JP2007187468A - Target tracking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a target tracking device for determining the schedule for assigning an efficient sensing how long from when which sensor observes the target so as to obtain the estimated impact area highly precisely at an early stage. <P>SOLUTION: A plurality of sensors 4a-4d observe a plurality of targets 1a-1d, a tracking process part 5 processes the tracking process based on the results of the observation, a tracking estimation part 7 estimates the tracking information till the impact of the target based on the tracking information processed by the tracking process. Then, a requested precision calculation part 8 calculates the precision to be satisfied based on the tracking information, an assigning part 9 determines a schedule 10 that how long, from when, which sensor observes the target so as to satisfy the requested tracking precision, and a sensor control part 11 is made to control the plurality of sensors 4a-4d along the assigning schedule 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a target tracking device that performs target observation with a plurality of sensors and tracks a target.

When tracking a target that flies at high speed over a long distance of several hundred km or more, from one sensor installed on the ground (mainly radar equipment) to launch and land with one sensor due to the limitation of its coverage area It is difficult to keep observing. For this reason, a sensor network system has been considered in which a plurality of sensors deployed in a wide area are managed and controlled in the center to continue tracking.
Here, if the impact position of the ballistic target can be predicted to be an important area / facility, it is necessary to take measures such as interception. Therefore, after the target is detected, the impact position is estimated with high accuracy as soon as possible. Must be done. In order to improve the estimation accuracy of the landing position, it is necessary to increase the accuracy of the tracking information that is the calculation source of the landing position. Tracking accuracy can be improved by increasing the observation frequency by assigning a plurality of sensors simultaneously.

  There is a sensor group management device disclosed in Patent Document 1 as a conventional technique for the request for assigning sensors to be observed to a target as described above. In this conventional technique, which sensor is assigned to which target is mainly determined based on tracking information or the like. The tracking means obtains the estimated values of the target motion parameters such as position, velocity, and acceleration, and the estimated value of the error as tracking information. (Sensors close to) are assigned.

JP 2002-277543 A (4th to 6th pages, FIG. 1)

By the way, sensor resources that can be used in the entire system (corresponding to the number of targets that the sensor can observe at the same time) are limited. Therefore, assuming that the number of targets increases, the required accuracy with as few allocated sensors as possible In order to satisfy, limited sensor resources must be efficiently allocated to the target.
However, in the conventional technique of Patent Document 1, a highly effective sensor is allocated, but a specific allocation method for allocating the minimum sensor necessary to satisfy the accuracy requirement has not been shown. . For this reason, there is a possibility that the sensors are assigned uselessly.
Further, in the conventional technique, an allocation method for satisfying the landing position accuracy has not been clarified.

  The present invention has been made to solve the above-described problems, and it is efficient to determine which sensor is observing which target from when to when so as to obtain a highly accurate estimate of the landing position at an early stage. The object is to obtain a target tracking device for determining the sensor allocation schedule.

In the target tracking device according to the present invention, in the target tracking device for observing and tracking a plurality of ballistic targets by managing and controlling a plurality of sensors each observing the ballistic target,
Sensor management means for managing the sensor state based on the operational status of each sensor input from a plurality of sensors, target tracking means for performing tracking processing based on the observation results of the ballistic targets input from the plurality of sensors, Based on the tracking information tracked by the target tracking means, the trajectory estimation means for estimating the trajectory information up to the landing of the ballistic target, and the tracking accuracy request to be satisfied is calculated based on the trajectory information estimated by the trajectory estimation means Request accuracy calculation means, allocation means for determining an allocation schedule for which sensor observes which target from when to when, so as to satisfy the tracking accuracy request calculated by the request accuracy calculation means, and the allocation means Sensor control means for controlling a plurality of sensors in accordance with the assigned schedule.

