Registers – Ordnance or weapon systems computer – With target tracking means
Reexamination Certificate
1998-08-11
2001-07-17
Lee, Michael G. (Department: 2876)
Registers
Ordnance or weapon systems computer
With target tracking means
C235S412000, C342S090000
Reexamination Certificate
active
06260759
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to target tracking and relates more particularly to a method for tracking one or more targets which have substantially constrained movement. The method of the present invention is particularly applicable to the tracking of ground targets upon roadways and the like via radar.
BACKGROUND OF THE INVENTION
As those skilled in the art will appreciate, the automatic creation and maintenance of coherent tracks from all radar detections substantially enhances the utility of such radar data. Moreover, the creation and maintenance of such tracks is essential to situational awareness and the data fusion process.
In some instances, there may be thousands of moving targets which must be monitored at any given time. Thus, radar information must be filtered before meaningful information can be provided thereby. Proper filtering of the radar data is necessary in order to provide a correct interpretation of the order of battle.
According to contemporary methodology, such radar filtering is performed by a tracking function. The tracking function generates and maintains a track for each desired target. Ideally, the tracking function prevents nearby targets, such as those on intersecting courses, from being confused with one another. The tracking function also mitigates clutter. Clutter is the presence of undesirable radar signals, which are typically due to radar returns from unimportant objects such as weather, birds, turbulent bodies of water, etc.
Such filtering of radar information by the tracking function substantially enhances situational awareness, particularly by freeing an operator from having to perform a visual association of radar returns. Such visual association or radar returns may, indeed, be an impossible task, particularly in very dense, dynamic target scenarios.
Contemporary tracking systems are only capable of manually creating a few tracks, which are then maintained by a computer. The computer must deduce traffic patterns from remaining radar returns, thus introducing an undesirable time delay. Those skilled in the art will appreciate that it is desirable to automatically generate tracked targets and to present radar operators therewith, so as to substantially enhance situation awareness by presenting useable data at a much faster rate. In this manner, automatic target tracking provides an overall picture of the monitored area, e.g., battle field, which assists in identifying the order of battle, as well as eventually preforming battle management.
SUMMARY OF THE INVENTION
The present invention specifically addresses and alleviates the above-mentioned efficiencies associated with the prior art. More particularly, the present invention comprises an automatic, moving target tracker which provides kinematic tracking of targets which have substantially constrained movement, particularly ground-based targets. Such targets are tracked over time via the processing of their derived position and velocity data, particularly via radar return information. However, those skilled in the art will appreciate that various other means for obtaining position and velocity data are likewise suitable. For example, position and velocity data may be obtained via video surveillance, intelligence reports, laser scanners, etc. Thus, discussion of radar in this patent application is by way of example only, and not by way of limitation.
Further, track association may be performed via other types of information, such as estimated length, domain knowledge, or feedback from the fusion function, when such information is available.
When radar return information is utilized, it may come from either ground-based vehicles or low-flying, relatively slow helicopters or aircraft.
More particularly, the present invention comprises a method from tracking a target having substantially constrained movement, such as a ground-based target traveling upon a roadway or a ground-based target whose movement is substantially constrained by terrain, e.g., hills, mountains, forests, lakes, rivers, etc. (physical constraints in the environment of the target).
Such ground-based targets typically include tanks, armored vehicles, troop transport vehicles, trucks, jeeps, and any other military or civilian vehicles, knowledge of the location of which is desirable, particularly in war-time.
The method of the present invention generally comprises the steps of determining constraints for movement of the target, the constraints comprising a plurality of alternate route segments, obtaining information on movement of the target, and predicting that the target will continue to move upon a route segment after the target has begun to move thereupon. As mentioned-above, these constraints generally comprise the location of roadways and terrain features for land-based targets.
Predicting that the target will continue to move upon the route segment facilitates targeting, intercept and intelligence with a substantial degree of reliability.
The method for tracking a target of the present invention further comprises the step of predicting which one of a plurality of alternate track segments a target will select based upon an assumption of the destination of the target. Thus, when a reasonable assumption of the ultimate destination of the target can be provided, then prediction of target movement can be made even when a target has alternate routes upon which it may move.
The target tracking methodology of the present invention particularly useful when consistent, periodic radar returns or the like are not available. In this situation, the targets remain unmonitored for various periods of time. As those skilled in art will appreciate, it is desirable to provide estimates of the likely position of such targets when reliable radar information relating thereto is not available. Such estimates may be utilized to facilitate targeting, intercept, and intelligence gathering.
Preferably, the present invention comprises predicting one of a plurality of alternative track segments, also called route segments, which a target is likely to accept based upon an assumption of the destination of the target, as discussed above. Prediction of the location of the target is based upon a previous speed of the target and/or at least one speed affecting condition of the route segment upon which a target is moving. Thus, the average speed, for instance, of the target may be utilized by assuming that the target maintains its average speed. Alternatively, an instantaneous speed may be utilized, if necessary. The assumed speed of the target may be modified by taking into consideration conditions of the route segment upon which a target is moving. For example, if the target was previously moving at a high rate speed upon a paved roadway and then enters a dirt or gravel road, then an appropriate reduction in speed may be assumed.
Preferably, radar information regarding the location and velocity of the target is obtained periodically. However, as those skilled in the art will appreciate, such radar information may be available only on an intermittent, and unpredictable basis.
However, according to the present invention, a plurality of targets having substantially constrained movement may be tracked by determining constraints for movement of the targets, the constraints comprising a plurality of alternate route segments for each target and obtaining information on movement of the targets. Then, predictions that each of the targets will continue upon a route segment after the target has begun movement thereupon is made. Predictions are made that each of the targets will continue to move upon a route segment after that target has begun to move thereupon. In this manner, the plurality of moving targets may be monitored with a substantial degree of reliability. Optionally, a group of targets may be defined and tracked as though the group were actually a single target. In this manner, large numbers of targets may be tracked without correspondingly burdening the computer performing the tracking algorithm.
REFERENCES:
patent:
Landau Herbert
Nguyen Quan Bach
Anderson Terry J.
Hoch, Jr. Karl J.
Lee Diane I.
Lee Michael G.
Northrop Grumman Corporation
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