JP3954993B2 - Vehicle object detection device - Google Patents

Description

  The present invention relates to a vehicle object detection device for detecting an object such as a preceding vehicle with a radar device using FM-CW waves (frequency modulated continuous waves).

  Such an object detection device for a vehicle is known from Patent Document 1 below.

  As shown in FIG. 9, in the conventional object detection apparatus using the FM-CW wave, the transmission operation of the oscillator 3 is modulated and controlled by the FM modulation control circuit 2 based on the timing signal input from the timing signal generation circuit 1. As shown by a solid line in FIG. 10, a transmission wave whose frequency is modulated in a triangular wave shape is transmitted from the transmission / reception antenna 6 via the amplifier 4 and the circulator 5. When the reflected wave obtained by reflecting the FM-CW wave on an object such as a preceding vehicle is received by the transmission / reception antenna 6, the received wave has a frequency of the transmission wave as shown by a broken line according to the distance from the object. On the rising side, which increases linearly, it appears delayed from the transmitted wave at a frequency lower than the transmitted wave, and on the descending side, where the frequency of the transmitted wave decreases linearly, it appears delayed from the transmitted wave at a higher frequency than the transmitted wave. To do.

  The received wave received by the transmission / reception antenna 6 is input to the mixer 7 via the circulator 5. In addition to the reception wave from the circulator 5, the transmission wave distributed from the transmission wave output from the oscillator 3 is input to the mixer 7 via the amplifier 8, and the transmission wave and the reception wave are mixed by the mixer 7. As shown in FIG. 10, the beat having the peak frequency Fup on the rising side where the frequency of the transmission wave increases linearly and the peak frequency Fdn on the falling side where the frequency of the transmission wave decreases linearly. A signal is generated.

  The beat signal obtained by the mixer 7 is amplified to an amplitude of a necessary level by the amplifier 9, A / D converted by the A / D converter 10 at every sampling time, and the digitized amplified data is stored in the memory 11 in time series. Is stored in memory. A timing signal is input to the memory 11 from the timing signal generation circuit 1, and in accordance with the timing signal, the memory 11 stores data on the rising side where the frequency of the transmission / reception wave increases and on the falling side where the frequency decreases. Will be stored in memory.

  The data stored and held in the memory 11 is input to a CPU 12 including a frequency analysis unit 13, a detection peak determination unit 14, and an object detection unit 15, and the CPU 12 executes arithmetic processing based on the input data.

  The frequency analysis means 13 performs frequency analysis on beat signal data stored in the memory 11 to obtain a spectrum distribution, and FFT (Fast Fourier Transform) is used as a frequency analysis technique.

  The detection peak determination unit 14 detects a spectrum (peak signal) having a maximum value when the detection level is equal to or higher than a predetermined detection threshold, based on the spectrum data obtained by the frequency analysis in the frequency analysis unit 13. As shown in FIG. 10, when the relative speed of the host vehicle and the preceding vehicle is zero, the peak signal on the rising side and the peak signal on the lowering side overlap, but for example, the host vehicle is stationary as shown in FIG. When approaching an object with relative speed, the peak signal on the rising side and the peak signal on the descending side are symmetrical with respect to the peak position when the relative speed with respect to the object is zero. Detected.

  The object detection means 15 calculates the relative distance and relative speed of the object based on the rising peak frequency Fup and the falling peak frequency Fdn obtained by the detection peak determination means 14.

The FM modulation width is Δf, the speed of light is c, the modulation repetition period is Tm, the distance between the vehicle and the object is r, the transmission center frequency is f ₀ , and the relative speed between the vehicle and the object is v. When the peak frequency Fup on the rising side is
Fup = (4 · Δf · r) / (c · Tm) + {(2 · f ₀ ) / c} · v
... (1)
The descending peak frequency Fdn is given by
Fdn = (4 · Δf · r) / (c · Tm) − {(2 · f ₀ ) / c} · v
... (2)
Given in. Here, if FM modulation width Δf, modulation repetition period Tm, and transmission center frequency f ₀ are constant, constants k ₁ and k ₂ are used,
Fup = r · k ₁ + v · k ₂ (3)
Fdn = r · k ₁ −v · k ₂ (4)
It is represented by

