JPH0680436B2 - Airborne particle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a particulate matter detection apparatus suspended in the air, and is suitable for use in a vehicle distance measurement apparatus, a vehicle traveling speed control apparatus, and the like.

[Conventional technology]

Conventionally, for example, in a device that prevents a collision with an obstacle existing around the vehicle, detects an inter-vehicle distance with a preceding vehicle,
Various optical distance measuring devices using laser light have been proposed.

This device measures the time from when the laser light is sent from the light transmitter toward the detection area until the laser light is reflected by an obstacle or a preceding vehicle and returns to the light receiver. And the distance to the preceding vehicle.

[Problems to be solved by the invention]

However, when the above-mentioned device is used in an environment of rain, fog, snow, etc., the light emitted from the light transmitter is reflected by an obstacle and returns to the light receiver. The laser light is blocked by particles such as snow and reaches the obstacles, and the particles are reflected by these particles, so the distance to the particles that reflected the light is not the distance to the obstacle or the preceding vehicle that you are originally trying to detect. There is a problem in that the obstacle and the distance to the preceding vehicle cannot be accurately obtained.

Further, when the vehicle travels, it has to travel under various weather conditions such as rain, fog, and snow. In such a case, in order to drive safely, it is necessary to accurately detect the occurrence of rain, fog, snow, etc., and turn on the fog lamp or slow down the traveling speed.

Therefore, in view of the above problems, the present invention provides a suspended particle detection device that can accurately detect the presence of particles suspended in the air and can apply this information to various vehicle travel controls.

[Means for solving problems]

Therefore, in order to achieve the above-mentioned object, the present invention provides a light transmitting means for transmitting light of a predetermined wavelength corresponding to the size of fine particles floating in the air to be detected in a detection region outside a vehicle, and The light detecting means for receiving the reflected light, which is the reflected light reflected by the reflector, and the time required for the light to be received by the light detecting means after the light is sent from the light sending means, and the detection area A distance data calculating means for calculating distance data to the reflector, a speed detecting means for detecting a traveling speed of the vehicle and outputting a vehicle speed signal, and the vehicle speed signal and the distance data calculating means of the speed detecting means. When the vehicle speed signal of the vehicle indicates a traveling state of a predetermined value or more and the content of the distance data continues a state of a predetermined short distance for a predetermined time or more, the detection range is detected. A determination unit that particles suspended in the air to determine the presence, and adopts a technical means that comprises a.

[Action]

According to the present invention, since the light is sent from the light sending means toward the detection area, the light is reflected by the reflector (obstacle, preceding vehicle,
It measures the time it takes for the light to be reflected by rain, fog, snow, etc.) and return to the light detection means, and obtain the distance data to the reflector.

When the distance data is reflected by fine particles such as rain, fog, and snow, the content of the distance data holds a state of a predetermined short distance, and thus the duration of the short distance state is a predetermined time. Detects whether or not to continue,
It is possible to accurately determine the presence of fine particles floating in the air, such as rain, fog, and snow.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments based on the drawings.

FIG. 1 shows a schematic configuration of the first embodiment of the present invention. The pulse drive circuit 1 drives the pulse semiconductor laser 2 and emits pulsed laser light to the front space of the vehicle through the lens 3. The wavelength of the pulsed semiconductor laser 2 is set based on the following principle. That is, the reflection due to the scattering of light is such that when the diameter of fine particles such as fog, rain, and snow is sufficiently larger than the wavelength of light, the scattering of light by particles is small, and conversely, the diameter of the particles is sufficiently smaller than the wavelength of light. The smaller the value, the greater the light scattering.

Therefore, for example, if the wavelength of light is set to around 0.9 μm, the diameter of fine particles of normal fog is about 1 to 20 μm, and
Since the diameter of snow particles is about 600 μm or more, the light reflected by rain particles and snow particles is different from the size relationship between the wavelength of the emitted light and the particles suspended in the air.
It becomes much smaller than the light reflected by the fine particles of the fog, and it is no longer detected, so that only the fog can be detected.
Therefore, the wavelength of light may be determined in advance according to the diameter of the suspended particles to be detected.

The fog existing in the front space or the laser light reflected by another vehicle is condensed by the lens 4, enters the light receiving surface of the light receiving element 5 located at the focal point thereof, is photoelectrically converted, and receives high-speed minute pulses. A signal (Fig. 2 (b)) is generated. The received light signal is input to the distance data generating circuit 8 through the variable gain wide band amplifier 6 and the peak detection circuit 7.

The distance data generating circuit 8 outputs a time signal until the pulse laser light is reflected from the semiconductor laser 2 and is received by the light receiving element 5, and a determination signal as to whether or not the time signal is correct. The output signals of the distance data generation circuit 8 and the vehicle speed detection circuit 9 for detecting the vehicle speed are input to the discrimination circuit 10, and the discrimination circuit 10 detects the fog and the vehicle-to-vehicle distance from the both signals, and outputs this. Display on the display unit 11.

A detailed block diagram of the decision circuit 10 is shown in FIG.

The output signal of the distance data generating circuit 8 is input from the terminal 10a, and the pulse width of the distance data signal e ₁ (the time required to transmit / receive the pulsed light) is measured by the counter 100, converted into a digital amount, and input. It is supplied to the microcomputer 105 via the port 101. On the other hand, the signal of the vehicle speed detection circuit 9 is supplied to the microcomputer 105 from the input terminal 10b as an interrupt signal. Microcomputer 105
A ROM 102 and a RAM 103, which are memories, are connected to the. The fog detection gate and the inter-vehicle distance data are provided to the display circuit 11 from the output terminal 10c via the output port 104.

