JP2009229374A - Radar system, and azimuth angle detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect an azimuth angle of a target by a radar system by using a detected position from an image recognition device operated at a different cycle. <P>SOLUTION: The azimuth angle of the target is accurately detected by providing the radar system with an input means for inputting the detected position from the image recognition device detecting a position of the target each first cycle on the basis of a photographed image of a search area, an azimuth angle estimating means for estimating the azimuth angle of the target each second cycle shorter than the first cycle on the basis of a plurality of the input detected positions, and an azimuth angle detecting means for detecting the azimuth angle of the target in units of first azimuth angles in the estimated azimuth angle vicinity and in units of second azimuth angles larger than the first azimuth angles in other zones of the search area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus that transmits and receives radar waves in a search area, and in particular, a detection position is input from an image recognition apparatus that detects the position of a target using a captured image of the search area, and the input detection position The present invention relates to a radar apparatus that detects the azimuth angle of the target by using.

  An on-vehicle radar device detects a azimuth angle of a target by forming a radar wave (beam) narrowed to a desired width and scanning the search area with this beam. The radar apparatus forms a beam by a millimeter-wave continuous wave (electromagnetic wave) that is frequency-modulated at this time, and detects the relative distance and relative velocity of the target from the beat frequency of the transmission wave and the reception wave.

  Such a radar apparatus is used as a means for detecting a preceding vehicle in order to perform follow-up running control that causes the host vehicle to follow a preceding preceding vehicle. In recent years, in addition to this, it has been used as a means for detecting other vehicles, etc., for collision response control for causing the own vehicle to perform collision avoidance operations and safety device operations with oncoming vehicles and other vehicles encountered in encounters. It is being advanced. Therefore, it is required to widen the scanning range of the beam.

  Here, the beam scanning method by the radar apparatus generally includes a mechanical scanning method and an electronic scanning method.

  A mechanical scanning radar device scans a search region by changing the beam directing direction by mechanically rotating an antenna. Then, the intensity of the received wave is obtained for each predetermined azimuth angle step by the digital signal processing device, and the azimuth angle at which the maximum value of the distribution is formed is detected as the azimuth angle of the target. Then, in such a radar device of the mechanical scanning system, the number of azimuth increments for widening the scanning range increases, so that the calculation amount of the digital signal processing device increases.

  On the other hand, an electronic scanning radar device receives a radar wave reflected from a target using a plurality of antennas instead of rotating the antenna, and changes the phase of the received wave from each antenna in small increments. The direction of the beam as a whole is changed. In a DBF (Digital Beam Forming) processing method, which is one form of such an electronic scanning method, a digital signal processing device performs an operation for changing the phase of a received wave for each antenna as a parameter to obtain a combined amplitude of the received wave. Then, the phase of the received wave when the calculated combined amplitude becomes the maximum value is obtained, and the received wave of the same phase arrives from the phase difference of the received wave between the antennas at that time, the distance between the antennas, and the wavelength of the received wave The digital signal processing device executes a calculation for calculating the calculated azimuth as the azimuth of the target.

  In such a DBF processing type radar apparatus, the unit for changing the phase of the received signal is determined in correspondence with the azimuth step for changing the beam directing direction. Then, as the scanning range becomes wider, the number of azimuth increments increases, so the parameters for DBF processing increase and the amount of computation of the digital signal processing device increases.

  As described above, in the radar apparatus of the mechanical scanning method and the electronic scanning method (particularly the DBF processing method), when the scanning range is widened, the amount of calculation of the digital signal processing device increases, which causes output delay of the detection result. Therefore, a method of using an image recognition device in combination has been proposed in order to reduce the calculation load. Patent Document 1 describes an example of a radar apparatus that performs target detection using an image recognition result.

According to this method, the image recognition apparatus first captures the search area with a digital still camera, recognizes the shape of the subject in the captured image, and determines whether a target exists. Then, the detection position determined that a target such as another vehicle exists is sent from the image recognition apparatus to the radar apparatus, and the radar apparatus changes the azimuth angle increment when detecting the azimuth angle based on the position, The calculation load of the entire signal processing device is reduced. Specifically, the radar apparatus detects the azimuth angle by small azimuth angle increments in the vicinity of the azimuth angle corresponding to the detection position sent from the image recognition apparatus, and azimuth of the target by large azimuth angle increments in other search areas. Detect corners.
JP 2006-234513 A

  However, the above prior art has the following problems. That is, the image recognition device and the radar device are generally provided in different parts of the vehicle. For example, the image recognition device is installed near the top of the windshield, and the radar device is mounted inside the front bumper. These are configured to be communicable via an in-vehicle LAN (Local Area Network). Many other sensors and microprocessors are connected to the in-vehicle LAN, and access control is performed by the gateway device. Then, real-time communication between the image recognition device and the radar device becomes difficult. Therefore, when the radar apparatus detects an azimuth in the vicinity of the azimuth corresponding to the position of the target that has been image-recognized in small azimuth steps, the target may move outside the range. Then, since the azimuth angle of the target is detected by a large azimuth angle step, the azimuth angle detection accuracy of the target is lowered.

