JP3147675B2 - Radar equipment for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular radar apparatus for automatically detecting the presence of a preceding vehicle and the distance to the preceding vehicle.

[0002]

2. Description of the Related Art Conventionally, a certain vehicle emits a pulse signal in the forward direction, and the signal is reflected from a target ahead to receive a signal from a returning direction to automatically process a distance to a preceding vehicle. FIG. 16 shows a configuration of a vehicle radar device that detects an object. This conventional radar apparatus for a vehicle includes a pulse signal transmission circuit 1 for periodically transmitting a pulsed signal such as an electromagnetic wave and a laser beam to the outside, and a signal transmitted by the pulse signal transmission circuit 1 for a target ahead. The radar head 3 includes a reflected signal receiving circuit 2 that continuously receives a signal from the direction of reflection and returns and binarizes the signal in accordance with the signal intensity. Further, a sampling circuit 4 for sampling a binarized signal from the reflected signal receiving circuit 2 of the radar head 3 at each of a plurality of different sampling points after the signal transmission timing of the pulse signal transmission circuit 1.
And an addition circuit 5 for adding a predetermined number of sampling values for each sampling point sampled by the sampling circuit 4, and comparing the addition value for each sampling point obtained by the addition circuit 5 with a predetermined threshold value. By determining that a preceding vehicle is present at a forward position corresponding to the sampling point by finding a sampling point indicating an added value exceeding the threshold value, and a determination circuit 6 for outputting the distance information, and control for controlling the operation of each of these circuits. The circuit 7 is provided.

In such a conventional vehicle radar device,
The pulse signal sending circuit 1 periodically outputs a pulse signal to the outside. A signal from the direction in which the reflected signal receiving circuit 2 returns the transmitted signal to the target (the signal contains not only the reflected signal but also many other noises entering from that direction). Are continuously received, converted to a binary signal depending on whether the signal level exceeds or does not exceed a certain signal level, and continuously output. The sampling circuit 4 samples the binarized signal at each of a plurality of sampling points at different times after the transmission timing of the pulse signal transmission circuit 1 to obtain a sampled value of 0 or 1 and provides the sampled value to the addition circuit 5; The addition is performed by the addition circuit 5 for each sampling point. The number of additions at each sampling point of the addition circuit 5 is equal to the predetermined number of transmissions of the pulse-like signal repeatedly transmitted by the pulse signal transmission circuit 1 at a constant cycle (usually,
When the sampling and adding process for the predetermined number of times is completed, an added value for each sampling point is output to the determination circuit 6.

Therefore, a determination circuit 6 compares the added value for each sampling point with a predetermined threshold value, and determines whether or not there is a sampling point at which a reflected signal from an external target exists based on the magnitude of the addition value. When it is determined that there is a reflected signal from the target, the transmitted signal is further propagated within the elapsed time from when the signal is transmitted by the pulse signal transmitting circuit 1 to when it is received at a sampling point indicating an added value larger than a predetermined threshold. The distance to the vehicle is calculated, the distance to the target in front of the vehicle is automatically calculated and displayed on a display device (not shown) to notify the driver.

[0005]

However, such a conventional vehicle radar apparatus has the following problems. That is, as shown in FIG.
In order to detect only the vehicle 10 traveling ahead of the own vehicle traveling lane 9 as a target, the reflected pulse detection range 1
1 is also limited to the own vehicle traveling lane 9. For this reason, as shown in FIG. 18, when the interrupting vehicle 13 is in a short distance range from the adjacent traveling lane 12, the detection may be delayed because it is out of the signal detection range 11.

Therefore, conventionally, as shown in FIG. 19, a plurality of pulse signal transmitting elements are prepared in the pulse signal transmitting circuit 1 of the radar device 8 in order to extend the detection range 14 of the reflected pulse in the short range. There has been proposed a laser light emitting device having a characteristic having a large intensity and a narrow range for use for an LED, and an LED light emitting device having a characteristic having a small intensity but a wide range for a short range.

However, even in such a proposed vehicle radar device 8, a range 15 in which a reflected pulse cannot be detected occurs in the intermediate range as shown in FIG. If the stop-in car 13 interrupts, the detection may still be delayed.

In order to solve these problems, FIG.
When the detection range 16 is expanded as shown in FIG. 7, not only the vehicle 10 in the driving lane 9 of the own vehicle but also the vehicle 17 in the adjacent lane 12 will be detected, and the detection accuracy may be deteriorated. is there.

The present invention has been made in view of such a conventional problem, and is capable of accurately detecting a target located in front of a traveling lane of a vehicle equipped with the present apparatus from a short distance to a long distance. It is an object of the present invention to provide a vehicular radar device that can be used.

[0010]

According to a first aspect of the present invention, there is provided a radar apparatus for a vehicle, comprising: a transmitting means for periodically transmitting a pulse signal to the outside; and a signal transmitted by the transmitting means being reflected on a target. Receiving means for continuously receiving a signal from the returning direction; binarizing the signal received by the receiving means; sampling at a plurality of sampling points having different elapsed times from the signal sending timing of the sending means; Sampling means, adding means for adding the sampling value of the sampling means for each predetermined number of transmissions for each sampling point, threshold setting means for individually setting a threshold for each sampling point,
Distance calculating means for comparing the added value of each sampling point of the adding means with the threshold value of each sampling point provided by the threshold value setting means, and calculating the distance corresponding to the sampling point providing the added value larger than the threshold value as the distance to the target. It is provided with.

In the radar apparatus according to the first aspect of the present invention, the transmitting means periodically outputs a pulse signal to the outside, and receives the signal from the direction in which the transmitted signal is reflected by the target and returned. Receive continuously by means. The signal received by the receiving means is binarized by the sampling means depending on whether the signal level exceeds or does not exceed a predetermined signal level, and the binarized signal is converted at each of a plurality of sampling points at different times after the sending timing of the sending means. Sampling is performed to obtain a sampling value of 0 or 1, and this is added by a predetermined number of pulse signal transmission times for each sampling point by an adding unit.

