JP2004117257A - Vehicle-to-vehicle distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle-to-vehicle distance measuring device which is hardly affected by circumferential lightness at a low cost and is excellent in responsiveness. <P>SOLUTION: The vehicle-to-vehicle distance measuring device 10 is constituted with a module 12 combined with an active unit 14 and a passive unit 16 vertically overlapping, and a plurality of the modules 12 are horizontally arrayed in a line. The active unit 14 is equipped with a light projecting lens 18 and a light receiving lens 20 on its front surface and their optical axes are in the same vertical line. The passive unit 16 overlapping the active unit 14 having the same outer size as the active unit 14 in its width and depth so as to be used as the module 12. The passive unit 16 is equipped with light receiving lenses 22 and 24 on its front surface, and their optical axes are in a same vertical line. The active unit 14 and the passive unit 16 are provide with fitting parts 30 respectively, they can form the module 12 precisely and substantially. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inter-vehicle distance measuring device.
[0002]
[Prior art]
Conventionally, an inter-vehicle distance measurement device using active and passive distance measuring devices, a device that recognizes a preceding vehicle using image processing technology, a vehicle speed or an obstacle using a device embedded on the road surface, etc. There are devices that measure the distance and devices that use radar. (For example, see Patent Documents 1 to 4)
However, the active distance measuring device has a short measuring distance, and the passive distance measuring device has disadvantages such as deterioration of the distance measuring accuracy in the dark, and other methods have disadvantages such as high cost and long response time. There is.
[0003]
[Patent Document 1]
JP-A-8-43083 (pages 2 and 3, FIGS. 1 and 2)
[Patent Document 2]
JP 2000-339594 A (pages 2 to 5, FIGS. 1 and 6)
[Patent Document 3]
JP 2000-268298 A (pages 2 to 4)
[Patent Document 4]
Japanese Patent Laid-Open No. 9-309358 (pages 2-4, FIG. 2)
[0004]
[Problems to be solved by the invention]
In consideration of the above-mentioned facts, the present invention provides a distance measurement device that is low-cost, excellent in responsiveness, and hardly affected by ambient brightness by applying a distance measurement technique conventionally used in an AF mechanism of a camera. This is the issue.
[0005]
[Means for Solving the Problems]
The inter-vehicle distance device according to claim 1 includes a luminance detecting means for detecting the luminance of the outside world, and a distance measuring light emitted from a built-in light source forwardly projected from a light receiving position of reflected light reflected by the preceding vehicle. An active distance measuring device that measures a distance to a passive distance measuring device that measures a distance from an image position of a preceding vehicle imaged on a pair of sensor arrays each having a light receiving lens to the preceding vehicle; And measuring the distance by switching between the active distance measuring device and the passive distance measuring device in accordance with the brightness of the outside world detected by the brightness detecting means.
[0006]
In the invention having the above-described configuration, both the active-type distance measuring device and the passive-type distance measuring device are provided, and distance measurement is performed by switching between active / passive according to the luminance of the outside world detected by the luminance detecting means. By using different types of passive, which can measure the distance with high accuracy even when it is bright, and active that is strong against darkness when it is dark, it is possible to provide an inter-vehicle distance measuring device with low cost and excellent responsiveness.
[0007]
The inter-vehicle distance device according to claim 2 is characterized in that the light source of the active distance measuring device is a near infrared LED.
[0008]
In the invention of the above configuration, there is a risk of adversely affecting the eyes of the driver of the preceding vehicle or the oncoming vehicle by using a high-intensity LED without using a laser that is highly dangerous to the human body and using a wavelength in the near infrared region. There is no.
[0009]
The inter-vehicle distance device according to claim 3 is characterized in that the luminance detecting means is a light receiving portion of the passive distance measuring device.
[0010]
In the invention having the above-described configuration, the light receiving unit of the passive distance measuring device is used as the luminance detecting means for detecting the luminance of the outside world, whereby the entire device can be reduced in size, simplified, and reduced in cost.
[0011]
The inter-vehicle distance device according to claim 4 is characterized in that a plurality of distance measuring devices in which the luminance detecting means, the active distance measuring device, and the passive distance measuring device are modularized are installed.