  Also, since image recognition processing generally requires a large amount of computation, the period during which the image recognition device performs image recognition processing and outputs the target detection position scans the search area and detects the azimuth angle of the target. Longer than the cycle to do. Then, since the radar device cannot always use the latest detection position, when the radar device detects the azimuth in small azimuth steps near the azimuth angle corresponding to the past target position, the target is out of the range. The probability that it has moved to becomes even greater.

  Accordingly, an object of the present invention made in view of the above problems is to provide a radar device capable of accurately detecting the azimuth angle of a target even when the detection position from an image recognition device operating at a different period is used. There is to do.

  In order to achieve the above object, a radar apparatus according to a first aspect of the present invention is a radar apparatus that transmits and receives a radar wave to a predetermined search area, and has a first period based on a captured image of the search area. An input means for inputting the detected detection position from an image recognition device that detects the position of the target every time, and a second shorter than the first period based on a plurality of the input detection positions. And azimuth angle estimating means for estimating the azimuth angle of the target for each period, and azimuth angle detecting means for detecting the azimuth angle of the target near the estimated azimuth angle.

  According to a preferred aspect of the above aspect, the azimuth angle detecting means is a first azimuth angle step near the estimated azimuth angle, and a second azimuth step larger than the first azimuth angle step otherwise. A mark is detected.

  Since the radar apparatus according to the above aspect includes azimuth angle estimation means for estimating the azimuth angle of the target for each second period based on a plurality of input detection positions, the operation period of the image recognition apparatus and the radar apparatus is Even in a different case, the azimuth angle of the target can be estimated in its own operation cycle using the image recognition result. And by detecting the azimuth angle of the target in the vicinity of the estimated estimated azimuth angle, the azimuth angle of the target can be detected in the azimuth angle range where the probability that the target exists is high, so that An azimuth angle can be detected.

  Furthermore, according to the preferable aspect described above, by detecting the target at a first azimuth step near the estimated azimuth, and at a second azimuth step larger than the first azimuth step otherwise. It is possible to reduce the calculation load of the entire digital signal processing apparatus and to accurately detect the azimuth angle of the target.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 1 is a diagram for explaining a situation where the radar apparatus according to the present embodiment is mounted on a vehicle. The radar apparatus 3 is an electronic scanning radar apparatus, particularly a DBF processing radar apparatus, and transmits a radar wave obtained by performing frequency modulation on a continuous wave that is an electromagnetic wave having a millimeter wavelength. This is an FM-CW (Frequency Modulated-Continuous Wave) type radar device. The radar device 3 is installed inside the front bumper of the vehicle 1, transmits a radar wave to the search area SA in front of the vehicle 1, and receives a reflected wave from the target.

  The image recognition device 2 is installed in a passenger compartment near the top of the windshield of the vehicle 1. The image recognition device 2 includes a digital still camera 2a that captures a capturing range PA in front of the vehicle 1 through a windshield, and an image processing unit 2b that processes image data captured by the digital still camera 2a.

  Note that the image recognition device 2 and the radar device 3 are positioned so that the imaging range PA of the digital still camera 2a matches or includes the search area SA of the radar device 3.

  The vehicle 1 includes a vehicle ECU 8 that controls actuators such as a brake and a throttle, a vehicle speed sensor 4 that detects the speed of the vehicle 1, a G sensor 5 that detects acceleration of the vehicle 1, and a steering that detects the steering angle of the vehicle 1. A sensor 6 is mounted.

  The radar device 3, the image recognition device 2, the vehicle ECU 8, the vehicle speed sensor 4, the G sensor 5, and the steering sensor 6 are connected to an in-vehicle LAN (Local Area Network) 9. In this in-vehicle LAN 9, for example, data communication is performed by a CAN (Controller Area Network) system. With such a configuration, the image recognition device 2 sends the detected position of the recognized object to the radar device 3. The radar apparatus 3 scans the search area SA by DBF processing using the detection position by a method described in detail later to obtain the azimuth angle of the target, and uses the FM-CW method to calculate the relative velocity and relative distance of the target. And detect. The detected target information is sent to the vehicle ECU 8, and the vehicle ECU 8 controls the operation of the vehicle 1 based on the target information. At this time, detection results of the vehicle speed sensor 4, the G sensor 5, and the steering sensor 6 are also sent to the vehicle ECU 8 and used for controlling the vehicle 1. As a result, the vehicle 1 travels following the preceding vehicle, avoids a collision with an oncoming vehicle, or warns an occupant.