When the addition process for a predetermined number of times is completed, the distance calculation means compares the addition value for each sampling point of the addition means with a predetermined threshold value, and based on the magnitude, a reflected signal from an external target exists. Is determined, and based on this, the presence or absence of an external target is determined.

Here, when there is no external target and the receiving means receives only noise, the noise signal has the probability that 0 appears as a binary signal because the signal level appears equally on both the positive and negative sides. The probability that 1 appears is constant. Therefore, an addition value obtained by adding only the noise at a certain sampling point for the predetermined number of times Na indicates a substantially constant value Na / 2.

On the other hand, since the reflected signal in which the pulse-shaped transmission signal is reflected on an external target is biased in either the positive or negative direction, the reflected signal is received and binarized to be 0. The probability and the probability of becoming 1 are not constant depending on the waveform of the received signal. Therefore, if there is a signal reflected on the target in the binarized signal at a certain sampling point, the added value of the sampling point shows a value different from that for the background noise.

Therefore, a threshold value is individually set for each sampling point by the threshold value setting means, and when a distance calculation means finds a sampling point indicating an added value exceeding the threshold value, the threshold value is set at a position in front of the sampling point. By determining that the target exists, the presence of the target and the distance to it are accurately detected.

According to a second aspect of the present invention, there is provided the vehicle radar device according to the first aspect, wherein the threshold is set for each sampling point by the threshold setting means, and the target exists somewhere in the running lane width for each sampling point. Is the lowest value of the added value obtained by the adding means.

Therefore, even if the target exists at any point in front of the traveling lane on which the vehicle equipped with the radar device is traveling, the existence and the distance can be accurately detected. In particular, it is possible to accurately detect an interrupted vehicle from an adjacent traveling lane.

According to a third aspect of the present invention, in the vehicle radar device of the second aspect, the threshold for each sampling point set by the threshold value setting means is slightly wider than the traveling lane width for each sampling point corresponding to a short distance range. When the target exists somewhere in the width, the minimum value of the added value obtained by the adding means is used.

Therefore, it is possible to accurately and quickly detect an interrupting vehicle in a short distance range in which it is necessary to detect the interrupting vehicle promptly.

According to a fourth aspect of the present invention, there is provided a vehicle radar apparatus comprising: a transmitting means for periodically transmitting a pulsed signal to the outside; and a signal transmitted from the transmitting means reflected from a target and returned from the target. Receiving means for continuously receiving a signal, sampling means for binarizing the signal received by the receiving means, and sampling for each of a plurality of sampling periods having different elapsed times from the signal sending timing of the sending means, and sampling means Integrating means for integrating a sampling value for each sampling period for each predetermined number of transmissions,
Threshold value setting means for individually setting a threshold value for each sampling period; and sampling for providing an integral value larger than a predetermined threshold value by comparing an integral value of each sampling period of the integrating means with a threshold value for each sampling period provided by the threshold value setting means. Distance calculating means for calculating the distance corresponding to the period as the distance to the target.

In the vehicle radar apparatus according to the fourth aspect of the present invention, the transmitting means periodically outputs a pulse-like signal to the outside, and the transmitted signal is reflected from the target and returned from the direction of the signal. Is continuously received by the receiving means. Then, the instantaneous value of the signal received by the receiving means is binarized by the sampling means depending on whether the signal level exceeds or does not exceed a certain signal level, and further, for each sampling period in which a plurality of time zones after the sending timing of the sending means are different. The binarized signal is sampled to obtain a sampled value of 0 or 1 and supplied to the integrating means. Therefore, the integrating means integrates the binarized signal for each predetermined number of transmissions of the signal by the transmitting means for each sampling period.

When the integration process for the predetermined number of times is completed, the distance calculation means compares the integrated value for each sampling period integrated by the integration means with a predetermined threshold value, and based on the magnitude, the reflected signal from the external target is calculated. It is determined whether or not it exists, and based on this, the presence or absence of an external target is determined, and the distance to that point is calculated.

Here, when there is no external target and the receiving means receives only noise, the noise signal has the probability that 0 appears as a binary signal because the signal level appears equally on both the positive and negative sides. The probability that 1 appears is constant. Therefore, the integration value obtained by integrating only the noise binarized signal input during the certain sampling period for the predetermined number of times Na shows a substantially constant value.

On the other hand, since the reflected signal in which the pulse-shaped transmission signal is reflected on the external target is biased in either the positive or negative direction, the reflected signal is received and binarized to be 0. The probability and the probability of becoming 1 are not constant depending on the waveform of the received signal. Therefore, 2 in a certain sampling period
If there is a signal reflected on the target in the quantified signal,
The integrated value during the sampling period shows a large value different from that for the background noise.

Therefore, a threshold value is individually set for each sampling point by the threshold value setting means, and when a sampling period showing an integral value exceeding the threshold value is found by the distance calculating means, the threshold value is set at a front position corresponding to the sampling period. By determining that the target exists, the presence of the target and the distance to it are accurately detected.

According to a fifth aspect of the present invention, there is provided the vehicle radar device according to the fourth aspect, wherein the threshold value for each sampling period set by the threshold value setting means is such that the target exists somewhere in the running lane width for each sampling period. Is the lowest value of the integral value obtained by the integrating means.

Therefore, even if the target exists at any point ahead of the traveling lane in which the vehicle equipped with the radar device is traveling, the existence and the distance can be accurately detected. In particular, it is possible to accurately detect an interrupted vehicle from an adjacent traveling lane.

According to a sixth aspect of the present invention, in the vehicle radar device of the fourth aspect, the threshold value for each sampling period set by the threshold value setting means is slightly wider than the traveling lane width for each sampling period corresponding to a short distance range. When the target exists somewhere in the width, the minimum value of the integration value obtained by the integration means is used.