[0012]
In the invention with the above configuration, by installing a plurality of modular ranging devices in the vehicle, it becomes possible to increase the accuracy of ranging, backup at the time of failure by mutual complementing between devices, and the like.
[0013]
6. The inter-vehicle distance measuring device according to claim 5, wherein the active-type distance measuring device and the passive-type distance measuring device include direction adjusting means for changing a direction of distance measurement according to a traveling direction of the vehicle. To do.
[0014]
In the invention with the above-described configuration, the distance measurement direction is not the front of the vehicle but the traveling direction, so that it is possible to improve the inter-vehicle distance measurement accuracy during cornering.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of the inter-vehicle distance measuring device according to the first embodiment.
[0016]
As shown in FIG. 1, the inter-vehicle distance measuring device 10 has a configuration in which an active unit 14 and a passive unit 16 are combined and a plurality of stacked modules 12 are arranged.
[0017]
The active unit 14 has a substantially rectangular parallelepiped shape. A light projecting lens 18 and a light receiving lens 20 are provided on the front surface, and the optical axes of the light projecting lens 18 and the light receiving lens 20 are on the same plane. The near-infrared light for distance measurement emitted from the light projection lens 18 is affected by water splashes and dust near the road surface during bad weather or when traveling on an unpaved road, so it is projected above the device at a distance from the road surface. It may be desirable to provide an optical lens 18. Alternatively, depending on the shape of the front end of the vehicle and the front grill, it may be desirable to provide the light receiving lens 20 above the device in order to avoid the influence of steady light, so that the entire device or the active unit alone can be installed upside down. Also good.
[0018]
The front surface of the active unit 14 is covered with an infrared filter 26 to protect the lens and to cut visible light from the light beam emitted from the light projecting lens 18 and transmit only infrared light.
[0019]
The passive unit 16 has a substantially rectangular parallelepiped shape, is stacked with the active unit 14, and has a lateral width and a depth equal to the active unit 14 for use as the module 12. The passive unit 16 is provided with light receiving lenses 22 and 24 on the front surface, and the optical axes of the light receiving lenses 22 and 24 are on the same vertical line. The front surface of the passive unit 16 is covered with a transparent filter 28 to protect the lens.
[0020]
Further, each of the active unit 14 and the passive unit 16 includes a fitting portion 30, and the module 12 can be formed with high accuracy and robustness by being fitted to each other.
[0021]
FIG. 2 shows a cross-sectional view of the inter-vehicle distance measuring device according to the first embodiment.
[0022]
As shown in FIG. 2, the active unit 14 is provided with a high-intensity LED 32 at the focal position of the projection lens 18. The high-intensity LED 32 has a spectral characteristic in the near-infrared region, and the emitted light beam is converged by the projection lens 18, the visible light is cut by the filter 26, and is projected forward only by the near-infrared light component. The image is formed as a spot.
[0023]
A light receiving element 34 is provided on the focal plane of the light receiving lens 20. Near-infrared light emitted from the high-intensity LED 32 and applied to the preceding vehicle is received by the light receiving lens 20 and forms a spot image on the light receiving element 34. The light receiving element 34 measures the distance from the position of the spot image to the preceding vehicle. At this time, the distance d1 between the optical axis a1 of the light projecting lens 18 and the optical axis a2 of the light receiving lens 20 is the base line length of the active unit 14.
[0024]
The passive unit 16 is provided with photosensor arrays 36 and 38 at the focal planes of the light receiving lenses 22 and 24, respectively. An image of the preceding vehicle is formed on the photosensor arrays 36 and 38 by the light receiving lenses 22 and 24, and the distance from the image position to the preceding vehicle is measured. At this time, the distance d2 between the optical axis a3 of the light receiving lens 22 and the optical axis a4 of the light receiving lens 24 is the base line length of the passive unit 16.
[0025]
Further, the light amount information detected by the optical sensor array 36 or 38 or both is output to the switching determination unit 46, and the brightness of the outside world is measured.
[0026]
In the present embodiment, the active unit 14 and the passive unit 16 are vertically arranged and stacked vertically. However, the present invention is not limited to this, and it is needless to say that both units may be horizontally arranged to have a flat stacked structure. Particularly in recent vehicles that emphasize aerodynamics, the vertical dimension of the front nose portion is small, so that the merit of using a flat stack structure is great.