As apparent from the equations (3) and (4), when the relative speed v between the vehicle and the object does not exist (v = 0), the peak frequency Fup on the rising side and the peak frequency Fdn on the descending side coincide with each other. (See FIG. 10). Further, when the relative speed v between the vehicle and the object exists (v ≠ 0), the ascending peak frequency Fup and the descending peak frequency Fdn do not coincide (see FIG. 11). The distance r to the object can be calculated based on the sum of the two peak frequencies Fup and Fdn, and the relative speed v with the object can be calculated based on the difference between the two peak frequencies Fup and Fdn.
Japanese Patent No. 3305624

  By the way, as shown in FIG. 12, when there are two preceding vehicles having different relative speeds in front of the host vehicle, an ascending peak signal and a descending peak signal are generated for each preceding vehicle. Four peak signals are obtained. Accordingly, if the pairing of these four peak signals (the combination of the rising peak signal and the falling peak signal to be paired) is incorrect, there is a problem that the distance and relative velocity of the object cannot be detected correctly.

  What is described in the above-mentioned patent document is to perform pairing based on past history data by time series processing, but in order to perform pairing processing for all combinations of peak signals, the result of pairing Therefore, it takes a long time to determine the problem, and there is a problem in applying it to a system that requires quick control such as an inter-vehicle distance control device.

  When performing inter-vehicle distance control, etc. using a radar device, it is particularly important to distinguish between data on a moving body such as a preceding vehicle and roadside objects such as guardrails and side walls. If the roadside object can be easily and reliably identified, the performance of the radar device can be greatly improved.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to make it possible to easily and reliably identify a moving object and a roadside object in an object detection apparatus using FM-CW waves.

To achieve the above object, according to the first aspect of the present invention, a transmission / reception means for transmitting an FM-CW wave and receiving a reflected wave from an object of the FM-CW wave, a transmission wave and a reception wave A mixer that generates a beat signal by mixing waves, a frequency analysis unit that performs frequency analysis of the beat signal obtained by the mixer, and a peak signal obtained based on the frequency analysis results of the rising and falling sides by the frequency analyzing unit Among them, the detection peak determination means for determining a peak signal equal to or higher than the detection threshold as the detection peak, and the distance from the object and the relative speed with respect to the object based on the detection peaks on the rising side and the falling side obtained by the detection peak determination means In an object detection device for a vehicle comprising an object detection means for calculating at least one, a vehicle position detection means for detecting a current position of the own vehicle, and a map information storage for storing map information. Means, and the road shape estimation means for estimating the traveling direction of the road shape of the vehicle based on map information obtained from the vehicle position information detected and the map information storage unit by the vehicle position detecting means, a plurality of sensing directions Roadside object peak determination means for determining at least a part of the detection peaks in the plurality of detection directions as detection peaks due to roadside objects based on the detected peak in the vehicle and the predicted road shape in the traveling direction of the vehicle. An object detection device for a vehicle is provided, wherein the object detection means calculates at least one of a distance to the object and a relative speed to the object based on a detection peak other than the roadside object peak.

According to the second aspect of the invention, the transmission / reception means for transmitting the FM-CW wave and receiving the reflected wave from the object of the FM-CW wave, and the beat signal by mixing the transmission wave and the reception wave Of the peak signal obtained based on the frequency analysis results of the rising and falling sides by the frequency analyzing means Object detection for calculating at least one of the distance to the object and the relative velocity with respect to the object based on the detection peak determination means for determining the signal as a detection peak and the detection peak on the rising side and the descending side obtained by the detection peak determination means Vehicle object detection device comprising means for obtaining information on the road shape in the traveling direction of the vehicle by communicating with transmission means provided on the road A road-to-vehicle communication unit, at least some of the detection peaks in the plurality of sensing directions based on the vehicle traveling direction of the road shape information regarding the obtained by detecting the peak and the road-vehicle communication means in a plurality of sensing directions Roadside object peak determination means for determining that the roadside object detection peak is detected, and the object detection means calculates at least one of the distance to the object and the relative speed with respect to the object based on the detection peak other than the roadside object peak. An object detection device for a vehicle is proposed.

