JPS6355410A - Front road surface state deciding device for vehicle - Google Patents

Abstract

PURPOSE:To suppress to the minimum the light energy accumulation amount which is caused by an incidence of a laser beam to the same part on the front road surface, and also, to delicately decide a state of the front road surface, by extending each period of a first and a second timing signals. CONSTITUTION:A timing signal generating circuit 30 generates the first - a third timing signals and a fourth timing signal, and each distance measuring circuit 20a - 20c responds to the first - the third timing signals, respectively, emits successively a laser beam to the front road surface, photodetects each laser beam reflected from the front road surface, respectively, measures a distance between an emitting position of each laser beam and a reflecting position, and outputs it as a first - a third distance measuring signals. As a result, a multiplexer 40 responds to each fourth signal from the timing signal generating circuit 30, outputs successively the first - the third distance measuring signals from each distance measuring circuit 20a - 20c, and the values of these respective distance measuring signals are compared with the reference distance and decided 50. In this case, when the front road surface is in a projecting state, it is decided that the value of each distance measuring signal is smaller than the reference distance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle front road surface condition determination device suitable for determining conditions such as unevenness of a road surface in front of a vehicle.

[Prior art]

Conventionally, in this type of forward road surface determination device for a vehicle, an optical position sensor is disposed at the front end of the vehicle, as disclosed in Japanese Patent Laid-Open No. 60-142209, for example.
By emitting a laser beam from this optical position sensor toward the road surface in front of the vehicle, and receiving the laser beam reflected from the road surface in front of the vehicle, the distance between the emission position and the reflection position of this laser beam is measured. Some devices are designed to determine the condition of the road ahead, such as unevenness.

[Problem that the invention seeks to solve]

However, in such a configuration, if the distance measurement sensitivity is to be increased, the energy of the laser beam must be increased, which is generally undesirable. On the other hand, if the energy of the laser beam is reduced too much, a problem arises in that sufficient distance measurement sensitivity cannot be ensured.

SUMMARY OF THE INVENTION In order to deal with this problem, the present invention provides a front road surface condition determination device for a vehicle that uses a laser beam to properly maintain distance measurement sensitivity to the front road surface necessary for determining the condition of the front road surface. The aim is to reduce the beam energy as much as possible.

[Means for solving problems]

In order to solve this problem, the present invention has a structure that is arranged at the front end of a vehicle, emits a first laser beam toward the road surface in front of the vehicle, and receives the first laser beam reflected from the road surface in front of the vehicle. a first distance measuring means for measuring the distance to the road surface in front of the vehicle and generating a first distance measuring signal; 2nd direction towards the front road surface.
a second distance measurement, emitting a laser beam parallel to the first laser beam and receiving the second laser beam reflected from the front road surface to measure the distance to the front road surface and generate a second distance measurement signal; means for generating a first timing signal necessary for emitting the first laser beam and applying it to the first distance measuring means, and a second timing signal necessary for emitting the second laser beam to the first timing signal; timing signal generating means for generating timing signals which are generated in different phases and applied to the second distance measuring means;
and determining means for sequentially determining the state of the road surface ahead based on each value of the second distance measurement signal.

[Effect]

By configuring the present invention in this manner, when the timing signal generating means generates the first and second timing signals while the vehicle is running, the first distance measuring means generates the first timing signal. In response, a first laser beam is emitted toward the road ahead, the first laser beam reflected from the road ahead is received, the distance to the road ahead is measured, and a first distance measurement signal is generated; A second distance measuring means responds to the second timing signal to emit a second laser beam toward the road ahead in parallel with the first laser beam, and receives the second laser beam reflected from the road ahead. to measure the distance to the front road surface and generate a second distance measurement signal, and the determining means sequentially responds to the first and second distance measurement signals and determines the distance to the front road surface based on the values of these signals. The state of each is determined sequentially.

〔effect〕

As described above, the first and second distances are set such that the first and second laser beams from the first and second distance measuring hands m are incident in parallel on mutually different positions on the front road surface. Measuring means are disposed at different positions in the horizontal direction at the front end of the vehicle, and the emission timings of the first and second laser beams are made to be different from each other in accordance with the first and second timing signals, respectively. Since the state of the road ahead is judged, by lengthening each period of the first and second timing signals, the amount of optical energy accumulated when the laser beam is incident on the same spot on the road ahead can be minimized. In addition, due to the shortening of the firing interval of the first and second laser beams due to the phase difference between the first and second timing signals, the timing signal can be suppressed according to the progress of the vehicle, regardless of the speed of the vehicle. It is possible to judge the condition of the road surface in front of you, which changes from moment to moment, in an extremely detailed manner.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
The figure shows an example of a front road surface determination device according to the present invention applied to a vehicle 10, and this front road surface determination device includes distance measuring circuits 20a and 20b.