Therefore, it is possible to accurately and promptly detect an interrupting vehicle in a short distance range where it is necessary to detect the interrupting vehicle promptly.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a circuit configuration of a common embodiment of the first and second aspects of the present invention. The radar head 21 includes a pulse signal transmitting circuit 22 for transmitting a pulse signal and a reflected signal receiving circuit 23 for receiving a reflected pulse. The sampling adder 24 is roughly divided into the reflected signal receiving circuit 2
3 is provided with a sampling circuit 25 for sampling the received signal and an adding circuit 26 for sequentially adding the sampling result for each sampling point. The arithmetic circuit 27
It has a function of mainly determining the presence or absence of a reflected pulse from the data of the adding circuit 26 and calculating the distance to the reflected target.
A threshold setting circuit 29 for individually setting a threshold as a criterion for determining the presence or absence of a reflected pulse is connected for each sampling point, and a display device 30 for displaying a distance calculation result is connected.

The control circuit 31 has a function of controlling the driving of the entire radar device, that is, the driving of the pulse signal transmission circuit 22, a function of controlling the activation of the sampling circuit 25 and the addition circuit 26 of the sampling addition section 24, and the activation of the arithmetic circuit 27. It has a function to control

The above-mentioned pulse signal sending circuit 22 is composed of a first driving circuit 22a-1 for a short distance range and a second driving circuit for a long distance range which are driven in accordance with a trigger signal output from a control circuit 31. 22a-2 and these drive circuits 2
LED light emitting element 22b-1 for the short range and laser diode light emitting element 22b-2 for the long range that emit light in response to driving of 2a-1 and 22a-2, and these light emitting elements 22b-1 and 22b-2. It is composed of lenses 22c-1 and 22c-2 for condensing each light emission toward a predetermined irradiation range. Then, the first driving circuit 22a-1 for the short distance range and the second driving circuit 22a-2 for the long distance range are driven together, and the light emitting element 22b-
When both the light emitting devices 1 and 22b-2 emit light, as shown in FIG. 3, the entire surface of the traveling lane 9 on which the automobile on which the radar device 20 is mounted is traveling from the short range to the long range is displayed. The setting is made so as to have a light transmission range 32 that covers with a margin.

The reflected signal receiving circuit 23 receives the incoming light from the outside (including the reflected light that is reflected and returned from the target ahead) and receives the reflected light inside (ie, a light receiving surface of a photodiode or the like). 23a that focuses light while focusing toward the light source, and a light receiving element 23 such as a photodiode that converts light transmitted through the lens 23a and collected into an electric signal
b, a limiter amplifier 23c for appropriately amplifying the electric signal output from the light receiving element 23b, and binarizing the output of the limiter amplifier 23c in accordance with positive and negative, converting the output to a logic level (for example, 5V and 0V), And outputs the zero cross comparator 23d.

FIG. 2 is a timing chart of various signals. The transmission pulse (1) is transmitted from the control circuit 31 to the drive circuit 22.
a-1 and 22a-2 are pulse signals that are repeatedly input a predetermined number of times Na, for example, 8000 times at predetermined intervals, for example, every 4 μs, for example, 8000 times.
2a-1, 22a-2 are light emitting elements 22b-1,
The light transmission pulse signal is transmitted a predetermined number of times repeatedly so as to cover the light transmission range 32 shown in FIG.

The received signal (2) in FIG.
a and an instantaneous signal received by the limiter amplifier 23c through the light receiving element 23b. The received signal (2) is binarized by the zero-cross comparator 23d according to the sign of the signal, and the binarized signal is sampled by the sampling circuit. 25. This received signal (2) together with a noise signal
At each transmission timing of the transmission pulse (1), a delay time Td proportional to the distance from the transmission timing to the time when the light transmission pulse signal hits the front target and is reflected back.
The reflected pulse Rf appears at a position delayed by a minute.

The sampling pulse (3) is sent from the control circuit 31 to the sampling circuit 2 every time the output pulse (1) is output.
5 whose period is Δt (for example,
66.7 ns). The binarized instantaneous value of the received signal (2) is given to the addition circuit 26 at each ON timing of each sampling pulse (3), that is, at each sampling point, and the addition circuit 26 performs distance measurement once for each sampling point. During the operation process, a predetermined number of times Na is repeatedly added.

The above-described addition circuit 26 has n memories M1 to Mn corresponding to sampling pulses 1 to n (for example, n = 14), and the memory M1 performs sampling at a first sampling point. If the value is "1", it is added to the previous stored value, and if the value sampled at the second sampling point is "1", the memory M2 adds 1 to the previous stored value. The processing is continuously performed up to the memory Mn corresponding to the n-th sampling pulse, and the above addition and storage processing is repeated a predetermined number of times Na.

When the addition processing of the predetermined number of times Na is completed as one distance measurement operation, the arithmetic circuit 27 reads the added value of each of the memories M1 to Mn of the addition circuit 26 and receives the received signal (2).
It is determined whether or not a reflected pulse Rf corresponding to the light transmission pulse signal is included in the signal, and the time delay from the transmission pulse timing to the sampling point at which the reflected pulse is detected is determined based on the sampling pulse period Δt. Measure. That is, the time Td = m · Δt (when the reflected pulse is detected at the m-th sampling point) until the reflected pulse is detected is calculated. Here, when the binarized data sampled by the sampling circuit 25 has no target and includes only noise in the received signal, since the signal wave is random, the appearance of “1” and “0” appears. The probability is 1/2 of Na (the value obtained by dividing the addition value by the number of additions Na and being normalized is 0.5). If there is a target, the probability of Na / 2 being changed from Na / 2 to the SN ratio of the received signal. An added value between the values (between 0.5 and 1 in a normalized value) is obtained.

