JPH09171075A - Distance-measuring apparatus for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a distance up to an object with higher reliability, simply and stably in a distance-measuring apparatus, for a vehicle, which is provided with a radar distance-measuring device and with a triangulation distance- measuring device. SOLUTION: A changeover signal is output from a filter 12 when the change rate of the output of a radar distance-measuring device 1 exceeds a set value on the increase side of a distance. Then, in a state that the measuring reliability, of a triangulation distance-measuring device 2, computed by a reliability computing device 5 is higher than a prescribed level, the output of the triangulation distance-measuring device 2 is selected by a selector 13 when the output of the triangulation distance-measuring device 2 is less than a set distance. In a normal state other than it, the output of the radar distance-measuring device 1 is selected by the selector 13, and an alarm 9 is alarmed and operated when a changeover signal is output from the filter 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar range finder which calculates a distance to a reference object in front of a vehicle based on a time between transmission of a signal to the reference object and reception of a reflected signal from the reference object. And a triangulation distance measuring device for calculating a distance to a reference object based on a parallax obtained from a correlation calculation of outputs of a pair of image sensors arranged at intervals.

[0002]

2. Description of the Related Art Conventionally, such an apparatus is disclosed in, for example,
It is already known from Japanese Patent Publication No. -230115, and in this one, the reliability of the distance information obtained by the radar range finder and the reliability of the distance information obtained by the triangulation range finder are respectively calculated to obtain a higher value. The distance information having reliability is selected.

[0003]

However, in the above-mentioned conventional one, since it is necessary to calculate the measurement reliability of both distance measuring devices at each measurement, the calculation time becomes relatively long, and a more expensive microprocessor is required. Will be needed. In addition, the selected distance information may change due to a slight change in environmental conditions, and when the vehicle is controlled based on the distance information, the distance information input to the control device varies and the control becomes unstable. Sometimes.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle distance measuring device capable of obtaining a distance to a reference object with higher reliability, in a simple and stable manner. And

[0005]

In order to achieve the above object, the invention according to claim 1 provides a time between transmission of a signal toward a reference object in front of a vehicle and reception of a reflected signal from the reference object. Radar distance finder that calculates the distance to the reference object based on the above, and triangulation that calculates the distance to the reference object based on the parallax obtained from the correlation calculation of the output of the pair of image sensors that are spaced apart. In a vehicle distance measuring device equipped with a distance measuring device, a filter that outputs a switching signal when the rate of change of the output of the radar distance measuring device exceeds a set value on the distance increasing side, and the measurement of the triangulation distance measuring device A reliability calculator that calculates the reliability, an alarm that operates in response to the switching signal output from the filter, and a measurement reliability calculated by the reliability calculator while the switching signal is output from the filter When the output of the triangulation distance measuring device is lower than the set distance when the level is higher than the specified level, the output of the triangulation distance measuring device is selected as the distance to the reference object, but in other normal times, the output of the radar distance measuring device is selected. And a selector for selecting the distance to the reference object.

[0006] The second aspect of the present invention is the first aspect of the present invention.
In addition to the configuration of the invention described, in the reliability calculator, the measurement reliability is calculated based on the correlation value at the maximum correlation of the outputs of both image sensors in the triangulation distance measuring device and the correlation value change before and after the correlation value. It is characterized by

Further, the invention according to claim 3 is characterized in that, in addition to the constitution of the invention according to claim 1, the set distance is set so as to become large as the vehicle speed increases.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a block diagram showing the structure of a vehicle distance measuring device, and FIG. 2 shows the structure of a head in a triangulation distance measuring device. FIG. 3, FIG. 3 is a view showing the image pickup surfaces of both image sensors in the triangulation distance measuring device, FIG. 4 is a flowchart showing a switching control procedure in the selector controller, and FIG. 5 is a view showing a change in set distance according to the vehicle speed. is there.

