JP2004132734A - Vehicle-mounted radar installation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle-mounted radar installation which determines the continuity of this-time target data with last-time target data and performs pairing of the target data, and captures a target correctly. <P>SOLUTION: This is a vehicle-mounted frequency modulated continuous wave (FM-CW) radar installation, and has a continuity determination means which determines the continuity of the this-time target data with target data detected in the past, by criteria of its differences in distance, relative speed, and horizontal position from the target. In the vehicle-mounted radar installation, the continuity determination means performs continuity determination whether or not the last-time and this-time target data satisfy the criteria of the vertical position difference or angle difference, in addition to the determining criteria of the differences in distance and relative speed from the target, when the continuity determination means determines the continuity of the target. It does not matter if the continuity of the target is by the vertical position difference when the distance up to the target is less than a predetermined value, and is determined by the angle difference when the distance is not shorter than the predetermined value. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an on-vehicle radar device, and in particular, a target signal in front of a vehicle is obtained from a beat signal obtained by mixing a transmission signal whose frequency is modulated and a reception signal reflected by a target traveling in front of the vehicle and returned. In the on-vehicle radar device to be detected, the continuity of the previously detected target data and the currently detected target data is determined, and the target data is paired, so that the target can be accurately captured. The present invention relates to an on-vehicle radar device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, due to monotonous highway driving and increased opportunities for long-time driving, the driver's attention has been distracted and the number of automobile collision accidents tends to increase. Further, in addition to the automatic constant-speed traveling by the constant-speed traveling device, there is also a demand for performing an automatic traveling while tracking a preceding vehicle on a highway.
[0003]
Under such circumstances, the distance between the preceding car and the car that you drive is always measured, and when the decrease in this distance is large, the running speed of the car that you drive is automatically reduced. A vehicle-mounted radar device that prevents a collision by applying a brake, and a vehicle-mounted radar device that performs automatic driving while constantly monitoring the positions of a plurality of vehicles traveling ahead are in practical use. .
[0004]
Such an in-vehicle radar device generally includes a system such as an FM-CW (frequency modulated continuous wave) radar and a pulse drive radar. Among them, the FM-CW radar apparatus applies a triangular baseband signal to a transmission voltage-controlled oscillator (VCO), performs frequency modulation, transmits the signal to the front of the vehicle from an antenna, and contacts a target such as a preceding vehicle. While the reflected signal is received by the antenna, the target ahead is detected from the beat signal obtained by mixing the transmitted signal and the received signal.
[0005]
In this case, the transmission signal causes the antenna to scan in a predetermined angular range in front of the vehicle, so that a plurality of beams are transmitted at predetermined angular intervals. When detecting a target ahead of the vehicle with such a scan-type on-vehicle radar device, the target is determined by determining the continuity between target data detected in the past and target data detected this time. Had been detected. The target data to be detected are a distance, a relative speed, a lateral position, and an angle, and a distance difference, a relative speed difference, and a lateral position difference have been used as conditions for determining the continuity of the target data. Then, within the range of the continuity condition, it has been determined that the target indicated by the past target data and the target indicated by the current target data are continuous.
[0006]
In addition, among such scan-type on-vehicle radar devices, the predicted position of the target is calculated by taking into account the same angle of beam and the rate of change of the distance, and an object similar to the predicted position is identified with the target. (For example, Patent Document 1) is known.
[0007]
[Patent Document 1]
JP-A-9-264955
[0008]
[Problems to be solved by the invention]
However, the above-described scan type vehicle-mounted radar device has the following problems.
(1) Since the value of the horizontal position of the target is calculated from the angle value of the target, there is a possibility that a variation corresponding to the beam interval emitted from the radar device may occur, and this variation is caused by the distance of the target. Becomes larger as the distance from the vehicle increases, so that the continuity of the distant target may be erroneously determined.
(2) In the case of a target having a small number of detected beams, such as a motorcycle, there is a possibility that the target data may have a variation corresponding to the beam interval, so that pairing may not be possible.
(3) In the radar device described in Patent Document 1, the previous and current detected objects are compared at a predicted position, and the same object is determined based on the angle and the distance. Since the determination is not performed by setting the threshold value, there is a risk of erroneous determination.
[0009]
Therefore, the present invention solves the problem of the conventional on-vehicle radar device, and changes a condition for determining the continuity of past detection data of a target and current detection data in a scan-type on-vehicle radar device. Accordingly, it is possible to provide an in-vehicle radar device that can determine the continuity of normal target data regardless of the distance of the target from the vehicle and perform normal pairing regardless of the type of the target. The purpose is.
[0010]
[Means for Solving the Problems]
According to a first aspect of the present invention, which achieves the above object, a frequency modulated signal is transmitted, a signal reflected from a target in front of the vehicle and returned is received, and a signal obtained by mixing the transmitted signal and the received signal is obtained. An on-vehicle radar device that detects a target ahead of a vehicle from a beat signal detected, and determines the continuity between the detected past target data and the current target data based on a distance difference from the target and a relative speed. Difference, and in a vehicle-mounted radar device having continuity determining means for performing a lateral position difference condition, the continuity determining means determines a distance difference from a target, a relative speed difference, and a lateral position difference or an angle difference. It is characterized by satisfying either one.