20c, and these distance measuring circuits 20a, 20b.

20c, and the multiplexer 4 connected to the distance measuring circuits 20a, 20b, 20c and the timing signal generation circuit 30.
0 and a judgment circuit 50 connected to this multiplexer 40.
It is composed of.

The distance measuring circuits 20a, 20b, 20c are shown in FIGS.
As shown in the figure, the distance measuring circuits 20a are arranged horizontally along the front end 10a of the vehicle 10 at intervals from each other, and the distance measuring circuits 20a emit laser beams toward the road surface in front of the vehicle 10. (See FIG. 3) A laser beam reflected from the front road surface is received, and the distance between the emission position and the reflection position of this laser beam is measured and generated as a first distance measurement signal. The distance measuring circuit 20b emits a laser beam toward the road surface in front of the vehicle 10, receives the laser beam reflected from the road surface in front of the vehicle 10, and measures the distance between the emission position and the reflection position of the laser beam. 2
Generated as a distance measurement signal. In addition, the distance measurement circuit 20
c emits a laser beam toward the road surface in front of the vehicle 10, receives the laser beam reflected from the road surface in front of the vehicle 10, measures the distance between the emission position and the reflected position of the laser beam, and generates a third distance measurement signal. occurs as.

In this case, the emission angles of the laser beams emitted from the distance measuring circuits 20a, 20b, and 20C with respect to the horizontal plane are the same, and the emission directions of the laser beams are parallel to each other.

The timing signal generation circuit 30 is connected to the distance measurement circuit 20a.
, 20 b, and 20 c, respectively. The second and third timing signals (see FIGS. 4(a), (b), and (C)) are generated at the same period with a predetermined phase difference from each other, and are sent to the distance measuring circuits 20a, 20b, and 20c. Grant each. Further, the timing signal generation circuit 30 has the first .
A fourth timing signal (see Td in FIG. 4) is generated in synchronization with each of the second and third timing signals. The multiplexer 40 connects the distance measuring circuits 20a, 20
b, 20c outputs any one of the first to third distance measurement signals from the timing signal generation circuit 30 in response to the fourth timing signal from the timing signal generation circuit 30. The determination circuit 40 determines the first to third distances jlii! from the multiplexer 30! III
In response to the J constant signal, the values of these signals are compared with a reference distance to determine whether there are any unevenness on the road ahead.

In this embodiment configured as described above, when the device of the present invention is operated while the vehicle 10 is running, the timing signal generation circuit 30 generates the first to third timing signals and the fourth timing signal. Distance measurement circuits 20a, 20b
, 20c is the first. In response to the second and third timing signals, the laser beams are sequentially emitted toward the road ahead, as shown in FIGS. 2 and 3, and each laser beam reflected from the road ahead is received. and measure the distance between the emission position and the reflection position of each laser beam. Second. A third distance measurement signal is generated.

Then, the multiplexer 40 responds to each of the fourth timing signals from the timing signal generation circuit 30 and sequentially outputs the first to third distance measurement signals from each of the distance measurement circuits 20a, 2Ob, and 20G. The value of each distance measurement signal is compared with the reference distance; at this stage, since the road surface ahead is in a convex state as shown in FIGS. 2 and 3, the determination circuit 50 compares the value of each distance measurement signal It is determined that the value is smaller than the reference distance. This means that it has been determined that the road ahead is in a convex state.

As explained above, each distance measuring circuit 20a.

