number of said platforms including Φ

{circumflex over (x)}_k of said one node of said node pair to the second set of state integrators for generating control signals controlling the pointing of the directed beams of electromagnetic energy from one platform to another,

where F is a measurement of specific force on a platform, or node, {dot over (θ

)} is a measurement of attitude rate, K represents a matrix of Kalman gains, y_k+1 represents measurements of range and rate between platforms at time k+1, H is an observation matrix expressing the relationship between y and {circumflex over (x)}_k, where {circumflex over (x)}_k corresponds to state estimates of position, velocity and attitude at time k, Φ

is a state transition matrix used to extrapolate the state estimate {circumflex over (x)}_k, Φ

{circumflex over (x)}_k is the extrapolated state of estimate, del(t) corresponds to range and del(f) corresponds to range rate measurements of the respective platforms.

10. A local area positioning system for providing vehicular navigation within a common spatial reference system, comprising:

a plurality of networked platforms including air, space and/or ground vehicles communicating with one another by means of directed beams of electromagnetic energy;

wherein each of the platforms includes an identical tracking system which is responsive to on-board range and range rate measurements of predetermined operational parameters, the measurements being not only used by the respective platform, but also communicated to a selected number of other platforms of said plurality of platforms, said platform in return receiving like measurements from said other platforms for calculating and updating a respective navigation stat e of the respective platform relative to the other platforms;

wherein said tracking system comprises a Kalman filter tracking system which generates updated estimates of respective platform position, velocity and attitude within said navigation coordinate frame; and

wherein said Kalman filter tracking system includes;

a set of state integrators for generating state vector estimates of position and velocity of the respective platform in response to inputs from an inertial measurement unit;

a Kalman filter section for updating the state vector estimates generated by the set of state integrators of the respective platform in response to range and range rate measurements, as well as state vector estimates of position and velocity received from said selected number of other platforms;

a communications link for coupling state vector estimates, range and range rate measurements between said platforms; and

,

another set of state integrators which receive and update state vector estimates of position and velocity of the respective platform as well as the state vector estimates of position and velocity of said selected number of other platforms for controlling the pointing of said beams of electromagnetic energy to said selected number of other platforms.

11. A local area positioning system for providing vehicular navigation within a common spatial reference system, comprising:

a plurality of networked platforms including air, space and/or ground vehicles communicating with one another by means of directed beams of electromagnetic energy;

wherein each of the platforms includes an identical tracking system which is responsive to on-board range and range rate measurements of predetermined operational parameters, the measurements being not only used by the respective platform, but also communicated to a selected number of other platforms of said plurality of platforms, said platform in return receiving like measurements from said other platforms for calculating and updating a respective navigation state of the respective platform relative to the other platforms;

wherein each said tracking system comprises a Kalman filter tracking system which generates updated estimates of respective platform position, velocity and attitude within said navigation coordinate frame; and

wherein said plurality of platforms operate in a pairwise mode as node pairs by transferring state and covariance estimates to each other when respective on-board range and range rate measurements are made; and

where the Kalman filter tracking system of each of said platforms or nodes includes a Kalman filter, first and second sets of state integrators for each platform, and a communications link coupling said pair of said platforms whenever pairwise measurements are made, and

wherein the first set of state integrators has inputs of F and θ

from a respective inertial measurement unit and an input of K[y_k+1−

HΦ

{circumflex over (x)}_k] from the Kalman filter, said first set of state integrators generating an output of Φ

{circumflex over (x)}_k of the respective platform of said pair of platforms which is coupled to the communications link,

wherein the Kalman filter receives inputs of del(t)/del(f), Φ

{circumflex over (x)}_k and P generated by the tracking system of the other platform of said pair of platforms and coupled thereto via the communication link,

the Kalman filter additionally providing an output of P of the respective platform which is fed to the communications link for coupling to said other platform,

wherein the communications link additionally receiving inputs of Φ

{circumflex over (x)}_k and P from said other platform while coupling outputs of del(t)/del(f), Φ