The presence or absence of the reflected pulse Rf is determined as follows. The addition data at each sampling point as shown in FIG. 2D is read from the addition circuit 26 and divided by 8000 which is the number of additions Na to obtain a normalized value.
This is converted to sampling points 1 to n by the threshold setting circuit 29.
Each of the normalized addition values of the sampling points i is compared with the threshold values TH1 to THn set in advance for each of the threshold values TH1 to THn.
It is determined whether Hi is exceeded. (The method of setting the threshold value for each sampling point is a feature of the present invention and will be described later.) Next, the peak detection circuit 28 compares the comparison result between the threshold value for each sampling point of the arithmetic circuit 26 and the added value. And the peak position is detected here. In the peak position detection process, as shown in FIG. 2 (5), the maximum value of the sampling addition output and the sampling point showing the next largest value are found, and the addition value of the peak point and the sampling points before and after the peak point is determined. Are connected by a straight line, the intersection of the two straight lines is determined, the temporal position of the intersection is determined, and the distance is converted to a distance.
Here, if the peak of the received light signal is steep and there is only one sampling point exceeding the threshold value, the sampling point is output as the temporal position data of the peak.

The arithmetic circuit 27 converts the temporal position data of the peak given from the peak detecting circuit 28 into the light emitting element 22.
The light transmission pulse signal is emitted from b-1 and 22b-2, and is converted into the spatial distance to the target from the relationship between the time required for the light signal speed to be emitted from the target and reflected back to the target. The distance data is output to and displayed on the display device 30 to inform the driver.

Along with the output of the distance calculation result, the arithmetic circuit 27 supplies a distance measurement processing completion signal to the control circuit 31, and the control circuit 31 starts a new distance measurement operation.

Next, in such a distance measuring process, the threshold value setting circuit 29 for individually setting the threshold value for each sampling point used by the arithmetic circuit 27 to determine the presence or absence of the reflected pulse Rf.
The function of will be described. As shown in FIG. 3, the range 32 irradiated by the light emitting elements 22 b-1 and 22 b-2 of the radar head 21 is adjusted by adjusting the condenser lenses 22 c-1 and 22 c-2 so that the vehicle on which the radar device 20 is mounted is mounted. The driving lane 9 is set to be slightly wider than one lane width.

At this time, a certain sampling point (in FIG. 3, a position separated from the radar device 20 by a certain distance is shown. FIG. 4 shows a distribution state of the added value when a small reflective target is placed at each point in the AOB direction (a direction crossing the traveling lane 9) and distance measurement is performed. As shown. That is, the added value when the reflective target is placed at the center point O of the traveling lane 32 is the largest, and the added value decreases as the target is shifted in the outer A and B directions.

FIG. 5 is a graph in which the experimental results are plotted, and the center point of the traveling lane, a point shifted by 0.5 m, a point shifted by 1.0 m at each of the points 30 m, 40 m, 50 m and 60 m ahead. 12 is a graph showing a result obtained by placing a reflection target at each of a point shifted by 1.5 m and a point shifted by 2.0 m, and performing a distance measurement in which a radar apparatus repeats 8000 addition processes in a single distance measurement process. The light emitting element used at this time was an LED having an output of 150 mW, and the light was transmitted using a condenser lens having a diameter of 2 cm and a focal length of 2.5 cm.

As can be seen from the experimental results, assuming that the width of the driving lane is 1.5 m on one side from the center O and the total width is 3.0 m, the short distance from 0 to 60 m, which is dangerous especially when there is a sudden interruption, is considered. In order to accurately detect a target entering the traveling lane 32 in the range, 0 to 4 as shown in FIG.
At the 0 m point, an additional value of about 5000 (a normalized value of 0.
63), about 4900 at the 50 m point (0.61 in normalized value), and 4700 lower at 60 m.
Degree (normalized value is about 0.59), and if it exceeds that, about 4500-4200 (normalized value is 0.55
By setting a threshold value to about 0.52), the detection range 33 is set so as to detect only targets existing on one lane width of the traveling lane 9 of the radar device 20 as shown in FIG. Will be able to

That is, as shown in FIG. 3, when the threshold value is uniformly set without changing the threshold value for each sampling point, the detection range becomes the range indicated by reference numeral 32, and the preceding vehicle 34 and the forward What detected not only the interrupting vehicle 35 but also the traveling vehicle 36 in the adjacent lane 12
As shown in FIG. 7, the traveling vehicle 36 in the adjacent lane 12 is not erroneously detected, and only the vehicle interrupting ahead of the traveling lane 9 of the own vehicle can be accurately and distinctively detected.

Next, the distance calculation processing in the arithmetic circuit 27 will be described with reference to the flowchart of FIG. First, it is assumed that the above-described thresholds TH1 to THn for each sampling point are set in the threshold setting circuit 29 in advance. This threshold value is slightly different depending on the vehicle and the individual difference of the light emitting element and the lens. Therefore, the threshold value is adjusted and set by the manufacturer at the manufacturing stage. However, the settings can be changed as needed.

Therefore, when the sampling is completed a predetermined number of times Na in one distance measurement process, the arithmetic circuit 27 is switched to the addition circuit 2
6 is read out for each sampling point, and a predetermined uniform preliminary determination threshold (this is N
(a is about 4100 when a is 8000 times, and about 0.51 in a normalized value) (steps S1 and S1).
2). This preliminary determination is to avoid the fact that performing the following processing in a case where there is no reflective target at all is wasteful and delays the determination of no target. Therefore, it is possible to quickly determine that there is no target by this preliminary determination.

If there is a target in the preliminary determination (step S3), a normal threshold value for each sampling point exceeding the preliminary determination threshold value is read from the threshold value setting circuit 29 (step S4) and compared with those threshold values. (Step S5).

Here, if there is no added value exceeding the regular threshold, it is determined that there is no target, and the distance measurement processing is terminated (step S9). As described above, the fact that there is a sampling point indicating an added value that exceeds the threshold value for the preliminary determination but does not exceed the normal threshold value means that the vehicle is traveling on an adjacent lane at a distance position corresponding to the sampling point. Although a vehicle may be detected, such a vehicle is not detected by the logical processing, and only the vehicle on the own traveling lane is accurately detected.

