JPH09113610A - Target tracking radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable target tracking radar equipment to track a moving target which makes complicated motions including revolving motions by providing a tracking filter to the radar equipment. SOLUTION: A received input 201 which is obtained by irradiating a moving target 7 with a transmitting signal 101 transmitted from a transmitter 1 through a radar antenna 6 is supplied to a signal processor 3 through a receiver 2 as a received signal 202 and the signal processor 3 outputs target information 301 including the information on the position and attribute of the target 7 to a data processor 4. The processor 4 estimates the position of the target 7 at the next plotting time in the optimum state by using a tracking filter as a predicting filter and, at the same time, improves the accuracy of the optimum estimation by updating the information 301 on the observed value required for the predicting filtering, the observation error associated with the observed value, and the error resulting from the noise caused by the speed/acceleration of the motions of the moving target whenever the information 301 is acquired. Target tracking radar equipment tracks the target 7 in the optimum state by radiating a tracking beam scanning signal 401 based on these results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target tracking radar device, and more particularly, in a radar device for tracking a moving target such as an aircraft, a tracking filter for tracking a detected moving target based on a predictive filtering process is optimal for the tracking target. The present invention relates to a target tracking radar device in which tracking filter processing is adaptively controlled by an acquisition input of a radar device so as to provide highly accurate tracking characteristics.

[0002]

2. Description of the Related Art A target tracking radar apparatus for forming a tracking beam having a desired directional characteristic for tracking a moving target of an aircraft and the like and pointing the tracking beam to a future position of the moving target while tracking the moving target. , Phased array antennas are being widely used as radar antennas. This phased array antenna can direct the tracking beam in an arbitrary spatial direction by controlling the phase of the drive current of the array element. Therefore, it is possible to track the moving target by continuing to control the tracking beam so as to direct it to the predicted position of the tracking target.

For the future position of the moving target, the moving target is detected from the received signal, target information based on the distance information and angle information including azimuth angle and elevation angle information is calculated based on signal processing, and then the tracking filter is applied. When estimating,
As a prediction filter that estimates a state parameter that determines a future state from a past state parameter that represents the state of an event, for example, a Kalman filter or the like is used.

Therefore, future state parameters can be estimated by supplying state parameters that determine past states one after another to a prediction filter such as this Kalman filter. In the tracking filter provided to the target tracking radar device, the state is the spatial position of the moving target, and the parameter is the distance information of the moving target that determines this spatial position and the angle information including the azimuth angle and the elevation angle. .

However, there is a factor that causes an error in the prediction value of such a tracking filter, and the optimum estimation of the future position of the moving target cannot be ensured unless the prediction filter processing in consideration of this factor is performed. The future position mentioned here is a predicted position in the next evaluation.

In order to perform the above-mentioned optimum estimation, in the conventional target tracking using a tracking filter, an estimation is performed by adding the following observation error and plant noise to the prediction conditions. The observation error is a range error that is caused depending on the inherent noise of the system receiver and the size of the target. That is, the inherent noise of the receiver is apt to cause fluctuations in the received signal level in the vicinity of the inherent noise level, especially for a received signal in a long-distance region, which is one of the factors of the distance error.

Further, the size of the target, in particular, the wing length of the aircraft is related to the size of the reflectivity as a reflector, which causes a distance error especially in a short range. Moreover, what is called plant noise is noise that causes an error in the estimation process due to the velocity and acceleration associated with the movement of the tracking target.

In the conventional tracking filter, the initial values of velocity / acceleration which cause these observation errors and plant noise are set as constants uniquely determined in consideration of system operation parameters including target motion and magnitude. It was handled and the prediction process was performed.

[0009]

In the above-mentioned conventional target tracking radar device, the tracking error for predicting the future position of the moving target and the plant noise, which should be taken into consideration in order to perform the optimum estimation, are calculated as the moving target. It is determined uniquely based on the motion and unique operational specifications of the system, and the initial values of observation noise and target velocity / acceleration set as constants are used. However, there is a problem that the processing error of all tracking filters increases, and the tracking performance deteriorates significantly.

An object of the present invention is to solve the above-mentioned problems, and update the observation error and the plant noise that determine the superiority or inferiority of the characteristics of the tracking filter with the latest observation value of the tracking target that is input at every moment of evaluation. However, by ensuring the optimum tracking filter characteristics for the moving target, it is possible to provide a target tracking radar device that can significantly suppress the tracking error with respect to the tracking target performing a complicated motion and the tracking target in the long-distance area where the error increases. To do.