  According to the invention described in claim 3, in addition to the configuration of claim 1, the roadside object peak determination means arranges the plurality of detection peaks on coordinates having the detection direction and the peak frequency as parameters, respectively. In addition, an object detection apparatus for a vehicle is proposed in which an array of detection peaks similar to the road shape predicted by the road shape prediction means is determined to be detection peaks due to roadside objects.

According to the invention described in claim 4, in addition to the configuration of claim 2, the roadside object peak determination means arranges the plurality of detection peaks on coordinates having the detection direction and the peak frequency as parameters, respectively. as well as, the object detecting apparatus for a vehicle, characterized in that to determine the sequence of the detection peaks similar to road shape obtained by the road-vehicle communication means to be detected peak due roadside object is proposed.

  In addition, the transmission / reception antenna 6 of an Example respond | corresponds to the transmission / reception means of this invention.

According to the first aspect, based on the detected peak and the road shape prediction unit road shape in the traveling direction of the vehicle predicted by the plurality of detection direction determined by detecting the peak determination means, wherein the roadside object peak determining means It is determined that at least some of the detection peaks in a plurality of detection directions are detection peaks due to roadside objects, and the object detection means determines the distance to the object and the relative speed with respect to the object based on the detection peaks other than the roadside object peak. Since at least one of them is calculated, when both the roadside object and the moving object are detected, the detection data of the roadside object can be excluded and only the detection data of the moving object can be obtained.

According to the configuration of the second aspect, the roadside object peak determination is based on the detection peaks in the plurality of detection directions determined by the detection peak determination means and the information on the road shape in the traveling direction of the own vehicle obtained by the road-to-vehicle communication means. The means determines that at least some of the detection peaks in the plurality of detection directions are detection peaks due to roadside objects, and the object detection means determines the distance between the object and the object based on the detection peaks other than the roadside object peaks. Since at least one of the relative speeds is calculated, when both the roadside object and the moving object are detected, the detection data of the roadside object can be excluded and only the detection data of the moving object can be obtained.

  According to the configuration of claim 3, a plurality of detection peaks are arranged on the coordinates having the detection direction and the peak frequency as parameters, and an array of detection peaks similar to the road shape predicted by the road shape prediction means indicated on the coordinates. Therefore, the detection peak of the moving object and the detection peak of the roadside object can be easily and reliably identified.

According to the configuration of claim 4, a plurality of detection peaks are arranged on the coordinates having the detection direction and the peak frequency as parameters, and detection peaks similar to the road shape obtained by the road-to-vehicle communication means indicated on the coordinates are displayed. Since the arrangement is determined to be a detection peak due to a roadside object, the detection peak of the moving object and the detection peak of the roadside object can be easily and reliably identified .

  Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.

  1 to 7 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of an object detection device, FIG. 2 is a diagram showing the positional relationship between a host vehicle, a preceding vehicle, and a road, and FIG. FIG. 4 is a flowchart illustrating the operation, FIG. 5 is a diagram illustrating two-dimensional coordinates for performing pairing, and FIG. 6 is a channel ch3. FIG. 7 is a diagram corresponding to FIG. 5, showing the final pairing of the peak signals on the ascending side and the descending side of FIG.

  FIG. 1 shows a circuit configuration of the CPU 12 of the object detection apparatus of the present embodiment. The configuration and operation other than the CPU 12 are the same as those in FIG. The conventional CPU 12 described in FIG. 9 includes the frequency analysis means 13, the detection peak determination means 14, and the object detection means 15. However, the CPU 12 of this embodiment further includes the vehicle position detection means 21 and a map. Information storage means 22, road shape prediction means 23, and roadside object peak determination means 17 are provided.