As described above, the present invention provides a target tracking device that manages and controls a plurality of sensors for observing and tracking a plurality of ballistic targets, respectively.
Sensor management means for managing the sensor state based on the operational status of each sensor input from a plurality of sensors, target tracking means for performing tracking processing based on the observation results of the ballistic targets input from the plurality of sensors, Based on the tracking information tracked by the target tracking means, the trajectory estimation means for estimating the trajectory information up to the landing of the ballistic target, and the tracking accuracy request to be satisfied is calculated based on the trajectory information estimated by the trajectory estimation means Request accuracy calculation means, allocation means for determining an allocation schedule for which sensor observes which target from when to when, so as to satisfy the tracking accuracy request calculated by the request accuracy calculation means, and the allocation means Sensor control means to control multiple sensors according to the assigned schedule It is possible to obtain an allocation schedule of the sensor as satisfactory.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a target tracking apparatus according to Embodiment 1 of the present invention.
In FIG. 1, targets 1a to 1d as objects to be observed are ballistic targets that are accelerated by combustion of the propellant for several minutes after launch, and perform inertial motion after combustion of the propellant. Are collectively referred to as a target group 2. The observation beams 3a to 3d are emitted toward the target group 2 from the sensors 4a to 4d. The sensors 4a to 4d observe the targets 1a to 1d using the observation beams 3a to 3d. Here, a radar device is considered as a sensor.
In FIG. 1, which sensor 4a-4d is observing which target 1a-1d is observed. The target 1a is observed simultaneously from the two sensors 4a and 4b. The sensor 4b observes the target 1a and the target 1c simultaneously. The sensor 4d observes the target 1d.
Here, even if it is said that it is simultaneous, it represents the observation within the unit time, not the same time. Since recent radar devices can observe and track multiple targets in a time-division manner within a unit time, such an observation is considered possible. It is assumed that the upper limit of the number of observation beams (number of resources) that can be irradiated within a unit time is determined for each sensor.

The tracking processing unit 5 receives the observation information output from the sensors 4a to 4d, tracks each of the targets 1a to 1d, and outputs the tracking information of each target. The sensor management unit 6 receives the operation information output from the sensors 4a to 4d and manages the operation state of the sensors 4a to 4d. The trajectory estimation unit 7 receives the tracking information from the tracking processing unit 5 and calculates trajectory information until the target lands. The required accuracy calculation unit 8 receives the trajectory information output from the trajectory estimation unit 7 and calculates an index to be satisfied by the target tracking accuracy as a tracking accuracy request.
The allocation unit 9 receives the sensor operation information from the sensor management unit 6, the tracking information from the tracking processing unit 5, the trajectory information from the trajectory estimation unit 7, and the tracking accuracy request from the required accuracy calculation unit 8, and receives the tracking accuracy request from the sensors 4 a to 4. The assignment of 4d to each target 1a-1d is determined. The allocation result by the allocation unit 9 is held as an allocation schedule 10. The sensor control unit 11 controls the sensors 4 a to 4 d according to the allocation schedule 10. The sensors 4 a to 4 d observe the target group 2 according to the control information sent from the sensor control unit 11.

FIG. 2 is a diagram showing an example of an allocation schedule of the target tracking device according to the first embodiment of the present invention.
FIG. 2 shows the target observation start and observation end for each sensor. Each sensor can observe the target simultaneously by the number of resources.
FIG. 3 is a flowchart showing a processing flow of the allocation unit of the target tracking device according to Embodiment 1 of the present invention.

FIG. 4 is a diagram for confirming a sensor close to the track surface of the target tracking device according to the first embodiment of the present invention.
FIG. 4 shows a target, its predicted trajectory and estimated landing position, and an example of sensor arrangement.

FIG. 5 is a diagram showing the relationship between the tracking error estimated value of the landing time and the landing error range of the target tracking device according to Embodiment 1 of the present invention.
In FIG. 5, the error range of the landing position is projected according to the path angle at the time of landing. The larger the error in the vertical direction, the wider the range in the traveling direction by the projection, and the estimated value of the landing position error (landing error range) is also the traveling direction. Shows the maximum state.