[0011]

The present invention has the following means in order to achieve the above object. That is, a first configuration of the present invention relating to a target tracking radar device is a target tracking radar device characterized by performing optimum estimation of a future position of a moving target of an aircraft or the like with a tracking filter, and is shown below. Each of the configurations (a) to (d) is provided. (A) Transmitting / receiving means for transmitting / receiving to / from the moving target with a tracking beam sent from the radar antenna while pointing to the future position of the moving target. (B) Detecting the moving target from the signal received by the transmitting / receiving means, and measuring the distance and direction of the moving target. Signal processing means for transmitting target information including angle and elevation angle (c) The receiver-specific thermal noise and the magnitude of the moving target in the transmitting / receiving means, which is updated with the distance data included in the target information as a parameter for each input of the target information Error that is caused by noise that occurs depending on the target information and the plant information that occurs based on the velocity and acceleration of the moving target that is updated for each target information input, and the target information in consideration of the estimation conditions. The optimal estimation process for is performed by the tracking filter as a prediction filter, and the future position of the moving target in the next rating is specified. Predicting a predicted value, and based on the predicted value, outputs a tracking beam scanning signal for transmitting the tracking beam that directs the predicted position of the moving target from the transmitting and receiving means, and a symbol related to the moving target with respect to the predicted value. Data processing means for outputting a tracking target display signal including attribute information such as marks (d) Display means for displaying the tracking target display signal on a radar display

A second structure of the present invention is the same as the above-mentioned first structure, except that the radar antenna in the transmitting / receiving means is a phased array antenna.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a target tracking radar device that performs a tracking process of a moving target by using a prediction filter that performs a prediction process of estimating a future state from a past state as a tracking filter, It is necessary to perform optimal estimation by eliminating the effects of observation errors and plant noise that are factors that cause errors.

The observation error is an error seen from the receiving system of the target tracking radar device for tracking the tracking target, and is a range error generated based on the inherent noise of the receiving system and the size of the target (for example, the wing length of the aircraft). Is. The plant noise is a noise that causes a system error in the observed value due to the velocity or acceleration of the moving target.

In the conventional target tracking radar apparatus, a constant initial value is uniquely set in advance on the basis of the movement of the tracking target targeted for the system error due to these observation errors and plant noise and the peculiar operational data of the system. Therefore, it is unavoidable that the prediction processing error of the tracking filter increases with respect to the moving target that makes a complicated motion, and the tracking performance is significantly deteriorated.

In the present invention, the observation error and the system error are
Calculate and update based on the latest observation value of the tracking target that is input moment by moment, and update the plant noise by calculating and updating the velocity / acceleration from the motion of the tracking target, and let the tracking filter perform optimal prediction processing. As a result, an optimal estimation with significantly improved accuracy is implemented.

[0017]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the embodiment shown in FIG. 1, a transmitter 1 and a receiver 2 having an integrated structure which constitute a transmitting / receiving means, a signal processor 3 which constitutes a signal processing means, and a data processing which constitutes a data processing means and includes a tracking filter. 1, a radar display 5 constituting a display means, and a radar antenna 6 having a phased array antenna configuration, and FIG. 1 also shows a moving target 7 for an aircraft.

Next, the operation of this embodiment will be described.
The transmitter 1 sends out a transmission signal 101 for spatially forming a tracking beam 601 directed to a future position of a moving target with a radar antenna 6 based on a tracking beam scanning signal 401 provided from a data processor 4 described later. .

Moving target 7 irradiated with tracking beam 601
The reception input 201 as an echo from is amplified and received by the receiver 2 and supplied to the signal processor 3 as a reception signal 202. The signal processor 3 detects the target information 301 as a reflection signal from the moving target 7 from the received signal 202. The target information 301 includes position information including target distance and azimuth and elevation information, and attribute information including an identification code of the moving target 7 and associated symbol marks.

The data processor 4 uses a Kalman filter driven by an algorithm that incorporates a tracking filter algorithm in a program format, and a tracking filter 41.
A display signal output circuit 42 for generating and outputting a tracking target display signal 402 to be provided to the radar display 5 based on the predicted value of the tracking filter 41.

FIG. 2 is a block diagram showing the configuration of the tracking filter 41 shown in FIG. The tracking filter 41 is configured as a Kalman filter, and specifies an optimum estimated value rating device 411 that optimally estimates the future position of the moving target, and specifies the future position of the moving target based on the optimal estimated value output by the optimum estimated value rating device 411. Based on the output of the predicted value output circuit 412 and the predicted value output circuit 412, the tracking beam 60 from the radar antenna 6 in the predicted value direction.
1. A tracking beam scanning signal generation circuit 415 for generating and outputting a tracking beam scanning signal 401 for controlling the transmitter 1 to generate a transmission signal 101 for sending 1 and an updated value of observation noise each time the target information 301 as an observation value is input. , An observation noise update value setting circuit 416, a velocity / acceleration update value setting circuit 417 that updates the velocity and acceleration of the moving target each time the target information that is an observation value is input, and an observation error based on the updated observation noise is output. Observation error output circuit 413
And a plant noise output circuit 414 that outputs plant noise based on the updated velocity / acceleration.