[0011]
In this case, the continuity determination means uses the horizontal position difference as a determination condition when the distance to the target is less than a predetermined value, and uses the angle difference as a determination condition when the distance to the target is equal to or more than a predetermined value. You may do it.
[0012]
According to a second aspect of the present invention, which achieves the above object, a frequency modulated signal is transmitted, a signal reflected from a target ahead of the vehicle and returned is received, and the transmitted signal and the received signal are mixed. An in-vehicle radar device that detects a target ahead of the vehicle from the beat signal detected, predicts the position of the current target from detected past target data, and determines the position of the target in the currently detected target data. In a vehicle-mounted radar device having continuity determining means for determining the continuity of a target based on whether or not the target is within a predetermined horizontal position range in the predicted position data, Whether the lateral position of the target is within a predetermined horizontal position range at the predicted position of the target or within a predetermined angle range at the predicted position of the target; The feature is that it is configured to judge That.
[0013]
In this case, when the distance to the target is less than the predetermined value, the continuity determining means determines whether the horizontal position of the target detected this time is within a predetermined horizontal position range in the predicted position of the target. The continuity of the target is determined, and if the distance to the target is equal to or greater than a predetermined value, the target is determined based on whether the lateral position of the target detected this time is within a predetermined angle range of the predicted position of the target. Can be determined.
[0014]
According to a third aspect of the present invention, which achieves the above object, a frequency modulated signal is transmitted, a signal reflected from a target ahead of the vehicle and returned is received, and the transmitted signal and the received signal are mixed. An on-vehicle radar device that detects a target ahead of the vehicle from the beat signal, and calculates a representative peak by grouping peak data in an upbeat and a downbeat with a grouping unit, and calculates a representative peak. In an in-vehicle radar device that detects a target by pairing the representative peaks in a pair with each other by a pairing unit, the grouping that sets an angle at which the peak data is searched for as a reference angle when grouping the peak data by the grouping unit. An angle setting means for determining whether or not the number of peak data searched within the reference angle is equal to or greater than a predetermined number; Means for determining the number of peak data, grouping angle increasing means for increasing the reference angle in a beat having a peak data number less than the predetermined number when the number of peak data is less than the predetermined number, and increasing the grouping angle. Grouping angle limiting means for determining whether or not the maximum angle is exceeded is provided, and when the grouping angle exceeds the allowable maximum angle, the pairing means stops pairing of the target.
[0015]
As a modification of the third embodiment, when the peak data is grouped by the grouping means, the grouping angle setting means for setting the angle at which the peak data is searched for at a predetermined angle is compared with the number of peak data searched within the predetermined angle. And a grouping angle changing means for changing a predetermined angle in a bead having a smaller number of peak data when the number of peak data does not match, and calculating a representative peak in an upbeat and a downbeat. The peak data numbers may be matched.
[0016]
According to the on-vehicle radar devices of the first and second embodiments of the present invention, an angle condition is added to the determination of the continuity between the past target data and the current target data in addition to the lateral position condition of the target. Therefore, the continuity of the normal target can be determined regardless of the distance of the target from the vehicle. Further, according to the vehicle-mounted radar device of the third embodiment of the present invention, normal pairing can be performed regardless of the type of the target.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings based on specific examples.
[0018]
FIG. 1 shows the overall configuration of a millimeter-wave radar device 10 which is a vehicle-mounted radar device according to the present invention. In the millimeter-wave radar device 10, a signal from the transmitter control circuit 3T built in the analog circuit 3 causes the circuit in the millimeter-wave RF unit 2 to give the transmission signal a modulation frequency Δf in the form of a triangular wave or a waveform close thereto. The signal is modulated, converted into a millimeter wave, and emitted to the front of the vehicle through the antenna 1. The returned millimeter wave reflected by the target in front of the vehicle is received by the antenna 1 and supplied to a mixer (not shown) in the millimeter wave RF unit 2. Since a part of the transmission signal is input to the mixer, a signal corresponding to the distance from the target and the relative speed is obtained as a beat signal. This beat signal is sent to a DSP (Digital Signal Processor) 4 through a receiving circuit 3R built in the analog circuit 3.
[0019]
The DSP 4 performs a frequency analysis for extracting a frequency band in which a component exists by performing FFT (Fast Fourier Transform) analysis on the beat signal. The frequency-analyzed beat signal has a peak at which power increases relative to the target, and the frequency corresponding to this peak is called a peak frequency. This peak frequency is sent to the microprocessor 5 as peak data. The peak frequency has information on the distance, and the peak frequency differs when the frequency of the transmitted wave increases and decreases due to the Doppler effect due to the relative speed with the target ahead. The microprocessor 5 calculates and obtains the distance and speed to the target ahead from the peak frequency when the frequency of the transmission wave rises and when it falls.