If it is determined that there is a target in the comparison with the normal threshold value in step S5 (step S6), if there are a plurality of points exceeding such a threshold value, the peak point is calculated by the above-described peak detection circuit 28, and If only the point exceeds the threshold, the point is determined, the point is converted into a corresponding distance, and displayed on the display device 30 (step S).
7, S8).

As described above, in the vehicle radar apparatus of this embodiment, the threshold value for judging the presence / absence of the target is individually set for each sampling point, and the threshold is compared with the added value at each sampling point. Since the presence / absence is determined and the distance is calculated, the light-emitting element and condenser lens are accurately adjusted so that the light-transmitting pulse signal reaches only the front of the traveling lane of the vehicle on the radar head side as in the past. Even if it is not performed, it is possible to accurately determine only the target in the traveling lane of the own vehicle by individually setting the threshold value for each sampling point, and the range of the light transmission pulse signal slightly extends to the adjacent lane Even if the size is large, the detection range can be narrowed down to the own vehicle lane on the threshold value side, and the target detection and the distance measurement without a blind spot can be performed.

As a common embodiment of the first and third aspects of the present invention, as shown in FIG. 9, the range 32 in which the light transmission pulse signal reaches is the same as that of the first embodiment shown in FIG. For example, in order to detect a dangerous interrupting vehicle more quickly, especially in the range of 20 m to 40 m, the lane 12 may be set in order to quickly detect a dangerous interrupting vehicle.
The threshold value for each sampling point can be set lower so that the detection can be performed a little wider, and the detection range 37 can be set as indicated by hatching. In other words, in the experimental example shown in FIG. 5, a threshold value that can be detected from the lane center O to the outside of 2.0 m is set.
What was about 0.6 in the first embodiment is reduced to about 0.55.

Next, an embodiment common to the fourth and fifth aspects of the present invention will be described with reference to FIGS. A feature of the invention according to claims 4 and 5 is that a sampling integrator 41 is provided instead of the sampling adder 24 in the first embodiment, and the sampling integrator 41 is provided.
A calculation circuit 44 for calculating the position where the reflection target exists by comparing the integrated data for each sampling period (hereinafter referred to as a range block) obtained by the above with a threshold value, a peak detection circuit 45 for performing peak detection, A threshold setting circuit 46 for individually setting a threshold for judging the presence / absence of a target is provided for each range block, and other components are common to those of the first embodiment. Omitted.

The sampling integrator 41, which is a characteristic part of the second embodiment, comprises a receiving circuit 23 of the radar head 21.
A switching circuit 42 for switching the integral range block one by one for each sampling pulse period Δt, and a binary instantaneous value for switching the integral range block for each sampling pulse. It is composed of an integrating circuit 43 that integrates every Δt and repeats this integration process Na times (= 8000 times) every 4 μs in one ranging process.

The switching circuit 42 receives a sampling pulse signal having a period Δt from the control circuit 31 and outputs an ON signal for each sampling pulse period Δt to the integrating circuit 43.
Of the integration circuit 43 by receiving the end pulse indicating the end of the distance measurement process from the control circuit 31 when the one-time distance measurement process is completed by repeating the processing for sequentially giving each range block of Na and the sampling of Na times. A process of giving a switching signal for outputting the integrated data to each range block is performed.

The integration circuit 43 has the internal configuration shown in FIG. 11, and repeats Na times for each of a plurality of n range blocks (sampling periods) to convert the binarized instantaneous value signal into the time width Δt of the range block (= the sampling pulse period). In order to integrate each of the input analog switches 43a-1 to 43a-n, the input analog switches 43a-1 to 43a-n are controlled by the above-described switching circuit 42 in order to integrate the input analog switches 43a-1 to 43a-n. N RC integrators 43b-1 to 43b-n for integrating the binarized signals input from each of them during their on-time, and controlled by the above-described switching circuit 42, these integrators 43b-1 to 43b -N is composed of n output analog switches 43c-1 to 43c-n for outputting respective integrated values.

As shown in FIG. 12, each of the input analog switches 43a-1 to 43a-n is connected to a switching circuit 42.
ON / OFF is sequentially switched for each of the range blocks # 1 to #n by a time width Δt by the input switching signal 47 from the input device and the output analog switches 43c-1 to 43c.
The switch -n is sequentially switched on / off by an output switching signal 48 from the switching circuit 42. That is, each of the input analog switches 43a-1 to 43a-n of the integration circuit 43 is turned on by the input switching signal 47 when the signal corresponding to the own switch is the "H" signal, and turned off when the signal is switched to "L". During the ON state, the binarized instantaneous value signal is output to the integrator 43b-
The binarized signal is output to the integrator of the corresponding range block among 1 to 43b-n and charged by the capacitor to integrate the binarized signal by the sampling period Δt. And n input analog switches 43a-1 to 43a-n
Is turned on / off once each time, and when one integration operation is completed, the next integration operation is repeated in synchronization with the next transmission pulse, and the above integration operation is repeatedly output for a predetermined number of times Na Repeat several times.

Output analog switch 43 of integrating circuit 43
Each of c-1 to 43-n is turned on when a signal corresponding to its own switch among the output timing signals 48 becomes "H", turned off when switched to "L", and turned on during the on state. Integrators 43b-1 to 43b-1 connected to the own switch
The integrated values of 43b-n are sequentially output to the arithmetic circuit 44.

When the arithmetic circuit 44 receives the integrated values of all n integrators 43b-1 to 43b-n,
After this is normalized, scanning is performed to determine whether there is any range block exceeding each of the threshold values TH1 to THn individually set by the threshold setting circuit 46 for each range block in order to identify the noise level.