Under such a configuration, the optimum estimated value evaluator 411 targets the past data information of the target information 301, and adds the observation error and the plant noise updated every time the target information 301 is input. The distance and azimuth of the next predicted position of the moving target by applying the above-mentioned prediction filtering,
The optimum value of the elevation angle information is estimated and supplied to the predicted value output circuit 412.

From the predicted value output circuit 412, the predicted position of the moving target, in which the prediction error, that is, the tracking error, is remarkably suppressed, is also applied to the moving target that makes a complicated motion and the moving target in the long-distance area where the error increases. A predicted value containing information is output. The tracking beam scanning signal generation circuit 415 provided with this predicted value generates and outputs a tracking beam scanning signal 401 designating a highly accurate predicted position to the transmitter 1, and the predicted value is also supplied to the display signal output circuit 42. As a result, a tracking target display signal 402 for display including attribute information such as a symbol mark is formed and supplied to the radar display 5 for display.

FIG. 3 is a block diagram showing the structure of a conventional tracking filter. The conventional tracking filter shown in FIG.
The same optimum estimated value evaluator 411, predicted value output circuit 412, and observation error output circuit 4 as the tracking filter of the present invention shown in FIG.
13, a plant noise output circuit 414 and a tracking beam scanning signal generation circuit 415, an observation noise initial value setting circuit 418 and a velocity / acceleration initial value setting circuit 419 peculiar to the conventional tracking filter.

Of these constituent elements, those having the same reference numerals as those in FIG. 2 have the same contents, and detailed description thereof will be omitted. The characteristic of the conventional tracking filter shown in FIG. 3 is that the observation noise initial value setting circuit 418 and the velocity / acceleration initial value setting circuit 419 are based on the intrinsic noise of the receiver as an error when the tracking target is seen from the receiving system. An observation error including an error and an error depending on the size of the moving target,
It is a circuit that sets an initial value of velocity / acceleration that is a source of an error caused by noise based on velocity and acceleration corresponding to the motion of a moving target to be tracked. In the conventional tracking filter,
Since these observation errors and system errors were uniquely set as the initial values of constants based on the expected motion of the moving target and the operational specifications peculiar to the system, the prediction processing by the tracking filter was applied to the target with complicated motion. As described above, there is a problem in that the error with respect to 1 is increased and the tracking performance is significantly deteriorated.

Next, the observation error will be described in more detail with reference to FIG. FIG. 4 is a diagram illustrating an example of the distance characteristic of the observation error. FIG. 4A shows an observation error characteristic due to receiver noise (mainly thermal noise). This observation error characteristic is
As the distance from the radar device (strictly speaking, the radar antenna) increases, noise peculiar to the receiver, that is, system noise mainly due to thermal noise causes a dominant observation error. This is because the reception input level decreases as the distance increases, and particularly the S / N ratio of moving target recognition near system noise decreases relatively.

FIG. 4b is an error characteristic caused by so-called glint noise, which depends on the shape of the moving target, that is, mainly on the wing length of the aircraft that represents the size of the moving target.

Observation error characteristic a due to the above-mentioned receiver noise
And the observation error characteristic b depending on the shape of the moving target are combined to obtain the total observation error characteristic c. That is, the observation error due to the inherent noise of the receiver is dominant at a long distance, and the glint noise depending on the size of the moving target is dominant at a short distance. When the thermal noise due to the receiver is σ _ta , it is expressed by the following formula 1.

[0029]

(Equation 1)

Further, when the glint noise due to the target size is θ _ga , it is expressed by the following equation 2.

[0031]

(Equation 2)

These noises are combined as a function of distance and are shown by the characteristics shown in FIG. The observation error brought to the tracking filter processing by the mathematical expressions 1 and 2 is expressed by the determinant of the following mathematical expression 3.

[0033]

(Equation 3)

The plant noise as another error factor that causes a significant error in the tracking filter processing expresses the magnitude of the error generated in the tracking calculation processing due to the turning movement or acceleration of the moving target. It is a variable that changes depending on the target acceleration (and hence the change in speed). The plant noise variance matrix Q is expressed by the following Equation 4.

[0035]

(Equation 4)

FIG. 5 is a diagram showing an example of a turn-up motion pattern at a short distance of a moving target. 6 is a diagram showing the tracking prediction error characteristic of the angle information of the tracking filter according to the embodiment of FIG. 1 with respect to the moving target that behaves in the upward turning motion pattern shown in FIG.

As the angle information in this case, an angle (θ) which is a polar coordinate expression (ρ.θ) of the spatial position of the moving target is shown, and the distance, the azimuth angle, and the elevation angle information are expressed. It can be seen that the angle error increases in the vicinity of the time zone including the turning start time t1 and the turning end time t2.

