JP2002006040A - Object sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably sense the relative speed of an object irrespective of whether the reception level of reflected waves reflected by the object is large or small. SOLUTION: In order to sense the relative speed of a target by a radar device, a recent relative speed is used as a relative speed for output as it is when three reception levels in the past are sufficiently large (when all the levels are at '8' or more) (Step S28). When two relative speeds at '8' or more are contained in the three reception levels in the past, the mean value of one relative speed in the past and the recent relative speed is used as the relative speed for output (Step S29). When one relative speed at '8' or more is contained in the three reception levels in the past, the mean value of the three reception levels in the past and the recent relative speed is used as the relative speed for output (Step S30). When no relative speed at '8' or more is contained in the three reception levels in the past, the mean value of five relative speeds in the past and the recent relative speed is used as the relative speed for output (Step S27).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting means for transmitting an electromagnetic wave, a receiving means for receiving a reflected wave of the electromagnetic wave transmitted by the transmitting means reflected by the object, and an object based on a reception result by the receiving means. And a relative speed calculating means for calculating a relative speed with respect to the object detection device.

[0002]

2. Description of the Related Art A radar device used as such an object detection device includes a pulse transmission type and an FMCW (FMCW).
frequency Modular Continu
ouWave) is known. The pulse transmission type radar device calculates the relative distance of the target based on the time difference between the transmission of the pulsed electromagnetic wave and the reception of the reflected wave, the relative distance calculated by the previous transmission and the relative distance calculated by the current transmission. The relative speed of the target is calculated based on the deviation of the target. The FMCW transmission type radar device transmits a signal whose frequency is increased or decreased in a triangular waveform with time, and calculates the relative distance and relative speed of the target based on the frequency of the beat signal obtained by mixing the transmitted signal and the received signal. It is supposed to.

[0003] In any of the above-mentioned radar systems, the reception level of the reflected wave from the target changes variously in accordance with the weather, the state of the target, the distance to the target, and the like. As shown in FIG. 14, when the reception level is high, the ratio (S / N ratio) between the reception signal and the noise increases, so that the variation in the calculated relative distance and relative speed can be reduced. When the level is small, the S / N ratio becomes small, so that the dispersion of the relative distance and the relative speed becomes large. Therefore, conventionally, data of the calculated relative distance and relative speed is filtered to eliminate the influence of noise so that stable performance can be obtained regardless of the reception state of the radar device.

[0004]

However, since only one type of filter has been used in the past, if the characteristics of the filter are set according to the case where the reception level is high,
When the reception level is low, the variation becomes large and cannot be suppressed by the filter. Conversely, if the characteristics of the filter are set according to the low reception level, the variation can be suppressed, but if the reception level is high, There has been a problem that a response delay occurs and the response is reduced.

The present invention has been made in view of the above circumstances, and has as its object to stably detect the relative speed of an object irrespective of the level of the reception level of the reflected wave reflected by the object. I do.

[0006]

According to the first aspect of the present invention, there is provided a transmitting means for transmitting an electromagnetic wave, and a reflection means for transmitting the electromagnetic wave transmitted from the transmitting means to an object. In an object detection device including a receiving unit that receives a wave and a relative speed calculating unit that calculates a relative speed with respect to an object based on a reception result of the receiving unit, an average value of relative speeds calculated by the relative speed calculating unit A plurality of filtering means for calculating the reception level, a reception level detection means for detecting a reception level of the reflected wave received by the reception means, and any one of the plurality of filtering means based on the reception level detected by the reception level detection means. There is proposed an object detection device including a selection unit for selecting.

According to the above arrangement, one of the plurality of filtering means for calculating the average value of the relative velocity of the object is selected based on the result of detecting the reception level of the reflected wave from the object. From among the means, it is possible to select the optimum filtering means according to the level of the reception level of the reflected wave. Accordingly, it is possible to avoid a situation in which the variation in the relative speed cannot be completely suppressed by the filter when the reception level is low, or a situation in which the responsiveness decreases when the reception level is high, and to stably detect the relative speed. .