The normalized value of the integral value can be calculated by the following procedure, for example. In a certain integration range block, if the input binary instantaneous value signal is always “1” during one sampling period Δt, it is integrated Na times (8000 times in this embodiment). Is set to 1 when the integration is repeated, and when the integration is repeated Na times for the same sampling period Δt when there is only external noise, the integration voltage obtained when the integration is repeated is 0.5. This is the value when the integrated voltage value is proportionally distributed among these reference values. That is, the integrated voltage value for the entire period “1” is S
1. The noise level integrated voltage value is S2, and the normalized integrated value s of the obtained integrated voltage value S is given by the following equation.

S = 0.5S / (S1−S2) By normalizing in this way, the value becomes 0.5 in the case of only noise, and becomes 0. 0 in accordance with the SN ratio if the reflected pulse by the target is included. It will be distributed between 5 and 1. Therefore, as shown in FIG. 13, if a range block indicating a normalized integral value exceeding a threshold value, for example, a range block of #i is detected, the operation time 44 is from the transmission timing until a reflected pulse is detected in the range block. Is obtained by τ = Δt × i, and the distance to the target is calculated by multiplying the distance corresponding to one range block by, for example, 10m for i in increments of 10m, and displaying the distance data. Output to the device 30 for display.

In FIG. 13, the normalized integral value is plotted in correspondence with the center position of each range block. However, this is for convenience sake in order to show the integral value in correspondence with each range block. , And does not actually show the integral value of the intermediate position for each range block. That is, the # 1 range block is 0 m, the # 2 range block is 10 m, the # 3 range block is 20 m,..., The #i range block is (i-
1) × 10 m,... Indicate sampling periods corresponding to the respective positions.

Next, when there are a plurality of range blocks exceeding the threshold value in comparison with the threshold value of each range block at a plurality of points, the arithmetic circuit 44 outputs this to the peak detection circuit 45, where the peak position is detected. As shown in FIG. 14, the peak position is detected by the range blocks # i + 2 and # i + 1 indicating the maximum value a1 of the integrated output and the next largest value a2.
Are found, and the points and the integral values of the range blocks before and after the points are connected by straight lines A1 and A2, an intersection a of the two straight lines is obtained, a time position of the intersection is calculated by a proportional calculation, and the calculation circuit 44 Then, the arithmetic circuit 44 converts the time position of the peak point a into a distance and outputs it to the display device 30.

Along with the output of the distance calculation result, the arithmetic circuit 44 outputs a new start command to the control circuit 31 to start the next distance measuring process.

Next, a method of individually setting a threshold value for each range block in the threshold value setting circuit 46 will be described. Also in the vehicle radar device of the second embodiment, the pulse signal transmission circuit 22 is adjusted so that the traveling pulse signal can be applied to the irradiation range 32 shown in FIG. 3 as in the first embodiment.
At each sampling point, a distribution state of the integrated value when a small reflective target is placed at each point in the AOB direction (a direction crossing the traveling lane 9) and distance measurement is performed, and a boundary point of one lane width is determined. Compare the integrated value obtained in the corresponding range block when measuring with the target at the target and the integrated value of the corresponding range block when measuring with the target outside the target, and calculate those integrated values. An integral value that can be identified is set as a threshold value in the range block. That is, when the target is placed at a position 1.5 m outside the center O of each sampling point, the integral value of the corresponding range block is s1,
Assuming that the integral value of the corresponding range block when the target is placed outside the position is s2, the threshold value is set to be slightly smaller than s1 within a range that does not become smaller than s2.

The threshold value for each range block in the second embodiment is set in substantially the same manner as in the case shown in FIG. 6, that is, as shown in FIG. About 0.63, at the 50m point, the normalized value is 0.1.
61, and about 0.59 lower at 60m,
Then, by setting the threshold value to about 0.55 to 0.52 when it exceeds the threshold value, the radar apparatus 2 is set as shown in FIG.
The detection range 33 can be set so as to detect only targets existing on one lane width of the traveling lane 9 of zero.

As described above, according to the second embodiment, similarly to the first embodiment shown in FIG. 7, in the related art, the threshold value is uniformly set without changing the threshold value for each range block (each sampling period). As a result, the detection range becomes the range indicated by reference numeral 32, and not only the preceding vehicle 34 and the interrupting vehicle 35 in the long range are detected, but also the traveling vehicle 36 in the adjacent lane 12 is detected. Therefore, the traveling vehicle 36 in the adjacent lane 12 is not erroneously detected, and only the vehicle that is interrupted ahead of the traveling lane 9 of the own vehicle can be accurately and distinctively detected.

Next, the distance calculation processing by the arithmetic circuit 44 will be described with reference to the flowchart of FIG. First, it is assumed that the above-described threshold values TH1 to THn for each range block are set in the threshold value setting circuit 46 in advance.
This threshold value is slightly different depending on the vehicle and the individual difference of the light emitting element and the lens. Therefore, the threshold value is adjusted and set by the manufacturer at the manufacturing stage. However, the settings can be changed as needed.

When the sampling of a predetermined number of times Na is completed in one distance measurement process, the arithmetic circuit 44 sets the integration circuit 4
3 and reads the integrated value data for each range block, and compares the normalized integrated value with a preset uniform pre-determination threshold value (this is about 0.51 in the normalized value) (step S11, S12). This preliminary determination is to avoid the fact that performing the following processing in a case where there is no reflective target at all is wasteful and delays the determination of no target. Therefore, it is possible to quickly determine that there is no target by this preliminary determination.

If there is a target in the preliminary determination (step S13), a normal threshold value for each range block exceeding the threshold value for the preliminary determination is read from the threshold value setting circuit 46 (step S14) and compared with those threshold values. (Step S1
5).

