JP2006162341A - Radar system of scanning type - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system of scanning type capable of precisely widening the scanning range without necessitation of enhancement of signal process capacity in the radar controller. <P>SOLUTION: When the control object recognition part provided in the radar controller is performing a target detection process, when a scanning mechanism is indicated with an angle of scan beam, and when the target in a range of three lanes including adjacent lanes is needed to detect, the effective distance Le regarding each lane is operated from the angle of scanning of each beam and the width of running lane of three lane width. Each effective distance Le is compared with the magnitude of control distance Lc. If Le is larger than the Lc, the number of detection data for the beam is set as default value. If the Le is shorter than the Lc, the number of detection beams for the beam is obtained and set by multiplying the default value of the number of detection data with the ratio Le/Lc. The process time for the restricted number of detection beams can be used for widening the scan range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a scanning radar apparatus, and more particularly, mounted on a vehicle, sequentially emits a beam at a predetermined angle to perform scanning, detects a position of an object in front, and detects a collision warning or prevention, and auto cruise control. The present invention relates to a scanning radar apparatus that can improve the detection accuracy and widen the beam scan without increasing the signal processing capability of the apparatus itself.

  Conventionally, a radar apparatus has been used as means for acquiring control information for automatically driving a car such as a passenger car, and various radar apparatuses have been proposed. Among the proposed radar devices, a scanning radar device is often used. For example, it is a scanning radar apparatus based on the FM-CW method using a millimeter wave band.

  FIG. 5 shows an outline of the configuration of the inter-vehicle distance control device using the FM-CW scan type radar device. In this inter-vehicle distance control device, the radar sensor unit includes a radar antenna 1, a scanning mechanism 2, and a radar control unit 3. The vehicle control electronic control unit (ECU) 4 controls the inter-vehicle distance based on information obtained from the sensor unit 5. The sensor unit 5 includes, for example, a steering sensor 5-1, a yaw rate sensor 5-2, a vehicle speed sensor 5-3, and the like.

  The vehicle control ECU 4 receives the target detection information obtained by the radar control unit 3 of the radar sensor unit, and based on the information obtained from the sensor unit 5, as the control load 6, an alarm device 6-2 and a brake 6-3. The throttle 6-4 is controlled. And vehicle control ECU4 displays the information regarding the control state of a vehicle, a message, etc. on the indicator 6-1. The inter-vehicle distance control device is usually provided with an operation unit that allows a user to make various settings for the device. However, the display 6-1 itself may be an input operation unit using a touch panel method.

  FIG. 6 shows an outline in which the inter-vehicle distance control device shown in FIG. 5 is mounted on a vehicle, and the distance to the vehicle traveling in front of the vehicle is measured by the device. FIG. 6 shows a case where two vehicles, vehicle A and vehicle B, are traveling in a travel lane indicated by a broken line. Car A is traveling at speed Va and Car B is traveling at speed Vb. A beam is transmitted from the radar antenna 1 provided in the inter-vehicle distance control device mounted on the A car toward the front of the A car, and the beam is scanned by the scanning mechanism 2 at the scanning angle θ.

  When the beam transmitted from the radar antenna 1 is reflected from the B vehicle traveling ahead, the reflected wave is received by the radar antenna 1. This received signal is sent to the radar control unit 3, where it is subjected to fast Fourier transform (FFT) processing to detect the power spectrum for the target. Based on this, the distance R and the relative speed (Va−Vb) with the target vehicle B are calculated, and the width W at the distance R to the target, that is, the vehicle width W of the vehicle B is detected. The

  For example, in the case of a millimeter-wave scanning radar apparatus, various factors other than the expansion of the detection area due to the antenna pattern affect the accuracy of target position detection. Even when obtaining the vehicle width W of the preceding traveling vehicle B, the vehicle width W is obtained by estimating the end position of the preceding vehicle from the form of the reception level of the reflected wave. However, depending on the shape of the vehicle, the reflection of the transmitted beam is not uniform, and noise is superimposed on the reflected wave signal, so that it is not always possible to accurately detect the end position of the preceding vehicle. For example, when there is a target at a long distance or when the intensity of the reflected wave is small, for example, as a target, the vehicle width W is narrow, as in a motorcycle, and the intensity of the reflected wave is originally reduced. In some cases, the accuracy of target detection will be reduced.