[0027]
FIG. 3 shows a principle diagram of the active unit according to the first embodiment.
[0028]
As shown in FIG. 3, the near-infrared light emitted from the high-intensity LED 32 of the active unit 14 is imaged as a spot on the preceding vehicles 40 and 42 by the light projecting lens 18. Reflected light (near-infrared light) from the preceding vehicle is received by a light receiving lens 20 on a light receiving element 34 made of PSD (Position Sensing Device: position detecting element) or multi-split SPC (Silicon Photo Cell: silicon light receiving element). Spot images are connected, and the position of the spot image is detected as a displacement amount x1 or x2 on the light receiving element 34.
[0029]
When the preceding vehicle is at the position 42, the distance from the light receiving lens 20 to the preceding vehicle is L2, and the position of the spot imaged on the light receiving element 34 by the reflected light is such that the optical axis of the light receiving lens 20 is the light receiving element 34. If the point intersecting with the light receiving surface is the origin x0, it is detected as a displacement amount x2 from x0.
[0030]
Similarly, when the preceding vehicle is at the position 40, the distance from the light receiving lens 20 to the preceding vehicle is L1, and is detected as a displacement amount x1 on the light receiving element 34.
[0031]
Here, if the focal length of the light receiving lens 20 is f, the relationship L2: d1 = f: x2 is established. That is, L2 × x2 = f × d1. Since f and d1 are fixed numerical values, the distance L2 from the displacement amount x2 on the light receiving element 34 to the preceding vehicle 42 is derived. Similarly, if the displacement amount is x1, the distance to the preceding vehicle 40 is L1.
[0032]
FIG. 4 shows a principle diagram of the passive unit according to the first embodiment.
[0033]
As shown in FIG. 4, when the preceding vehicle is at the position 40, an image of the preceding vehicle 40 is formed on the photosensor arrays 36 and 38 at the positions x1 and x1 ′ by the light receiving lenses 22 and 24.
[0034]
Similarly, when the preceding vehicle is at the position 42, the image of the preceding vehicle 42 is formed on the photosensor arrays 36 and 38 at the positions x2 and x2 'by the light receiving lenses 22 and 24.
[0035]
Here, similarly to the active unit 14, if the focal lengths of the light receiving lenses 22 and 24 are f 'and the points where the optical axes of the light receiving lenses 22 and 24 intersect with the optical sensor arrays 36 and 38 are x0 and x0', The distance L1 is derived from the amount of displacement from x0 to x1 (referred to as dx1), the amount of displacement from x0 ′ to x1 ′ (referred to as dx1 ′), the focal length f ′, and the baseline length d2. Similarly, the distance L2 is derived from the amount of displacement from x0 to x2 (referred to as dx2), the amount of displacement from x0 ′ to x2 ′ (referred to as dx2 ′), the focal length f ′, and the baseline length d2.
[0036]
That is, when the preceding vehicle 40 is in front of the light receiving lenses 22 and 24, that is, equidistant from the light receiving lenses 22 and 24, a relationship of L1: d2 / 2 = f ′: dx1 is established.
[0037]
Similarly, when the preceding vehicle is at the position 42, the relationship L2: d2 / 2 = f ′: dx2 is established, and d2 and f ′ are fixed numerical values, so that L1 and L2 can be obtained from dx1 and dx2. At this time, depending on the arrangement direction of the optical sensor arrays, it is difficult to distinguish between the movement of the target across the front and the movement in the perspective direction, so that the accuracy of distance measurement is improved by combining a plurality of optical sensor arrays and modules.
[0038]
FIG. 5 shows a block diagram of the inter-vehicle distance measuring apparatus according to the first embodiment.
[0039]
As shown in FIG. 5, the passive unit 16 has a function of detecting the brightness of the outside world, and the brightness of the outside world is detected by the optical sensor array provided in the passive unit 16 without providing a device for brightness detection. To do. The obtained luminance value is sent to the switching determination unit 46. In the switching determination unit 46, when the brightness of the outside world is lower than a certain value, the active unit 14 is operated to collect distance measurement data and send it to the calculation unit 48. When the luminance is higher than the certain value, the distance measurement from the passive unit 16 is performed. A determination is made to send the data to the calculation unit 48.