[0020]
If the antenna 1 is only facing the front, only the vehicle traveling in front of the vehicle can be detected, so that the antenna 1 is swung right and left (scanned) by the motor 7 driven by the drive circuit 6. The angle at which the antenna 1 is swung left and right by the motor 7 is about 10 ° to the left and right, for example, 8 ° each, with the front of the vehicle being 0 °. Then, a plurality of millimeter waves radiated from the antenna 1 are radiated at predetermined angles as beams within the range of 16 °.
[0021]
An inter-vehicle distance control ECU (electronic control unit) 20 is connected to the microprocessor 5. An alarm 11, a brake 12, and a throttle valve 13 are connected to the inter-vehicle distance control ECU 20, and these operations are performed according to a relative speed and a distance to a target (preceding vehicle) obtained from the microprocessor 5. Controlled. For example, when the distance from the preceding vehicle becomes equal to or less than a predetermined value, the alarm 11 is sounded to alert the driver, the brake 12 is operated, and the throttle valve 13 is operated in order to ensure safety. Squeeze to reduce engine speed.
[0022]
Further, a steering sensor 14, a yaw rate sensor 15, and a vehicle speed sensor 16 for detecting a steering angle of a steering wheel are connected to the microprocessor 5 in order to obtain road curve information described later. Note that both the steering sensor 14 and the yaw rate sensor 15 are not essential, and only one of them may be provided.
[0023]
FIG. 2 shows the principle of the millimeter wave radar device 10 when a target approaches at a relative speed V. The transmission wave is a triangular wave whose frequency changes as shown by the solid line in FIG. The center frequency of the transmission wave is fo, the FM modulation width is Δf, and the repetition period is Tm. This transmission wave is reflected by the target and received by the antenna 1, and a reception wave shown by a broken line is obtained as a reception signal. The received wave causes a frequency shift (beat) with the transmission signal according to the distance from the target. In this case, since there is a relative velocity V between the target and the target, the beat signal and its frequency are as shown in FIGS. That is, the frequency difference fbu from the upbeat when the frequency of the transmission wave increases is smaller than the frequency difference fbd from the downbeat when the frequency of the transmission wave decreases. When the relative speed with respect to the target is 0, the frequency of the beat signal is the same for the upbeat and the downbeat.
[0024]
When there are a plurality of targets in front of the vehicle, since each target reflects a plurality of beams, a plurality of peak frequencies due to upbeat and downbeat are applied to one target. Exists. In each of the upbeat and the downbeat, the microprocessor 5 performs grouping around a highest peak among peaks having the same frequency from among a plurality of peak frequencies. For example, when there are three targets in front of the vehicle, a graph showing the detected angle-frequency characteristics of the beat signal as shown in FIG. 3 is obtained by the reflected waves of the beam. Among the beat signals, the beat signal having the highest power (the peak of the mountain formed by the beat signal) is called a peak, and the microprocessor 5 selects the group g1 having the peak P1 among the peaks having the same frequency fa. Group g2 having peak P2 and group g3 having peak P3 are grouped. The peak frequencies need not be exactly the same, but may be approximately the same frequency.
[0025]
After performing the grouping, the microprocessor 5 performs a one-to-one pairing process between the target obtained from the grouping in the upbeat and the target obtained from the grouping in the downbeat. The distance to the target is calculated from the sum of the frequencies of the two peaks subjected to the pairing process, and the relative speed to the target is calculated from the difference. Further, the microprocessor 5 determines the continuity of each target based on data on the position and relative speed of each target obtained at predetermined time intervals, and also predicts the position (distance) of the next target. .
[0026]
Here, an outline of a first embodiment of a method of recognizing a target traveling in front of a vehicle by the microprocessor 5 of the present invention will be described with reference to a processing flow shown in FIG. The process shown in FIG. 4 is performed each time the antenna scans the front of the vehicle once.
[0027]
In this process, as shown in step 401 of FIG. 4, first, a peak data extraction process is performed. The peak data is, for example, assuming that the front of the vehicle is 0 °, 8 ° each to the left and right, the antenna is swung from left to right or right to left within a range of 16 °, and the beam is emitted at every uniform angle within this range. A total of 16 beams are radiated and can be obtained from an upbeat signal and a downbeat signal by the reflected wave of each beam. In the following step 402, the peak data of the beat signal is collected, a representative frequency and an angle are calculated, the peak data are grouped, and a grouping process for detecting the presence of the target is performed.
[0028]
In step 403, pairing is performed by a pairing process. After the pairing is performed in this manner, the continuity determination processing of the target is performed in step 404. The continuity processing of the target is to check the continuity of the pairing result with the previous internal data. The determination of the continuity is performed using, for example, a distance difference, a speed difference, a difference in a lateral position of the target (lateral position difference), and the like. Next, in step 405, the data grouped as a stationary object is paired, and this routine ends.
[0029]
Here, the first embodiment of the method for determining the continuity of the target according to the present invention in such a scan-type on-vehicle radar device will be described in comparison with a conventional method for determining the continuity of the target.
[0030]
FIG. 5A is a diagram illustrating a conventional method for determining the continuity of a target. When detecting a target ahead of a vehicle with the radar device, the target is detected by determining continuity between target data detected in the past and target data detected this time. In this figure, target data indicated by (t) is target data detected this time, and target data indicated by (t-1) indicates target data detected last time. Therefore, the target data indicated by (t-2) indicates the target data detected two times before, and the target data indicated by (t-3) indicates the target data detected two times before.