  Here, a specific example of the radar control unit 3 in the inter-vehicle distance control apparatus shown in FIG. 5 is shown in FIG. The radar control unit 3 includes a scanning control unit 31, a radar signal processing unit 32, a control object recognition unit 33, and the like. The radar antenna 1, the scanning mechanism 2, and the vehicle control ECU 4 connected to the radar control unit 3 are the same as those shown in FIG. 5, and are given the same reference numerals.

  The beam transmitted from the radar antenna 1 is reflected by a target to be controlled, and the reflected wave is received by the radar antenna 1. The received signal of the reflected wave is sent to the radar signal processing unit 31, where the received signal is subjected to FFT processing, and the power spectrum for the target is detected. And in the control object recognition part 33, B vehicle is recognized as the target of a control object, and distance R and relative speed (Va-Vb) with B vehicle are calculated | required. The scan control unit 31 receives from the vehicle control ECU 4 the scan angle set based on the vehicle information obtained from the steering sensor 5-1, the yaw rate sensor 5-2, the vehicle speed sensor 5-3, etc. via the vehicle control ECU 4. Upon receiving the instruction, the scanning mechanism 2 is controlled at the scanning angle according to the instruction.

  In the case of a scanning radar, the scanning control unit 31 controls the scanning scanning angle. The scanning mechanism 2 performs scanning by sequentially emitting beams at a predetermined scanning angle in response to a control signal from the scanning control unit 31. A beam transmitted from the radar antenna 1 is scanned by the scanning mechanism 2 and reception control of the radar antenna 1 with respect to a reflected wave signal reflected from the target is performed. The reflected wave signal received by the radar antenna 1 is sent to the radar control unit 3 to determine the target to be controlled. This result is transmitted to the vehicle control ECU 4.

  By the way, an FM-CW scanning radar device mounted on a vehicle outputs a continuous transmission wave having a triangular wave-like frequency modulation to scan a vehicle (target) ahead, Seeking distance etc. That is, in the inter-vehicle distance control device for obtaining the distance to the target, the transmission wave from the radar antenna at a certain scan angle is reflected by the target, and a beat signal of the reception signal and the transmission signal of the reflected wave is formed, and the FFT is performed. The frequency is analyzed by processing. The beat signal obtained by this frequency analysis has a peak power with respect to the target portion, and the frequency corresponding to this peak is obtained as the peak frequency. The peak frequency has information related to the distance, and is different when rising and falling due to the Doppler effect due to the relative velocity with the target. The distance to the target and the like can be obtained from the frequency peak at the time of rising and falling. Thus, after waiting for the radar signal processing, the radar control unit 3 sets the next beam scan angle, controls the scanning mechanism 2, and outputs the next transmission wave from the radar antenna 1.

  According to such a target detection signal processing method, when the processing time of the received signal for each scan in the radar control unit is long, the scan speed of the beam transmitted from the radar device cannot be increased. There is. Therefore, various FM-CW radar devices have been proposed that can shorten the processing time and increase the scanning speed while maintaining the processing accuracy (see, for example, Patent Documents 1 and 2).