  FIG. 2 shows a configuration example of the radar apparatus 3 in the present embodiment. As described above, the radar apparatus 3 is a DBF processing type radar apparatus, and includes an antenna unit 32 including a plurality of receiving antennas 32_1, 2, 3,... A radar wave is generated as a transmission signal, transmitted from the antenna for transmission of the antenna 32, and a transceiver 33 that generates a beat signal of the reception signal and the transmission signal for each of the antennas 32_1, 2, 3,. Further, the radar apparatus 3 includes an A / D converter 34 that converts the beat signal for each of the antennas 32_1, 2, 3,... Into digital data, and a digital signal processing apparatus 35 that processes the beat signal converted into digital data. Have.

  For example, the digital signal processing device 35 includes a processor such as a DSP (Digital Signal Processor) that performs FFT (Fast Fourier Transform) processing on the beat signal, and a microcomputer that executes DBF processing using the FFT result. The microcomputer includes a CPU that performs various calculations using input data, a memory that stores a program in which calculation procedures executed by the CPU are described, and a RAM as a work area. Here, the azimuth angle estimation means 38, the distance / speed detection means 40, and the output determination means 42 are constituted by a CPU of a microcomputer that executes each procedure described later and its processing program, and the azimuth angle detection means 39 is used for FFT processing. It is comprised by DSP and its processing program, CPU of a microcomputer, and its processing program.

  The digital signal processing device 35 also includes an input / output interface 36 that performs various data communications with the in-vehicle LAN 9. Here, the input / output interface 36 is an input for receiving information input such as the detection position and detection time of the target from the image recognition device 2, the vehicle speed from the vehicle speed sensor 4, and the traveling direction of the vehicle from the G sensor 5 and the steering sensor 6. Corresponds to the means.

  The image recognition apparatus 2 includes a digital still camera 2a and an image recognition unit 2b that processes image data captured by the digital still camera 2a. For example, the image recognition unit 2b is configured by an ASIC (Application Specific Integrated Circuit), binarizes the captured image data, and performs histogram processing of the binarized data to detect the edge of the subject. Thereby, the presence or absence of the subject, that is, the target is determined. Then, the image recognition unit 2b matches the detected shape of the edge with a shape pattern stored in advance in an internal memory, and identifies the type of the target. Here, whether the target is another vehicle or an installation such as a road sign or a guardrail is identified from its shape. And the image recognition part 2b calculates | requires the apparent position in the picked-up image of the target recognized as the vehicle. Then, the detection position and the detection time for detecting the position of the target are output to the input means of the radar apparatus 3. The time when the target is photographed may be set as the detection time.

  FIG. 3 is a flowchart showing an operation procedure of the radar apparatus 3 having the above configuration. The radar device 3 transmits and receives radar waves in the search area SA in front of the vehicle 1 by the transceiver 33 (S2), and FFT processing is performed on the beat signal for each antenna by the azimuth angle detection means 39 of the digital signal processing device 35 (S4). . Then, the azimuth angle detection means 39 scans the search area SA by performing DBF processing using the beat signal subjected to the FFT processing, and detects the azimuth angle of the target (S6). Then, the distance / speed detection means 40 detects the relative distance and the relative speed of the target whose azimuth angle is detected using the frequency of the beat signal (S8). Then, the output determination unit 42 determines continuity with the past detection history (S10), and whether or not the detection result is appropriate as a control target, for example, whether the continuity connection history is a predetermined number of times or more. Whether or not output is possible is determined depending on whether or not (S12), and the target information determined to be output is output to the vehicle ECU 8 (S14).

  In the DBF process executed in the above step S6, the azimuth angle detection means 39 changes the beat signal phase for each antenna 32_1, 32_2, 32_3,. The search area SA is scanned while changing every azimuth angle. Then, the composite amplitude of the beat signal is calculated for each azimuth step to obtain the composite amplitude distribution. Here, when the beam directing direction coincides with the azimuth angle at which the target is located, the beat signals have the same phase, and as a result, the combined amplitude becomes maximum. Utilizing this fact, the radar apparatus 3 uses the azimuth angle detection means 39 to detect the azimuth angle corresponding to the maximum value of the obtained distribution as the azimuth angle of the target.

  Here, when DBF processing is performed on the entire search area SA, the number of azimuth increments increases as the search area SA becomes wider, so the number of parameters increases. Further, since the number of parameters increases as the azimuth angle step decreases, the amount of calculation of the entire digital signal processing device 35 increases and calculation time is required. Therefore, in order to prevent the output of the target information to the vehicle ECU 8 from being delayed due to the computation time, the azimuth angle detection means 39 uses the target detection position sent from the image recognition device 2 to reduce the azimuth direction. Azimuth angle detection is performed by dividing a range in which azimuth angle detection is performed in angular increments and a range in which azimuth angle detection is performed in large azimuth angle increments.

