# US 10,310,068 B2 · Variational track management

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- Number: US 10,310,068 B2
- Document ID: US10310068B2
- Status: Granted
- Kind: B2
- Application number: 14/563,824
- Filed: 2014-12-08
- Published: 2016-06-09
- Granted: 2019-06-04
- Earliest claimed: 2014-12-08
- Assignees: Northrop Grumman Systems Corporation
- Applicants: Ryan D. Turner; Steven Bottone; Bhargav R. Avasarala; Clay J. Stanek
- Inventors: Ryan D. Turner; Steven Bottone; Bhargav R. Avasarala; Clay J. Stanek
- Web page: https://patentgrep.com/patent/US10310068B2

## CPC

- G01S 13/726: {Multiple target tracking}
- G01S 7/411: {Identification of targets based on measurements of radar reflectivity (G01S7/415 takes precedence)}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

Systems and methods are provided for tracking moving objects from a set of measurements. An estimate of a posterior probability distribution for a plurality of track states is determined from an estimate of the posterior probability distribution for a plurality of possible assignments of the set of measurements to a set of tracks representing trajectories of the plurality of moving objects and the set of measurements. A new estimate of the posterior probability distribution for the assignments is determined from the measurements and the estimate of a posterior probability distribution for the track states. A variational lower bound is determined from the new estimate of the posterior probability distribution for the assignments, the estimate of the posterior probability distribution for the track states, and the set of measurements. These steps are iteratively repeated until the variational lower bound is less than a threshold value.

## Claims

### Claim 1

A system for tracking a plurality of moving objects comprising:
a sensor system configured to provide a set of measurements representing at least respective positions of the plurality of moving objects;
a track state updating component configured to determine an estimate of a posterior probability distribution for a plurality of track states from an estimate of the posterior probability distribution for a plurality of possible assignments of the set of measurements to a set of tracks representing trajectories of the plurality of moving objects and the set of measurements;
a track assignment updating component configured to determine a new estimate of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks from the set of measurements and the estimate of a posterior probability distribution for a plurality of track states; and
a lower bound computation component configured to compute a variational lower bound, representing a lower bound for a marginal probability of the set of measurements given a model defined by the new estimate of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks and the estimate of the posterior probability distribution for a plurality of track states, from the new estimate of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks, the estimate of a posterior probability distribution for a plurality of track states, and the set of measurements;
wherein each of the track state updating component, the track assignment updating component, and the lower bound computation component collectively perform an iterative determination of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks and the posterior probability distribution for a plurality of track states until the variational lower bound is less than a threshold value.

### Claim 2 (depends on 1)

The system of claim 1, further comprising an initialization component configured to initialize the estimate of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks, utilized at the track state updating component, as a default distribution with a plurality of random perturbations.

### Claim 3 (depends on 1)

The system of claim 1, wherein the plurality of track states include, for each track, an associated position state and an associated metastate representing the activity or dormancy of a track, such that the track update component manages a status of the plurality of tracks.

### Claim 4 (depends on 3)

The system of claim 3, wherein the track update component comprises a soft hidden Markov model, the metastates of the plurality of tracks being updated via the soft hidden Markov model.

### Claim 5 (depends on 1)

The system of claim 1, wherein the track update component comprises a Kalman smoother configured to calculate an update for the plurality of track states from a set of computed pseudomeasurements.

### Claim 6 (depends on 1)

The system of claim 1, wherein the track assignment updating component is configured to calculate the new estimate of the posterior probability distribution for the plurality of possible assignments of the set of measurements to the set of tracks comprising a loopy belief propagation algorithm.

### Claim 7 (depends on 1)

The system of claim 1, wherein the sensor system comprises a radar system.