  In the radar apparatus disclosed in Patent Document 1, when the radar beat signal is converted from analog to digital, one sampling frequency of the rising and falling beat signals is set to half of the other sampling frequency, In the frequency analysis of each beat signal at the time of falling, when obtaining the power peak for each target, the number of beat signal acquisition samples with the sampling frequency set to half in analog to digital conversion is obtained by half. When pairing the rising and falling peak frequencies with respect to the power peak in the frequency analysis to be detected, the folding peak frequency is detected from the frequency analysis with the sampling frequency set to half, and this folding peak frequency is not folded. Convert to peak frequency for pairing

  In this way, in this radar apparatus, while maintaining the frequency resolution, the processing time of the frequency analysis of any beat signal during ascending and descending is shortened by half, and the amount of radar analysis is reduced accordingly. This makes it possible to quickly scan the beam transmitted from the antenna.

  In the radar apparatus disclosed in Patent Document 2, the frequency BIN included in the frequency region before and after the predicted peak to be detected on the distance power spectrum is registered as peak data from the information on the detected target, and the host vehicle Is predicted, the power spectrum along the travel line is obtained, and the peak of the power spectrum is registered as peak data. Further, the distance power spectrum obtained for each channel is averaged, the peak of the averaged distance power spectrum is registered as peak data, and the azimuth power spectrum is obtained only for the registered peak data (frequency BIN). Yes.

  As described above, according to the radar device disclosed in Patent Document 2, it is possible to reduce the calculation processing load in the radar control unit, to quickly detect a target, and to ensure sufficient detection capability. I can do it.

JP-A-11-271426 JP 2003-270341 A

  On the other hand, as described above, in addition to the necessity of increasing the scanning speed by shortening the processing time while maintaining the processing accuracy, for the scanning radar apparatus mounted on the vehicle, From the viewpoint, it is necessary to widen the angle so that the blind spot of the radar apparatus is reduced.

  By the way, the detection range of the target in the radar apparatus according to the prior art and the number of detections of the signal related to the target are determined for each scan of the transmission wave, and the detection number is the same for all the beams of one scan. Is set. Therefore, in order to measure a wide range so as to reduce the blind spot, measures such as increasing the number of detected beams or expanding the interval between beams can be considered.

  When a measure for increasing the number of detection beams is adopted, this means that the amount of data to be processed also increases and depends on the signal processing capability of the radar control unit. Therefore, when this processing capability is insufficient, the amount of data per beam must be reduced, and as a result, the target detection performance is limited. Alternatively, if the signal processing capability is increased, this can be realized, but the cost increases accordingly. In addition, when the measure for widening the beam interval is adopted, the gap between the beams is widened, so that the angle accuracy and the separation performance are deteriorated, so that the controllability with respect to a necessary target is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a scanning radar apparatus that does not require enhancement of signal processing capability in a radar apparatus and can achieve a wide angle with high accuracy.

  In order to solve the above problems, in the present invention, a transmission wave beam mounted on a vehicle can be scanned and transmitted at a predetermined angle, and a reflected wave reflected from a target in front of the vehicle can be received. A radar antenna capable of performing scan control of the transmission wave beam, and generating and processing target information related to the target based on a received signal received by the radar antenna, the radar control unit Is configured to generate the target information by controlling the amount of signal information to be extracted for the beam in accordance with the beam position in the lateral range with respect to the transmission direction of the transmission wave beam.

  The radar control unit reduces the amount of the signal information with respect to the beam located at the end of the lateral range less than the amount of the signal information with respect to the beam located at the center of the lateral range, The target information is generated by processing the target information or reducing the amount of the signal information for each beam scanned in the lateral range from the center of the lateral range to the outside. It was decided to process.

  In addition, when the vehicle is traveling on a curved road, the radar control unit determines the amount of the signal information for the beam scanned in the lateral range corresponding to the outside of the curved road. The amount of the signal information for the beam scanned in the lateral range corresponding to the inside is reduced.

  Further, the radar control unit has the same frequency component as the other beams in the signal information for each beam scanned in the lateral range when the vehicle is traveling on a road having a side wall. Data was removed and the target information was generated.