  The own vehicle position detection means 21 detects the current position of the own vehicle by receiving radio waves from GPS satellites. The map information storage means 22 comprises a storage medium such as a DVD and stores a wide range of road data as a set of coordinate points. The road shape prediction means 23 predicts the road shape in the traveling direction of the own vehicle based on the own vehicle position detected by the own vehicle position detection means 21 and the road data stored in the map information storage means 22. The functions of the vehicle position detection means 21, the map information storage means 22, and the road shape prediction means 23 are provided in the navigation system, and the existing navigation system can be used as it is.

  The roadside object peak determination means 17 excludes roadside object detection peaks from the detection peaks obtained by the detection peak determination means 14 based on the road shape in the traveling direction of the host vehicle predicted by the road shape prediction means 23. Thus, the detection peak of a moving body such as a preceding vehicle that should be detected is identified, and the object detection means 15 can accurately detect only the moving body.

  FIG. 2 shows a state in which the host vehicle is following the preceding vehicle. Of the five channels ch1 to ch5 of the object detection device mounted on the host vehicle, two channels ch1 and ch2 are guardrails. Only the roadside objects F1 and F2 are detected, and the other two channels ch3 and ch4 detect the roadside objects F3 and F4 and the moving bodies M1 and M2 such as the reflectors of the preceding vehicle, and the remaining one channel. It is assumed that nothing is detected in ch5.

  Here, paying attention to the channel ch3 (the same applies to the channel ch4), the channel ch3 detects both the roadside object F3 and the moving body M1 at the same time. As shown in FIG. Two up2 appear, and two descending peak signals dn1 and dn2 appear. Accordingly, as shown in Table 1, there are four pairs of Pair1 to Pair4 of the pair of peak signals up1 and up2 on the rising side and the pair of peak signals dn1 and dn2 on the descending side, If the pairing is not confirmed, the roadside object F3 detected by the channel ch3 and the moving body M1 cannot be identified.

  Therefore, in the present embodiment, the pairing is determined as follows.

In the flowchart of FIG. 4, first, the road shape in the traveling direction of the host vehicle is predicted by the road shape prediction means 23 in step S1. In the subsequent step S2, the beat signal data stored in the memory 11 by the frequency analysis means 13 is subjected to FFT processing to obtain a detection spectrum. In the following step S3, the detection peak determination means 14 causes the total of six peak frequencies Fup on the rising side corresponding to the four roadside objects F1 to F4 and the two moving bodies M1 and M2 from the detection spectrum and the lowering side. a total of six of the peak frequency Fdn of, to extract so as to correspond to each channel ch1~ch5. In subsequent step S4, the six peak frequencies Fup on the rising side and the six peak frequencies Fdn on the descending side of the channels ch1 to ch5 are plotted on different two-dimensional coordinates. This two-dimensional coordinate is a polar coordinate having an angle and a radius as parameters, the direction of each channel ch1 to ch5 corresponds to the angle, and the distance (peak frequency) of the detected object corresponds to the radius. The two-dimensional coordinates are displayed together with the predicted road shape.

  In the two-dimensional coordinates of FIG. 5A, six peak frequencies Fup on the rising side and the predicted road shape are displayed. Of these, four points f1 to f4 are arranged along the road shape. Therefore, it is determined to correspond to the four roadside objects F1 to F4. On the other hand, it is determined that the remaining two points m1 and m2 do not follow the road shape, and therefore correspond to the moving bodies M1 and M2 that are the reflectors of the preceding vehicle. In the two-dimensional coordinates of FIG. 5B, six descending peak frequencies Fdn and predicted road shapes are displayed, and four points f1 to f4 are arranged along the road shape. Therefore, it is determined to correspond to the four roadside objects F1 to F4. On the other hand, it is determined that the remaining two points m1 and m2 do not follow the road shape, and therefore correspond to the moving bodies M1 and M2 that are the reflectors of the preceding vehicle.