[0031]
The data to be detected as target data is distance, relative speed, lateral position, and angle, and distance, relative speed, and lateral position differences are used as conventional conditions for determining the continuity of target data. I was Then, within the range of the continuity condition, it has been determined that the target indicated by the past target data and the target indicated by the current target data are continuous.
[0032]
However, in such a conventional determination of the continuity of a target, the radar device emits a transmission beam at a certain beam interval, but a target at a distant position has a large fluctuation amount when viewed at a horizontal position, Without considering this variation, continuity could not be obtained simply by the behavior of the vehicle. For example, as shown in FIG. 6A, when the previous target position is represented by a white circle and the current target position is represented by a hatched circle, the target is located at a short distance from the vehicle C. Since the previous target position falls within the range of the lateral position difference that is the continuity determination condition with respect to the current target position, the continuity of this target can be obtained.
[0033]
However, when the target is at a distance far from the vehicle C, the previous target position becomes the current target position even if the target moves by the same angle (beam interval) as the above-described short distance. On the other hand, the continuity of the target could not be obtained because the target does not fall within the range of the lateral position difference which is the continuity determination condition.
[0034]
Therefore, in the first embodiment of the present invention, as shown in FIG. 5B, the continuity between the previous target position indicated by (t-1) and the current target position indicated by (t) is determined. As a determination condition, an angle difference condition is added as an OR condition to a conventional condition for determining continuity of target data such as a distance difference, a relative speed difference, and a lateral position difference. Then, by using these four continuity determination conditions, it is determined that the target indicated by the past target data and the target indicated by the current target data are continuous. More specifically, if the target satisfies either of the lateral position difference condition and the angle difference condition, it is determined that the continuity is satisfied.
[0035]
FIG. 6B illustrates a map for determining the continuity of the target according to the first embodiment of the present invention. A range A shown in this figure is a conventional lateral position difference condition for determining the continuity of the target, and for example, indicates a range where the lateral position difference is 1.8 m. The range B is the angle difference condition added this time. For example, the angle difference indicates a range of 2.4 ° in total by 1.2 ° left and right with respect to the current target position. The overlapping range of the lateral position difference condition A and the angle difference condition B indicates the continuity determination condition for the previous target position according to the present invention. According to this condition, the previous target position that is far from the vehicle C for which continuity was denied in FIG. 5A falls within the range of the angle difference condition B, The continuity with the previous target position can be obtained.
[0036]
From the above, in this embodiment of the first embodiment of the present invention,
| Lateral position difference | <1.8m or | angle difference | <1.2 °
Is satisfied, it is determined that the targets are continuous. At this time, the beam interval is, for example, 1 °.
[0037]
On the other hand, as is apparent from FIG. 6B, the range from the vehicle C to the target has a wider range under the lateral position condition A up to the distance D, and the range under the angle difference condition B is larger than the distance D. Is wide. Therefore, when the distance from the vehicle C to the target is within the distance D, the continuity of the target is determined under the lateral position condition A, and when the distance is longer than the distance D, the continuity of the target is determined under the angle difference condition B. good.
[0038]
Note that as another example of the first embodiment,
| Angle difference | <1. The larger of 2 ° or [(1.8 m / distance (m)) × (180 / π)] °
Alternatively, as yet another embodiment,
| Lateral position difference | <1. When the larger of 8 m or [(1.2 ° × distance (m)) / (180 / π)] m is satisfied, it can be determined that the targets are continuous.
[0039]
Note that the lateral position difference condition of 1.8 m and the angle difference condition of 1.2 ° are merely examples, and the first embodiment is not limited to these numerical values.
[0040]
Next, an outline of a second embodiment of a method for recognizing a target traveling in front of a vehicle by the microprocessor 5 of the present invention will be described with reference to a processing flow shown in FIG. The process shown in FIG. 7 is also performed each time the antenna scans the front of the vehicle once. In this process, the same processes as those described in FIG. 4 will be described with the same step numbers.
[0041]
In the process of this example, peak data is extracted in step 401. Peak data is, for example, 8 ° left and right, with the front of the vehicle at 0 °, and the antenna is swung from left to right or right to left within a range of 16 °, and the beam is steered at a uniform angle within this range. A total of 16 beams are radiated and can be obtained from an upbeat signal and a downbeat signal by the reflected wave of each beam. In the following step 701, a process of predicting the distance (position) of the target from the vehicle is performed. That is, in order to determine the continuity of the target, a predicted value (predicted position) of the distance of the target from the current vehicle is calculated. In this calculation, the current distance is calculated from the previously calculated distance, assuming that the relative speed of the target is constant. The current predicted frequency of the target is also calculated.
[0042]
In the next step 402, the peak data of the beat signal is collected, a representative frequency and an angle are calculated, these peak data are grouped, and a grouping process for detecting the presence of the target is performed. In step 403, pairing is performed by a pairing process. After the pairing is performed in this manner, the continuity determination processing of the target is performed in step 404. The continuity processing of the target is to check the continuity of the pairing result with the previous internal data. The continuity is determined, for example, within a predetermined range from the predicted value of the target predicted in step 701 from the current vehicle, the distance difference, the speed difference, and the difference in the lateral position of the target (lateral position difference). And so on. Next, in step 405, the data grouped as a stationary object is paired, and this routine ends.