  As described above, in the present invention, in the radar control unit provided in the scan radar device mounted on the vehicle, the radar control unit is configured to detect the target existing in front of the vehicle. The amount of signal information to be extracted for the beam is limited according to the beam position in the lateral range with respect to the transmission direction of the transmission wave beam, and in particular, the signal information for the beam located at the end of the lateral range. The amount of signal information for a beam located in the center of the lateral range or the amount of signal information for each beam scanned in the lateral range is the center of the lateral range. The range of target detection can be expanded by changing the processing procedure program in the control unit without changing the signal processing speed of the radar control unit. It has become possible.

  Also, since the radar control unit limits the amount of signal information to be extracted for the beam in accordance with the beam position in the lateral range with respect to the transmission direction of the transmission wave beam, unnecessary data for target detection. Therefore, it is not necessary to use an erroneously detected target for the operation control system.

  Next, an embodiment of a scanning radar apparatus according to the present invention will be described with reference to the drawings. As described above, it has been described with reference to FIG. 6 that the distance between vehicles traveling on a road can be measured using the conventional scanning radar apparatus shown in FIGS.

  In the scan type radar apparatus according to the present embodiment, the configuration of the scan type radar apparatus according to the prior art is used as it is, and the signal processing program in the radar control unit is devised to improve the accuracy without increasing the signal processing capability. The beam was widened well and the target detection range of the radar device was expanded.

  Therefore, when a vehicle equipped with a scanning radar apparatus is traveling on a straight road, control of signal processing in the radar control unit of the radar apparatus will be described with reference to FIG. In FIG. 1, it is shown that the A vehicle on which the radar apparatus is mounted is traveling in a traveling lane on a straight road having three lanes indicated by broken lines. The radar apparatus for car A emits a transmission wave beam while scanning forward at a scan angle θ.

  In the figure, this beam is indicated by a thick arrow. Normally, however, a plurality of beams are sequentially radiated from the radar antenna so that the beam interval is 2 degrees, for example, within the scan angle θ. The Each radiated beam is reflected from a target existing ahead of Car A, for example, a vehicle traveling ahead, a road sign, a side wall / guardrail, etc., and this reflected reflected wave is received by the radar antenna for each beam. Then, signal processing for target detection is executed by the radar control unit.

  FIG. 1 typically shows a state in which three transmission wave beams A1, A2, and A3 are radiated forward from the radar device of car A traveling in the middle traveling lane. The beam A1 is emitted at the center of the beam scanning range. Here, the effective distance Le1 at which the target can be detected by the beam A1 is determined by the magnitude of the transmission output of the radar device and the signal processing speed in the radar control unit, and is the control distance Lc set in the vehicle operation control system using the radar device. It is much longer.

  Further, in the vehicle operation control system, when the lateral direction range of target detection is three lanes, when the beam A2 is emitted at the scan angle shown in the figure, the effective distance at which the target can be detected by the beam A2 is Le2. It becomes. This effective distance Le2 is relatively close to the control distance Lc. Furthermore, in this case, it is also assumed that another vehicle traveling in the adjacent lane is interrupted immediately before vehicle A, so that this other vehicle can also be detected, so the maximum scan range of the radar device is The scan angle θ is set wider than the three lanes in the lateral range of target detection. Therefore, the effective distance of the beam A3 emitted at the end of the beam scanning range is Le3 as shown in the figure.

  In the radar control unit of the radar apparatus, the target detection process is executed for each beam based on the reflected wave related to each beam received by the radar antenna. In the case of a radar device mounted on a vehicle, it is important to detect, for example, a vehicle that interrupts immediately before the own vehicle at the end of the lateral range of target detection. Detection data related to a target that is necessary and is located far away is not necessary for target detection. This means that the traveling lane of the host vehicle and the traveling lanes on both sides of the traveling lane need only be within the target detection range. With respect to the beam emitted at the end of the scan range, This is because the signal information related to the target is included and exceeds the detection range in the vehicle operation control system.

