JPH05249232A - Millimeter-wave radar equipment - Google Patents

Abstract

PURPOSE:To prevent millimeter-wave radar equipment from becoming unstable in distance, etc., due to the fluctuation of the frequency data of beat signals. CONSTITUTION:The radar equipment is provided with a same object measuring value extracting section 53 which extracts data from the same object out of the frequency data of beat signals and a storing section 54 which stores the frequency data of past beat signals and stores '0' data in place of the frequency data when the section 54 discriminates that the frequency data are not from the same object. In addition, the radar equipment is also provided with a latest data extracting section 55 which extracts the latest data except '0' out of the stored data, '0' data number counting section 56 which counts the number of stored '0' data, and '0' data number rate deducing section 57 which deduces the rate of the number of '0' data. Furthermore, the radar equipment is also provided with an averaging section 60 which averages the stored frequency data and data output section 58 which outputs the averaged data of the section 60 for deducing a distance and speed only when the rate of the number of '0' data to the number of all data is lower than a fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a millimeter wave radar device for measuring the distance and speed by subjecting a transmission signal of a continuous wave radar to frequency modulation and simultaneously receiving a reflection signal from a target. In particular, the present invention has an object to prevent the frequency data of the beat signal, which is measured due to noise or the like, from fluctuating and thus the distance and the velocity from becoming unstable.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to a millimeter wave radar distance velocity measuring device in such a field, there is "radar technique".
There was one described in (Incorporated Association: The Institute of Electronics, Information and Communication Engineers). This is because the transmission signal of the CW continuous wave radar is frequency-modulated to increase the frequency of the reception signal (U
P), take a beat between the falling side (DOWN) and the transmission signal, combine the frequencies of the respective beat signals,
The distance and the relative speed to the object are continuously obtained.

[0003]

However, in the conventional millimeter-wave radar device, in order to obtain the distance and velocity, basically, only the data for one time is taken into consideration and the result obtained is calculated as , Which corresponded to the speed, but in this method, the frequency of the received signal is increased (UP) and decreased (D).
There is a problem that the variation in the measurement result of OWN) cannot be suppressed.

That is, a stable display cannot be obtained because the result is displayed only once (or only a few times) due to the influence of noise or the like or only once. When it is used not only for display but also for control, a higher degree of stability is required. Therefore, in view of the above problems, it is an object of the present invention to provide a millimeter wave radar device that does not affect the distance and speed even if the frequency of the received signal varies due to noise or the like.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a millimeter range for obtaining distance and velocity from beat signals of a transmission signal and a reception signal of a continuous wave radar which is frequency-modulated with a triangular wave. The wave radar device is provided with an identical object measurement value extraction unit, a storage unit, a latest data extraction unit, a 0 data number ratio derivation unit, an averaging unit, and a data output determination unit.

The same object measurement value extraction unit extracts data from the same object in the frequency data of past beat signals. The storage unit stores frequency data of past beat signals, and stores “0” data when the same object measurement value extraction unit determines that the data is not from the same object. The latest data extraction unit extracts the latest data that is not “0” from the data stored in the storage unit and supplies it to the same object measurement value extraction unit. The 0 data number counting unit counts the number of “0” data stored in the storage unit. The 0 data number ratio deriving unit derives a ratio of the “0” data number to the total data number stored in the storage unit.
The averaging unit averages the frequency data stored in the storage unit. The data output determination unit outputs the latest data of the latest data extraction unit for deriving the distance / velocity only when the ratio of the number of “0” data to the total number of data is less than a certain value.

The 0-data-number counting section includes a first 0-data-number counting section, a second 0-data-number counting section, and a summing section.
The data number ratio deriving unit is the first “0” data ratio deriving unit,
A second “0” data ratio derivation unit is provided. The first 0
The data number counting unit counts the number of “0” data near the current point in the data stored in the storage unit.
The second 0-data-number counting unit counts the number of “0” data far away from the current point in the data stored in the storage unit. The summing unit sums the "0" data numbers of the first 0 data number counting unit and the second 0 data number counting unit.

The 0 data number ratio deriving unit includes a first "0" data ratio deriving unit and a second "0" data ratio deriving unit. The first “0” data ratio deriving unit is the first unit for the total number of data stored in the storage unit.
The ratio of the "0" data number of the 0 data number counting unit is derived. The second “0” data ratio deriving unit derives the ratio of the “0” data number of the total part to the total number of data stored in the storage unit.