The light transmitting section 1 and the light transmitting scanning section 2 of the embodiment
Corresponds to the transmitting means of the present invention, and the light receiving section 3 and the light receiving scanning section 4 of the embodiment correspond to the receiving means of the present invention.

According to the invention described in claim 2,
In addition to the configuration of claim 1, each of the filtering means obtains an arithmetic average of a plurality of past relative velocities calculated by the relative velocity calculating means, and the number of data of the relative velocities to be arithmetically averaged is each An object detection device characterized by different features is proposed.

According to the above arrangement, each filtering means selects a different number of data from the relative velocity data calculated a plurality of times in the past and calculates the arithmetic mean. It is possible to obtain an optimal filtering characteristic according to the magnitude of the above.

In the second aspect of the present invention, it is assumed that the relative speeds in the past plural times include the relative speed calculated this time. The number of data for which the arithmetic average is obtained may be one, and the arithmetic average in this case is the one data itself.

According to the invention described in claim 3,
3. The object detection method according to claim 2, wherein the selection means selects a filtering means having a smaller number of data of the relative speed to be arithmetically averaged as the reception level detected by the reception level detection means is higher. An apparatus is proposed.

According to the above configuration, since the reception level is high, the smaller the variation of the relative speed is, the smaller the number of data of the relative speed to be arithmetically averaged becomes, so that the occurrence of a response delay by the filtering means is effectively prevented. be able to. Also, since the reception level is small, the larger the variation of the relative speed, the larger the number of data of the relative speed to be arithmetically averaged, so that the relative speed without variation can be calculated.

According to the fourth aspect of the present invention,
In addition to the configuration of claim 2 or claim 3, the selection means includes:
An object detection device is proposed, wherein when the reception level detected by the reception level detection means is equal to or higher than a predetermined value, a filtering means in which the number of data of the relative speed to be arithmetically averaged is one is selected.

According to the above arrangement, when the reception level is equal to or higher than the predetermined value and the variation in the relative speed is sufficiently small,
Since the number of data of the relative speed to be arithmetically averaged is set to one, unnecessary calculations are eliminated to reduce the calculation load, and the occurrence of a response delay can be more effectively prevented.

According to the invention described in claim 5,
In addition to the configuration of claim 1, each of the filtering means smoothes the past plurality of relative speeds calculated by the relative speed calculating means, and the smoothing coefficients of the smoothing process are different from each other. A featured object detection device is proposed.

According to the above arrangement, each of the filtering means makes the averaging coefficient different when averaging the relative velocity data calculated a plurality of times in the past. It is possible to obtain an optimum filtering characteristic according to the above.

In the invention of claim 5, the relative speeds in the past plural times include the relative speed calculated this time. Further, the number of data to be subjected to the annealing process is not limited to two, and may be three or more.

According to the invention described in claim 6,
In addition to the configuration of claim 5, an object detection device is proposed in which the selection unit weights the current relative speed heavily as the reception level detected by the reception level detection unit increases.

According to the above configuration, when the reception level is high, the current relative speed is heavily weighted. Therefore, when the reception level is low, the variation in the relative speed cannot be suppressed by the filter, or when the reception level is high, It is possible to avoid a situation in which an error occurs due to the filtering, and to stably detect the relative speed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 13 show an embodiment of the present invention. FIG. 1 is a block diagram of an object detecting device, FIG. 2 is a perspective view of the object detecting device, and FIG. 3 is a circuit for calculating a relative speed. 4 is a block diagram showing the configuration, FIG. 4 is a flowchart of a main routine, FIG. 5 is a flowchart of a relative speed calculation routine,
FIG. 6 is a diagram showing the positional relationship between the vehicle and the target, and FIG.
Is a diagram explaining the transfer of data in the target memory,
FIG. FIG. 9 shows a target memory of No. 3; FIG. 10 shows a target memory of No. 6; FIG. 11 shows a target memory of No. 10; FIG. 12 is a diagram showing 50 target memories, FIG. 12 is a time chart showing changes in relative distance, reception level and relative speed, and FIG.
2 is an enlarged view of a main part of FIG.