  In general, the reflected wave level from a target existing in the lateral direction is not so large, and the reflected wave level decreases as the target is located farther away. For this reason, in this target detection process, priority is given to those having a high reflected wave level. Therefore, according to the signal processing capability of the radar control unit, for example, a selection criterion for limiting the number of detected data is set such that the number of extractions of signal information related to a target is 10 per process for each beam. Has been.

  In a vehicle operation control system using a scanning radar device, detection data necessary for distance control is divided into a traveling lane in which the host vehicle is traveling, and an adjacent traveling lane that is necessary to increase the responsiveness such as interruption of other vehicles. The number of beams to be scanned and the number of detected data in the target detection processing for each beam are determined according to the signal processing capability of the radar control unit acquired in the related detection range.

  Therefore, in the scan type radar apparatus of the present embodiment, the setting of the number of detection data for the beam radiated from the radar antenna is set in the center portion without changing the signal processing capability in the radar control unit. By reducing the number of detected data for the beam, the signal processing time for the beam is reduced, and the reduced processing time is directed to increasing the number of beams. Since the processing time can be reduced, the number of beams can be increased even at the same signal processing speed, and the beam scan can be widened.

  Specific example 1 of this embodiment will be described below with reference to FIG. This specific example 1 is an embodiment of a scanning radar apparatus when the host vehicle is traveling on a straight road, and target detection information by the radar apparatus is used in a vehicle operation control system.

  In this system, as shown in FIG. 1, it is necessary to extract more information about the beam A1 emitted near the center of the scan range. However, with respect to the beam A3 radiated at the end of the scan range, for example, it is only necessary to detect another vehicle that is interrupted immediately before the own vehicle from the adjacent traveling lane, so that the target at a distance exceeding the effective distance Le3. There is no need to extract data about. Therefore, it is only necessary to extract data corresponding to a short distance, so the number of detection data for the beam A3 emitted at the end of the scan range is reduced to half of the number of detection data for the beam A1 emitted near the center of the scan range. Set to restrict.

  According to such a limitation on the number of detection data, for example, in the scan range of the scan angle θ, when 10 beams are sequentially emitted and scanned at a beam interval of 2 degrees, at both ends of the scan range. When the emitted beam is used as a detection beam for the adjacent driving lanes, the signal processing time for one beam can be reduced by limiting the number of detection data for the emitted beam at both ends to half. Therefore, signal processing for 12 beams can be realized at the same signal processing speed in the radar control unit, and the wide angle of the beam can be achieved.

  On the other hand, in the scanning radar apparatus according to the first specific example described above, only the number of detection data for the beam emitted at both ends of the scan range is set to the detection data for the beam emitted near the center of the scan range. Although the limit is set to be half of the number, the method of limiting the number of detection data for the beam is not limited to this. Next, with reference to FIGS. 1 and 2, a specific example 2 of a scanning radar apparatus that adopts a method of limiting the number of detection data for each beam within the scanning range will be described.

  In the scan type radar apparatus of the specific example 2, for example, in the case of a vehicle operation control system with a control distance Lc of 100 m, assuming that the number of detection data for the beam near the center of the scan range is 10 and the beam interval is 2 degrees, The effective distance Le, which is the maximum distance of the detection range necessary for each beam, is determined for the range of three lanes including adjacent lanes, and the ratio with the beam near the center according to the size of the effective distance Le. And the number of detection data corresponding to the ratio may be set for each beam scanned within the scan range. In this way, the number of detection data for each beam can be reduced from the number of detection data set for the beam near the center, depending on the size of the effective distance Le. Therefore, it is possible to process more ranges in the same signal processing time that the radar control unit has.

  The flowchart shown in FIG. 2 shows a procedure for setting the number of detection data for each beam when the target detection process is executed in the control object recognition unit provided in the radar control unit. First, when an angle of the scan beam is instructed to the scanning mechanism, an effective distance Le related to each beam is calculated (step S1).