When the ratios of the first "0" data ratio deriving unit and the second "0" data ratio deriving unit are within predetermined ranges, the data output judging unit outputs the latest data.

[0010]

According to the distance velocity measuring device by the millimeter wave radar of the present invention, the same object measurement value extraction unit extracts data from the same object among the frequency data of the past beat signals. Frequency data of past beat signals is stored in the storage unit, and “0” data is stored if the same object measurement value extraction unit determines that the data is not from the same object. The latest data extraction unit extracts the latest data other than “0” from the data stored in the storage unit, and supplies the latest data to the same object measurement value extraction unit.
The number of “0” data stored in the storage unit is counted by the 0 data number counting unit. The 0 data number ratio deriving unit derives the ratio of the “0” data number to the total data number stored in the storage unit. The averaging unit averages the frequency data stored in the storage unit. The data output determination unit outputs the average data of the averaging unit for deriving the distance / velocity only when the ratio of the number of “0” data to the total number of data is less than a certain value. Therefore, an object that existed only once or twice was judged as noise and was not displayed. On the contrary, even once, the output is averaged and stable and smooth output can be obtained.

Further, the first 0-data-number counting section counts the number of "0" data near the current point in the data stored in the storage section. The second 0
The data number counting unit counts the number of “0” data far from the current point in the data stored in the storage unit. The summing unit sums the number of “0” data in the first 0 data number counting unit and the second 0 data number counting unit.

The first “0” data ratio deriving unit derives the ratio of the “0” data number of the first 0 data number counting unit to the total number of data stored in the storage unit. It The second “0” data ratio deriving unit derives the ratio of the “0” data number of the total part to the total number of data stored in the storage unit. The average data is output from the data output determining unit when the ratios of the first “0” data ratio deriving unit and the second “0” data ratio deriving unit are within predetermined ranges. Therefore, the accuracy is improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a millimeter wave radar device which is a premise of the present invention. The millimeter-wave radar device shown in this figure transmits the continuous wave (CW) signal to the target object, and at the same time, receives the reflected signal from the target object and the antennas 1 and 2 for transmitting the continuous wave signal to the antenna 1. CW transmitter 3
And a mixer 4 for mixing the continuous wave signal of the CW transmitter 3 and the received signals of the frequency rising side (UP) and the frequency falling side (DOWN) at the antenna 2 to form a beat signal, and the mixer. A signal processing unit 5 for obtaining a distance and a speed from a beat signal formed by 4, and a device for performing device control based on the distance data and the speed data obtained by the signal processing unit 5 and displaying them. The control / display unit 6 is included.

FIG. 2 is a diagram showing the relationship between frequency band times when a reflected signal from a moving target is received by the millimeter wave radar device. As indicated by the solid line in this figure (a), CW
The transmitter 3 repeatedly transmits a triangular wave of frequency modulation (FM). On the other hand, as shown by the dotted line in this figure (b), the antenna 2 receives the frequency-modulated signal of repeating triangular wave, and the frequency of the beat signal on the rising side in the mixer 4 is set to fd The frequency of the beat signal on the side is fu.

As shown in FIG. 3B, the following equation is established. fd = fr + fp fu = fr-fp Here, it can be expressed as fr = 4R · fm · Δf / c. Here, R is the distance to the target, fm is the frequency modulation repetition frequency, Δf is the frequency shift width, and c is the speed of light.

Fp = 2f0V / c where f0 is the transmission center frequency, and V is the relative speed to the target. FIG. 3 is a diagram showing a distance velocity measuring device using a millimeter wave radar according to an embodiment of the present invention. The signal processing unit 5 shown in the figure is an A / D converter 51 (Analog to Digital Co) that converts an analog signal from the mixer 4 into a digital signal.
nverter), a fast Fourier transform unit 52 (FFT) that analyzes the frequency of the beat signal from the A / D converter 51,
The same object measurement value extraction unit 53 that extracts measurement values of the same object from the frequency data obtained by the fast Fourier transform unit 52, and 2n pieces of data extracted from the same object measurement value extraction unit 53 are stored and the same If it is not an object, the storage unit 54 that stores “0” data, and the latest data that is not “0” is extracted from the storage unit 54 to determine whether or not the same object measurement value extraction unit 53 measures the same object. Latest data extraction unit 55 used for
And a ratio of the number of “0” data counted by the 0 data number counting unit 56 to the total number of data stored in the storage unit 54 is calculated. 0 data number ratio deriving unit 57,
A data output unit 58 that outputs frequency data of a beat signal when the 0 data number ratio by the data number ratio deriving unit 57 is, for example, half or less, and prohibits output of the beat signal frequency data when the ratio is 0 or more, and the data. A distance / velocity deriving unit 59 that derives the distance to the target and the relative velocity based on the frequency data of the beat signal from the output determination unit 58 and outputs the relative velocity to the device control / display unit 6, and the beat stored in the storage unit 54. An average value averaging unit 60 for averaging the frequency data of the signal and supplying the averaged frequency data to the data output determining unit 58.