As shown in FIGS. 1 and 2, an object detecting device St for detecting a relative distance, a relative speed and an azimuth of a target such as a preceding vehicle, for example, includes a light transmitting unit 1 and a light transmitting scanning unit 2. , Light receiving unit 3, light receiving scanning unit 4, measurement processing unit 5
It is composed of

The light transmitting section 1 includes a laser diode 11 integrally provided with a light transmitting lens, and a laser diode driving circuit 12 for driving the laser diode 11. The light transmission scanning unit 2 includes a light transmission mirror 13 that reflects the laser light output from the laser diode 11, and a light transmission mirror 13.
And a motor drive circuit 16 for controlling the driving of the motor 15. The laser light emitted from the light transmitting mirror 13 has a vertically elongated pattern with a limited width in the left and right directions, and is scanned in the left and right direction at a predetermined cycle. The light transmitting unit 1 and the light transmitting scanning unit 2 constitute a transmitting unit of the present invention.

The light receiving section 3 includes a light receiving lens 17, a photodiode 18 that receives the reflected light converged by the light receiving lens 17 and converts it into an electric signal, and a light receiving amplifier circuit 19 that amplifies an output signal of the photodiode 18. Prepare. The light receiving scanning unit 4 includes a light receiving mirror 20 that reflects reflected light from a target and guides the light to the photodiode 18, and a motor 22 that reciprocates the light receiving mirror 20 about a left-right axis 21.
And a motor drive circuit 23 for controlling the drive of the motor 22. The light receiving area scanned by the light receiving mirror 20 in the vertical direction at a cycle shorter than the predetermined cycle has an elongated pattern in the horizontal direction with a limited vertical width. The light receiving unit 3 and the light receiving scanning unit 4 constitute a receiving unit of the present invention.

The measurement processing unit 5 includes a control circuit 24 for controlling the laser diode drive circuit 12 and the motor drive circuits 16 and 23, and an electronic control unit 2 for controlling an adaptive cruise control system and a traffic jam following system.
And a counter circuit 27 for counting the time from transmission of the laser beam to reception of the laser beam.
And a central processing unit 28 for calculating a relative distance, a relative speed, and an azimuth of the target.

As shown in FIG. 3, the central processing unit 28 of the measurement processing unit 5 includes a relative speed calculating unit M1, a plurality of filtering units M2, a reception level detecting unit M3,
Selection means M4.

The relative speed calculating means M1 calculates the relative distance of the target based on the time from the transmission of the laser light to the reception of the reflected light, and calculates the relative speed of the target as the deviation between the previous relative distance and the current relative distance. Is calculated. In the embodiment, the four filtering means M2 provided are for arithmetically averaging (arithmetic averaging) the relative velocities of a plurality of times including the present time, and the number of the relative velocities to be arithmetically averaged is determined by each filtering means M2. Is different. Receiving level detecting means M3
Detects the reflected light received in a plurality of levels (16 levels from level “0” to level “15” in the embodiment). The determination unit M4 selects one of the four filtering units M2 based on the magnitude of the reception level detected by the reception level detection unit M3.

Next, a method of calculating the relative speed will be described with reference to the flowchart of FIG.

First, in step S1, all targets in the detection area are detected, and their left and right positions (azimuths), relative distances and reception levels are stored in the current frame memory of FIG. The state at this time is shown in FIG. 6, in which 3 is provided on the road side of the road ahead of the own vehicle equipped with the object detection device St.
The three delineators A, B, and C and one preceding vehicle D are detected as targets. Two delineators A and B near the own vehicle and the preceding vehicle D are targets that have been detected continuously from the previous time, and one delineator C far from the own vehicle is a target that has been detected for the first time this time. Here, the target numbers of the delineators A, B, C and the preceding vehicle D are 3, 6, 10, and 50, respectively.

In the following step S2, the data of the previous frame memory and the data of the current frame memory are compared to take over the corresponding data. That is, the data of the previous frame memory and the data of the current frame memory are compared, and the data closest to the current position predicted from the target position and the relative speed of the previous frame memory is estimated to be the same target, and its target number is determined. And whether the data in the frame memory this time is for a target that has been continuously detected from the previous time or a target that has been newly detected this time is stored. Then, in step S3, the relative speed of the target is calculated as a deviation between the relative distance of the target stored in the previous frame memory and the corresponding relative distance of the target stored in the current frame memory. Remember. The previous frame memory and the previous frame memory are used by switching roles alternately.