  Here, in the vehicle operation control system, when it is necessary to detect a target in the range of three lanes including adjacent driving lanes, the scanning angle of each beam and the driving lane width for three lanes are used. The effective distance Le relating to each beam can be calculated. For example, the effective distance Le3 is calculated for the beam A3 at the end of the scan range, and the effective distance Le2 is calculated for the beam A2 in the middle of the scan angle θ.

  Next, when the effective distance Le is calculated every time each beam is emitted, the effective distance Le is compared with the control distance Lc (step S2). Here, when the calculated effective distance Le is greater than 100 m from the control distance Lc, for example, in this system (Y in Step S2), a default value is set for the number of detection data for the beam (Step S2). S3). The default value is 10. Thereby, a predetermined detection accuracy is ensured for target detection using a beam in which the effective distance Le is longer than the control distance Lc.

  On the other hand, when the calculated effective distance Le is shorter than the control distance Lc, for example, 100 m (N in Step S2), the default value of the number of detected data is multiplied by the ratio Le / Lc between the effective distance Le and the control distance Lc. Then, the calculated value is set as the number of detected beams for the beam (step S4). In this case, since the effective distance Le is a value smaller than the control distance Lc, the detection data number to be set becomes smaller as the position of the beam to be scanned becomes outside as viewed from the center of the scan range. This is less than the number of detection data set for the beam near the center.

  As described above, in the scan-type radar apparatus according to the second specific example relating to the case where the vehicle is traveling straight on a straight road, a predetermined number of detection data is set near the center of the scan range where detection accuracy is required, and is outside the predetermined range. Since the number of detected data can be reduced with a beam, a larger number of ranges can be processed in the same signal processing time of the radar control unit.

  In the scan type radar device of the above-described specific example 2, the radar control unit calculates the effective distance Le for each scanned beam and calculates the number of detected data for each beam in the target detection process. If the vehicle speed sensor and yaw rate sensor connected to the vehicle control ECU of the vehicle operation control system can be determined to be traveling on a straight road, detection is performed for each beam as long as the vehicle continues traveling straight. Since it is not necessary to change the setting of the number of data, the effective distance Le calculated at the start of linear traveling is stored, and when it is determined that the linear traveling is continued, the number of detected data for each beam is kept set. .

  In the scanning radar apparatus according to the first and second specific examples described above, it is assumed that the vehicle travels in a straight line. However, a road on which the vehicle travels, such as an expressway, is not only a straight road but also a curve. There are many parts. However, when controlled by the method of setting the number of detected data employed in the scanning radar apparatus of specific examples 1 and 2, when the vehicle is traveling on a curved road, each beam is within the range of the scan angle θ. When scanned, it becomes impossible to secure data necessary for target detection inside the curve.

  FIG. 3 shows a situation when the vehicle is traveling on a curved road. In FIG. 3, as indicated by the solid line arrow, it is assumed that a vehicle A equipped with a scanning radar device is traveling on a road having a radius of curvature R. Therefore, the beam radiated from the radar apparatus is scanned within the range of the scan angle θ as in the case of FIG. However, since each beam is radiated toward the front of car A at a scan angle θ, when the road is curved, the effective distance Le of each beam differs between the outer portion and the inner portion of the road curve. It will be a thing.

  For this reason, if the number of detection data for the beam is limited at the end of the scan range as in the case of the scanning radar apparatus according to specific examples 1 and 2, it is necessary when the vehicle is traveling on a curved road. Target detection data cannot be secured. Therefore, in the scan type radar apparatus of the specific example 3, when traveling on a curved road, when determining the number of extraction from the control distance Lc, the condition of the curvature radius R of the curved road is taken into the calculation of the effective distance Le. Thus, it is determined which of the beams is necessary for detection by the control distance Lc.