Next, the operation of the target tracking device according to the first embodiment of the present invention will be described with reference to FIG.
The allocation schedule 10 has a format as shown in FIG. 2, for example. It shows which sensor observes which target from when to what time with respect to the time axis after the current time. The resource corresponds to the target number that each sensor can observe simultaneously. In the example of FIG. 2, it means that three sensors can simultaneously observe three targets. The time designation from when to when (observation start, observation end) has a one-to-one correspondence with the designation from where to where in the estimated trajectory, and a sensor that can capture the estimated trajectory within the coverage is selected.
The sensor control unit 11 sends the observation start / end instructions of the targets 1a to 1d to the sensors 4a to 4d so that the observations of the sensors indicated in the allocation schedule 10 are started and ended according to the time. The sensors 4a to 4d observe the targets 1a to 1d according to the input instructions, and obtain observation information of the targets 1a to 1d.

Next, based on the observation information sent from the sensors 4a to 4d, the tracking processing unit 5 performs a correlation process for associating the observation information with the tracked targets 1a to 1d, and using the corresponding observation information, The tracking information is updated by predicting / estimating the targets 1a to 1d. The tracking processing unit 5 outputs, as tracking information, estimated values of motion parameters such as position, velocity, and acceleration, and estimated values of errors thereof.
For example, the estimated value of the position tracking error at the orthogonal three-dimensional coordinates x, y, z is calculated as a position tracking error covariance matrix P defined by the following equation (1).

P = E [(Xs−Xm) (Xs−Xm) ^T ] (1)
here,
Xs: tracking position vector of 3 rows and 1 column Xm: true position vector A ^T of 3 rows and 1 column: transposed matrix of matrix A

  Further, the size is represented by a range of X (tracking error ellipse) satisfying the following equation (2) using a quadratic form of P, and in particular, the ellipse of the ellipse is used.

(X−Xs) ^T P ⁻¹ (X−Xs) ≦ d (m) (2)
here,
Xs: 3 × 1 tracking position vector X: 3 × 1 position vector P ⁻¹ : Inverse matrix d (m) of tracking position error covariance matrix P: m percent confidence interval of chi-square distribution.
It should be noted that both equations (1) and (2) can be similarly calculated with respect to velocity and acceleration.

Next, the trajectory estimation unit 7 estimates the trajectory and the landing position from the current time to the landing based on the tracking information. The calculation method of the orbit is an inertial motion that uses the estimated position and velocity of the tracking information as initial values, and is based on physical calculations that take into account the earth's gravity and air resistance as external forces. The position where the estimated trajectory intersects the ground surface is defined as the estimated landing position, and the time is defined as the estimated landing time.
Further, as an estimated value (landing error range) of the landing position error, the tracking error estimated value is obtained by time development (same calculation as the tracking process prediction) until the landing estimated time. These are output as trajectory information.

It is assumed that the required accuracy calculation unit 8 holds in advance how much the landing position error should be made as a request for the landing position error. Since the contents to be held are intended to identify the landing position at an early stage, for example, the landing position error is set to 100 km or less within 100 seconds after a new target is found (detected). At this time, 100 seconds after the detection time is called the required time, and 100 km is called the required landing position accuracy.
The required accuracy calculation unit 8 calculates the required landing position accuracy (Rmax in the equation (3)) from the trajectory information output from the trajectory estimation unit 7 (t, th in the equation (3)) according to the equation (3) described later. ) Is used to convert to required accuracy (Pp, Pv in equation (3)) in the form of tracking accuracy (tracking error estimated value) to be satisfied at the required time and output.
The sensor management unit 6 grasps whether or not each sensor can be used based on the operation information periodically sent from the sensors 4a to 4d.