The distance measuring circuits 20a, 20b, 20c are connected to the front end 10a of the vehicle 10 so that the laser beams from the laser beams 20b, 20c are incident parallel to different positions on the front road surface.
The distance measuring circuits 2 are arranged at different positions in the horizontal direction.
The emission timing of each laser beam from 0a, 20b, and 20c is determined by the first . Second. The respective distance measuring circuits 20a, 20b,
The distance measurement signal from 20c is sent to the timing signal generation circuit 3.
Since the fourth timing signal from 0 is sequentially applied to the determination circuit 50 via the multiplexer 40, by lengthening the period of each timing signal from the timing signal generation circuit 30, The amount of optical energy accumulated due to the incidence of a laser beam on the same location can be suppressed to a minimum, and each distance measuring circuit 20a can be adjusted according to the mutual phase difference of the first to third timing signals from the timing signal generation circuit 30. By shortening the firing interval of the laser beams from ~20c, the convex state of the road surface ahead can be accurately determined regardless of the speed of the vehicle 10. Further, based on such a determination result, vehicle height control of the vehicle 10, etc. can be smoothly performed in advance of a convex state of the road surface in front of the vehicle. In addition, in the above explanation, the case where the front road surface is in a convex state has been explained, but the present invention is not limited to this, and substantially the same operation and effect as described above can be achieved even when the front road surface is in a concave state. It is possible.

In implementing the present invention, each laser oscillation section having a laser beam oscillation function in the distance measurement circuits 208 to 20C described in the above embodiment is made independent from the distance measurement circuits 208 to 20G, as shown in FIG. As shown in the figure, distance measuring circuits 20A to 20C and a single laser oscillation unit 20D are adopted in place of distance measuring circuits 20a to 20c, and a step motor 21, a tilting reflector 22, and fixed reflectors 23 to 25 are added. Alternatively, the number of laser oscillation units may be reduced. In such a case, the laser oscillation unit 20D sequentially emits a laser beam toward the tilting reflector 22 in response to each fourth timing signal from the timing signal generation circuit 30, and the tilting reflector 22 responds to each fourth timing signal from the timing signal generation circuit 30. The step motor 21 is tilted in response to the rotation of the step motor 21, which sequentially responds to each of the fourth timing signals from the laser generator 30, and sequentially reflects the laser beam sequentially generated from the laser oscillation unit 20D toward each of the fixed reflecting mirrors 23, 24, and 25. The measurement circuits 20A, 20B, and 20C receive the first signal from the timing signal generation circuit 30. In response to the second and third timing signals, each reflected laser beam is received from each of the fixed reflecting mirrors 23, 24, and 25 and is emitted toward the road ahead. However, the tilting reflector 22 is connected to the timing signal generation circuit 3.
It is arranged to return to the original position every time the third timing signal from 0 is generated.

Further, in the embodiment, the distance measuring circuit 20a,
20b and 20c are used, but the present invention is not limited to this, and the number of distance measuring circuits may be changed as appropriate.

Further, in the above embodiment, the timing signal generation circuit 10 that always generates each timing signal at the same period was employed, but instead of this, a vehicle speed sensor may be used to generate each timing signal at a period corresponding to the vehicle speed. A timing signal generation circuit that generates a signal may be employed.

Further, in the embodiment, the distance measuring circuits 20a, 2
Although the case where the emission directions of the laser beams from 0b and 20c are parallel to each other has been described, the present invention is not limited to this.
It is only necessary that the emission directions of the respective laser beams from the distance measuring circuits 20a, 20b, and 20c are parallel to each other.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams showing the installation state of each distance measuring circuit in FIG. 1 and the emission direction of each laser beam,
FIG. 4 is a time chart showing the first to fourth timing signals from the timing signal generation circuit in FIG. 1, and FIG. 5 is a block diagram showing main parts of a modification of the embodiment. Explanation of symbols 10--Vehicle, 20a, 20b, 20c--Distance measurement circuit, 30...Timing signal generation circuit, 50...
・Judgment circuit.

Claims (1)

[Claims] A first laser beam disposed at the front end of the vehicle emits a first laser beam toward the road surface in front of the vehicle, receives the first laser beam reflected from the road surface in front of the vehicle, measures the distance to the road surface in front of the vehicle, and measures the distance to the road surface in front of the vehicle. a first distance measuring means that generates a distance measuring signal; and a second laser beam that is disposed at the front end of the vehicle with a horizontal spacing from the first distance measuring means and emits a second laser beam toward the road surface in front of the vehicle. a second distance measuring means that is emitted in parallel with the first laser beam and receives the second laser beam reflected from the front road surface to measure the distance to the front road surface and generate a second distance measurement signal; A first timing signal necessary for emitting the first laser beam is generated and applied to the first distance measuring means, and a second timing signal necessary for emitting the second laser beam is set in phase with the first timing signal. timing signal generating means for generating a timing signal differently and applying it to the second distance measuring means; A front road surface condition determining device for a vehicle, comprising determining means for sequentially determining the condition of the front road surface.