In step S4, target data is read from the current frame memory. In step S5, when the target data is continuous data that has been taken over, if the target memory corresponding to the continuous data is full in step S6, After deleting the old data, the continuation data is stored in the corresponding target memory in step S7. Then, in step S8, the relative speed of the target is calculated based on the data stored in the target memory. The details will be described later with reference to the flowchart of FIG. If the target data is new data in step S5, the new data is stored in a new target memory in step S9. When reading of all target data of the current frame is completed in step S10, step S1
In step 1, the relative speeds of all targets detected this time are output.

FIGS. 8 to 11 each show a target N
o. 3 (derinator A) and the target memory No. 6 (derinator B) and a target No. 10 (delineator C) and a target No. The target memory 50 (preceding vehicle D) is shown. Target No. 3, N
o. 6, No. In the target memory No. 50, six data from the current time to the previous five times are stored. Only the current data is stored in the 10 target memories.

Step S21 of the flowchart of FIG.
Then, the data stored in the target memory is filtered by the first filtering means M2, and a value obtained by arithmetically averaging the relative speed of the past (last time) and the current relative speed is calculated. In the following step S22, the data stored in the target memory is filtered by the second filtering means M2, and a value obtained by arithmetically averaging the past three relative speeds and the present relative speed is calculated. Subsequent step S
At 23, the data stored in the target memory is filtered by the third filtering means M2.
Then, a value obtained by arithmetically averaging the relative speed of this time and the current relative speed is calculated.

In the following step S24, if the previous two reception levels and the current reception level are all "8" or more out of 16 levels, the current relative speed is directly used as the output relative speed in step S28. In this case, only the current relative speed is arithmetically averaged by the virtual zeroth filtering means M2, and the current relative speed itself calculated as a result is the output relative speed. In step S25, of the reception level of the past two times and the reception level of this time,
If there are two “8” or more, in step S29, the first filtering means M2
The relative speed (arithmetic average of the two relative velocities) calculated in (1) is used as the output relative speed. In addition, in step S26, if there is one of the reception levels of the past two times and the current reception level of “8” or more, in step S30, the relative speed (4) calculated by the second filtering means M2 in step S22. (Arithmetic average of the relative speeds of the two) is used as the output relative speed. If there is no reception level equal to or more than "8" in the past two reception levels and the present reception level in step S26, in step S27, the relative speeds (6 times) calculated by the third filtering means M2 in step S23 are used. (Arithmetic average of relative speeds) is used as the output relative speed.

Next, the above operation will be described in detail with reference to FIGS.

The target No. shown in FIG. 3 (the delineator A in FIG. 6) and the target N shown in FIG.
o. 6 (the delineator B in FIG. 6), the reception levels of the past two times (frame No.-2, No.-1) and this time (frame No. 0) are all "8" or more, which is sufficient. Since the reception level has been obtained, the condition of step S24 in the flowchart of FIG. 5 is satisfied. Therefore, the relative speed <0> (−2) of this time (frame No. 0)
1 m / s) becomes the current output relative speed as it is. Also, the frame No. As for the relative speed for output before the previous time indicated by -1 to -5, the relative speed <0> at that time is the output relative speed as it is.

The target No. shown in FIG. 10 (FIG. 6
In the case of the delineator C), only one data of the reception level and one data of the relative distance exist, and it is impossible to calculate the relative speed for output.