[0043]
Here, a second embodiment of the method for determining the continuity of a target according to the present invention in such a scan-type on-vehicle radar device will be described in comparison with a conventional method for determining continuity of a target.
[0044]
FIG. 8A is a diagram illustrating a conventional method of determining the continuity of a target based on a predicted value. In the method of determining the continuity of a target based on the predicted value, the current predicted value is calculated from the previous position of the target. This predicted value is indicated by an asterisk in FIG. Conventionally, an allowable range E (indicated by hatching) of the current position of the target is determined based on the horizontal direction condition (horizontal position difference) and the distance direction condition (frequency difference) around the predicted position, The continuity of the target has been determined based on whether or not the current detection position of the target is within the allowable range E.
[0045]
In this conventional determination method, when the current detection position TG of the target is within the allowable range E, it is determined that the target has continuity. Was determined to be missing.
[0046]
However, in such a conventional determination of the continuity of a target, the radar device emits a transmission beam at a certain beam interval, but a target at a distant position has a large fluctuation amount when viewed at a horizontal position, Without considering this variation, continuity could not be obtained simply by the behavior of the vehicle. For example, as shown in FIG. 8B, when the current predicted position of the target is at a short distance from the vehicle C, the detected position TG of the current target falls within the allowable range E of the predicted position. The continuity of this target can be obtained.
[0047]
On the other hand, if the predicted position of the target this time is far from the vehicle C, even if the target moves by the same angle (beam interval) as in the case of the above-described short distance, the detected position of the target is Since the TG does not fall within the allowable range E of the predicted position, continuity of the target cannot be obtained.
[0048]
Therefore, in the second embodiment of the present invention, as shown in FIG. 8C, a horizontal condition centering on the predicted position (ie, a condition for determining the allowable range E of the current position based on the conventional predicted position) In addition to the horizontal position difference) and the distance direction condition (frequency difference), an angle difference condition is added as an OR condition. For this reason, in the present invention, when the current target predicted position is far from the vehicle C, the current target detection position TG is the extended allowable range EX of the predicted position allowable range E based on the angle difference condition. , The continuity of the target can be obtained. More specifically, if the target satisfies either of the lateral position difference condition and the angle difference condition, it is determined that the continuity is satisfied.
[0049]
FIG. 9 illustrates a map for determining continuity of a target according to the second embodiment of the present invention. A range A shown in this figure is a conventional lateral position difference condition for determining the continuity of the target, and for example, indicates a range in which the lateral position difference is 1.5 m. The range B is the angle difference condition added this time. For example, the angle difference indicates a range of 1.5 ° left and right with respect to the predicted position of the target this time, for a total of 3.0 °. . The overlapping range of the lateral position difference condition A and the angle difference condition B is an allowable range E for the predicted position of the current target with respect to the previous target position according to the present invention, and a restricted region based on the allowable range EX, that is, a continuity determination condition. Is shown. According to this condition, the position TG of the target far from the vehicle C, for which continuity was denied in FIG. 8B, falls within the range of the allowable range EX (angle difference condition B). The continuity of the target can be obtained.
[0050]
From the above, in this example of the second embodiment of the present invention,
| Lateral position difference | <1.5m or | angle difference | <1.5 °
Is satisfied, it is determined that the targets are continuous. At this time, the beam interval is, for example, 1 °.
[0051]
On the other hand, as is clear from FIG. 9, the distance from the vehicle C to the target has a wider range under the lateral position condition A (allowable range E) up to the distance D, and the angle difference condition B over the distance D. Is wider by the allowable range EX. Therefore, when the distance from the vehicle C to the target is within the distance D, the continuity of the target is determined under the lateral position condition A, and when the distance is longer than the distance D, the continuity of the target is determined under the angle difference condition B. good.
[0052]
As another example of the second embodiment,
| Angle difference | <1. The greater of 5 ° or [(1.5 m / distance (m)) × (180 / π)] °, or as still another embodiment,
| Lateral position difference | <1. When the larger of 5 m or [(1.2 ° × distance (m)) / (180 / π)] m is satisfied, it can be determined that the targets are continuous.
[0053]
Note that the lateral position difference condition of 1.5 m and the angle difference condition of 1.5 ° are merely examples, and the second embodiment is not limited to these numerical values.
[0054]
Lastly, an outline of a third embodiment of the method for recognizing a target traveling in front of the vehicle by the microprocessor 5 of the present invention will be described. The third mode is a method of the pairing process in step 403 in the procedure described with reference to FIGS.
[0055]
Here, a pairing processing method according to the third embodiment of the present invention in such a scan-type vehicle-mounted radar device will be described in comparison with a conventional pairing method.