[0040]
The calculation unit 48 determines whether the inter-vehicle distance at the current vehicle speed is safe from the distance measurement data sent and the vehicle speed data detected by the vehicle speed sensor unit 52. If it is determined that the vehicle is not safe, a command is sent to the warning unit 50. The warning unit 50 alerts the driver or controls the engine to increase the inter-vehicle distance, thereby reducing the vehicle speed.
[0041]
In this case, since the brightness of the outside world is always detected, the passive unit 16 is always operating in this embodiment. In this case, since the photometric unit is not required, the configuration is simple, the number of parts is small, and the cost can be reduced.
[0042]
FIG. 6 shows a block diagram of the inter-vehicle distance measuring device according to the second embodiment.
[0043]
As shown in FIG. 6, the photometry unit 44 measures the brightness of the outside world and sends the obtained brightness value to the switching determination unit 46. The switching determination unit 46 operates the active unit 14 when the external brightness is lower than a certain value, collects distance measurement data and sends it to the calculation unit 48, and activates the passive unit 16 when the luminance is higher than the certain value. It is determined that the distance measurement data is collected and sent to the calculation unit 48.
[0044]
In this case, the number of parts increases, but it is not necessary to always operate the passive unit 16, and since the installation location of the photometry unit 44 can be freely set, there is an advantage that the influence of the headlight of the oncoming vehicle can be reduced.
[0045]
FIG. 7 shows a flowchart relating to the operation of the inter-vehicle distance measuring device according to the first embodiment.
[0046]
First, at step 60, the vehicle speed vn is detected. The vehicle speed vn may be taken from the speedometer, or a new vehicle speed sensor unit 52 may be provided as shown in FIGS.
[0047]
Next, at step 62, the safe inter-vehicle distance ks is calculated. The safe inter-vehicle distance ks can be expressed by a function of the vehicle speed vn, that is, ks = f (vn).
[0048]
In step 64, the distance measurement data kn is taken. This distance measurement data kn is sent from the plurality of modules 12 to the calculation unit 48, and either an active or passive unit is selected depending on the brightness of the outside world.
[0049]
Next, at step 66, the safety distance ks is compared with the distance measurement data kn. If the distance measurement data kn is equal to or greater than the safe inter-vehicle distance ks, that is, kn ≧ ks, the process returns to step 60 without doing anything and the flow is repeated from the detection of the vehicle speed vn again. If the distance measurement data kn is less than the safe inter-vehicle distance ks, that is, kn <ks, the routine proceeds to step 68.
[0050]
In step 68, the driver is warned by warning that the inter-vehicle distance is less than the safe inter-vehicle distance, or if the electronic control fuel injection device is installed, the fuel is cut to reduce the vehicle speed, or the electronic control transmission If the vehicle is equipped, reduce the vehicle speed by dropping the gear about 1 to 2 steps or by operating the foot brake to increase the distance between the vehicles. After performing these correspondences, the process returns to step 60 again to repeat the flow.
[0051]
However, when decelerating by fuel cut or braking, the fluctuation of the inter-vehicle distance is predicted from the speed of the preceding vehicle, and if the speed control of the host vehicle is not performed, overshoot will occur, and the ride quality will deteriorate, such as the vehicle body snatching. Therefore, detailed vehicle speed control and advanced calculation processing, and further improvement in the speed of processing the steps 60 to 68 are important. In the present application, since the technology already put into practical use in the AF camera is adopted, it is possible to provide a low-cost and high-speed distance measuring device by application of predictive driving AF or the like.
[0052]
FIG. 8 is a perspective view of the inter-vehicle distance measuring device according to the third embodiment.
[0053]
As shown in FIG. 8, the base plate 70 is rotatably held around the fulcrum 72 at one end in the longitudinal direction. The other end of the base plate 70 is fixed to the slide plate 74 with a screw 76, and the screw hole 80 is a long hole extending in the longitudinal direction of the base plate 70.
[0054]
A rack gear 82 is carved on the top surface of the end portion of the slide plate 74, and is engaged with a pinion gear 84 driven by a motor 78. Thereby, the rotation of the motor 78 is transmitted from the pinion gear 84 to the rack gear 82, and the slide plate 74 is slid in the arrow direction.