{circumflex over (x)}_k and P of the respective platform to said other platform,

wherein the communications link further couples Φ

{circumflex over (x)}_k of at least said one platform and said other platform to the second set of state integrators for generating control signals for controlling the pointing of a beam of electromagnetic energy from said one platform to said other platform, and

where F is a measurement of specific force on the platform, θ

is a measurement of attitude rate of the platform, K represents a matrix of Kalman gains, y_k+1 represents measurements of range and rate between said pair of platforms at time k+1, H is an observation matrix expressing the relationship between y and {circumflex over (x)}_k, where {circumflex over (x)}_k corresponds to state vector estimates of position, velocity and attitude of a particular platform at time k, Φ

is a state transition matrix used to extrapolate the state estimate {circumflex over (x)}_k, Φ

{circumflex over (x)}_k is the extrapolated state estimate, del(t) corresponds to range, del(f corresponds to range rate, and P represents a state covariance matrix.

12. The local area positioning system according to claim 11 and additionally including a frequency and time reference section for adding a clock bias to the state vector estimates and receiving del(t) and del(f) inputs from the Kalman filter section for updating and providing corrections to time and frequency standard therein.

13. A local area positioning system for providing vehicular navigation within a common spatial reference system, comprising:

a plurality of networked platforms including air, space and/or ground vehicles communicating with one another by means of directed beams of electromagnetic energy;

wherein each of the platforms includes an identical tracking system which is responsive to on-board range and range rate measurements of predetermined operational parameters, the measurements being not only used by the respective platform, but also communicated to a selected number of other platforms of said plurality of platforms, said platform in return receiving like measurements from said other platforms for calculating and updating a respective navigation state of the respective platform relative to the other platforms;

wherein said tracking system comprises a Kalman filter tracking system which generates updated estimates of respective platform position, velocity and attitude within said navigation coordinate frame; and

wherein said plurality of platforms operate in a fully coupled mode wherein data is passed between all networked platforms so as to achieve greater accuracy, and wherein respective estimates of platform position, velocity and attitude of all nodes within the common spatial reference system are jointly updated; and

,

wherein the Kalman filter tracking system of each of said platforms or nodes includes a Kalman filter, first and second sets of state integrators, said first set of state integrators forming a portion of the Kalman filter, and a communications link for mutually coupling all of said platforms together,

the first set of state integrators have inputs of F and θ

from a respective inertial measurement unit and an input of K[y_k+1−

HΦ

{circumflex over (x)}_k] from the respective Kalman filter, said first set of state integrators generating outputs of Φ and

{circumflex over (x)}_k which are coupled to the other node of said node pair as well as all other platforms via the communications link,

the Kalman filter receiving inputs via the respective communications link of del(t)/del(f), Φ

generated in the Kalman tracking section of all of the other platforms, and {circumflex over (x)}_k from the other node of said node pair,

the communications link receiving additional inputs of Φ

from all the other platforms or nodes including the other node of said node pair, and {circumflex over (x)}_k from the other node of said node pair, and coupling outputs of del(t)/del(f), Φ and

{circumflex over (x)}_k to all nodes including {circumflex over (x)}_k of said one node of the node pair to the other node thereof,

the communications link further coupling Φ

{circumflex over (x)}_k of a predetermined number of said platforms including Φ

{circumflex over (x)}_k of said one node of said node pair to the second set of state integrators for generating control signals controlling the pointing of the directed beams-of electromagnetic energy from one platform to another,

where F is a measurement of specific force on a platform, or node, θ

is a measurement of attitude rate, K represents a matrix of Kalman gains, y_k+1 represents measurements of range and rate between platforms at time k+1, H is an observation matrix expressing the relationship between y and {circumflex over (x)}_k, where {circumflex over (x)}_k corresponds to state estimates of position, velocity and attitude at time k, Φ

is a state transition matrix used to extrapolate the state estimate {circumflex over (x)}_k, Φ

{circumflex over (x)}_k is the extrapolated state of estimate, del(t) corresponds to range and del(f) corresponds to range rate measurements of the respective platforms.