  However, when the image recognition apparatus 2 outputs the detection position and the radar apparatus 3 receives the detection position via the in-vehicle LAN 9, there is a time difference for access right arbitration in the in-vehicle LAN 9. Furthermore, the operation cycle of the image recognition device 2 and the operation cycle of the radar device 3 are different. Then, when the radar apparatus 3 performs azimuth angle detection as described above, the target may move outside the range in which azimuth angle detection is performed in small azimuth angle increments.

  Therefore, in the present embodiment, the detection time when the position is detected from the image recognition device 2 is sent to the radar device 3, and the azimuth estimation means 38 of the radar device 3 uses the detection time to detect the position of the radar device 3. The position of the target is linearly approximated for each operation cycle, and the azimuth angle corresponding to the position is estimated. Then, the azimuth angle detection means 39 of the radar device 3 detects the azimuth angle in small azimuth steps near the estimated azimuth angle, and detects the azimuth angle in large azimuth steps in other ranges.

  In this way, the radar apparatus 3 detects the azimuth in small azimuth steps in the vicinity of the azimuth with a high probability that the vehicle exists for each operation cycle, and other azimuths with a low probability that the target exists. At the corner, the azimuth is detected in large azimuth increments. By doing so, the radar apparatus 3 can detect the azimuth angle of the target with high accuracy.

  Here, the correspondence between the detected position of the target sent from the image recognition apparatus 2 and the azimuth angle will be described. Since the digital still camera 2a of the image recognition apparatus 2 is fixed toward the front of the vehicle and the radar apparatus 3 is also fixed, the positional relationship between the imaging range PA of the digital still camera 2a and the search area SA of the radar apparatus 3 Is also fixed. Therefore, the position of the subject in the captured image, that is, the apparent position is associated with the azimuth angle in the search area SA.

  An example of the relationship between the apparent position of the target in the captured image and the azimuth is shown in FIG. FIG. 4A shows the captured image Ph, and FIG. 4B shows the search area SA on the horizontal plane with the radar device 3 as a reference. Here, the central portion M of the captured image Ph is the azimuth angle 0 degree which is the front of the radar device 3 (that is, the traveling direction of the vehicle 1), and the left and right end portions EL and ER of the captured image Ph are the end portions of the search region. This corresponds to the azimuth angles θL and θR. In addition, the apparent position in the captured image Ph is a horizontal position that is a horizontal deviation from the center M. Then, when the vehicle Ba in the lateral position S1 and the vehicle Bb in the lateral position S2 are recognized as targets, the azimuth angles θa and θb in the search area SA are associated with the lateral positions S1 and S2 in the captured image.

  By storing such correspondence in advance in the memory in the digital signal processing device 35 as map data, the azimuth angle detection means 39 can specify the azimuth angle corresponding to the lateral position of the vehicles Ba and Bb from the map data. Therefore, the azimuth angle estimating means 38 can estimate the azimuth angle at which the target exists by specifying the azimuth angle corresponding to the estimated lateral position of the target based on the map data.

  In addition, the following points can be given as an advantage of using the detection position detected by the target. In other words, with the radar device alone, a so-called multipath phenomenon occurs in which reflected waves from the target are reflected by the road surface or stationary object and received by multiple paths, resulting in an azimuth angle where the target does not actually exist. Although it may be erroneously detected, the image recognition apparatus recognizes the target based on the shape of the subject, so that the possibility of such erroneous detection is small. Therefore, the azimuth angle of the target can be detected with high accuracy by detecting the azimuth angle in the vicinity of the estimated azimuth angle estimated based on the detection position by the image recognition apparatus.

  Next, azimuth angle estimation by the radar device 3 and azimuth angle increments when detecting the azimuth angle will be described. FIG. 5 is a diagram for explaining azimuth angle estimation of the radar apparatus 3 in the present embodiment. FIG. 6 shows an example of azimuth angle increments when detecting the azimuth angle.

  5A to 5C, the horizontal axis indicates the elapsed time, FIG. 5A shows the operation cycle of the image recognition apparatus 2, and FIG. 5B shows the operation cycle of the radar apparatus 3. FIG. 5C shows an estimated position of the target in each cycle of the radar apparatus 3 shown in FIG. As shown in FIG. 5A, the image recognition apparatus 2 performs image recognition by processing an image captured by a digital still camera, for example, every cycle Ca1, Ca2, Ca3,... Of 30 milliseconds. Detection positions Pt1, Pt2, Pt3,..., And detection times t1, t2, t3,. On the other hand, as shown in FIG. 5B, the radar apparatus 3 scans the search area SA every period Cb1, Cb2, Cb3,..., For example, 10 milliseconds, for example, the azimuth angle, relative speed, and relative distance of the target. And the target information is output to the vehicle ECU 8. For convenience of explanation, it is assumed that the operation cycle of the image recognition device 2 in FIG. 5A and the operation cycle of the radar device 3 in FIG. 5B are started simultaneously.