FIG. 4 is a diagram showing the configuration of the latest data extraction unit of FIG. The latest data extraction unit 55 shown in this figure stores the latest data from the storage unit 54 and outputs the latest data to the same object measurement value extraction unit 53 and the data output determination unit 58, and the latest data storage unit 551. Data storage unit 55
If the data of 1 is "0", and if it is "0" data, the latest data storage unit 551 includes a "0" data determination unit 552 for reading the next new data from the storage unit 54.

The operation of the main part of each part will be described in detail. FIG. 5 is a diagram showing an example of frequency data of beat signals processed by the signal processing unit. It is assumed that the frequency of the beat signal as shown in FIG. 9A is formed by the fast Fourier transform unit 52 and is input to the same object measurement value extraction unit 53. In the initial state, only "0" data is initially output from the latest data extraction unit 55, and in this case, the same object measurement value extraction unit 53 outputs the frequency data of the input beat signal to the storage unit 54 as it is. When the data other than "0" is stored in the storage unit 54, the same object measurement value extraction unit 53 determines at the present time T whether the frequency of the beat signal from the same object is as follows.

Fu (new) -wu ≤ fu (T) ≤ fu
(New) + wu fd (new) −wd ≦ fd (T) ≦ fd (new) +
wd where T is the measurement time, and ± w u and ± wd are allowable widths for judging whether they are the same object. fu (new) is given from the latest data extraction unit 55 to the same object measurement value extraction unit 53.

When the above equation is satisfied, fu (T), f
d (T) is output to the storage unit 54 from the same object measurement value extraction unit 53. If the above equation is not satisfied, “0” data is output to the storage unit 54 from the same-object measurement value extraction unit 53. Therefore, when the data for the target cannot be obtained, "0" data is transmitted to the storage unit and it is determined that the object did not exist at the time T.

In the storage unit 54, the same object measurement value extraction unit 5
2n pieces of data sent from 3 are stored and sequentially updated. In the example of FIG. 5A, fu (T-5), fu (T-)
4) = 0, fu (T-3), fu (T-2), fu (T
-1) is stored. In this case, the latest data extraction unit 55 determines that fu (new) = fu (T-
Extract 1). The same object measurement value extraction unit 53 inputs the latest data at present and compares it with fu (T) to determine whether they are the same object. As shown in FIG. 5C, fu (T-
If 1) is skipped, the latest data is: fu (ne
w) = fu (T-2).

Next, in the 0 data number counting unit 56, the storage unit 54
The number of “0” data among the 2n pieces of data stored in is measured. In the example of FIG. 5A, the “0” data is one of the five data, and in the example of FIG. 5C, the “0” data is two of the five data. In the 0 data number ratio deriving unit 57, “0” is included in the above 2n pieces of data.
Derive the ratio of the number of data. 1 in the example of FIG.
/ 5, and 2/5 in the example of FIG. 7C. In the data output determination unit 58, the 0 data number ratio derivation unit 57
From the ratio of “0” data, for example, if the ratio of “0” data is less than the majority, it is determined that the same object exists, and the average data from the averaging unit 60 is used as the distance velocity deriving unit 5.
Output to 9. If the ratio of “0” data is a majority or more, it is determined that the same object does not exist and the average data is not sent to the distance velocity deriving unit 59. In this case, "0" in the past
Even if a large amount of data is not used for display or the like, the data is stored in the storage unit 54 for the next time.

Specifically, as shown in FIG. 3A, when there is data for the past 6 times (including T), and when there is a value for T, 2 of the remaining 5 times are used. If the object is present once (three times in total), it is determined that this object is present, and this value is displayed. As shown in FIG. 5B, even if there is no beat signal frequency data at this time, in this case, it is determined that the data is accidentally skipped due to noise. For example, fu (T-1) is Used. The data used for display or the like is, for example, the value one time before (in this case, T-1
This is because the values are displayed even in the cases of FIGS. 7B and 7C, so that stable results can be obtained. As it uses past values, it seems that old ones are displayed, but the measurement interval is 1
Since it is as short as 0 ms order, it is not a problem.
That is, the relative distance and relative velocity to the same object do not change significantly, and the object does not suddenly appear, disappear suddenly, or disappear for a moment.