Here, if there is no normalized integral value exceeding the normal threshold value, it is determined that there is no target, and the distance measuring process is terminated (step S19). As described above, the fact that there is a range block indicating an integral value that exceeds the threshold value for the preliminary determination but does not exceed the normal threshold value means that the vehicle is traveling on an adjacent lane at a distance position corresponding to the range block. Although a vehicle may be detected, such a vehicle is not detected by the logical processing, and only the vehicle on the own traveling lane is accurately detected.

If it is determined that there is a target in the comparison with the regular threshold value in step S15 (step S16), if there are a plurality of points exceeding such a threshold value, the above-described peak detection circuit 45 finds a peak point, and If only the point exceeds the threshold value, the point is determined, converted to a corresponding distance, and displayed on the display device 30 (steps S17, S18).

As described above, in the vehicle radar apparatus of this embodiment, the threshold value for judging the presence / absence of the target is individually set for each range block, and the threshold value is compared with the normalized integral value for each range block. Since the presence / absence of the target is determined and the distance is calculated, the light emitting element and the condensing lens are accurately set so that the light transmission pulse signal reaches only the front of the traveling lane of the vehicle on the radar head side as in the past. Even if adjustment of the threshold is not performed, it is possible to accurately determine only the target in the traveling lane of the own vehicle by individually setting the threshold value for each range block, and the range of the light transmission pulse signal reaches the adjacent lane. Even if the area slightly protrudes, the detection range can be narrowed down to the own vehicle lane on the threshold value side, so that target detection and distance measurement without blind spots can be performed.

As a common embodiment of the fourth and sixth aspects of the present invention, as shown in FIG. 9 as a modification of the first embodiment, the range 32 in which the light transmission pulse signal reaches is 1. Set in the same manner as in the second embodiment. In order to detect a dangerous interrupting vehicle more quickly, especially in order to overtake the vehicle in the rear and immediately ahead, for example, 20 m to 4 m
The threshold value for each range block can be set lower so that the detection can be performed a little wider to the adjacent lane 12 in the range of 0 m, and the detection range 37 can be set as shown by hatching. In this case as well, a threshold value is set so as to be detectable from the lane center O to 2.0 m outside. The normalized value is set to about 0.6 in the second embodiment, which is about 0.6 in the second embodiment. It is reduced to about 55.

[0076]

As described above, according to the first aspect of the present invention,
A pulse-like signal is periodically output to the outside, and a signal from the direction in which the transmitted signal is reflected back to the target is continuously received, and the received signal does not exceed or does not exceed a certain signal level. The binarized signal is sampled at each sampling point having a plurality of different time zones after the transmission timing of the transmission signal to obtain a sampling value of 0 or 1, and this is predetermined for each sampling point. When the addition process for the predetermined number of times is completed, the addition value for each sampling point is compared with a predetermined threshold value, and based on the magnitude of the addition value, it is determined whether or not there is a reflected signal from an external target. It determines whether there is an external target and measures the distance to the target based on this, but in this distance measurement process, the vehicle equipped with the radar device travels On the driving lane A threshold is individually set for each sampling point so as to detect only existing targets, and when a sampling point having an added value exceeding the threshold is found, a target is located at a position in front of the sampling point. Since the target is determined and the distance to the target is calculated, the conventional method of adjusting the signal transmission system so that the pulse signal transmission circuit irradiates only the traveling lane of the vehicle is used instead of the conventional method It is also possible to easily cover blind spots that could not be achieved, and accurately detect the presence of a target and the distance to the target.

According to the second aspect of the present invention, in the vehicle radar device according to the first aspect, the target exists at somewhere in the running lane width for each sampling point as the threshold value for each sampling point set by the threshold value setting means. In this case, the minimum value of the added value obtained by the adding means is used, so that even if the target exists at any point ahead of the traveling lane in which the vehicle equipped with the radar device is traveling, The presence and the distance can be detected, and in particular, the detection of the interrupting vehicle from the adjacent traveling lane can be accurately performed.

According to a third aspect of the present invention, in the vehicle radar device according to the second aspect, the threshold value for each sampling point set by the threshold value setting means is smaller than the travel lane width for each sampling point corresponding to the short distance range. Since the lowest value of the added value obtained by the adding means is used when a target exists somewhere in a slightly wide range, detection of an interrupting vehicle in a short distance range where it is necessary to detect the interrupting vehicle quickly is required. Can be performed accurately and quickly.

According to the fourth aspect of the present invention, a pulse-like signal is periodically output to the outside, and a signal from the direction in which the transmitted signal is reflected back to the target is continuously received. The instantaneous value of the received signal is binarized depending on whether the signal level exceeds or does not exceed a predetermined signal level, and further, the binarized signal is integrated for each of a plurality of fixed time periods after the transmission timing of the transmission signal. This integration is repeated for a predetermined number of transmissions of the transmission signal. When the integration process for the predetermined number of times is completed, the integration value for each sampling period is compared with a predetermined threshold value individually set for each sampling period, and the magnitude is compared with the threshold. Since it is determined whether there is a reflected signal from an external target based on it and the distance to the target is calculated,
The pulse signal transmission circuit can easily cover blind spots that could not be eliminated by the conventional method of adjusting the signal transmission system to irradiate only the traveling lane of the own vehicle, and the existence of the target and its The distance to the target can be accurately detected.

According to the fifth aspect of the present invention, in the vehicle radar device according to the fourth aspect, the target exists somewhere in the running lane width for each sampling period as the threshold value for each sampling period set by the threshold value setting means. In this case, the minimum value of the integration value obtained by the integration means is used, so that even if the target exists at any point ahead of the traveling lane in which the vehicle equipped with the radar device is traveling, The presence and the distance can be detected, and in particular, the detection of the interrupting vehicle from the adjacent traveling lane can be accurately performed.

According to the sixth aspect of the present invention, in the vehicle radar device according to the fifth aspect, the threshold value for each sampling period set by the threshold value setting means is smaller than the travel lane width for each sampling period corresponding to the short distance range. Since the minimum value of the integration value obtained by the integration means is used when a target exists somewhere with a slightly wide width, the detection of an interrupting vehicle in a short distance range where it is necessary to detect the interrupting vehicle promptly Can be performed accurately and quickly.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a common embodiment of the first and second aspects of the present invention.