Next, the allocation unit 9 calculates the required accuracy from the required accuracy calculation unit 8 based on the operation status of each sensor from the sensor management unit 6, the tracking information from the tracking processing unit 5, and the trajectory information from the trajectory estimation unit 7. In order to meet this requirement, an assignment schedule 10 is created for which target is observed by which sensor from when to when.
The allocation calculation timing is such that the change in the operating status of the sensor, the addition / deletion of the tracking target, the change in the trajectory, etc. are monitored, and the schedule cannot be established after the previous allocation schedule is calculated. It is sufficient if only.

Next, the required accuracy calculation method in the required accuracy calculation unit 8 will be described in detail.
Since the landing position error estimated value is represented by the time evolution of the tracking error estimated value, the tracking accuracy request values (Pp, Pv) relating to the position and velocity satisfying the relationship of the following expression (3) are set as the required accuracy. .

(D (m) ^0.5 × (Pp + Pv × t)) / min {tan (th), 1} ≦ Rmax (3)
here,
Pp: Position tracking accuracy request value at the required time (the square root of the maximum eigenvalue of the position error covariance matrix)
Pv: Speed tracking accuracy required value at required time (square root of maximum eigenvalue of speed error covariance matrix)
t [s]: Time from the requested time to the estimated landing time d (m): m percent confidence interval in the chi-square distribution (m percent is defined as a landing accuracy requirement)
th [rad]: Landing path angle (An angle formed by the trajectory at the time of landing and the ground plane. 0 degrees parallel to the ground plane and 0 to π / 2)
min {a, b}: Function Rmax [m] indicating the smaller value of a and b: Required landing accuracy (the required distance within which the difference from the true value is within Rmax).

The principle of converting the required landing accuracy into the tracking accuracy required value is as follows.
As a feature of the radar, the distance accuracy is good regardless of the distance to the target, but the accuracy in the angular direction (azimuth angle, elevation angle) becomes worse as the target becomes farther away. When observing the same target with a plurality of radars at different positions, the azimuth angle direction can overlap the distance direction of other radars, but the elevation angle direction cannot overlap. Therefore, as a result of tracking using these observation information, the error in the elevation direction, that is, the vertical direction, appears the largest as the tracking error estimated value.
Even if this tracking error estimated value is propagated along the estimated trajectory until the estimated landing time, the error in the vertical direction remains the same.
Further, if the range obtained by projecting this propagated tracking error estimated value according to the path angle at the time of landing is considered as the error range of the landing position, the larger the error in the vertical direction, the wider the range in the traveling direction by projection, and the landing position error Is also the maximum in the direction of travel (see FIG. 5).
Therefore, focusing on the error estimated value in the vertical axis direction that maximizes the tracking error, the above tracking accuracy requirement value is used.

Next, the operation of the assigning unit 9 will be described in more detail based on FIG.
The assigning unit 9 determines a schedule for which target is observed by which sensor. Target targets and sensors are determined from tracking information and sensor operation information, respectively.
Next, it is determined for each target according to the flow of FIG. 3 which sensor is allocated from when to when the estimated trajectory up to the request time of the target to be requested. For a target that is not a request target and an estimated trajectory after the request time has passed, one sensor that can be captured in the coverage is appropriately allocated and tracking is continued.
In STEP1, the tracking accuracy at the requested time is predicted. For tracking accuracy prediction, for example, it is assumed that observation information is obtained along an estimated trajectory, and a pseudo-observation value is created, followed by tracking processing to obtain a tracking error estimation value. In the first loop, one of the currently assigned sensors is selected and implemented, or a sensor that can be observed until the requested time is selected appropriately.
In STEP 2, tracking accuracy request values Pp and Pv are obtained from the predicted tracking accuracy (error covariance matrix), and it is determined whether or not Expression (3) is satisfied.