As shown in FIG. 5 (c), the number of fu (T-1) is not the same as the present time T, but the number is small as a whole. Therefore, it is assumed that the same object exists. The average values fuav (T-1) and fdav (T-1) of the frequency data of the beat signal from the next averaging unit 60 are output. For example, when fuav (T-1) and fdav (T-1) are input as the latest data, the distance / velocity deriving unit 59 calculates the distance and velocity as follows.

Frav (T-1) = {fdav (T-1) +
fuav (T-1)} / 2 fpav (T-1) = {fdav (T-1) -fuav (T-
1)} / 2 to the object from the distance R (T-1) and the velocity V (T-
1) is R (T-1) = flav (T-1) .c / (4.fm.Δ
f) Obtained as V (T-1) = fpav (T-1) .c / (2.f0).

FIG. 6 is a diagram showing an averaging process of beat signal frequency data. As shown in the figure, the averaging unit 6
In 0, if the current time is “4”, 3 times from 1 to 3 times
The average value of the frequency data of the beat signal at the point is calculated, and when the current time is “5”, the average value of the three points from the second to the fourth is calculated. Generally, the average value fuav at the present time is as follows.
(T-1) and fdav (T-1) are calculated.

Fuav (T-1) = {fu (T-1) + f
u (T-1) + ... + fu (T-n)} / n fdav (T-1) = {fd (T-1) + fd (T-1)
+ ... + fd (T-n)} / n FIG. 7 shows the relative distance obtained from the average value of the frequency data of the beat signal. As shown in FIG. 2B, the change in distance to the same object obtained by averaging the frequency data of the beat signal is smooth against the conventional variation in distance to the same object as shown in FIG. become.

The averaging unit 60, the 0 data number counting unit 5
The relationship with the 6,0 data number ratio deriving unit 57 will be described. There are many variations in the measurement results for the same object, which may not be displayed only once or the data may be missing. The averaging unit 60 smoothes the data, but outputs it as long as past data is present, so there is a risk of erroneously determining that the same object exists even if noise or the like occurs. In such a case, the data output judging unit 58 judges from the 0 data number ratio deriving unit 57 based on the ratio of “0” data, for example, if the ratio of “0” data is a majority or less, it is determined that the same object exists. The average data from the averaging unit 60 is output to the distance / velocity deriving unit 59. If the ratio of “0” data is a majority or more, it is determined that the same object does not exist and the average data is not sent to the distance velocity deriving unit 59. By such a method, the component considered to be noise is not output and the output result can be made continuous.

By the way, in the above description, the more past values are held, the higher the accuracy (whether actually existing or not) is, but on the other hand, there are cases where there is no result closer. FIG. 8 is a diagram showing the necessity of further improvement in this embodiment. As shown in the figure, if the frequency data of the beat signal is described as 6 points, the interpolation processing is performed so that the result is not continuously output in the wide time of the 4th to 6th times, but is always output. The explanation for improving this will be given below.

FIG. 9 is a diagram showing a modification of the “0 data number counting unit” and the “0 data number ratio deriving unit” according to the embodiment of the present invention, and FIG. 10 is a diagram showing a counting state of 0 data. is there. As shown in FIG. 10, the 0 data number counting unit 56 shown in FIG. 9 has a frequency of 2 of the beat signal stored in the storage unit 54.
A first 0-data-number counting unit 56 that counts the number of “0” data included in the n-number of data close to the present time out of the n-number of data
1 and 2n of the frequency of the beat signal stored in the storage unit 54
A second 0-data-number counting unit 56 that counts the number of “0” data included in n data far from the present data
2 and a total unit 563 that totals the number of “0” data included in the first 0 data number counting unit 561 and the second 0 data number counting unit 562.

The 0 data number ratio deriving unit 57 derives the ratio of the “0” data number obtained by the first 0 data number counting unit 561 to the total data number, and the first “0” data ratio deriving unit 571. And a second “0” data ratio deriving unit 572 that derives the ratio of the number of “0” data obtained by the summing unit 563 to the total number of data, and the first “0” data ratio deriving unit 571 If both the ratio of “0” data and the ratio of “0” data of the first “0” data ratio deriving unit 571 are, for example, ½ or less, the data output determination unit 58 is one of the current measured values. The previous value is output to the distance / velocity deriving unit 59.