[0056]
FIG. 10 is a diagram illustrating a conventional condition for pairing a target detected on an upbeat and a target detected on a downbeat in a radar apparatus. The figure on the left is the peak data of a certain target detected in the upbeat, and the figure on the right is the peak data of the same target detected in the downbeat. As can be seen from this figure, when one target is normally captured, a plurality of peak data is detected in the upbeat, and the same peak data is detected at a position that is similar to the downbeat with a time delay. The shape of the peak data is usually a mountain shape.
[0057]
Conventionally, an angle difference and a power difference are used as a pairing condition for such peak data in the upbeat and the downbeat, and pairing is performed when these conditions are satisfied.
[0058]
However, when one target is captured by the three peak data, an accurate curve can be obtained by drawing an approximate curve from the relationship of the reflection intensity, but one beam is missing when the reflection intensity is low. In this case, an approximate curve cannot be drawn. Then, variations in the angle of measurement resulted in beam intervals, and accurate pairing could not be performed.
[0059]
Therefore, in the third embodiment of the present invention, the pairing angle range condition is changed according to the number of peak data obtained from the target, and the pairing is performed with three or more peak data. Can be performed accurately. That is, when the number of detected peak data is small, the angle range for detecting the reflected wave is widened to widen the detection range to increase the number of detected peak data, and perform pairing with three or more peak data. Like that.
[0060]
FIG. 11 shows a procedure of changing the angle condition of the pairing according to the third embodiment of the present invention for pairing the target detected at the upbeat and the target detected at the downbeat in the radar apparatus. It is a flowchart which shows an example. The procedure of FIG. 11 is performed each time the antenna scans the front of the vehicle once and the reflected wave from the target is detected as peak data at the upbeat and the downbeat.
[0061]
In step 101, the angle for searching for peak data in the upbeat and the downbeat is set to the angle θ. In the following step 102, the number of peak data of a predetermined target in the upbeat is counted.
[0062]
Then, in step 103, it is determined whether or not the number of peak data for the predetermined target detected in the upbeat is 2 or less. If the number of peak data is 2 or less, the process proceeds to step 104, and as shown in FIG. 13, the search angle θ is increased by a predetermined angle α to widen the search angle. Then, it is determined whether or not the search angle increased in the next step 105 exceeds the maximum allowable search angle θmax. If the increased search angle θ does not exceed the maximum allowable search angle θmax, the process returns to step 102, and steps 102 and 103 are repeated.
[0063]
In this way, the peak data search process is performed by increasing the search angle θ by the predetermined angle α when the number of upbeat peak data becomes 3 or more in step 103 and when the search angle θ increased in step 105 becomes the maximum. The process is continued until the time exceeds the allowable search angle θmax. If the search angle θ increased in step 105 exceeds the maximum allowable search angle θmax, the process proceeds to step 111, and the routine ends without executing the pairing for the target. This is because the group in which the number of peak data is 2 or less has large angle variation. On the other hand, in step 103, it is determined that the number of peak data of the upbeat is 3 or more.
[0064]
In step 106, the number of peak data of a predetermined target in the downbeat is counted. Then, in step 107, it is determined whether or not the number of peak data for the predetermined target detected at the downbeat is 2 or less. If the number of peak data is 2 or less, the process proceeds to step 108, in which the angle θ to be searched is increased by a predetermined angle α, and it is determined whether or not the search angle increased in the next step 109 exceeds the maximum allowable search angle θmax. If the increased search angle θ does not exceed the maximum allowable search angle θmax, the process returns to step 106, and steps 106 and 107 are repeated.
[0065]
In this way, the peak data search processing is performed by increasing the search angle θ by the predetermined angle α when the number of downbeat peak data becomes 3 or more in step 107 and when the search angle θ increased in step 109 becomes the maximum. The process is continued until the time exceeds the allowable search angle θmax. If the search angle θ increased in step 109 exceeds the maximum allowable search angle θmax, the process proceeds to step 111, and the routine ends without executing pairing for the target. On the other hand, if it is determined in step 107 that the number of peak data of the downbeat is 3 or more, the process proceeds to step 110.
[0066]
In step 110, it is determined whether or not the peak data searched for on the upbeat and the peak data detected on the downbeat satisfy the power difference condition. If the power difference condition is not satisfied, the process proceeds to step 111. This routine ends without performing pairing for this target. On the other hand, if the determination in step 110 satisfies the power difference condition, the flow advances to step 112 to perform pairing and end this routine.
[0067]
As described above, in the third embodiment, pairing for a certain target is always performed when the number of peak data is 3 or more, so that pairing can be performed accurately.
[0068]
FIG. 12 shows another example of the procedure of changing the angle condition of the pairing according to the present invention for pairing the target detected on the upbeat and the target detected on the downbeat in the radar apparatus. It is a flowchart. The procedure in FIG. 12 is also performed each time the antenna scans the front of the vehicle once and the reflected wave from the target is detected as peak data at the upbeat and the downbeat.
[0069]
In step 201, the angle for searching for peak data in the upbeat is set to the angle θu, and the angle for searching for peak data in the downbeat is set to the angle θd. In the following step 202, the number of peak data of a predetermined target in the upbeat and the downbeat is counted.