FIG. 2 is a timing chart showing a signal waveform of each part of the embodiment.

FIG. 3 is an explanatory diagram showing an irradiation range covered by a light transmission pulse signal of the embodiment.

FIG. 4 is AOB of a certain sampling point in FIG. 3;
The graph which shows the addition value distribution of a direction.

FIG. 5 is a graph showing an added value distribution at each point in the horizontal direction at each sampling point in the embodiment.

FIG. 6 is a timing chart showing an example of setting a threshold value at each sampling point in the embodiment.

FIG. 7 is an explanatory diagram of a target detection range based on threshold setting in the embodiment.

FIG. 8 is a flowchart showing a distance measuring process of the embodiment.

FIG. 9 is an explanatory diagram of a target detection range based on a threshold setting in a common embodiment of the first and third aspects of the present invention.

FIG. 10 is a circuit block diagram of a common embodiment of the inventions of claims 4 and 5;

FIG. 11 is a circuit diagram of an integrating circuit in the embodiment.

FIG. 12 is a timing chart showing integration timing for each range block of the integration circuit in the embodiment.

FIG. 13 is a timing chart showing a threshold setting example of each range block in the embodiment.

FIG. 14 is a timing chart showing a peak detection process in the embodiment.

FIG. 15 is a flowchart showing a distance measuring process according to the embodiment.

FIG. 16 is a circuit block diagram of a conventional example.

FIG. 17 is an explanatory diagram showing an irradiation range of a light transmission pulse signal in a conventional example.

FIG. 18 is an explanatory diagram showing a target detection operation of a conventional example.

FIG. 19 is an explanatory diagram showing an irradiation range of a light transmission pulse signal of another conventional example.

FIG. 20 is an explanatory diagram showing operation characteristics of another conventional example.

FIG. 21 is an explanatory diagram showing an irradiation range of a light transmission pulse signal of still another conventional example.

[Explanation of symbols]

 Reference Signs 9 running lane 20 radar device 21 radar head 22 pulse signal sending circuit 22a-1 first drive circuit 22a-2 second drive circuit 22b-1 first light emitting element 22b-2 second light emitting element 22c-1 1 condensing lens 22c-2 second condensing lens 23 reflected signal receiving circuit 23a lens 23b light receiving element 23c limiter amplifier 23d zero cross comparator 24 sampling addition section 25 sampling circuit 26 addition circuit 27 arithmetic circuit 28 peak detection circuit 29 threshold setting Circuit 30 Display device 31 Control circuit 32 Irradiation range 33 Detection range 37 Detection range 41 Sampling integrator 42 Switching circuit 43 Integration circuit 43a-1 to 43a-n Input analog switch 43b-1 to 43b-n Integrator 43c-1 to 43c -N output analog Switch 44 operation circuit 45 a peak detection circuit 46 the threshold setting circuit 47 inputs the switching signal 48 output switching signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/51 G01S 17/00-17/95 G01S 13/00-13/95

Claims (6)

(57) [Claims] 1. A transmitting means for periodically transmitting a pulse-like signal to the outside, and a receiving means for continuously receiving a signal from a direction in which a signal transmitted by the transmitting means is reflected on a target and returned. Sampling means for binarizing the signal received by the receiving means and sampling at each of a plurality of sampling points having different elapsed times from the signal sending timing of the sending means; and sampling points of the sampling means. Adding means for adding a predetermined number of times of transmission for each sampling point; threshold setting means for individually setting a threshold value for each of the sampling points; and sampling points provided by the threshold setting means to provide an addition value for each of the sampling points of the adding means. Comparison with each threshold,
A vehicle radar apparatus comprising: distance calculating means for calculating a distance corresponding to a sampling point giving an added value larger than the threshold value as a distance to a target. 2. The vehicular radar device according to claim 1, wherein the threshold value for each sampling point set by the threshold value setting means is added when a target exists somewhere in a running lane width for each of the sampling points. A vehicle radar apparatus characterized by using a minimum value of an addition value obtained by the means. 3. The vehicle radar device according to claim 2, wherein the threshold value for each sampling point set by the threshold value setting means is a threshold value which is slightly wider than a traveling lane width for each sampling point corresponding to a short distance range. A vehicular radar apparatus characterized by using a minimum value of an addition value obtained by the addition means when a crab target exists. 4. A transmitting means for periodically transmitting a pulsed signal to the outside, and a receiving means for continuously receiving a signal from a direction in which the signal transmitted by the transmitting means is reflected on a target and returned. Sampling means for binarizing the signal received by the receiving means, and sampling for each of a plurality of sampling periods in which the elapsed time from the signal sending timing of the sending means is different, and sampling the sampling value of the sampling means for a sampling period. Integrating means for integrating a predetermined number of transmissions for each sampling period; threshold setting means for individually setting a threshold value for each sampling period; and a sampling period in which the threshold setting means gives an integrated value of each sampling period of the integrating means. The distance corresponding to the sampling period in which an integral value larger than the predetermined threshold value is compared with the threshold value for each of the distances to the target. Vehicle radar device comprising a distance calculating means for calculating as a. 5. The vehicle radar apparatus according to claim 4, wherein the threshold value for each sampling period set by the threshold value setting means is set when the target exists somewhere in the travel lane width for each sampling period. A vehicle radar apparatus, wherein a minimum value of an integral value obtained by a means is used. 6. The vehicle radar device according to claim 4, wherein the threshold value for each sampling period set by the threshold value setting means is a threshold value that is slightly wider than a traveling lane width for each sampling period corresponding to a short distance range. A vehicular radar apparatus characterized by using a minimum value of an integration value obtained by the integration means when a crab target exists.