  From the above, in step S5, the points f1 to f4 corresponding to the roadside objects F1 to F4 among the six points f1 to f4, m1, and m2 of the two-dimensional coordinates in FIGS. The peak signal of f4 (marked with x) is excluded. That is, in the example of the channel ch3 shown in FIG. 6, the detection peak up2 corresponding to the roadside object F3 is excluded from the detection peaks up1 and up2 on the rising side, and the roadside object F3 is detected among the detection peaks dn1 and dn2 on the lowering side. The corresponding detection peak dn2 is excluded. Therefore, in step S6, it can be determined that Pair1 (that is, detection peaks up1, dn1) surrounded by an ellipse shown in Table 2 corresponds to the moving object M1.

  In the subsequent step S6, two detection peaks that are not excluded (up1, dn1 in the example of Table 2) are paired, and in step S7, the rising peaks corresponding to the paired detection peaks up1, dn1 By detecting the distance and relative speed of the object based on the frequency Fup and the descending peak frequency Fdn, only the moving object M1 excluding the point m1 in FIG. 5, that is, the roadside objects F1 to F4 in FIG. Can do. Similarly, for the channel ch4, only the moving body M2 excluding the point m2 in FIG. 5, that is, the roadside objects F1 to F4 in FIG. 2, can be detected.

  Thus, since the detection peak arranged along the road shape is determined to be due to the roadside object among the plurality of detection peaks obtained by the detection peak determination means 14, the necessary mobile object is excluded. A detection peak can be easily and reliably extracted, and only a moving object can be detected without requiring a conventional complicated and time-consuming pairing operation.

  Further, in FIG. 5, for example, when four points f1 to f4 on the ascending side (see FIG. 5A) are matched with the road shape and determined to be roadside objects F1 to F4, the corresponding descending side These four points f1 to f4 (see FIG. 5B) can be determined as roadside objects F1 to F4 without matching with the road shape. On the other hand, if the four points f1 to f4 on the descending side (see FIG. 5B) match the road shape and are determined to be the roadside objects F1 to F4, the four on the descending side corresponding to them. The points f1 to f4 (see FIG. 5A) can be determined as the roadside objects F1 to F4 without matching with the road shape. Thereby, it becomes possible to determine a roadside thing more rapidly.

  Further, as shown in FIG. 7B, for example, even if the detection peaks of the descending points f3 ′ and f4 ′ corresponding to the roadside objects F3 and F4 are missing for some reason, FIG. It is possible to determine the lack thereof by comparison with the detection peaks of the rising points f3 and f4 shown in FIG.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  As is clear from a comparison of FIG. 1 (first embodiment) and FIG. 8, the CPU 12 of the object detection device of the second embodiment has the vehicle position detection means 21, map information storage means 22 of the first embodiment, and Instead of the road shape prediction means 23, a road-to-vehicle communication means 25 is provided. The road-to-vehicle communication means 25 can acquire information on the road shape in the traveling direction of the host vehicle by communicating with the transmission means 26 such as a beacon provided at a predetermined interval on the road side.

  Accordingly, the roadside object peak determining means 17 is based on the road shape in the traveling direction of the own vehicle acquired by the road-to-vehicle communication means 25, out of the detected peaks obtained by the detected peak determining means 14 as in the first embodiment. By removing the detection peak of the roadside object from the detection peak, the detection peak of the moving body such as the preceding vehicle to be originally detected is identified, and the object detecting means 15 can accurately detect only the moving body.

  Thus, the second embodiment can achieve the same effects as those of the first embodiment described above.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, the circulator 5 may not be used by separately installing a transmitting antenna and a receiving antenna.

  In the embodiment, an object other than a roadside object is referred to as a moving object for convenience. However, the moving object includes a vehicle stopped on the road.

