JPS6355409A - Laser distance measuring instrument for vehicle - Google Patents

Abstract

PURPOSE:To measure a distance to an object to be measured, with high accuracy, by adjusting a period of a timing signal in response to a car speed detecting signal, and suppressing low an energy accumulation amount of a laser beam which is made incident on the object to be measured. CONSTITUTION:When a vehicle has reached to front of a projecting part X, when a car speed sensor 20 generates a pulse signal, a timing generating circuit 30 generates a timing signal in a period corresponding to a frequency of the pulse signal, and a driving signal is generated from a laser driving circuit 40. As a result, a laser oscillator 11 emits a laser beam, and the projecting part X is projected through a collimator lens 12. Subsequently, when a photodetecting lens 13 condenses a laser beam which has been reflected from the projecting part X, and an image is formed on a photodetecting surface of an optical position detecting element 14, the detecting element 14 generates a photodetecting signal, a synchronization detecting circuit 50 generates a position detecting signal, and a distance calculation 60 is executed. Next, by comparing a value of a distance measuring signal and a reference distance, the projecting part X on the front road surface can be decided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a distance measuring device for a vehicle, and particularly to a vehicle that measures the distance between the vehicle and an object to be measured using a laser beam. The present invention relates to a laser distance measuring device for use.

[Prior art]

Conventionally, in this type of vehicle laser distance measuring device, as disclosed in Japanese Patent Application Laid-Open No. 60-142209, a laser beam is emitted in response to a timing signal from an optical sensor provided at the front end of the vehicle. There is a device in which a laser beam is emitted toward an object to be measured, and an optical sensor receives the laser beam reflected from the object to be measured to measure the distance between the emission position and the reflection position of the laser beam. .

[Problem that the invention seeks to solve]

However, in such a configuration, the period of the timing signal is fixed, so if the period of the timing signal is long, the amount of energy stored in the laser beam incident on the object to be measured will be low, but the high speed of the vehicle When the vehicle is running, it is not possible to make extremely detailed measurements of the object to be measured, which changes from moment to moment, making it difficult to obtain accurate measurement results. On the other hand, if the period of the timing signal is shortened, when the vehicle is running at high speed, the period of the timing signal matches the degree of change in the object to be measured, ensuring accurate measurement results, but when the vehicle is running at low speed, the same This results in a problem that the number of times the laser beam is incident on the object to be measured increases, leading to an increase in the amount of accumulated energy.

Therefore, in order to cope with this problem, the present invention provides a laser distance measuring device for a vehicle, in which the period of a timing signal that specifies the firing interval of the laser beam emitted by the distance measuring means is adjusted to increase the traveling speed of the vehicle. The aim is to shorten (or lengthen) the length (or decrease) accordingly.

[Means for solving problems]

In solving this problem, the structural features of the present invention are as follows:
a distance measuring means disposed in a part of the vehicle and configured to emit a laser beam toward an object to be measured, receive the laser beam reflected from the object to be measured, and measure the distance to the object to be measured; A laser distance measuring device comprising timing signal generating means for generating a timing signal necessary for emitting the laser beam and applying it to the distance measuring means, detecting the traveling speed of the vehicle and using the detection result as a vehicle speed detection signal. A vehicle speed detection means for generating a vehicle speed is provided, and the timing signal generation means responds to the vehicle speed detection signal and shortens (or lengthens) the period of the timing signal in accordance with an increase (or decrease) in the value of the vehicle speed detection signal. It's what I chose to do.

[Effect]

By configuring the present invention in this manner, when the vehicle speed detection signal is generated from the vehicle speed detection means when the vehicle is traveling at high speed, the period of the timing signal generated from the timing signal generation means is determined to be equal to the vehicle speed detection signal. It gets shorter depending on the signal value.

Therefore, the distance measuring means measures the distance to the object by emitting a laser beam toward the object at short intervals in response to the timing signal. on the other hand,
When the vehicle speed detection signal is generated from the vehicle speed detection means when the vehicle is running at a low speed, the period of the timing signal generated from the timing signal generation means becomes longer in accordance with the value of the vehicle speed detection signal. Therefore, the distance measuring means
In response to the timing signal, a laser beam is emitted toward the object to be measured at long intervals to measure the distance to the object.

〔effect〕

For this reason, when the vehicle is running at low speed, the interval between laser beams emitted from the distance measuring means becomes longer, and as a result, the amount of energy accumulated in the laser beam incident on the object to be measured is reduced (suppressed) while reaching the object to be measured. On the other hand, when the vehicle is running at high speed, the distance between the laser beams emitted from the distance measuring means becomes shorter, and as a result, the distance to the object to be measured can be precisely measured. The amount of accumulated energy of the laser beam incident on the same object to be measured can be minimized.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
The figure shows an example in which the present invention is applied to a forward road surface determination device for a vehicle. This forward road surface determination device has a photodetector 10 (see FIG. 2) disposed at the front end of the vehicle.
The photodetector 10 includes a laser oscillator 11, a collimator lens 12, a light receiving lens 13, and an optical position detecting element 14. The laser oscillator 11 is
When driven, it oscillates and emits a laser beam. The collimator lens 12 directs the laser beam from the laser oscillator 11 toward the road surface in front of the vehicle. The light-receiving lens 13 receives the laser beam reflected from the front road surface, condenses it, and forms an image on the light-receiving surface of the optical position detection element 14. Optical position detection element 1
4 is constructed by arranging a plurality of light receiving elements in a row, and the entire light receiving surface of each of these light receiving elements is the optical position detecting element 1.
4 light receiving surfaces are formed. Therefore, the optical position detection element 1
4 generates the light reception results of each of the light receiving elements in time series as a light reception signal. In such a case, as shown in FIG. 1, the image formation position on the light receiving surface of the optical position detecting element 14 is determined by the distance between the reflection position of the laser beam by the road surface in front and the light receiving position of the optical position detecting element 14. Move accordingly.