In this modified example, if data is processed several times in the past (2n), there are n pieces near the time point and n pieces at the far side point, and there are n / 2 or more pieces near the time point. Also, if there are n or more values, including near and far, the average measurement value this time will be displayed, so weight the near places to determine if there is noise. did. Therefore, the accuracy is higher for the object.

[0033]

As described above, according to the present invention, the frequency data of the past beat signal is stored, and the average data is the distance only when the ratio of the "0" data count to the total data count is less than a fixed value. Since the data is output for speed derivation, it is judged that the object existing only once or twice is noise and is not displayed. On the contrary, even if it is once, it is possible to obtain a stable and smooth output because it is compensated by the average value.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a millimeter wave radar device which is a premise of the present invention.

FIG. 2 is a diagram showing a relationship between frequency band times when a millimeter wave radar device receives a reflection signal from a moving target.

FIG. 3 is a diagram showing a distance velocity measuring device using a millimeter wave radar according to an embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a latest data extraction unit of FIG.

FIG. 5 is a diagram showing an example of frequency data of a beat signal processed by a signal processing unit.

FIG. 6 is a diagram showing an averaging process of beat signal frequency data.

FIG. 7 is a diagram showing a relative distance obtained from an average value of frequency data of beat signals.

FIG. 8 is a diagram showing the need for further improvements in the present embodiment.

FIG. 9 is a diagram showing a modification of the “0 data number counting unit” and the “0 data number ratio deriving unit” according to the embodiment of the present invention.

FIG. 10 is a diagram showing a counting situation of 0 data.

[Explanation of symbols]

 1, 2 ... Antenna 3 ... CW transmitter 4 ... Mixer 5 ... Signal processing unit 6 ... Equipment control / display unit 53 ... Same object measured value extraction unit 54 ... Storage unit 55 ... Latest data extraction unit 56 ... 0 Count data number Part 57 ... 0 data number ratio deriving unit 58 ... Data output determination unit 59 ... Distance speed deriving unit 60 ... Averaging unit 561 ... First 0 data number counting unit 562 ... Second 0 data number counting unit 563 ... Total Part 571 ... First "0" data ratio deriving unit 572 ... Second "0" data ratio deriving unit

Claims (2)

[Claims] 1. A millimeter-wave radar device for obtaining a distance and a velocity from beat signals of a transmission signal and a reception signal of a continuous wave radar that is frequency-modulated with a triangular wave. The same object measurement value extraction unit (53) for extracting data and frequency data of past beat signals are stored, and if the same object measurement value extraction unit (53) determines that the data is not from the same object, “0” data Storage unit (5
4), and the latest data that is not "0" is extracted from the data stored in the storage unit (54) to extract the same object measurement value extraction unit (53).
To the latest data extraction unit (55), the 0 data number counting unit (56) for counting the number of “0” data stored in the storage unit (54), and the storage unit (54). A zero data number ratio deriving unit (57) for deriving the ratio of the “0” data number to the total number of data; and an averaging unit (60) for averaging the frequency data stored in the storage unit (54). A data output unit (58) for outputting the average data of the storage unit (54) for deriving a distance velocity only when the ratio of the number of “0” data to the total number of data is a certain value or less.
A millimeter-wave radar device comprising: 2. The first 0 data number counting section (56) counts the number of “0” data near the present time among the data stored in the storage section (54). (561), a second 0-data-number counting unit (562) that counts the number of “0” data that is far from the current point in the data stored in the storage unit (54), and a first 0-data number. A counting unit (561) and a second counting unit (562) for counting the number of “0” data, and a summing unit (563) for summing the number of “0” data. A first "0" data ratio deriving unit (571) for deriving the ratio of the "0" data number of the first 0 data number counting unit (561) to the total number of data stored in the unit (54). ) And the total number of data stored in the storage unit (54) A second "0" data ratio deriving unit (572) for deriving a ratio of the number of "0" data of the total unit (563), and a first "0" data ratio deriving unit (571) and a second unit. 2. The millimeter wave radar device according to claim 1, wherein the average data is output from the data output determination unit (58) when the ratios of the "0" data ratio deriving units (572) are within respective predetermined ranges.