1 is an overall configuration diagram of an object detection apparatus according to a first embodiment of the present invention. A diagram showing the positional relationship between the vehicle, the preceding vehicle, and the road The figure which shows four types of pairing of the peak signal of the rising side and falling side of channel ch3 Flow chart explaining operation Diagram showing 2D coordinates for pairing The figure which shows the final pairing of the peak signal of the rising side and falling side of channel ch3 The figure corresponding to the said FIG. 5 which shows the case where the detection peak of the descending side of a roadside thing is missing. Overall configuration diagram of an object detection apparatus according to a second embodiment of the present invention Overall configuration diagram of a conventional object detection device Action diagram of radar device when traveling following a moving body with zero relative speed Action diagram of the radar device when traveling close to a stationary object Action diagram of the radar device when traveling following a plurality of moving bodies with different relative speeds

Explanation of symbols

6 Transmission / reception antenna (transmission / reception means)
7 mixer 13 frequency analysis means 14 detection peak determination means 15 object detection means 17 roadside object peak determination means 21 own vehicle position detection means 22 map information storage means 23 road shape prediction means 25 road-to-vehicle communication means 26 transmission means

Claims (4)

A transmission / reception means (6) for transmitting an FM-CW wave and receiving a reflected wave from an object of the FM-CW wave;
A mixer (7) for generating a beat signal by mixing a transmission wave and a reception wave;
Frequency analysis means (13) for frequency analysis of the beat signal obtained by the mixer (7);
Detection peak determination means (14) for determining, as a detection peak, a peak signal equal to or higher than a detection threshold among peak signals obtained based on the frequency analysis results on the rising side and the falling side by the frequency analysis means (13);
An object detection means (15) for calculating at least one of the distance to the object and the relative speed with respect to the object based on the detection peaks on the rising side and the falling side obtained by the detection peak determination means (14);
In a vehicle object detection device comprising:
Own vehicle position detecting means (21) for detecting the current position of the own vehicle;
Map information storage means (22) for storing map information;
Road shape prediction means (23) for predicting the road shape in the traveling direction of the own vehicle based on the own vehicle position information detected by the own vehicle position detection means (21) and the map information obtained from the map information storage means (22). When,
A plurality of at least a portion of a detection peak due roadside object determines roadside object peak of detecting peaks in the detection peak and predicted the plurality of sensing direction based on the traveling direction of the road shape of the vehicle in the detection direction Determination means (17),
An object detection device (15) for calculating a vehicle object, wherein the object detection means (15) calculates at least one of a distance to the object and a relative speed to the object based on a detection peak other than the roadside object peak. A transmission / reception means (6) for transmitting an FM-CW wave and receiving a reflected wave from an object of the FM-CW wave;
A mixer (7) for generating a beat signal by mixing a transmission wave and a reception wave;
Frequency analysis means (13) for frequency analysis of the beat signal obtained by the mixer (7);
Detection peak determination means (14) for determining, as a detection peak, a peak signal equal to or higher than a detection threshold among peak signals obtained based on the frequency analysis results on the rising side and the falling side by the frequency analysis means (13);
An object detection means (15) for calculating at least one of the distance to the object and the relative speed with respect to the object based on the detection peaks on the rising side and the falling side obtained by the detection peak determination means (14);
In a vehicle object detection device comprising:
Road-to-vehicle communication means (25) capable of acquiring information on the road shape in the traveling direction of the host vehicle by communicating with transmission means (26) provided on the road;
Based on the detection peaks in the plurality of detection directions and the information on the road shape in the traveling direction of the own vehicle obtained by the road-to-vehicle communication means (25), at least some of the detection peaks in the plurality of detection directions are caused by roadside objects. Roadside object peak determination means (17) for determining that it is a detection peak,
An object detection device (15) for calculating a vehicle object, wherein the object detection means (15) calculates at least one of a distance to the object and a relative speed to the object based on a detection peak other than the roadside object peak.   The roadside object peak determination means (17) arranges a plurality of detection peaks on coordinates using the detection direction and the peak frequency as parameters, respectively, and is similar to the road shape predicted by the road shape prediction means (23). The vehicle object detection device according to claim 1, wherein an array of detection peaks to be detected is determined to be a detection peak due to a roadside object. The roadside object peak determination means (17) arranges a plurality of detection peaks on coordinates having the detection direction and the peak frequency as parameters, respectively, and is similar to the road shape acquired by the road-vehicle communication means (25). The vehicle object detection device according to claim 2, wherein an array of detection peaks to be determined is a detection peak due to a roadside object .

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