[0070]
Then, in step 203, it is determined whether or not the number of peak data for a predetermined target detected in the upbeat is 2 or less. If the number of peak data is 3 or more, the process proceeds from step 203 to step 204, where the value of the flag UBP indicating that the number of upbeat peak data exceeds 3 is set to 1, and the process proceeds to step 206. On the other hand, if the number of peak data is 2 or less, the process proceeds from step 203 to step 204, where the value of the flag UBP indicating that the number of upbeat peak data has exceeded 3 is set to 0, and the angle θu to be searched is set to a predetermined angle The value is incremented by α and the process proceeds to step 206.
[0071]
In step 206, it is determined whether or not the number of peak data for a predetermined target detected at the downbeat is 2 or less. If the number of peak data is 3 or more, the process proceeds from step 206 to step 207, where the value of the flag DBP indicating that the number of downbeat peak data exceeds 3 is set to 1, and the process proceeds to step 209. On the other hand, when the number of peak data is 2 or less, the process proceeds from step 206 to step 208, where the value of the flag DBP indicating that the number of downbeat peak data has exceeded 3 is set to 0, and the angle θd to be searched is set to a predetermined angle The process proceeds to step 209 after increasing by α.
[0072]
In step 209, it is determined whether the value of the flag UBP indicating that the number of peak data of the upbeat has exceeded 3 is 1 and the value of the flag DBP indicating that the number of peak data of the downbeat has exceeded 3 is 1. Determine whether or not. If UBP = 0 or DBP = 0, the process proceeds to step 210, and the search angle θu increased in step 205 exceeds the maximum allowable search angle θmax, or the search angle θd increased in step 208 becomes the maximum allowable search angle θmax. Is determined. If the increased search angle θu or θd does not exceed the maximum allowable search angle θmax, the process returns to step 202 and the processes from step 202 to step 209 are repeated.
[0073]
The process of searching for peak data while increasing the search angles θu and θd by the predetermined angle α in this manner continues until UBP = 1 and DBP = 1 in step 209. If any one of the search angles θu or θd increased in step 210 exceeds the maximum allowable search angle θmax in the middle of this processing, the process proceeds to step 213, and the pairing for this target is not executed. This routine ends. On the other hand, when it is determined in step 209 that UBP = 1 and DBP = 1, the process proceeds to step 211.
[0074]
In step 211, it is determined whether or not the absolute value of the angle difference (θd−θu) between the upbeat and the downbeat is within a predetermined angle, for example, 1.5 °. However, if it exceeds 1.5 °, the routine proceeds to step 213, where the routine is terminated without executing pairing for this target. In step 212, it is determined whether the peak data searched for in the upbeat and the peak data detected in the downbeat satisfy the power difference condition. If the power difference condition is not satisfied, the process proceeds to step 213. This routine ends without performing pairing for this target. On the other hand, if the determination in step 212 satisfies the power difference condition, the flow advances to step 214 to execute pairing and terminate this routine.
[0075]
As described above, in another example of the third embodiment, the pairing to a certain target is always performed when the number of peak data is 3 or more, so that the pairing can be performed accurately.
[0076]
Further, in the third embodiment, the number of peak data in the upbeat and the downbeat is detected and compared, and the smaller peak data number is matched with the larger peak data number (3 or more). The number of peak data for calculating the representative peak in the downbeat may be matched.
[0077]
In the above embodiment, the embodiment of the on-vehicle radar device has been described using the millimeter wave radar as an example, but the type of the radar is not particularly limited.
[0078]
【The invention's effect】
As described above, according to the in-vehicle radar devices of the first and second embodiments of the present invention, the determination of the continuity between the past target data and the current target data is based on the horizontal position condition of the target. In addition, since the angle condition is added, the continuity of the normal target can be determined regardless of the distance of the target from the vehicle. Further, according to the on-vehicle radar device of the third embodiment of the present invention, there is an effect that normal pairing can be performed regardless of the type of the target.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an overall configuration of a millimeter wave radar device that is a vehicle-mounted radar device according to the present invention.
2 (a) is a waveform diagram showing a change in a transmission wave and a reception wave with time when the relative speed with respect to a target in the millimeter wave radar device of FIG. 1 is V, and FIG. 2 (b) is a waveform diagram of FIG. FIG. 7C is a waveform diagram illustrating a change in frequency of a transmission wave, and FIG. 7C is a waveform diagram illustrating a state of occurrence of a beat which is a frequency shift between the transmission wave and the reception wave in FIG.
FIG. 3 is a graph showing detected angle-frequency characteristics when three targets are present in front of a vehicle, and is a diagram for explaining microprocessor grouping.
FIG. 4 is a flowchart showing an embodiment of a flow of a target recognition process of the microprocessor according to the present invention.
FIG. 5A is a diagram illustrating a conventional method of determining the continuity of a target, and FIG. 5B is a diagram illustrating the continuity of a target according to the present invention.
FIG. 6A is a diagram illustrating a problem in a conventional target continuity determination, and FIG. 6B is a diagram illustrating a target continuity determination according to the present invention.
FIG. 7 is a flowchart showing another embodiment of the flow of the target object recognition processing of the microprocessor of the present invention.