  Then, first, in the cycles Cb1 to Cb3 immediately after the radar device 3 starts operating, the detection position is not sent to the radar device 3 because the image recognition device 2 is in the middle of the cycle Ca1. Accordingly, at this time, as shown in FIG. 6A, the radar apparatus 3 scans the entire search area SA in the same azimuth step and detects the azimuth angle of the target. At this time, azimuth angle increment β1 is used. In FIG. 6, azimuth angle increments are shown in three stages, β1, β2, and β3 (where β1> β2> β3). Therefore, the calculation load of the entire digital signal processing device 35 is reduced by using the largest azimuth step in the cycles Cb1 to Cb3.

  Next, the first detection position P1 detected in the cycle Ca1 and its detection time t1 are sent from the image recognition device 2 to the cycle Cb4 of the radar device 3. Here, in order to estimate the position of the target by linear approximation, two detection positions are required, but the only detection position that can be used is the first detection position P1. Therefore, as shown in FIG. 6B, the radar apparatus 3 has the azimuth angle range α1 near the azimuth angle θ1 corresponding to the position P1 in the periods Cb4 to Cb6 and the other ranges in the azimuth increments β2. Azimuth angle detection is performed by scanning with angle increment β1.

  Since the second detection position P2 and the imaging detection time t2 are input in the cycle Cb7, the radar apparatus 3 detects the first detection position P1 and the second detection position P2 in the next cycles Cb8 to Cb10. Is used to estimate the horizontal position of the target. At this time, the radar apparatus 3 calculates the displacement from the lateral position P1 to P2 at the time difference Δt (= t2−t1) of the detection time by using the target estimation means, so that the object for every 10 milliseconds operation period is calculated. The position of the mark, G8 to G10, is linearly approximated. The radar apparatus 3 scans the azimuth range near the estimated azimuth corresponding to the estimated positions G8 to G10 with the azimuth increment β3 and the other range with the azimuth increment β1 in the cycles Cb8 to Cb10. Perform corner detection. That is, when the estimated position G8 is shown as an example in FIG. 6C, the azimuth angle range α8 near the estimated azimuth angle θ8 corresponding to the estimated position G8 (α8 is smaller than α1 shown in FIG. 6B). ) Is detected by azimuth angle increment β3, and the other range is scanned by azimuth angle increment β1.

  Then, since the third detection position P3 and the imaging detection time t3 are input in the cycle Cb10, the radar apparatus 3 uses the second detection position P2 and the third detection position P3 in the next cycles Cb11 to Cb13. Is used to perform the same estimation as described above to detect the azimuth angle.

  Here, as shown in FIGS. 6A to 6C, the azimuth increments are assigned so that the amount of calculation in the entire search area SA is uniform. That is, in FIG. 6A, since the azimuth angle is not estimated, the amount of calculation is reduced by using the largest azimuth angle increment of β1 for the entire search area SA. In FIG. 6 (B), since one detection position is given, an azimuth angle range α1 having a higher probability that the target exists than in the case of FIG. 6 (A) is obtained. There is a high risk of moving outside. Therefore, by increasing the azimuth angle α1, it is possible to reduce this risk. Further, by using the medium azimuth angle step β2 in the range, and using the azimuth step β1 in the other range, the entire search area SA is obtained. Reduce the amount of computation in. In FIG. 6C, since the position for each operation cycle of the radar apparatus 3 can be linearly approximated from the two detection positions, the azimuth angle range α8 having a higher probability that the target exists than in the case of FIG. 6B. Is required as a narrower azimuth range. Therefore, the azimuth angle detection accuracy is increased by using the smallest azimuth angle step β3 within the range, and β1 azimuth step is used in other ranges. By doing so, the amount of calculation in the whole search area is reduced.

  For the estimation of the position of the target, the past three or more detection positions may be used, or curve approximation such as quadratic approximation may be used instead of linear approximation. Further, the azimuth angle increment is not limited to the above three steps, and may be two steps or four steps or more. Furthermore, the calculation may be performed by calculating the azimuth step according to the number of targets. In any case, the azimuth angle of the target is determined by detecting the azimuth angle in the small azimuth angle increment around the estimated azimuth angle corresponding to the estimated position, and detecting the other azimuth angle in the larger azimuth angle increment. In addition to accurate detection, it is possible to reduce the calculation load of the digital signal processing device 35 as a whole.

  Alternatively, the vicinity of the estimated azimuth angle may be detected in smaller azimuth steps, and the azimuth detection may not be performed for other ranges. Even in such a case, it is possible to accurately detect the azimuth angle of the target and reduce the calculation load of the entire digital signal processing device 35.

  Next, the procedure for detecting the azimuth angle of the radar apparatus 3 in this embodiment will be described in detail.

  FIG. 7 is a flowchart for explaining the scanning procedure of the radar apparatus 3 in the present embodiment. FIG. 7A shows an operation procedure of the image recognition apparatus 2 that operates separately from the radar apparatus 3, and FIG. 7B shows an operation procedure of the radar apparatus 3. Note that the procedure of FIG. 7B corresponds to the subroutine of the procedure S6 shown in FIG.