First, referring to FIG. 1, this vehicle distance measuring device comprises a radar distance measuring device 1 and a triangulation distance measuring device 2.
A first memory 3 for storing the distance Drc measured by the radar distance measuring device 1, a second memory 4 for storing the distance Dtc measured by the triangulation distance measuring device 2, and a triangulation distance measuring device 2. Reliability calculator 5 for calculating measurement reliability
A vehicle speed sensor 6 for detecting a vehicle speed, an electronic control unit 8 to which the signals 1 to 6 are input, and a speaker 9 as an annunciator whose notification operation is controlled by the electronic control unit 8.

Moreover, the electronic control unit 8 also has a function of controlling the traveling state of the vehicle, and more preferably the steering angle sensor 7 or another sensor is used as the vehicle speed sensor in order to control the traveling state of the vehicle. In addition to 6, the electronic control unit 8 is connected, and the acceleration device 10 and the deceleration device 1 are connected.
A control signal for changing the running state to 1 is given from the electronic control unit 8.

The radar range finder 1 is well known in the prior art (for example, Japanese Patent Laid-Open Nos. 6-160516 and 6-230).
No. 115), the detailed description of which is omitted, but a head capable of transmitting an electromagnetic wave such as a millimeter wave or infrared light to a reference object in front of the vehicle and receiving a reflected signal from the reference object. 1a and a processing unit 1b that calculates the distance Drc to the reference object based on the time between transmission and reception.

Referring also to FIG. 2, the triangulation distance measuring device 2 is well known in the art (for example, JP-A-6-174845 and JP-A-4-238212), and a detailed description thereof will be given. Although omitted, a pair of lenses 16 having the same focal length and spaced from each other
₁ and 16 ₂ and a head 2a including a pair of image sensors 17 ₁ and 17 ₂ arranged at the imaging positions of the lenses 16 ₁ and 16 ₂ , and both image sensors 17 ₁ and 17 ₂ in the head 2a. And a processing unit 2b that calculates a distance Dtc to a reference object V such as a preceding vehicle in front of the vehicle based on the output of.

Both image sensors 17 ₁ and 17 ₂ are shown in FIG.
As shown by, each pixel has n pixels in the vertical direction and m pixels in the horizontal direction, and the address of each pixel is represented by (i, j). When the brightness of the pixel at the address (i, j) in the image sensor 17 ₁ is IL _{i, j} and the brightness of the pixel at the address (i, j) in the image sensor 17 ₂ is IR _{i, j.} In the processing section 2b, while shifting the relative position of the reference object images picked up by the two image sensors 17 ₁ and 17 ₂ arranged at a distance from each other in the lateral direction by k pixels,
The calculation for obtaining the luminance difference C _k for each corresponding pixel is executed based on the following calculation formula.

[0015] _{C k = Σ (IR i,} j -IL i, (jk)) When Thus to by the calculation, both the image sensor 17 _1, 1
When the correlation of the reference object image on the image pickup surface of 7 ₂ becomes maximum, the difference C _k becomes the minimum value C ₀ , and the triangulation based on the relative positional deviation k _{0 in} the lateral direction at that time, that is, the parallax. According to the principle, the distance D _TC to the control object V is obtained.

In the reliability calculator 5, the measurement reliability is calculated based on the correlation value at the maximum correlation between the outputs of the image sensors 17 ₁ and 17 _{2 in} the triangulation distance measuring device 2, that is, the difference C ₀ in luminance at the maximum correlation. R is calculated as follows.

R = const-C _{0 In the} above equation, const is a constant determined based on the change in the correlation value before and after the maximum correlation. That is, the difference in brightness C ₀ between the outputs of both image sensors 17 ₁ and 17 ₂ at the maximum correlation and the difference in brightness C _{0 + m} , C at the positions shifted laterally by m from the maximum correlation. the absolute value of the difference between the _{0-m is, d m = | C 0 +} m -C 0 | d -m = | C 0-m -C 0 | is calculated as, d _m, the average value of d _-m is Const is set so that it becomes larger as it becomes larger.

That is, in the reliability calculator 5, the smaller the correlation value at the maximum correlation of the outputs of the image sensors 17 ₁ and 17 _{2 is} , the larger the correlation value is. Then, the measurement reliability R is calculated.

Referring again to FIG. 1, the electronic control unit 8
Includes a filter 12, a selector 13, a selector controller 14, and a vehicle control unit 15.

The filter 12 includes a radar distance measuring device 1
The distance Drc measured in 1 and the distance stored in the first memory 3 are input. Thus, the value Drc ′ read from the first memory 3 as the distance measured by the radar distance measuring device 1 at the time of the previous calculation or the weight up to several times before the distance measured by the radar distance measuring device 1. Average value Dr
c ′ is the distance Drc measured by the radar distance measuring device 1.
When the value (Drc-Drc ') subtracted from exceeds the set value th1, that is, when the change rate of the output of the radar distance measuring device 1 exceeds the set value th1 on the distance increasing side, the switching signal from the filter 12 is output. Is output.

The selector 13 includes a radar distance measuring device 1
The distance Drc measured in 3 and the distance Dtc measured in the triangulation distance measuring device 2 are input, and one of the distances Drc and Dtc is input to the selector controller 14
It is selectively selected by the selector 13 by the switching control by and is input to the vehicle control unit 15.

In the selector controller 14, the output of the filter 12, the distance Dtc measured by the triangulation distance measuring device 2 and stored in the second memory 4, and the triangulation distance measuring calculated by the reliability calculator 5 are measured. The measurement reliability R of the instrument 2 is input, and the selector controller 14 executes the switching control of the selector 13 according to the procedure shown in FIG. 4 based on those input signals.

In the first step S1 in FIG. 4, it is determined whether or not the switching signal is output from the filter 12, that is, whether the rate of change of the output of the radar distance measuring device 1 exceeds the set value th1 on the distance increasing side. When it is determined that the switching signal is not output from the filter 12 because the rate of change of the output of the radar distance measuring device 1 does not exceed the set value th1 on the distance increasing side, in the second step S2, the radar distance measuring device 1 A signal for controlling the selector 13 so as to select the measurement distance Drc is output from the selector controller 14.

In the first step S1, the change rate of the output of the radar range finder 1 is set to the set value th on the side of increasing distance.
If it is determined that the switching signal is being output from the filter 12 because the value exceeds 1, the third step S
At 3, it is determined whether or not the measurement reliability R is higher than the specified level th2. If R> th2, then at the fourth step S4, the measurement distance Dt of the triangulation distance measuring device 2 is determined.
It is determined whether or not c is less than the set distance th3. Thus, when R> th2 and Dtc <th3, the signal for controlling the selector 13 so as to select the measurement distance Dtc of the triangulation distance measuring instrument 2 is the selector controller in the fifth step S5. 14 is output, and in the next sixth step S6, a signal for outputting the first voice alarm is output from the selector controller 14.

In the third step S3, R≤th2
If it is determined that Dtc ≧ th3 in the fourth step S4, the selector controller 14 outputs a signal for outputting the second voice alarm in the seventh step S7.

By the way, the set distance th3 is determined according to the vehicle speed as shown in FIG. 5, and the set distance th is set so as to gradually increase as the vehicle speed increases.
3 is set.

The output of the filter 12 is input to the vehicle controller 15, and the speaker 9 is activated by the vehicle controller 15 according to the output of the switching signal from the filter 12. At this time, the selector controller 14
When the signal for outputting the voice alarm is output, a voice alarm indicating that the distance to the reference object is being measured by the triangulation distance measuring device 2 instead of the radar distance measuring device 1 is output from the speaker 9. , Selector controller 1
When the signal for outputting the second voice alarm is output from No. 4, the operation of the acceleration device 10 and the deceleration device 11 is based on the fact that the distance measurement by the radar distance measuring device 1 and the triangulation distance measuring device 2 is improper. The speaker 9 outputs a voice warning to the effect that the control of the running state of the vehicle will be stopped.

Further, the vehicle control unit 15 controls the operation of the acceleration device 10 and the deceleration device 11 so as to change the running state of the vehicle, and one of the measurement distances Drc, Dtc selected by the selector 13 and the vehicle speed. Signals from sensors such as the sensor 6 and the steering angle sensor 7 are input to the vehicle control unit 15.

By the way, the filter 12, the selector 13, the selector controller 14 and the vehicle control section 15 shown as blocks as the constituent elements of the electronic control unit 8 in FIG. 1 indicate the functions of the electronic control unit 8.
Their functions are carried by suitable electronic devices. At this time, it is not necessary for each block to correspond to the electronic device on a one-to-one basis, and each block may be allocated to the CPU, the memory, and other electronic devices in an overlapping or divided manner.

Explaining the operation of this embodiment, triangulation is performed in the state where the switching signal is output from the filter 12 in response to the change rate of the output of the radar range finder 1 exceeding the set value on the distance increasing side. When the measurement reliability R of the distance measuring device 2 is higher than the specified level th2 and the measurement Dtc of the triangulation distance measuring device 2 is less than the set distance th3, the distance Dtc measured by the triangulation distance measuring device 2 is measured.
Is used, and in other normal times the radar range finder 2
The distance Drc measured at is selected. Therefore, in a normal state, it suffices to monitor only whether the rate of change of the output of the radar distance measuring device 1 exceeds the set value on the distance increasing side, which reduces the calculation load of the microprocessor and reduces the cost of the microprocessor. Can be used. Moreover, the filter 12 detects that the output of the radar range finder 1 flies to the far side, and the radar range finder 1 is used when a vehicle with a weak reflected signal interrupts forward.
Can be effectively dealt with by switching to use the output of the triangulation distance measuring device 2 for the event in which the output of F.

When using the output of the triangulation distance measuring device 2, the switching condition is that the measurement reliability R exceeds the specified level th2 and the measurement distance Dtc is less than the set distance th3. It is possible to prevent the traveling control of the vehicle from being performed by using the measured value with the low measurement reliability R, and use the measured value by the triangulation distance measuring device 2 when the inter-vehicle distance is relatively short and the urgency of the control is high. Effective control becomes possible, and when the inter-vehicle distance is relatively long and the urgency is low, it is possible to avoid selective switching of the measurement distance, which is likely to cause deterioration of traveling feeling.

Moreover, since the set distance th3 is set so as to increase as the vehicle speed increases, fine control according to the traveling speed of the vehicle becomes possible.

By the way, in the reliability calculator 5, the correlation value when the correlation of the outputs of both image sensors 17 ₁ and 17 _{2 in} the triangulation distance measuring device 2 becomes maximum and the correlation value change before and after the correlation value The measurement reliability R is calculated based on this, and the measurement reliability R is easily and accurately calculated based on the correlation value used in the distance calculation processing in the triangulation distance measuring device 2.

Further, when the filter 12 outputs a switching signal, the speaker 9 is activated to inform, and when a change in the front situation occurs due to a vehicle having a weak reflected signal cutting forward or the like, It is possible to notify the driver of a change in the front situation to further warn the front and improve the safety of the vehicle. At that time, since the notification operation is a voice notification by the speaker 9, the driver can visually recognize the front. It does not interfere with surveillance.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is possible to do.

For example, the measurement reliability of the triangulation distance measuring device 2 may be represented by the correlation value of the outputs of both the image sensors 17 ₁ and 17 ₂ , and the set distance th3.
May be defined as (vehicle speed × constant).

[0037]

As described above, the invention according to claim 1 has a filter which outputs a switching signal when the rate of change of the output of the radar distance measuring device exceeds a set value on the distance increasing side, and a triangulation distance. A reliability calculator that calculates the measurement reliability of the measuring instrument, an alarm that operates in response to the switching signal output from the filter, and a measurement reliability that the switching signal is output from the filter and that is calculated by the reliability calculator. When the output of the triangulation distance measuring device is less than the set distance when the degree is higher than the specified level, the output of the triangulation distance measuring device is selected as the distance to the reference object, but in other normal times the radar distance measuring device Since it includes a selector that selects the output as the distance to the reference object, it reduces the computational load on the microprocessor and enables the use of a cheaper microprocessor, and the reflected signal It is possible to effectively cope with a weak vehicle when it breaks in the front, and it is possible to improve the control system by using a highly reliable measurement value even when using the measurement value of the triangulation distance measuring device. When the distance between vehicles is relatively short and the urgency of control is high, effective control is possible by using the measurement value of the triangulation distance measuring instrument. It is possible to avoid selection and switching of the measurement distance, which is likely to cause deterioration of the ring, and it is possible to notify the driver of frontal attention by notifying the change of the front situation by the alarm.

According to the invention described in claim 2, in addition to the configuration of the invention described in claim 1, in the reliability calculator,
It is used for the distance calculation processing in the triangulation distance measuring device because the measurement reliability is calculated based on the correlation value at the time of maximum correlation of the outputs of both image sensors in the triangulation distance measuring device and the correlation value change before and after that. It is possible to easily and accurately calculate the measurement reliability based on the correlation value.

Further, according to the invention of claim 3, in addition to the configuration of the invention of claim 1, the set distance is
Since it is set so as to increase as the vehicle speed increases, fine control according to the traveling speed of the vehicle becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle distance measuring device.

FIG. 2 is a diagram showing a configuration of a head in a triangulation distance measuring device.

FIG. 3 is a diagram showing image pickup surfaces of both image sensors in the triangulation distance measuring device.

FIG. 4 is a flowchart showing a switching control procedure in a selector controller.

FIG. 5 is a diagram showing a change in a set distance according to a vehicle speed.

[Explanation of symbols]

1 ... Radar distance measuring device 2 ... Triangulation distance measuring device 5 ... Reliability calculator 9 ... Speaker as an indicator 12 ... Filter 13 ... Selector 17 ₁ , 17 ₂ ..Image sensors

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G01S 11/12 G08G 1/04 C 13/93 G01S 11/00 B G08G 1/04 13/93 Z

Claims (3)

[Claims] 1. A radar range finder (1) for calculating the distance to a reference object in front of a vehicle based on the time between the transmission of a signal toward the reference object and the reception of a reflected signal from the reference object, A vehicle provided with a triangulation distance measuring device (2) for calculating a distance to a reference object based on a parallax obtained from a correlation calculation of outputs of a pair of image sensors (17 ₁ , 17 ₂ ) arranged at intervals. In the distance measuring device for
Calculate the measurement reliability of the filter (12) that outputs a switching signal when the rate of change of the output of the radar range finder (1) exceeds the set value on the side of increasing distance and the triangulation range finder (2) Reliability calculator (5) and an alarm device (9) for alarming in response to the switching signal output from the filter (12)
When the switching signal is output from the filter (12) and the measurement reliability calculated by the reliability calculator (5) is higher than the specified level, the output of the triangulation distance measuring device (2) is set to the set distance. Triangulation distance measuring device (2)
And a selector (13) for selecting the output of the radar distance measuring device (1) as the distance to the reference object during normal times other than that. measuring device. 2. The reliability computing unit (5) comprises both image sensors (17 ₁ , 17) in the triangulation distance measuring unit (2).
_2. The vehicle distance measuring device according to claim 1, wherein the measurement reliability is calculated based on the correlation value at the maximum correlation of the output of ₂ ) and the correlation value change before and after the correlation value. 3. The vehicle distance measuring device according to claim 1, wherein the set distance is set so as to increase as the vehicle speed increases.