JP3902738B2 - Radar data processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data processing apparatus of a radar, particularly a millimeter wave radar.
[0002]
[Prior art]
In millimeter wave radar (FM-CW radar), a continuous wave beam that is FM-modulated with a triangular wave that repeats ascending and descending alternately is emitted forward, and the reflected signal from the target is mixed with a part of the transmission signal. The beat signal is generated, and the peak on the frequency spectrum is associated (hereinafter referred to as pairing) between the peak when the frequency modulation is rising and the peak when the frequency modulation is falling. The distance and relative speed of each target are calculated from the sum and difference of the frequencies. Furthermore, the direction in which each target exists can be known by scanning the angle of the beam physically or electronically.
[0003]
In the above pairing process, for example, between the peak (up peak) in the beat signal (up beat) at the time of frequency modulation rise and the peak (down peak) in the beat signal (down beat) at the time of fall, for example The ones having close angles and intensities are associated as peaks based on the same target.
[0004]
In addition, continuity determination is also performed to determine that the target is from the same target by collating with past data, and the distance and relative speed data determined to be from the same target For example, the filter operation is performed by the following equation.
[0005]
[Relative speed] = ([Previous value] × 3 + [Current value]) / 4
[Distance] = ([Previous value] + [Current value]) / 2
The pairing process described above includes a past correspondence pairing that preferentially associates peaks that exist in a frequency range where a target is predicted to exist at a position / velocity predicted from past data, and a past correspondence pair. There is a new pairing that pairs the peaks that remain after the ring is finished. In past correspondence pairing, even if one or both peaks are not temporarily observed in the prediction range, extrapolation is performed on the assumption that the target exists at the predicted position within a certain period. In addition, since an up peak with a low frequency often disappears when the target relatively approaches, the extrapolation at this time is particularly called down beat extrapolation.
[0006]
The predicted value of the target data is calculated by the following equation assuming that the previous relative velocity continues this time, for example.
[0007]
[Distance] = [Previous distance] + [Previous relative speed] x [Time]
[Relative speed] = [Previous relative speed]
[0008]
[Problems to be solved by the invention]
Figure 1 shows the time variation of the frequency of the down-peak 10 and the up peak 12 until the run at the following distance constant after target has approached those traveling in front. The sum of both frequencies corresponds to the distance from the target, and the difference corresponds to the relative speed.
[0009]
As shown in FIG. 2, it is assumed that the up-peak frequency has decreased at time t ₁ and cannot be detected, and downbeat extrapolation has started. Since the distance is the sum of both frequencies, if the scale is appropriately taken, it can be represented by a one-dot chain line with reference number 14 between the two frequencies. As described above, when the downbeat extrapolation is performed, the estimated position of the target is calculated with a constant relative speed. Therefore, even if the filter operation is performed, the estimated value (14) of the distance decreases almost linearly, and the down peak The estimated frequency 16 and the estimated frequency 18 of the up peak decrease approximately linearly with a similar slope. Therefore the actual frequency difference is reduced relative velocity decreases, new pair a decrease of the frequency of the down-peak level off the difference between the estimated value spread, eventually down peak at time t ₂ also outside the expected range It becomes a ring. Time t ₃ is detected up peak in the still predicted range in which for re downbeat extrapolation begins even. Thereafter, at time t ₄ , the down peak is out of the prediction range and new pairing is performed, but at time t ₅ , the up peak is out of the prediction range and down beat extrapolation is started again.
[0010]
Thus, there is a problem that it takes time until the output value reflects the actual value when the actual relative speed fluctuates beyond a certain level during the extrapolation process.
[0011]
Accordingly, an object of the present invention is to provide a radar data processing apparatus that can quickly return even if the actual relative speed fluctuates during extrapolation processing.
[0012]
[Means for Solving the Problems]
The radar data processing apparatus according to the present invention includes means for determining continuity that the target data obtained up to the previous time and the target data obtained this time are based on the same target, And a means for performing a filter operation on the target data determined to be based on the same target as a result of the determination, the filter operation means being calculated from the actual measurement value obtained this time. In addition, when the previous target data is not an actual measurement value but calculated by extrapolation, the filter operation is not performed on the relative speed of the target included in the target data. It is.
[0013]