  First, the image recognition apparatus 2 executes the procedure of FIG. 7A for each operation cycle shown in FIG. That is, the image recognition unit captures a captured image (S20), performs binarization processing, histogram processing, and edge detection processing to recognize the subject image (S22). Then, it is determined whether or not the subject image is a detection target (S24), and the detected position of the determined target is obtained (S26). Then, the obtained detection position is output (S28).

  On the other hand, the radar apparatus 3 executes the procedure of FIG. 7B for each operation cycle shown in FIG. First, the input unit 36 acquires a detection position from the image recognition device 2 (S40). Here, as shown in FIG. 5, the radar apparatus 3 cannot acquire the detection position from the image recognition apparatus 2 in the cycles Cb1 to Cb4 immediately after the operation of the radar apparatus 3, and acquires the detection position after the period Cb5. it can. Therefore, the subsequent procedure is divided into a case where it is not acquired and a case where it is acquired.

  First, when the detection position is not acquired (NO in S40), that is, in the periods C1b to Cb4, the azimuth angle detection means 38 sets the azimuth angle increment β1 in the entire search area SA (S42), performs DBF processing, and performs azimuth. A corner is detected (S54). On the other hand, when the detection position is acquired (YES in S40), that is, after the period Cb5, the azimuth angle detection means 39 determines whether a plurality of detection positions have been acquired in the past (S44).

  When a plurality of detection positions have not been acquired in the past (NO in S44), that is, in the cycles Cb5 to CB7, as shown in FIG. 6B, the azimuth angle detection means 39 is set to one detection position P1. The corresponding azimuth angle range α1 near the azimuth angle θ1 is set to azimuth angle increment β2, and the other range is set to azimuth angle increment β1 (S46), and DBF processing is executed to detect the azimuth angle (S54). On the other hand, if a plurality of detection positions have been acquired in the past (YES in S44), that is, in the period Cb8, the azimuth angle estimation means 38 performs a linear approximation using the latest detection position P2 and the previous position information P1. The azimuth angle θ8 corresponding to the position G8 is estimated (S48). Then, the azimuth step β3 is set in the azimuth range α8 near the estimated azimuth angle θ8, and the azimuth step β1 is set in addition to that (S50), and the DBF process is executed to detect the azimuth (S54).

  In addition, even after the cycle Cb9, since YES in step S44, steps S48, S50, and S54 are executed.

  By such a procedure, even if the operation cycle is different, the detection position can be estimated using the image recognition result. And by detecting the azimuth in the small azimuth increments around the estimated azimuth, and detecting the azimuth in the other large azimuth increments, the azimuth of the target can be detected accurately, and the entire digital signal processing device Calculation load can be reduced.

  Next, a modified example in the present embodiment will be described. In this modification, the azimuth angle estimating means 38 of the radar device 3 acquires information related to the behavior of the host vehicle 1 and corrects the estimated position of the target. Specifically, the radar apparatus determines the traveling speed of the vehicle 1 from the vehicle speed sensor 4 shown in FIG. 1, the lateral acceleration applied to the vehicle 1 from the G sensor 5, and the steering angle of the vehicle 1 from the steering sensor 6. Obtained by input means. Here, the traveling speed corresponds to the moving speed of the vehicle, and the lateral acceleration and the steering angle correspond to the moving direction.

  Then, the radar apparatus 3 calculates, for example, a turning radius and a turning speed when the vehicle 1 turns based on the information by the azimuth angle estimation unit 38, and based on this, the relative moving direction of the target is calculated. The moving speed is obtained, and the estimated position of the target and the estimated azimuth angle corresponding thereto are corrected. By doing so, it is possible to estimate the azimuth angle with a high probability that the target exists more accurately.

  FIG. 8 is a flowchart for explaining the operation procedure of the radar apparatus according to this modification. The flowchart of FIG. 8 is obtained by adding steps S49a and S49b to the flowchart of FIG. That is, the radar apparatus 3 acquires the moving speed and moving direction of the vehicle by the input means (S49a), and the estimated position of the target and the estimated azimuth angle corresponding thereto based on these information by the azimuth angle estimating means 38. Are corrected (S49b). Then, in the vicinity of the corrected estimated azimuth angle, the azimuth angle is detected in small azimuth steps, and in other ranges, the azimuth angle is detected in large azimuth steps (S50, S54).

  Alternatively, when the turning speed of the vehicle 1 is larger than the reference value, the correction amount becomes too large and the reliability of the correction result is lowered. In this case, the procedure may be such that scanning is performed at the same scanning angle in the search area. Specifically, if the product of the moving direction (steering angle) and the moving speed (vehicle speed) is greater than the reference value, the azimuth angle is detected in the same azimuth step in the entire search area, and if it is less than the reference value, the correction is performed. Is possible. By doing so, it can prevent that the precision of an azimuth angle detection falls.

