System and method for multi-sensor multi-target 3D fusion using an unbiased measurement space

Patent metadata

Field	Value
Publication number	US-10527705-B2
Application number	US-201916380854-A
Country	US
Kind code	B2
Filing date	Apr 10, 2019
Priority date	Jun 3, 2016
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

System and method for determining a position of a target in an unbiased 3D measurement space: generating 2D measurement data in focal planes of each sensor; calculating a line of sight (LOS) from the target for each sensor; intersecting the LOSs and finding the closest intersection point in a 3D space; calculating a boresight LOS in 3D for each sensor; intersecting the boresight lines of sights for each sensor, and finding the closest intersection point in the 3D space to define an origin for forming the unbiased 3D measurement space; and forming local unbiased 3D estimates of the position of the target in the unbiased 3D measurement space as a difference between a closest point of the target LOS and a closest point of the boresight LOS.

First claim

What is claimed is:

1. A method for determining positions of multiple moving targets in an unbiased three dimensional (3D) measurement space using data collected from the multiple targets by a plurality of electro-optical or infrared (EO/IR) sensors, the method comprising:
receiving data collected from the multiple targets;
receiving range data from a LADAR configured to point to only one of the multiple moving targets;
generating two dimensional (2D) measurement data for each of the multiple targets in a focal plane of each of the plurality of EO/IR sensors;
calculating a line of sight (LOS) to each of the multiple targets for each of the plurality of EO/IR sensors;
synchronizing the plurality of EO/IR sensors in space and time, using the 2D measurement data and the line of sights;
establishing the unbiased 3D measurement space from rates of LOS biases for each of the plurality of EO/IR sensors, as a virtual 3D sensor, wherein a size of the unbiased 3D measurement space is a function of ranges from the plurality of EO/IR sensors to the multiple targets;
calculating local unbiased 3D estimates of the positions of the multiple targets in the unbiased 3D measurement space representing a local arrangement of the multiple targets;
fusing the range data from the LADAR with the local unbiased 3D estimates of the positions of the multiple targets; and
utilizing the fused range data with the local unbiased 3D estimates of the positions of the multiple targets to perform one or more of tracking the multiple targets, recognizing the multiple targets, and characterizing the multiple targets.

2. The method of claim 1 , wherein each of the plurality of EO/IR sensors includes a focal plane for a given waveband.

3. The method of claim 1 , further comprising determining focal planes of each of the plurality of EO/IR sensors.

4. The method of claim 1 , wherein the plurality of EO/IR sensors are used to measure positions of each multiple targets at each point in time.

5. The method of claim 1 , wherein at least one of the plurality of EO/IR sensors includes multiple focal planes for multiple wavebands, and wherein the unbiased 3D measurement space is invariant to waveband misalignments in multiple focal planes and to waveband-dependent atmospheric refraction effects.

6. The method of claim 1 , further comprising intersecting the calculated lines of sight for each of the plurality of EO/IR sensor; calculating a boresight line of sight in 3D for each of the plurality of EO/IR sensors; intersecting the boresight lines of sights for each of the plurality of EO/IR sensors; and calculating closest intersection point in the 3D space to define an origin for forming the unbiased 3D measurement space.

7. The method of claim 6 , wherein a generalized dynamic triangulation method is used to estimate positions and velocities of the multiple targets and the boresight LOS to form the unbiased 3D measurement.

8. The method of claim 1 , further comprising a plurality of target candidate pairs;
and associating the plurality of target candidate pairs by:
analyzing each of target candidate pairs to determine whether a target candidate pair constitutes a target,
generating differential azimuth/elevation values for each target candidate pair via a projection of closest points for target candidate pairs and boresight LOSs back into the focal plane of each target candidate pair,
generating a differential range for each target candidate pair via differencing the ranges to the closest points for said each target candidate pair and to a closest point of the boresight LOSs of said each target candidate pair,
transforming the differential azimuth/elevation values and the ranges into the unbiased 3D measurement space, and
searching for two locations in the unbiased 3D measurement space to associate the target candidate pairs, wherein a size of the locations is defined by a sensor resolution in the unbiased 3D measurement space.

9. The method of claim 1 , further comprising filtering the local unbiased 3D estimates of the positions of the multiple targets recursively and in time to continue improving tracking accuracy and target association probabilities as new measurements of the multiple targets become available.

10. The method of claim 9 , wherein said filtering comprises:
using the local unbiased 3D estimates of positions of the multiple targets and target velocity in the unbiased 3D measurement space to model target dynamics in the unbiased 3D measurement space;
using a calibration technique to estimate 2D boresights of each EO/IR sensor and the 3D boresight of the unbiased 3D measurement space in the absolute coordinate system (ECI); and
calculating the positions and velocities of the multiple targets in the absolute ECI system by adding the local unbiased 3D estimates of the positions of the multiple targets and the target velocity in the unbiased 3D measurement space to the 3D boresight of the unbiased 3D measurement space.

11. A system for determining positions of multiple moving targets in an unbiased three dimensional (3D) measurement space using data collected from the multiple targets by a plurality of electro-optical or infrared (EO/IR) sensors comprising:
a receiver for receiving data collected from electrical signals reflected from each of the multiple targets by the plurality of EO/IR sensors and range data from a LADAR configured to point to only one of the multiple moving targets;
one or more processors for generating two dimensional (2D) measurement data for each of the multiple targets in a focal plane of each of the plurality of EO/IR sensors; calculating a line of sight (LOS) to each of the multiple targets for each of the plurality of EO/IR sensors; synchronizing the plurality of EO/IR sensors in space and time, using the 2D measurement data and the line of sights; establishing the unbiased 3D measurement space from rates of LOS biases for each of the plurality of EO/IR sensors, as a virtual 3D sensor, wherein a size of the unbiased 3D measurement space is a function of ranges from the plurality of EO/IR sensors to the multiple targets; calculating local unbiased 3D estimates of the positions of the multiple targets in the unbiased 3D measurement space representing a local arrangement of the multiple targets; fusing the range data from the LADAR with the local unbiased 3D estimates of the positions of the multiple targets; and utilizing the fused range data with the local unbiased 3D estimates of the positions of the multiple targets to perform one or more of tracking the multiple targets, recognizing the multiple targets, and characterizing the multiple targets.

12. The system of claim 11 , wherein at least one of the plurality of EO/IR sensors includes multiple focal planes for multiple wavebands.

13. The system of claim 11 , wherein the one or more processors further determine focal planes of each of the plurality of EO/IR sensors.

14. The system of claim 11 , wherein at least one of the plurality of EO/IR sensors includes multiple focal planes for multiple wavebands, and wherein the unbiased 3D measurement space is invariant to waveband misalignments in multiple focal planes and to waveband-dependent atmospheric refraction effects.

15. The system of claim 14 , wherein the unbiased 3D measurement space is invariant to waveband misalignments in multiple focal planes and to waveband-dependent atmospheric refraction effects.

16. The system of claim 11 , wherein a generalized dynamic triangulation method is used to estimate positions and velocities of closest points for the multiple targets and a boresight LO

Assignees

• Raytheon Co

Inventors

• Karlov Valeri I
• Brody Julian S
• Hulsmann John D

Classifications

• G01S3/7867 Primary

  Star trackers (navigation using star trackers G01C21/025) · CPC title

• G01S5/16

  using electromagnetic waves other than radio waves · CPC title

• G01C3/08

  Use of electric radiation detectors · CPC title

• G01B11/002

  for measuring two or more coordinates · CPC title

• G01S3/785 Primary

  using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system · CPC title