  The flowchart shown in FIG. 4 shows each beam when the target detection processing is executed in the control object recognition unit provided in the radar control unit when the vehicle is traveling along a curved road having a radius of curvature R. Shows the procedure for setting the number of detected data. Here, the procedure according to the flowchart of FIG. 4 is based on the procedure of the flowchart shown in FIG. 2, but both procedures are different in terms of the calculation method of the effective distance Le. In the procedure of FIG. The condition of the radius of curvature R is added to the calculation, and step S1 shown in FIG. 2 is replaced with step S11.

  First, when an angle of the scan beam is instructed to the scanning mechanism, an effective distance Le related to each beam corresponding to the radius R of the curved path is calculated (step S11).

A method of calculating the effective distance Le in step S11 will be described with reference to FIG. For example, when the lateral range is set to three lanes at the control distance Lc, first, for each beam, a distance corresponding to a width that is 1.5 times the width of the traveling lane when the relative lateral position is scanned. calculate. Here, when the angle between the center in the scan range and the scanned beam A is θc, the angle θc is obtained by the following equation.
θc = (Lc / 2πR) × 180 °
The curvature radius R of the curved road on which the vehicle travels can be obtained by calculation from the traveling speed and the yaw rate of the vehicle A.

Thus, the center of the lateral position in the beam scanning range is set in accordance with the curve of the traveling curved road, and the lateral position of the beam A becomes the reference. Next, for each scanned beam, a distance at which the relative lateral position is 1.5 times the width of the traveling lane, that is, an effective distance Le is calculated from the angle difference between the beam and the reference beam. Here, assuming that the scan angle of the beam is θ, the effective distance Le is obtained by the following equation.
Le = 1.5 × H / sin (| θ−θc |)

  Therefore, every time each beam is emitted, the effective distance Le is calculated according to the above formula. The subsequent processing procedure is the same as the processing procedure of steps S2 to S4 in the flowchart shown in FIG. Yes, the calculated effective distance Le is compared with the magnitude of the control distance Lc (step S2). Here, when the calculated effective distance Le is greater than 100 m from the control distance Lc, for example, in this system (Y in Step S2), a default value is set for the number of detection data for the beam (Step S2). S3). The default value is 10. Thereby, a predetermined detection accuracy is ensured for target detection using a beam in which the effective distance Le is longer than the control distance Lc.

  On the other hand, when the calculated effective distance Le is shorter than the control distance Lc, for example, 100 m (N in Step S2), the default value of the number of detected data is multiplied by the ratio Le / Lc between the effective distance Le and the control distance Lc. Then, the calculated value is set as the number of detected beams for the beam (step S4). In this case, since the effective distance Le is a value smaller than the control distance Lc, the detection data number to be set becomes smaller as the position of the beam to be scanned becomes outside as viewed from the center of the scan range. This is less than the number of detection data set for the beam near the center.

  As described above, in the scan type radar device of the specific example 3, when traveling on a curved road, when determining the number of extractions from the control distance Lc, the effective distance Le is calculated by calculating the curvature radius R of the curved road. Conditions are taken in and it is determined which of each beam is necessary for detection by the control distance Lc, and the number of detection data is set based on that beam. Therefore, even when traveling on a curved road, it is necessary for target detection. The number of detection data can be ensured, and the detection range can be expanded more accurately with the same signal processing time.

  In the scan type radar devices of specific examples 1 to 3 described so far, it is assumed that the vehicle is traveling on a normal road. However, a vehicle equipped with the scan type radar device may travel through a tunnel, for example. Therefore, in the scanning radar device according to the specific example 4, while traveling in the tunnel, the reflected wave is influenced by the tunnel so as not to detect the target by mistake, and with the same signal processing time, In addition, the wide angle can be improved with high accuracy.