  In the above description, an electronic scanning radar apparatus, particularly a DBF processing radar apparatus has been described as an example. However, the present invention can also be applied to a mechanical scanning radar device. Next, an embodiment in which the present invention is applied to a mechanical scanning radar device will be described.

  A mechanically operated radar device scans a search area by changing the beam directing direction by mechanically rotating an antenna. At this time, the intensity of the beat signal of the transmission / reception signal is detected for each predetermined azimuth angle step in the rotation angle of the antenna, and the intensity distribution is formed so that the angle forming the maximum value is set at the center of the target. Identified as an azimuth.

  Here, when the scanning range becomes wide, the number of azimuth steps for detecting the intensity of the beat signal increases, and as a result, the amount of calculation increases, so that the timing for outputting the target information to the vehicle ECU may be delayed. .

  Therefore, in this embodiment, the beat signal intensity is detected in small azimuth steps in the vicinity of the estimated azimuth angle based on the detection position from the image recognition device, and the beat signal is decremented in large azimuth steps in other ranges. Intensity detection is performed. By doing so, the azimuth angle of the target can be detected with high accuracy, and the calculation load of the entire digital signal processing apparatus is reduced.

  FIG. 9 is a diagram for explaining the configuration of a mechanical scanning radar apparatus. The radar apparatus 3a is a machine operation type radar apparatus and an FM-CW type radar apparatus. The radar apparatus 3a includes a rotatable antenna 32a for transmission / reception, and a transmitter / receiver 33 that generates a transmission radar wave as a transmission signal and transmits the transmission signal from the antenna 32a, and generates a beat signal between the reception signal and the transmission signal. And a rotary encoder 34 for detecting the rotation angle of the antenna 32 a, and the detected rotation angle is input to the digital signal processing device 35.

  The configuration of the digital signal processing device 35 is the same as the configuration shown in FIG. 2, but the operation procedure of the azimuth angle detecting means 38 is different as will be described later.

  The configuration of the image recognition device 2 is the same as that shown in FIG.

  FIG. 10 is a flowchart for explaining the operation procedure of the radar apparatus 3a. The radar device 3a transmits and receives radar waves in the search area SA in front of the vehicle 1 by the transceiver 33 while rotating the antenna 32a (S2), and the rotation of the antenna is performed by the azimuth angle detection means 39 of the digital signal processing device 35. The beat signal is subjected to FFT processing for each angle, that is, for each azimuth step, the signal strength of the beat signal is detected, and the azimuth angle of the target is detected from the intensity distribution (S6a). And procedures S8-S14 are performed like the procedure shown in FIG.

  FIG. 11 is a flowchart detailing the azimuth angle detection procedure of the radar apparatus 3a. FIG. 11A shows an operation procedure of the image recognition apparatus 2, and FIG. 11B shows an operation procedure of the radar apparatus 3a. Note that the procedure in FIG. 11A is the same as the procedure shown in FIG. Further, the procedure of FIG. 11B corresponds to the subroutine of the procedure S6a shown in FIG. 10, and the procedure S54a is executed in place of the procedure S54 shown in FIG. 7B. The procedure is the same as that shown in (B). That is, in step S54a, the azimuth angle detection means 39 of the radar apparatus 3a sets the magnitude of the azimuth angle step in step S42 or S50, and then performs FFT on the beat signal for each set azimuth angle step and the intensity distribution thereof. And the azimuth angle is detected based on the intensity distribution (S54a).

  According to such a procedure, even if the operation periods of the image recognition device 2 and the radar device 3a are different, the position of the target can be estimated using the image recognition result, and the corresponding azimuth angle can be estimated. . And by detecting the azimuth in small azimuth increments near the estimated azimuth, and detecting the azimuth in large azimuth increments other than that, the azimuth angle of the target can be accurately detected, and the entire digital signal processing device The calculation load can be reduced.

  The procedure shown in FIG. 9 can be applied to the procedure shown in FIG.

  In the above-described embodiment, the image recognition apparatus 2 sends the detection time together with the detection position of the target to the radar apparatuses 3 and 3a, so that the radar apparatuses 3 and 3a can calculate the amount of change in the position of the target per elapsed time. It can be calculated and the target position can be linearly approximated. However, when the operation cycle of the image recognition apparatus 2 is known in advance, this may be stored in a memory in the digital signal processing apparatus 35 and only the detection position may be sent from the image recognition apparatus 2. In this case, since the detection time of the position input in time series can be read from the memory on the radar device side, the amount of change in the position of the target per elapsed time can be calculated. Therefore, even if the detection time is not sent from the image recognition device 2, the position of the target can be estimated on the radar device side.