The recovery takes time because, as seen in the example of FIG. 2, even if new pairing is performed after extrapolation processing, the estimated value does not approach the actual value very much due to the relative speed filter calculation. is there. Therefore, when this time is new pairing and the previous time is extrapolation processing, it is possible to quickly return by not performing the relative speed filter calculation.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 shows a configuration of an example of a millimeter wave radar apparatus to which the present invention is applied. In FIG. 3, the transmitter control circuit 20 outputs a triangular wave that repeats rising and falling alternately. In the RF unit 22, a millimeter wave frequency-modulated by the triangular wave is generated and radiated from the antenna 24. A reflected wave from the target is received by the antenna 24 and mixed with a part of the transmission signal in the RF unit 22 to generate a beat signal having a frequency that is the difference between the transmission signal and the reflection signal. The generated beat signal is converted to baseband by the receiving circuit 26 and then input to the DSP 28. In the DSP 28, conversion from the time domain to the frequency domain is performed by performing an FFT operation on each of the rising section (upbeat) and the falling section (downbeat) of the triangular wave. Further, the DSP 28 extracts a peak (up peak) and a peak (down peak) in the frequency spectrum in the rising section and sends them to the microcomputer 20. On the other hand, the drive circuit 32 drives the motor 34 to scan the direction of the antenna 24, and the angle data at that time is input to the microcomputer 30. The microcomputer 30 has a one-to-one relationship between each up-peak and each down-peak based on the intensity of each peak, the angle of the antenna at which it was obtained, and the continuity with the previous data. Are associated (pairing processing). The distance to each target is calculated from the sum of the frequencies of the two peaks subjected to the pairing process, and the relative velocity with respect to each target is calculated from the difference between the frequencies of the two peaks.
[0015]
FIG. 4 is a schematic flowchart of an example of processing from peak data input to data output in the microcomputer 30.
[0016]
In FIG. 4, first, peak data is input from the DSP 28 (step 1000). The predicted value of the current target data (distance, relative speed) and the predicted value of the peak frequency are calculated from the previous data (step 1002, details are described above), and past correspondence pairing is attempted based on the calculated values (step 1004, details). Is described above). Next, new pairing is attempted for the remaining peak (step 1006, details are described above). The distance and relative speed are calculated from the frequency of the paired peak, and the continuity with the previous data is determined (step 1008, details are described above). When there is no data in the prediction range from the previous data, the target data is calculated by extrapolation for a certain period.
[0017]
If the target data is not extrapolated this time (step 1010) and the target data was calculated by extrapolation in the previous time (step 1012), the current value is obtained from the current relative final speed without performing a filtering operation on the relative speed. (Step 1014), otherwise, a filtering operation is also performed for the relative speed (Step 1016).
[0018]
FIG. 5 is a diagram for explaining the operation in the situation described in FIG. 1 and FIG. Until time t _2, it is the same as in FIG. 2, but when new pairing is performed at t ₂ , the filtering operation is not performed on the relative speed, so the predicted value of the peak frequency approaches the actual value. Even if downbeat extrapolation is resumed at time t ₃ , the predicted value is closer to the measured value, so both up and down peaks are within the predicted range after the new pairing at time t _4. The prediction value converges to the actual measurement value.
[0019]
【The invention's effect】
As described above, according to the present invention, even when the actual relative speed fluctuates more than a certain amount during the extrapolation process, such as when a vehicle traveling ahead approaches and then travels at a certain inter-vehicle distance. Provided is a radar data processing apparatus capable of quickly following.
[Brief description of the drawings]
FIG. 1 is a diagram showing a transition of a peak frequency when traveling at a constant inter-vehicle distance after a front target approaches.
FIG. 2 is a diagram for explaining a problem of a conventional technique.
FIG. 3 is a block diagram showing an example of the configuration of a millimeter wave radar to which the present invention is applied.
4 is a flowchart showing processing of the microcomputer 30. FIG.
FIG. 5 is a diagram showing a processing result of data processing according to an embodiment of the present invention.

Claims (2)

Means for performing continuity determination that the target data obtained up to the previous time and the target data obtained this time are based on the same target;
Means for performing a filter operation on target data determined to be based on the same target as a result of the continuity determination;
The filter calculating means is configured such that when the current target data is calculated from the actual measurement value obtained this time, and the previous target data is not an actual measurement value but calculated by extrapolation, A radar data processing apparatus characterized by not performing a filter operation on the relative speed of a target included in the target data. Performing continuity determination that the target data obtained up to the previous time and the target data obtained this time are from the same target;
A step of performing a filter operation on target data determined to be based on the same target as a result of the continuity determination,
The filter calculation step is performed when the current target data is calculated from the actual measurement value obtained this time, and the previous target data is not an actual measurement value but calculated by extrapolation. A radar data processing method, wherein no filter operation is performed on the relative speed of a target contained in data.

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