Further, the forward road surface determination device includes a vehicle speed sensor 2o, a timing signal generation circuit 30 connected to the vehicle speed sensor 20, and a laser drive circuit 40 connected to the timing signal generation circuit 3° and the laser oscillator 11. The vehicle speed sensor 2o detects the vehicle speed of the vehicle and generates a series of pulse signals at a frequency proportional to the detection result.

The timing signal generation circuit 30 responds to each pulse signal from the vehicle speed sensor 2o and generates a timing signal at a period that decreases (or increases) in accordance with an increase (or decrease) in the frequency of each of these pulse signals. . Laser drive circuit 4
0 generates a drive signal necessary for driving the laser oscillator 11 in response to the timing signal from the timing signal generation circuit 30, and applies it to the laser oscillator II. This means that the emission period of the laser beam of the laser oscillator 11 is determined by the frequency of a series of pulse signals from the vehicle speed sensor 20.

The synchronization detection circuit 50 receives a light reception signal from the optical position detection element 14 in response to the timing signal from the timing signal generation circuit 30, and detects the light reception signal from the optical position detection element 14 based on the content.
A signal component corresponding to the image forming point on the light receiving surface of is detected and generated as a position detection signal. The distance calculation circuit 60 receives the position detection signal from the synchronization detection circuit 50, calculates the distance between the reflection position of the laser beam and the light reception position of the photodetector 10 based on the content thereof, and generates a distance measurement signal. The determination circuit 70 compares the value of the distance measurement signal from the distance calculation circuit 60 with a reference distance to determine the uneven state of the road surface ahead.

In this embodiment configured as described above, when the vehicle is running in the operating state of the forward road surface determination device, the convex portion
(See Figure 2), when the vehicle speed sensor 20 generates a series of pulse signals, the timing signal generation circuit 30 generates a timing signal at a period corresponding to the frequency of the pulse signal, and the laser drive circuit A drive signal is generated from 40. Then, the laser oscillator 11 emits a laser beam in response to a drive signal from the laser drive circuit 40 to irradiate the convex portion X through the collimator lens 12. Thereafter, when the light receiving lens 13 focuses the laser beam reflected from the convex portion X and forms an image on the light receiving surface of the optical position detecting element 14, the optical position detecting element 14 generates a light receiving signal, The synchronization detection circuit 50 generates a position detection signal, the distance calculation circuit 60 generates a distance measurement signal, and the judgment circuit 7° compares the value of this distance measurement signal with the reference distance to detect a convexity on the road surface ahead. It is determined that there is a part X.

As explained above, when the vehicle is running at low speed, the intervals between the laser beams emitted from the photodetector 10 are long.
As a result, the distance to the protrusion X can be accurately measured while suppressing the amount of accumulated energy of the laser beam incident on the protrusion X on the front road surface. On the other hand, when the vehicle is running at high speed, the intervals between the laser beams emitted from the photodetector 10 are short (and as a result, the distance to the convex part The amount of energy accumulated in the laser beam incident on the laser beam can be minimized.

In addition, in the above description of the operation, the case where the front road surface has a convex portion X has been explained, but even when the front road surface has a concave portion, the state of the front road surface can be determined by substantially the same operation.

Further, in the above embodiments, the present invention was applied to a device for determining the road surface condition ahead, but the present invention is not limited to this, and is applicable to a device for measuring an inter-vehicle distance between the vehicle concerned and a preceding vehicle, and an obstacle located on the side of the vehicle. The present invention may be applied to a distance measuring device, a vehicle height detecting device of the vehicle, or the like. In such a case, in the following distance measuring device, the emitting direction of the laser beam is set in the horizontal direction in front of the vehicle, in the obstacle distance measuring device, the emitting direction of the laser beam is in the downward direction of the vehicle, and in the vehicle height detecting device, the emitting direction of the laser beam is set in the horizontal direction in front of the vehicle. should be vertically downward.

Further, in the embodiment, the optical position detection element 14.
Although the synchronization detection circuit 50 is used to calculate the distance to the object to be measured, instead of this, a single light receiving element,
A timer is employed to calculate the distance by measuring the time from when the laser oscillator emits the laser beam until the light receiving element receives the laser beam reflected from the object to be measured. Good too.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a forward road surface determination device to which the present invention is applied, and FIG. 2 is a diagram showing the laser beam emission direction of the photodetector in FIG. 1. Explanation of symbols 10...Photodetector, 20...Vehicle speed sensor, 30...
- Timing signal generation circuit, 40... laser drive circuit.

Claims (1)

[Claims] a distance measuring means disposed in a part of the vehicle to emit a laser beam toward a measured object and measure the distance to the measured object by receiving the laser beam reflected from the measured object; A laser distance measuring device comprising timing signal generating means for generating a timing signal necessary for emitting the laser beam and applying it to the distance measuring means, detecting the traveling speed of the vehicle and using the detection result as a vehicle speed detection signal. A vehicle speed detection means for generating a vehicle speed is provided, and the timing signal generation means responds to the vehicle speed detection signal and shortens (or lengthens) the period of the timing signal in accordance with an increase (or decrease) in the value of the vehicle speed detection signal. A vehicle laser distance measuring device characterized by: