JPH04249706A - Distance detecting apparatus - Google Patents

Abstract

PURPOSE:To detect the two-dimensional relative position of a vehicle running ahead of one's vehicle by detecting the distance between the two vehicles by an optical measuring means, and calculating the relative positional relationship of the two vehicles based on the measured distance data the velocity data of the one's vehicle. CONSTITUTION:A distance measuring means 201 mounted to one's own vehicle X detects a distance R between the vehicle X and a vehicle Y running a head of the vehicle X from the phase difference of a modulated signal of a projecting light LT projected towards the vehicle Y by means of a light emitting diode or the like and a photoelectric converted signal obtained by a photodetecting element when the projecting light LT is reflected as a reflecting light LR by the vehicle Y. The means 201 outputs the distance R as a distance data of vehicles. A data processor 203 comprised of a microcomputer to which the distance information R from the means 201 and a velocity information Va from a vehicle speed sensor 202 are input judges whether or not the distance R between the vehicles is safe and whether or not the vehicle Y has started. In the case where a safe distance is not secured an when the vehicle Y is started, an alarm 204 is generated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance detection device for detecting the inter-vehicle distance between, for example, one's own vehicle and a preceding vehicle.

0002

2. Description of the Related Art As is well known, when driving a vehicle such as an automobile, one of the basic principles of driving is to check the distance between one's own vehicle and the vehicle in front.

As shown in FIG. 10, the distance between vehicles is checked by the driver of own vehicle
The actual inter-vehicle distance (hereinafter simply referred to as inter-vehicle distance) R is empirically recognized from the visual inter-vehicle distance R', and the system prevents a rear-end collision with the preceding vehicle Y, or confirms the start/stop of the preceding vehicle Y at an intersection, for example. That's what I do. Also, JP-A-55-8600
As shown in No. 0, it was configured to detect the inter-vehicle distance R between the host vehicle X and the preceding vehicle Y using a radar or the like.

However, when the relative positional relationship between the host vehicle X and the preceding vehicle Y is recognized by visual measurement, the inter-vehicle distance R may become short due to carelessness or an error in the visual measurement, resulting in the driver suddenly stepping on the brakes.

[0005]

OBJECTS OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. For example, the inter-vehicle distance R between the host vehicle It is an object of the present invention to provide a distance detection device capable of calculating the relative positional relationship between the own vehicle and the preceding vehicle using distance measurement information and vehicle speed information of the own vehicle, and detecting the two-dimensional relative positional relationship of the preceding vehicle with respect to the own vehicle. This is the purpose.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining the gist of the present invention, the inter-vehicle distance detecting device according to the present invention will be explained in detail with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram showing an inter-vehicle distance detection device.

In the figure, reference numeral 201 denotes a distance measuring means attached to the own vehicle
T detects the distance R between own vehicle Output as information.

A vehicle speed sensor 202 is attached to the own vehicle X to detect the vehicle speed of the own vehicle X, and outputs vehicle speed information Va.

Reference numeral 203 denotes an information processing circuit consisting of, for example, a microcomputer, into which inter-vehicle distance information R from the distance measuring means 201 and vehicle speed information Va from the vehicle speed sensor 202 are input, and the inter-vehicle distance between the preceding vehicle Y and own vehicle X is inputted. The system determines whether R is safe and whether or not the preceding vehicle Y has started, and outputs an alarm signal Sa to alert the driver if a safe inter-vehicle distance R is no longer maintained or if the preceding vehicle Y has started. vessel 204
activates and notifies the driver.

Next, the determination operation of the information processing circuit 203 will be explained based on the flowchart shown in FIG.

When the power is turned on to the device of this embodiment, the process starts from step 210 (written as S-210) to the next step 2.
Start towards 11th. First, in S-211, check whether the own vehicle speed Va (km/h) is in the range of 0<Va≦10, and if it is within this range, S-211
The counter N is set to zero at step S-213.

[0013] S-213 calculates the safety distance Rs.

0
014]

[Math 1]

Calculation is performed based on ##EQU2## and the process proceeds to S-214. However, k is a constant and is basically selected as R0=1 and k=2/5.

[0016] S-214 compares the following distance R with the above-mentioned safety distance Rs, and if R<Rs, S-215
Then, an alarm signal Sa is generated and the alarm device 204 is activated to warn the driver that the vehicle is getting too close to the preceding vehicle. Also, while R≧Rs in S-214, START
Return to point A next to S-210 and go to S-211~S-
214 loop and nothing happens.

In the case of R0=1, k=2/5 (
1) The relationship between Rs (m) and Va (km/h) in the formula is shown in Figure 3. In this case, the fixed margin distance is selected to be R0 = 1 m, the coefficient is selected to be k = 2/5 including the margin time of 1 sec for the driver's action delay, and the area shown by diagonal lines is set as the alarm generation area.

On the other hand, when own vehicle X stops, S-211
The vehicle advances to S-216, and it is determined that Va (km/h)≒0 (depending on the resolution of the vehicle speed sensor, but in reality Va=0).
~1 (km/h) range), the process proceeds to S-217, and since the counter N is initially N=0, S-218 sets the inter-vehicle distance R at this time to R0 and stores it in the first register in the microcomputer. Remember. In addition, Va > 10 (km/h
), return to point A. If the counter is not N=0 in S-217, the process advances to S-219.

Next, in S-219, 1 is added to the counter N, and the process proceeds to S-220, where the current inter-vehicle distance R is stored as RN in the second register in the microcomputer.
Proceed to -221.

[0020] S-221 is the RN stored in this second register and the R0 (
initial value) and the difference is -0.3≦RN-R0≦1
If it is within the range, the process moves to S-222 and waits for 0.2 seconds. In addition, the minus sign is the unconscious start of own vehicle X and the preceding vehicle Y.
considering the unconscious regression of 0.2 for S-222
After sec has passed, return to point A again S-221~S-2
Repeat loop 22 several times to confirm that the inter-vehicle distance R between the preceding vehicle Y and the own vehicle X has hardly changed.

[0021] When the preceding vehicle Y starts, S-221
Then, RN-R0>1(m), the process moves to S-215, generates an alarm signal Sa, and informs the driver that the preceding vehicle Y has started.

When the vehicle X notices this and starts moving, the counter N is also cleared at S-212.

[0023] In S-221, RN-R0<0.3(m)
In this case, it is own vehicle X that moves to S-215's ALARM.
This is to give a warning to prevent the vehicle Y from starting unconsciously due to creep of the torque converter, loosening of the brakes on a slope, etc., or from the preceding vehicle Y backing up unnoticed and coming into contact with each other.

Next, the gist of the present invention will be explained with reference to FIGS. 4 to 6.
The explanation will be based on.

As shown in FIG. 4, for example, when driving on a road with two lanes on each side, the vehicle X may drive in the straight-ahead area D and overtake the preceding vehicle Y traveling in the other lane, or It is possible to determine whether or not there will be contact even if the object passes through the object.

FIG. 5 shows a block diagram including the gist of this embodiment. 301 is a distance measuring means that detects the inter-vehicle distance R to the preceding vehicle Y from the emitted light LT and the reflected light LR, outputs inter-vehicle distance information, and also detects the distance R from the center line g of the own vehicle to one side edge of the preceding vehicle Y ( The distance lL to the left end in FIG. 4) and the distance lR to the other end of the preceding vehicle Y (the right end in FIG. 4) are detected, and the difference lL-lR between the detected distances lL and lR is calculated. Output.

In order to detect the inter-vehicle distance R to the preceding vehicle Y and the difference lL-lR therebetween, the distance measuring means 301 defines the preceding vehicle detection range C within the diagonally shaded range of the angle θ. θ=50° to 60° so that even a preceding vehicle Y at a close distance can be detected.

Reference numeral 302 is an information processing circuit composed of, for example, a microcomputer, which calculates the own vehicle speed Va from the vehicle speed sensor 202, and the inter-vehicle distance measurement R and difference l from the distance measuring means 301.
L-lR and the preset vehicle width (W) of own vehicle X +
Based on the allowance (ΔW), it is determined whether or not the own vehicle If the determination is negative, the alarm 204 is activated to notify the driver that overtaking is impossible.

FIG. 7 shows a schematic diagram of the distance measuring means 201, 301, and in the figure, 11, 11,
12 is a reflector (reflection plate) attached to the rear end of the preceding vehicle Y, and 14 is a light transmitting/receiving device attached to the front part of the own vehicle X.

The light transmitter/receiver 14 includes a light emitting diode 16 that emits infrared light forward from a window 15 as a transmitted beam with a spread angle θ, and sinusoidally modulates the infrared light emitted from the light emitting diode 16. A sine wave modulation circuit 25, convex lenses 17 and 18 which are arranged equidistantly on both sides of the light emitting diode 16 and which focus infrared light reflected by the reflectors 11 and 12 of the preceding vehicle (reflected light of the synchrotron radiation LT); LR
has the property of generally returning to the vicinity of the light source), this convex lens 17
, 18, the PSD (
Position Sensitive Device
) type light receiving elements 19, 20 and amplifiers 21, 22, 2 which convert the output currents outputted to the respective electrodes A1, B1, A2, B2 of the PSD type light receiving elements 19, 20 into voltages.
It consists of 3,24.

FIG. 8 shows the PSD type light receiving elements 19 and 20.
In the figure, 33 is a lens barrel, and 19 is a lens barrel.
a (20a) is the light receiving surface of the PSD type light receiving element 19 (20).

The principle of this operation will be explained below.

Infrared light LT= from the light emitting element 16 (not shown)
When Lsin2πf0t (amplitude modulated with a sine wave of frequency f0) is irradiated toward the reflectors 11, 12, reflected light LR is generated in the direction of the incident light LT due to the reflection characteristics of the infrared light. This reflected light LR is reflected by the convex lens 17.
images are formed on points P1 and P2 on the light-receiving surface 19a of the PSD type light-receiving element 19. Let L1 and L2 be the incident lights that enter these points P1 and P2, then L1≒L2≒L0
sin2πf0t. However, L0≒kArAe
L/4πθr2r2 where k: reflectors 11, 12
Ar: reflection area of reflectors 11, 12, Ae: light receiving area of convex lens 17, θr: divergence angle (radian) of reflected beam of reflectors 11, 12, L
: Intensity of infrared light incident on reflectors 11 and 12 (W
/m2), r: distance between the reflectors 11, 12 and the lens 17.

Further, if the distance between the output electrodes A and B of the PSD type photodetector 19 is d, and the distances between the output electrode A and points P1 and P2 are x1 and x2, then the PSD type photodetector 19
Due to the characteristics of the incident light L2,

[0035]

[Math 2]

[0036]

[Math 3]

By the incident light L2,

[0038]

[Math 4]

A photocurrent of [0039] is generated in electrodes A and B.

[0040] However, I≒ηL1≒ηL2≒ηL0si
n2πf0t Here, I: Photocurrent excited by incident light η: Conversion efficiency of the PSD type light receiving element 19.

Therefore, the currents IA and I generated in electrodes A and B
B is

[0042]

[Math 5]

[0043]

The currents IA and IB flow through the respective coupling capacitors C to the amplifiers 21 and 23, and these currents are converted into voltages and output voltages eA and eB are outputted from the amplifiers 21 and 23, respectively. This output voltage eA, eB
is the following formula

[0045]

[Math 6]

It is given by:

From the above formulas (5) to (8)

0048
]

[Math 7]

[0049]

[0050] Here, x1 and x2 are the reflectors 11,
12 and the convex lens 17 (vehicle distance) R and the distances l1 and l2 from the optical axis g of the convex lens 32 are as follows. ΔP1FO and ΔLHO are similar, P
Since 2FO and ΔRHO are similar,

[0051]

[Math. 8]

From formulas (12) and (13),

0053
]

[Math. 9]

Substituting (14) into equations (10) and (11),

[0055]

[Math. 10]

[0056]

Therefore, since the PSD type light receiving elements 19, 20 shown in FIG. 7 have the same configuration, characteristics, and shape as those shown in FIG. 8, the PSD type light receiving elements 19, 2
An output current similar to that shown in FIG. 8 is obtained from the output electrodes A1, B1, A2, and B2 of 0, and the output voltage e
A1, eB1, eA2, eB2 are (15), (16)
Given in a similar formation to Eq.

Here, FIG. 7 and FIG. 8 are made to correspond to each other (15
), the relational expression in FIG. 1 for l1, l2 in equation (16) is determined.

The optical axes of the convex lenses 17 and 18 are g1 and g2.
Figure 7 shows the distance between the reflectors 11 and 12
As shown, l1→lL-m, l2→lR+m, and eA1 can be found by equation (15). Similarly, l1→lL+m, l2→lR−m to eA2
is found. Also, l1→lL−m, l2→lR+m, and from equation (16), eB1 becomes l1→lL+m, l2
→ eB2 is determined from lR-m.

[0060] Therefore,

[0061]

[Math. 11]

Here, AC signals eA1 and eA of frequency f0
2, eB1, eB2 are expressed as follows.

However, it is assumed that ηL0Rf≡K.

[0064]

[Math. 12]

Therefore, each AC signal is as follows.

[0066] eA1 = EA1sin2πf0t e
A2 = EA2sin2πf0t eB1= EB1
sin2πf0t eB2 = EB2sin2πf0
t FIG. 9 shows a block configuration diagram of the distance measuring means 201, 301 that calculates the inter-vehicle distance R from the above AC signal using the above equations (21) to (24).
51 to 54 are narrowband amplifiers that remove noise caused by external light such as sunlight and have a voltage gain M; 61 to 64 are AC signals MeA1 and MeA output from the narrowband amplifiers 51 to 54;
2, MeB1, MeB2 as DC voltage M'EA1, M'
EA2, M'EB1, M'EB2 (where M'≡ξ・M, ξ: rectification efficiency), 71 is the DC voltage M'EA1, M'EA2, M'EB1, M'EB
an analog multiplexer that converts 2 into a multiplexed signal;
72 is an A/D converter, and 73 is a microcomputer that calculates the inter-vehicle distance R, etc. through arithmetic processing.

By the way, from the above equations (21) and (23),

[0068]

[Math. 13]

Next, from equations (21) and (22),

007
0]

[Math. 14]

From equations (25) and (26),

[0072]

[Math. 15]

We obtain: This equation (27) is stored in advance in the microcomputer 73. Therefore, the microcomputer 73 receives the input from the rectifier circuit 61 via the multiplexer 71 and the A/D converter 72.
~64 output voltages M'EA1, M'EA2, M'EB1
Then, the inter-vehicle distance R is calculated based on equation (27).

Next, a formula for determining the offset amount L is determined.

[0075]

[Math. 16]

[0076] In the above equation, 2M'K≒M'EA1 of equation (25)
Substitute +M'EB1

[0077]

[Math. 17]

[0078] When organized,

[0079]

[Math. 18]

From formulas (27) and (28),

0081
]

[Math. 19]

The offset amount L of the preceding vehicle Y with respect to the light transmitter/receiver 14 of the host vehicle X can be determined from the value of lL−lR. That is, if lL-lR=0, the light transmitter/receiver 1
4's center line g and the center line h of the preceding vehicle Y are the same, and l
It can be seen that when L-lR>0, the center line h of the preceding vehicle Y is offset to the left, and when lL-lR<0, the center line h of the preceding vehicle Y is offset to the right. Therefore, in the case of lL−lR<0 as shown in FIG.
The distance L between the centers of

[0083]

[Math. 20]

It can be found as follows. The above equation (29) is stored in the microcomputer 73 in advance. This microcomputer 73 then outputs the output voltage M'E.
The offset amount L is determined from A1, M'EA2, and M'EB1 based on the above equation (28). From this offset amount L, the positional relationship in the width direction between the host vehicle X and the preceding vehicle Y can be determined.

Next, the operation of the information processing circuit 302 is shown in FIG.
The explanation will be based on the flowchart shown in .

When the power is turned on to the device of this embodiment, S-3
10, the information processing is started and the process proceeds to S-311. In S-311,

[0087]

[Math. 21]

The offset amount L of the preceding vehicle Y with respect to the host vehicle X is determined by calculating the following.

Next, proceed to S-312 and set the offset amount L.
and the width of the straight-ahead area of own vehicle X W + ΔW (Basically, W = 1
．． 5m (passenger vehicle width), ΔW = 1.0m: selected as margin), and if L<W+ΔW, that is, there is a preceding vehicle within the straight-ahead area D, the information processing circuit 2 in the above-mentioned embodiment
The program moves to step S-313 (point A in FIG. 2) of the same program as in the flowchart of No. 03, and the same judgment and operation as in the above-described embodiment are performed.

In addition, if L≧W+ΔW in S-312, then the preceding vehicle Y does not exist in the straight-ahead area D of the own vehicle Inform the driver.

[0091]

SUMMARY OF THE INVENTION As explained above, the present invention is directed to a pair of reflectors 11 and 12 provided on the front object Y and spaced apart on an axis intersecting the front axis direction. A light emitting element 16, a pair of PSD light receiving elements 19 and 20 arranged to sandwich the light emitting element 16, and
This distance detection device is characterized by comprising a calculation means 302 for determining the distance to the forward object S based on the output from each of the SD light receiving elements.

[0092]

Therefore, according to the present invention, it is possible to accurately measure the distance to an object located in front or diagonally in front, and when the object is to be placed at a predetermined position from a reference point, without being installed in the wrong direction.
The effect is that it can be installed in the correct position.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a preceding vehicle position detection device according to the present invention.

FIG. 2 is a flowchart of the present invention.

FIG. 3 is a diagram showing the alarm operation range of the present invention.

FIG. 4 is a diagram showing the relationship between the own vehicle and a preceding vehicle.

FIG. 5 is a block diagram of a distance detection device.

FIG. 6 is a flowchart of the present invention.

FIG. 7 is a schematic diagram of a light transmitter/receiver.

FIG. 8 is a cross-sectional view of a PSD type light receiving element of the present invention.

FIG. 9 is a block diagram of distance measuring means.

FIG. 10 is a diagram showing a state in which the inter-vehicle distance is detected by visual measurement.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: A light emitting element (16) that emits light toward a pair of reflectors (11, 12) provided on the front object (Y) and spaced apart on an axis intersecting the front axis direction.
and a pair of PSD light-receiving elements (19, 20) arranged to sandwich the light-emitting element (16), and based on the output from each of the PSD light-receiving elements, A distance detection device comprising: calculation means (302) for determining distance.