The target No. shown in FIG. 50 (FIG. 6)
In the case of the preceding vehicle D), the past two times (frame No.−
2, No. -1) and the reception level of this time (frame No. 0) are “6”, “7”, and “7”, and none of them are “8” or more, so that the condition of step S26 in the flowchart of FIG. 5 is satisfied. Absent. Therefore, step S
The relative speed <3> (5.0 m / s) calculated in 23 is the current output relative speed. Also, the previous time (frame No.-
The output relative speed of 1) is the relative speed calculated in step S22 because the three previous reception levels are “8”, “6”, “7” and one is “8” or more. The speed <1> (5.1 m / s) is output. The output relative speed of the last two times (frame No.-2) is 3
Since the two reception levels are “8”, “8”, and “6”, and there are two that have “8” or more, the relative speed <1> (4.2 m / s) calculated in step S21 is output. Is done.
The relative speeds for output two times before (frame No. -3) are three reception levels "8", "8",
Since “8” is all “8” or more, the relative speed <0> (4.6 m / s) at that time is output as it is. Frame No. before that. -4 and frame N
o. At -5, since the corresponding three reception levels are all "8" or higher, the relative speed <0> at that time is output as it is.

FIG. 12 and FIG.
o. 50 (the preceding car D in FIG. 6), the reception level,
The original relative speed and the filtered relative speed are shown. FIG. 13 is an enlarged view of a part of FIG. 12 (a part where the elapsed time is 12 sec or more).

The relative speed between the own vehicle and the preceding vehicle is about 20 km /
h (= 5.6 m / sec), and since the relative distance to the preceding vehicle is gradually increasing from 30 m, the reception level is gradually lowered, and the variation is also increased to become unstable. As a result, the variation of the relative speed of the original which is not subjected to the filtering process increases from around the distance of 90 m or more. However, the variation of the relative speed is effectively suppressed by performing the filtering process of the present embodiment. I understand.

As described above, the smaller the reception level is, the more the number of past data to be arithmetically averaged is increased, so that the variation in the relative speed can be effectively suppressed. Since the number of past data to be averaged is reduced, it is possible to prevent a response delay from occurring due to filtering, and thereby to stably detect the relative speed of the target. When the reception level is sufficiently high, the current relative speed is output as it is, so that unnecessary calculations can be eliminated to reduce the calculation load, and the occurrence of a response delay can be more effectively prevented.

Although the embodiment of the present invention has been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the above embodiment, the filtering is performed by the filtering means M2 by arithmetically averaging the relative velocities. The filtering may be performed by calculating a weighted average value of the speed. In this case, the output relative speed V is
Using the current value Vn, the previous value V (n-1) and the averaging coefficient K, it is given by the following equation: V = K * V + (1-K) * V (1-n). Therefore, when the reception level is large,
By increasing the value of K and weighting the current relative speed heavily, variations in the relative speed can be effectively suppressed. When the reception level is low, the value of K is reduced and the previous relative speed is heavily weighted, so that the relative speed detection accuracy can be improved.

In the flowchart of FIG. 5, after determining which filtering means to use in accordance with the reception level, the filtering means may calculate the average value.

Although the object detecting apparatus of the embodiment uses a laser, other electromagnetic waves such as millimeter waves can be used instead of the laser.

[0047]

As described above, according to the first aspect of the present invention, a plurality of filtering methods for calculating the average value of the relative speed of an object based on the result of detecting the reception level of the reflected wave from the object. Since any one of the means is selected, it is possible to select an optimum filtering means according to the level of the reception level of the reflected wave from the plurality of filtering means. Accordingly, it is possible to avoid a situation in which the variation in the relative speed cannot be completely suppressed by the filter when the reception level is low, or a situation in which the responsiveness decreases when the reception level is high, and to stably detect the relative speed. .

According to the second aspect of the present invention,
Each filtering means selects a different number of data from the relative velocity data calculated in the past plural times and calculates the arithmetic mean. Therefore, the optimum filtering characteristic according to the level of the reception level is obtained. Can be obtained.

According to the third aspect of the present invention,
Because the reception level is large, the smaller the variation of the relative speed, the smaller the number of data of the relative speed to be arithmetically averaged, so that it is possible to effectively prevent the response delay from being caused by the filtering means. Also, since the reception level is small, the larger the variation of the relative speed, the larger the number of data of the relative speed to be arithmetically averaged, so that the relative speed without variation can be calculated.