Since STEP3 does not satisfy the tracking accuracy requirement, a sensor close to the track surface (surface perpendicular to the ground including the target position and the landing position) is added to the allocation.
Since STEP 4 satisfies the tracking accuracy requirement, the allocation schedule is updated by allocating the sensors added so far.
Until the tracking accuracy requirement is satisfied, the sensors sequentially selected in STEP 3 are, for example, as shown in FIG. Referring to FIG. 4, for the target # 1, allocation is determined in the order of sensors # 6, # 5, # 2, # 1, # 7, # 3, and # 4. For the target # 2, the order is sensors # 2, # 6, # 4, # 7, # 5, # 3, # 1.

The principle of the above selection method of the allocation sensor is as follows.
The sensor is assigned to satisfy the tracking accuracy requirement at an early stage within 100 seconds after detection. The ballistic target is likely to end the injection and move to inertia during this time. This change in motion causes the tracking error to increase because the acceleration due to the thrust suddenly becomes zero.
At this time, the difference between the target position predicted by the tracking process and the observed position of the target becomes large, but this difference occurs in the orbital plane (a plane perpendicular to the ground including the target position and the landing position). For tracking processing, the tracking error can be reduced by observing this difference in the distance direction with good observation accuracy. If the tracking error can be reduced, as a result, the estimated value of the landing position error is also reduced. Therefore, the allocation method as described above is used.

As described above, according to the first embodiment of the present invention, in the allocation flow of the allocation unit 9, in STEP 2, the landing error range is calculated by the same calculation as the trajectory estimation unit using the predicted value of the tracking accuracy. Although it can be compared with the required landing accuracy, it is heavy to calculate the trajectory prediction process until landing every time the above loop is turned, and the required accuracy calculation unit 8 requests the tracking accuracy to request the tracking accuracy. Therefore, the processing speed can be increased.
Further, by assigning in order from the sensor closest to the track surface in the assigning unit 9, only the sensors from the highly effective sensor until the request is satisfied are assigned in order, and sensor assignment without waste can be realized.

It is a block diagram which shows the target tracking apparatus by Embodiment 1 of this invention. It is the figure which showed the example of the allocation schedule of the target tracking apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing flow of the allocation part of the target tracking apparatus by Embodiment 1 of this invention. It is a figure for confirming the sensor close | similar to the track surface of the target tracking apparatus by Embodiment 1 of this invention. It is the figure which showed the relationship between the tracking error estimated value of the landing time of the target tracking apparatus by Embodiment 1 of this invention, and a landing error range.

Explanation of symbols

1a to 1d observation target, 2 target group, 3a to 3d observation beam,
4a to 4d sensor, 5 tracking processing unit, 6 sensor management unit, 7 orbit estimation unit,
8 required accuracy calculation unit, 9 allocation unit, 10 allocation schedule,
11 Sensor control unit.

Claims (3)

In a target tracking device that monitors and tracks multiple ballistic targets by managing and controlling multiple sensors each observing the ballistic target,
Sensor management means for managing the state of the sensor based on the operational status of each sensor input from the plurality of sensors, target tracking for performing tracking processing based on the observation results of the ballistic target input from the plurality of sensors Means, trajectory estimation means for estimating trajectory information up to the landing of the ballistic target based on the tracking information tracked by the target tracking means, tracking accuracy to be satisfied based on the trajectory information estimated by the trajectory estimation means Request accuracy calculation means for calculating a request, assignment means for determining an assignment schedule for which sensor will observe which target from when to satisfy so as to satisfy the tracking accuracy request calculated by the request accuracy calculation means, and the assignment Sensor control means for controlling the plurality of sensors according to an allocation schedule determined by the means Target tracking apparatus according to claim and.   2. The target tracking device according to claim 1, wherein the allocation means determines the allocation schedule based on a rule that a sensor close to the trajectory plane of the ballistic target is preferentially selected.   The required accuracy calculation means holds in advance a landing position accuracy request that is a request for the landing position accuracy, and the held landing position accuracy request is converted into the tracking accuracy request based on the trajectory information estimated by the trajectory estimation means. The target tracking device according to claim 1, wherein the target tracking device is converted.

Images