[0055]
A screw 76 fixed to the slide plate 74 rotates the base plate 70 about the fulcrum 72. Since the module 12 is mounted and fixed on the base plate 70, the direction of the module 12 changes according to the movement of the base plate 70. That is, the direction in which the module 12 measures the distance is adjusted by the rotation of the motor 78.
[0056]
9 and 10 are diagrams for explaining the operation of the inter-vehicle distance measuring device according to the third embodiment.
[0057]
As shown in FIG. 9, the traveling direction of the vehicle body is detected by a direction sensor 90 that detects the rotation of the steering wheel or the angle of the front wheel, and is sent to the calculation unit 48. The calculation unit 48 controls the rotation of the motor 78 based on the direction data so that the module 12 always faces the front wheel, that is, the traveling direction of the vehicle body.
[0058]
As a result, as shown in FIG. 10, even during cornering, the module 12 measures the distance in the direction in which the front wheel 88 faces rather than the front of the host vehicle 86, so that an accurate inter-vehicle distance can be measured.
[0059]
However, since the system is designed to measure the distance between vehicles, it is assumed that it is used in a state where the vehicle speed exceeds a certain level, and it is necessary to follow the vehicle body traveling direction in a fully locked state at a low speed like a garage. There is no. That is, it is sufficient for the direction change amount of the module 12 to cover a narrow range centering on the straight traveling state in the direction change of the steering / front wheel.
[0060]
【The invention's effect】
Since the present invention has the above configuration, it is possible to provide an inter-vehicle distance measuring device that is low in cost, excellent in responsiveness, and hardly affected by ambient brightness.
[Brief description of the drawings]
FIG. 1 is a perspective view of an inter-vehicle distance measuring device according to a first embodiment.
FIG. 2 is a cross-sectional view of the inter-vehicle distance measuring device according to the first embodiment.
FIG. 3 is a sectional view of an active unit according to the first embodiment.
FIG. 4 is a cross-sectional view of a passive unit according to the first embodiment.
FIG. 5 is a block diagram of the inter-vehicle distance measuring device according to the first embodiment.
FIG. 6 is a block diagram of an inter-vehicle distance measuring device according to a second embodiment.
FIG. 7 is a flowchart of the inter-vehicle distance measuring device according to the present embodiment.
FIG. 8 is a perspective view of an inter-vehicle distance measuring device according to a third embodiment.
FIG. 9 is a block diagram of an inter-vehicle distance measuring device according to a third embodiment.
FIG. 10 is an operation explanatory diagram of the inter-vehicle distance measuring device according to the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Inter-vehicle distance measuring device 12 Module 14 Active unit 16 Passive unit 18 Light projection lens 20 Light reception lens 22 Light reception lens 24 Light reception lens 26 Infrared filter 28 Transparent filter 30 Fitting part 32 High-intensity LED
34 Photodetector 36 Photosensor array 38 Photosensor array 40 Preceding vehicle 42 Preceding vehicle 86 Own vehicle 88 Front wheel

Claims (5)

Brightness detection means for detecting the brightness of the outside world;
An active distance measuring device that projects the distance measuring light emitted by the built-in light source forward and measures the distance from the light receiving position of the reflected light reflected by the preceding vehicle to the preceding vehicle;
A passive distance measuring device that measures the distance from the image position of a preceding vehicle imaged on a pair of sensor arrays each having a light receiving lens to the preceding vehicle;
With
An inter-vehicle distance measuring device that performs distance measurement by switching between the active-type distance measuring device and the passive-type distance measuring device in accordance with the luminance of the outside world detected by the luminance detecting means. The inter-vehicle distance measuring device according to claim 1, wherein the light source of the active distance measuring device is a near infrared LED. The inter-vehicle distance measuring device according to claim 1, wherein the luminance detecting means is a light receiving unit of the passive distance measuring device. The inter-vehicle distance measuring device according to claim 1, wherein a plurality of ranging devices in which the luminance detecting means, the active ranging device, and the passive ranging device are modularized are installed. 2. The inter-vehicle distance measuring device according to claim 1, wherein the active distance measuring device and the passive distance measuring device include a direction adjusting unit that varies a direction of distance measurement according to a traveling direction of the vehicle. .

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