FIG. 7 is a diagram showing the tracking prediction error characteristic of the angle information under the same conditions as in FIG. 6 by the conventional target tracking radar device. By comparing FIG. 6 and FIG. 7, it is clear that the tracking prediction error in the vicinity of the turning motion of the moving target is significantly improved.

FIG. 8 is a diagram showing an example of the tracking prediction error characteristic of the angle information in the long distance area of the tracking filter according to the embodiment of FIG. Further, FIG. 9 is a diagram showing an example of a tracking prediction error characteristic of angle information in a long-distance area under the same conditions as in FIG. 8 by the conventional target tracking radar device. In both cases of FIG. 8 and FIG. 9, the turning ascending motion is started at the turning start time t3, and the turning ascending motion is ended at the turning end time t4. However, the angular error according to the embodiment employing the tracking filter of the present invention The remarkable improvement of can be read.

According to the present invention, the observation noise is calculated and updated based on the observation values input moment by moment, and the velocity / acceleration is calculated from the motion of the moving target to update the plant noise while predicting the position of the moving target. Has a basic feature in that it is optimally estimated according to the above.

For example, in the present embodiment, the prediction filter for optimally estimating the position of the moving target is composed of a Kalman filter, but this is another prediction filter process that provides substantially the same effect, for example, a Wiener filter process. Etc. may be used.

[0042]

As described above, according to the present invention, in the target tracking radar device for tracking the moving target based on the estimated value of the tracking filter that performs the predictive filtering process to optimally estimate the future position of the moving target, The observation noise including the receiver's inherent noise and the noise depending on the size of the moving target, which is necessary as the optimum estimation condition of the future position of the moving target by the tracking filter together with the observation value including the position information of By updating the plant noise caused by acceleration with the observation value input sequence and based on the observation value, the tracking error by the tracking filter in the optimal estimation of the future position of the moving target can be reduced by the tracking of the moving target and complicated It has an effect of being able to remarkably suppress even when the exercise is developed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a tracking filter 41 of the embodiment shown in FIG.

FIG. 3 is a block diagram showing a configuration of a conventional tracking filter.

FIG. 4 is a distance characteristic diagram showing an example of an observation error included in an observation value of a moving target.

FIG. 5 is a diagram showing an example of a turn-up motion of a moving target at a short distance.

6 is a diagram showing an example of a tracking prediction error characteristic of angle information at a short distance according to the embodiment of FIG.

FIG. 7 is a diagram showing an example of tracking prediction error characteristics of angle information at a short distance of a conventional target tracking radar device.

8 is a diagram showing an example of a tracking prediction error of angle information at a long distance according to the embodiment of FIG.

FIG. 9 is a diagram showing an example of a tracking prediction error of angle information at a long distance of a conventional target tracking radar device.

[Explanation of symbols]

 1 Transmitter 2 Receiver 3 Signal Processor 4 Data Processor 5 Radar Display 6 Radar Antenna 7 Moving Target 41 Tracking Filter 42 Display Signal Output Circuit 411 Optimal Estimated Value Evaluator 412 Predicted Value Output Circuit 413 Observation Error Output Circuit 414 Plant Noise output circuit 415 Tracking beam scanning signal generation circuit 416 Observation noise update value setting circuit 417 Velocity / acceleration update value setting circuit 418 Observation noise initial value setting circuit 419 Velocity / acceleration initial value setting circuit

Claims (2)

[Claims] 1. A target tracking radar apparatus comprising the following respective configurations, and tracking while optimally estimating a future position of a moving target of an aircraft or the like with a tracking filter. (A) Transmitting / receiving means for transmitting / receiving to / from the moving target with a tracking beam sent from the radar antenna while pointing to the future position of the moving target. (B) Detecting the moving target from the signal received by the transmitting / receiving means, and measuring the distance and direction of the moving target. Signal processing means for transmitting target information including angle and elevation angle (c) The receiver-specific thermal noise and the magnitude of the moving target in the transmitting / receiving means, which is updated with the distance data included in the target information as a parameter for each input of the target information Error that is caused by noise that occurs depending on the target information and the plant information that occurs based on the velocity and acceleration of the moving target that is updated for each target information input, and the target information in consideration of the estimation conditions. The optimal estimation process for the moving target is performed by a tracking filter as a prediction filter to indicate the future position of the moving target in the next evaluation. The predictive value to be estimated,
Outputs a tracking beam scanning signal for transmitting the tracking beam that directs the predicted position of the moving target from the transmitting / receiving means based on the predicted value, and includes attribute information such as a symbol mark related to the moving target with respect to the predicted value. Data processing means for outputting a tracking target display signal (d) Display means for displaying the tracking target display signal on a radar display 2. The target tracking radar device according to claim 1, wherein the radar antenna in the transmitting / receiving means is a phased array antenna.