  In addition, when the image recognition device and the radar device operate in the same cycle, a communication method in which the transmission timing of the detection position from the image recognition device to the radar device is kept constant, for example, a communication method such as a FlexRay method is used. When employed, the configuration of the azimuth angle estimation means of the radar apparatus may be arbitrarily stopped. By doing so, the processing load of the radar apparatus can be further reduced.

  In addition, when there are a large number of image-recognized targets, based on the past detection history, for example, in the vicinity of the estimated azimuth angle of the target with a small relative distance and a high probability of collision, a small azimuth angle step is used. It is good also as a procedure which performs the azimuth angle detection of a large azimuth angle step with respect to the target. By doing so, the calculation load as the whole digital signal processor 35 can be reduced. In this case, the azimuth angle increment may be determined according to the relative distance of the target. By doing so, it is possible to reduce the calculation load as a whole while optimally allocating resources as a whole of the digital signal processing device 35.

  As described above, according to the present embodiment, even if the operation cycles of the image recognition device and the radar device are different, the radar device uses the image recognition result to determine the azimuth angle of the target in its own operation cycle. Can be estimated. Then, azimuth angle detection or azimuth angle detection processing is performed in small azimuth angle increments around the estimated azimuth angle, and azimuth angle detection or azimuth angle detection processing is performed in large azimuth angle increments for the rest of the digital signal processing device. The calculation load can be reduced and the azimuth angle of the target can be detected with high accuracy.

It is a figure explaining the condition where the radar apparatus in this embodiment is mounted in a vehicle. It is a figure which shows the structural example of the radar apparatus 3 in this embodiment. 4 is a flowchart showing an operation procedure of the radar apparatus 3. FIG. It is a figure which shows an example of the relationship between the apparent position of the target in a picked-up image, and an azimuth. It is a figure explaining the azimuth angle estimation of the radar apparatus 3 in this embodiment. It is a figure which shows the example of an azimuth angle step at the time of detecting an azimuth angle. It is a flowchart figure explaining the scanning procedure of the radar apparatus 3 in this embodiment. It is a flowchart figure explaining the operation | movement procedure of the radar apparatus in a modification. It is a figure explaining the structure of the radar apparatus of a mechanical scanning system. It is a flowchart explaining the operation | movement procedure of the radar apparatus 3a. It is a flowchart figure explaining the azimuth angle detection procedure of the radar apparatus 3a in detail.

Explanation of symbols

2: image recognition device, 3, 3a: radar device, 38: azimuth angle estimation means, 39: azimuth angle detection means, 40: distance / speed detection means

Claims (8)

In a radar device that transmits and receives radar waves to a predetermined search area,
An input means for inputting the detected detection position from an image recognition device that detects the position of the target for each first period based on the captured image of the search area;
Azimuth angle estimating means for estimating an azimuth angle of the target for each second period shorter than the first period based on a plurality of the input detection positions;
A radar apparatus, comprising: an azimuth angle detecting unit that detects an azimuth angle of the target near the estimated azimuth angle. In claim 1,
The azimuth angle detecting means detects the target at a first azimuth angle step near the estimated azimuth angle, and at a second azimuth angle step larger than the first azimuth angle step otherwise. Radar device. In claim 2,
A plurality of antennas for receiving the radar wave;
The azimuth angle detecting means changes a phase of a received wave by the plurality of antennas to change a directivity direction of a synthesized wave of the received wave for each of the first or second azimuth angle increments. A radar apparatus, wherein the pointing direction when the amplitude forms a maximum value is detected as an azimuth angle of the target. In claim 2,
An azimuth angle for transmitting and receiving the radar wave has an antenna that is variable in the search area,
The azimuth angle detecting means detects the level of a received wave received by the antenna for each of the first or second azimuth angle increments, and determines the azimuth angle of the antenna when the level forms a maximum value. A radar apparatus that detects an azimuth angle of a target. In any one of Claims 1 thru | or 4,
The input means further receives a detection time when the detection position is detected from the image recognition device,
The azimuth angle estimating means estimates the azimuth angle of the target by further using a plurality of the input detection times. In any one of Claims 1 thru | or 4,
Mounted on mobile objects,
The input means further receives the moving direction and moving speed of the moving body,
The radar apparatus according to claim 1, wherein the azimuth angle estimating means corrects the estimated azimuth angle using the moving direction and the moving speed. In claim 5,
Mounted on mobile objects,
The radar apparatus according to claim 1, wherein the input means acquires the detection position and detection time from the image recognition apparatus via a communication network mounted on the mobile body. In a method for detecting an azimuth angle of a target by a radar device that transmits and receives a radar wave to a predetermined search area,
An input step in which the detected detection position is input from an image recognition device that detects the position of the target for each first period based on the captured image of the search area;
An azimuth estimation step for estimating an azimuth of the target for each second period shorter than the first period based on a plurality of the input detection positions;
An azimuth angle detection step of detecting an azimuth angle of the target near the estimated azimuth angle.