According to the fourth aspect of the present invention,
When the reception level is equal to or higher than a predetermined value and the variation of the relative speed is sufficiently small, the number of data of the relative speed to be arithmetically averaged is set to 1, so that unnecessary calculations are eliminated to reduce the calculation load. The occurrence of a response delay can be more effectively prevented.

According to the fifth aspect of the present invention,
Each of the filtering means makes the averaging coefficient different when averaging the relative velocity data calculated a plurality of times in the past, so that an optimal filtering characteristic according to the level of the reception level can be obtained. Can be.

According to the invention described in claim 6,
When the reception level is high, the relative speed is weighted heavily, so that when the reception level is low, variations in the relative speed cannot be suppressed by the filter, and when the reception level is high, errors may occur due to filtering. By avoiding this, the relative speed can be detected stably.

[Brief description of the drawings]

FIG. 1 is a block diagram of an object detection device.

FIG. 2 is a perspective view of an object detection device.

FIG. 3 is a block diagram showing a circuit configuration for calculating a relative speed.

FIG. 4 is a flowchart of a main routine.

FIG. 5 is a flowchart of a relative speed calculation routine.

FIG. 6 is a diagram showing a positional relationship between the own vehicle and a target.

FIG. 7 is a view for explaining data transfer of a target memory;

FIG. Diagram showing target memory No. 3

FIG. 6 shows the target memory of FIG.

FIG. Diagram showing 10 target memories

FIG. Diagram showing 50 target memories

FIG. 12 is a time chart showing changes in relative distance, reception level, and relative speed.

FIG. 13 is an enlarged view of a main part of FIG. 12;

FIG. 14 is a view for explaining the relationship between the magnitude of the reception level and the variation in the reception data;

[Explanation of symbols]

 Reference Signs List 1 light transmitting section (transmitting means) 2 light transmitting scanning section (transmitting section) 3 light receiving section (receiving section) 4 light receiving scanning section (receiving section) M1 relative speed calculating section M2 filtering section M3 receiving level detecting section M4 selecting section

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J070 AB01 AC06 AD02 AE01 AF03 AH19 AH39 AK22 AK28 BA10 5J084 AA07 AA10 AB01 AC02 AD01 BA04 BA11 BA16 BA36 BA49 BB01 BB21 CA23 CA26 CA32 DA01 DA02 EA02 EA05 EA22 EA33 FA01

Claims (6)

[Claims] A transmitting means for transmitting an electromagnetic wave;
Receiving means (3, 4) for receiving a reflected wave of the electromagnetic wave transmitted by the transmitting means (1, 2) reflected by the object; and an object based on a reception result by the receiving means (3, 4). A relative speed calculating means (M1) for calculating a relative speed; and a plurality of filtering means (M2) for calculating an average value of relative speeds calculated by the relative speed calculating means (M1).
Receiving level detecting means (M3) for detecting the receiving level of the reflected wave received by the receiving means (3, 4); and a plurality of filtering means based on the receiving level detected by the receiving level detecting means (M3). (M2) a selection means (M4) for selecting any one of (M2). 2. The filtering means (M2),
2. The method according to claim 1, further comprising calculating an arithmetic mean of a plurality of past relative velocities calculated by the relative speed calculating means (M1), wherein data numbers of the relative velocities to be arithmetically averaged are different from each other. Object detection device. 3. The selecting means (M4) is configured to determine that the higher the reception level detected by the reception level detecting means (M3),
3. The filtering means (M2) having a small number of relative speed data to be arithmetically averaged is selected.
An object detection device according to claim 1. 4. The filtering means (M2), wherein when the reception level detected by the reception level detection means (M3) is equal to or higher than a predetermined value, the number of data of the relative speed to be arithmetically averaged is one. Is characterized by selecting
The object detection device according to claim 2 or 3. 5. Each of the filtering means (M2)
The object detection according to claim 1, wherein the relative speed calculated by the relative speed calculating means (M1) is smoothed a plurality of times in the past, and the smoothing coefficients of the smoothing process are different from each other. apparatus. 6. The selection means (M4), the higher the reception level detected by the reception level detection means (M3),
It is characterized by heavily weighting the relative speed this time,
The object detection device according to claim 5.