  For example, in a tunnel or the like, side walls having a property of reflecting radio waves exist on both sides of a traveling lane. Therefore, when the vehicle is traveling inside the tunnel, the transmission wave beam radiated from the scanning radar apparatus is reflected by the side wall, and the side wall is detected as a target by the radar apparatus. In this case, the level of the reflected wave from the side wall is increased, and the beam at the end of the scan range is simply used in the manner of preferentially extracting a detection signal having a high level, as in the first and second embodiments. However, if target detection is performed by limiting the number of detection data, there is a possibility that detection data relating to a target at a short distance that should be detected cannot be extracted.

  Therefore, in the scanning radar apparatus according to the fourth specific example, when the vehicle is traveling on a road having a side wall such as a tunnel, signal information obtained for each beam scanned in the lateral direction is provided. Of these, data having the same frequency component as that of other beams is removed, and target detection is performed. That is, when each beam is compared and it can be determined that there is a target having the same relative speed at the same distance, the data related to the target is obtained from the beam data lateral to the traveling axis of the radar apparatus. Remove.

  As described above, when the vehicle is traveling on a road having a side wall such as a tunnel, the number of detected data in each beam is limited so as not to be erroneously extracted in target detection. By setting the number of detection data to be limited, it is possible to widen the angle more accurately with the same signal processing time. Note that the embodiment according to the specific example 4 can also be applied to the scan radar apparatus according to the embodiment according to the specific example 1 or the specific example 2 described above.

It is a figure explaining embodiment when the vehicle carrying the scan type radar device by the present invention is running on a straight road. It is a figure explaining control of the scan type radar device by this embodiment when vehicles are running on a straight road. It is a figure explaining embodiment when the vehicle carrying the scanning radar apparatus by this invention is drive | working the curved road. It is a figure explaining control of the scan type radar device by this embodiment when vehicles are running on a curve road. It is a figure explaining the system configuration | structure which concerns on the scanning type radar apparatus by a prior art. It is a figure explaining the detection condition of the preceding vehicle by a scanning radar apparatus. It is a figure explaining the specific structure of the radar control part of the scanning radar apparatus shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radar antenna 2 Scanning mechanism 3 Radar control part 31 Scan control part 32 Radar signal processing part 33 Control object recognition part 4 Vehicle control ECU
5 Sensor unit 5-1 Steering sensor 5-2 Yaw rate sensor 5-3 Vehicle speed sensor 6 Control load 6-1 Display 6-2 Alarm 6-3 Brake 6-4 Throttle

Claims (5)

A radar antenna mounted on a vehicle, capable of scanning and transmitting a transmission wave beam at a predetermined angle, and receiving a reflected wave reflected from a target in front of the vehicle;
A scan control of the transmission wave beam, and a radar control unit that generates and processes target information related to the target based on a received signal received by the radar antenna,
The radar control unit generates the target information by controlling the amount of signal information to be extracted for the beam according to a beam position in a lateral range with respect to a transmission direction of the transmission wave beam. Scan type radar device.   The radar control unit reduces the amount of the signal information with respect to the beam located at the end of the lateral range less than the amount of the signal information with respect to the beam located at the center of the lateral range, The scanning radar apparatus according to claim 1, wherein the generation processing is performed.   The radar control unit generates the target information by reducing the amount of the signal information with respect to each beam scanned in the lateral range from the center of the lateral range toward the outside. The scanning radar apparatus according to claim 1.   When the vehicle is traveling on a curved road, the radar control unit sets the amount of the signal information for the beam scanned in the lateral range corresponding to the outside of the curved road to the inside of the curved road. The scanning radar apparatus according to claim 1, wherein the scanning radar apparatus reduces the amount of the signal information with respect to a beam scanned in the corresponding lateral range.   The radar control unit, when the vehicle is traveling on a road having a side wall, out of the signal information for each beam scanned in the lateral range, data having the same frequency component as the other beams The scan radar apparatus according to claim 1, wherein the target information is generated by removing the target radar information.

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