8A illustrates a predicted position of a target in the processing procedure of FIG. 7; FIG. 8B illustrates a problem of a conventional target continuity determination processing in the processing procedure of FIG. 7; FIGS. 8C and 8C are diagrams for explaining the target continuity determination processing of the present invention in the processing procedure of FIG.
FIG. 9 is a diagram illustrating a process of determining the continuity of a target according to the present invention in the process procedure of FIG. 7;
FIG. 10 is a diagram illustrating a conventional condition for pairing a target detected on an upbeat and a target detected on a downbeat in the radar apparatus.
FIG. 11 is a flowchart showing an example of a procedure for changing the angle condition of the pairing according to the present invention for pairing a target detected on an upbeat with a target detected on a downbeat in the radar apparatus. is there.
FIG. 12 shows another example of a procedure for changing the angle condition of the pairing according to the present invention for pairing a target detected on an upbeat and a target detected on a downbeat in the radar apparatus. It is a flowchart.
FIG. 13 is a diagram illustrating a process of expanding a search angle when the number of peak data is 2 or less.
[Explanation of symbols]
1. Antenna
2. Millimeter wave RF unit
3. Analog circuit
4 ... DSP
5. Microprocessor
6. Drive circuit
7 ... Motor
10. Millimeter wave radar device
20: Inter-vehicle distance control ECU

Claims (6)

Transmits a frequency-modulated signal, receives the signal reflected back from the target ahead of the vehicle, and detects the target ahead of the vehicle from the beat signal obtained by mixing these transmitted and received signals. A radar device, wherein continuity determination means for determining continuity between detected past target data and current target data based on conditions of a distance difference from the target, a relative speed difference, and a lateral position difference. In a vehicle-mounted radar device having
An on-vehicle radar device, wherein the determination condition of the continuity determination means is that one of a distance difference from a target, a relative speed difference, and a lateral position difference or an angle difference is satisfied. 2. The in-vehicle radar device according to claim 1, wherein the continuity determination unit uses a lateral position difference as the determination condition when the distance to the target is less than a predetermined value, and the continuity determination unit determines the continuity to the target. An angle difference is used as the determination condition when the distance is equal to or greater than a predetermined value. Transmits a frequency-modulated signal, receives the signal reflected back from the target ahead of the vehicle, and detects the target ahead of the vehicle from the beat signal obtained by mixing these transmitted and received signals. The radar device predicts the position of the current target from the detected past target data, and the position of the target in the currently detected target data is within a predetermined horizontal position range of the target in the predicted position data. In a vehicle-mounted radar device having continuity determining means for determining the continuity of the target by whether or not
The continuity determining means determines whether the horizontal position of the target detected this time is within a predetermined horizontal position range at the predicted position of the target, or is within a predetermined angle range at the predicted position of the target. An on-vehicle radar device characterized in that the continuity of the target is determined in either of the cases. 2. The in-vehicle radar device according to claim 1, wherein the continuity determining unit determines that the lateral position of the target detected this time is the prediction of the target when the distance to the target is less than a predetermined value. The continuity of the target is determined based on whether the position is within a predetermined horizontal position range at the position, and when the distance to the target is equal to or more than a predetermined value, the horizontal position of the target detected this time is determined by the target. A continuity of the target is determined based on whether the target position is within a predetermined angle range at the predicted position. Transmits a frequency-modulated signal, receives the signal reflected back from the target in front of the vehicle, and detects the target ahead of the vehicle from the beat signal obtained by mixing these transmitted and received signals. A peak data in an upbeat and a downbeat are grouped by a grouping unit to calculate a representative peak, and the representative peaks in the grouped beats are paired by a pairing unit. By this, in the vehicle-mounted radar device that detects the target,
When grouping the peak data by the grouping unit, a grouping angle setting unit that sets an angle to search for the peak data as a reference angle,
Peak data number determination means for determining whether the number of peak data searched within the reference angle is equal to or greater than a predetermined number,
When the number of peak data is less than a predetermined number, the reference angle in a beat in which the number of peak data is less than a predetermined number, a grouping angle increasing unit that increases by a predetermined angle,
Grouping angle limiting means for determining whether the increased grouping angle has exceeded an allowable maximum angle, and
When the grouping angle exceeds the maximum allowable angle, the pairing means stops pairing the target. Transmits a frequency-modulated signal, receives the signal reflected back from the target in front of the vehicle, and detects the target ahead of the vehicle from the beat signal obtained by mixing these transmitted and received signals. A peak data in an upbeat and a downbeat are grouped by a grouping unit to calculate a representative peak, and the representative peaks in the grouped beats are paired by a pairing unit. By this, in the vehicle-mounted radar device that detects the target,
When grouping the peak data by the grouping unit, a grouping angle setting unit that sets an angle to search for the peak data to a predetermined angle,
Peak data number comparing means for comparing the number of peak data searched within the predetermined angle,
When the peak data numbers do not match, a grouping angle changing unit that changes the predetermined angle in the bead with the smaller peak data number is provided,
An on-vehicle radar device, wherein the number of peak data for calculating the representative peak in the upbeat and the downbeat is matched.

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