The control flowchart of the control program of the microcomputer is shown in FIGS.

Next, regarding the operation of the first embodiment having the above configuration,
This will be described below.

The pulse drive circuit 1 has a repetition cycle of 2 msec and a pulse width of 200
Outputs a drive pulse signal of nsec and outputs pulse semiconductor laser 2
And a trigger signal a (FIG. 2 (a)) generated at the same time as this is supplied to the distance data generating circuit. The pulsed laser light emitted from the pulsed semiconductor laser 2 is reflected by fog in front of the vehicle or a vehicle, and a small light receiving signal b photoelectrically converted by a light receiving element 5 capable of detecting the reflected light.
(FIG. 2B) is amplified by the variable gain wideband amplifier 6. In the amplified signal c (FIG. 2 (c)), the peak detection circuit 7 detects the time at which the amplitude of the signal c is maximum, and outputs the signal d (FIG. 2 (d)). The distance data generating circuit 8 outputs a distance data signal e ₁ (FIG. 2 (e)) corresponding to the fog in front of the vehicle or the vehicle from the signal a and the signal d, and the amplitude of the received light signal b falls within a predetermined range. A signal e ₂ (FIG. 2 (e)) for determining whether or not it is present is superimposed on the signal e ₁ and output. That is, when the amplitude is within the predetermined range, the determination signal e ₂ that validates the distance data signal e ₁
When the amplitude is not within the predetermined range, the determination signal e ₂ that invalidates the distance data signal e ₁ is output.

Then, the determination circuit 10 performs fog detection and vehicle-to-vehicle distance detection based on the output signals e ₁ and e ₂ and the vehicle speed signal. Then, the display device 11 displays according to the result of this determination.

The specific operation of the determination circuit 10 will be described below with reference to the flowcharts of FIGS.

Before explaining the flowchart, the terms used in the flowchart will be described.

V _s ... Velocity of vehicle on which the device of the present invention is mounted D ... Distance data D flag ... Flag Cf indicating that the distance data D is valid Cf ... V _s > 30 km / h, and D is valid and D <5 m Variable that indicates how many seconds are continuing in 0.1 second unit C _v … Vehicle speed variable (+2 is added by vehicle speed pulse) Fog flag… Flag that indicates fog generation First, when the power is turned on when the vehicle key switch is turned on, step Initialize at 200 and proceed to step 201
Display routine 10 with Cf and C _{v set} to 0 and Fog flag set to false
Proceed to 00. In the display routine 1000, if the Fog flag is false in step 202, the process proceeds to step 203. In step 203, the distance to the obstacle based on the obtained average value of the distance data D is displayed on the display device 11 by the interrupt routine for selecting the correct distance data D shown in FIG. If the Fog flag is true in step 202, the flow advances to step 204 to display the fog generation on the display device 11. Now, a flow chart for obtaining the distance data D will be described with reference to FIG. When the counter 100 finishes measuring, it interrupts. This interrupt occurs every 2 ms after the key switch is turned on. Then, the microcomputer 105 checks whether the current measurement result is normal. The operation is the valid / invalid discrimination signal e _{2 in the} signal sent from the distance data generating circuit 8.
It can be realized by examining the contents. If it is valid in step 300, the D flag is set to true in step 301 and the process proceeds to step 302, where the microcomputer stores the distance data from the signal e _{1 in the} RAM 102. And step
At 303, it is determined whether the number of D's in the RAM 102 is 16, and when 16 is reached, the process proceeds to step 403 to obtain the average value. After that, in step 305, the data in the RAM 102 is erased and the number of D is reset to zero.

If the number of D's does not reach 16 in step 303, nothing is done and the process returns from the interrupt and returns to the display routine 1000. When it is determined that the flag is invalid in step 300, the flag in step 306D is set to false to return from the interrupt routine and return to the display routine 1000.

Next, the interrupt routine for setting the Fog flag will be described with reference to the flowchart of FIG. This interrupt routine is 0.
It is generated every 1 second. First, in step 400, the vehicle speed signal S
Calculate the vehicle speed V _s based on

Next, in steps 401, 402, and 403, it is sequentially checked whether or not V _s > 30 km / h, whether the D flag is valid, and whether D is within 5 m, and when all the conditions are satisfied, step 40
Proceed to 4 and increase the contents of Cf by one. If even one condition is not satisfied, the routine proceeds to step 407, where the content of Cf is set to 0, the Fog flag is set to false, and the routine returns from this interrupt routine and returns to the display routine 1000. And step 405
Then, when the content of Cf reaches 100 (when it lasts for 10 seconds), the Fog flag is set to true and the process returns to the display routine 1000 to inform the display device 11 that it is fog.

In the first embodiment described above, the occupant is notified of the occurrence of fog by the display device, but other than this, a voice alarm or a warning sound may be generated.

Next, a second embodiment of the present invention will be described. In the second embodiment, as shown in FIG. 7, automatic drive control is performed by detecting fog. The control circuit 12 includes a result of the vehicle speed detection circuit 9 (vehicle speed) and a result of the determination circuit 10 (distance data). And "fog" is input). With this auto drive control circuit 12, when there is no vehicle ahead (when there is no distance data e ₁ ), the vehicle is in the constant speed mode in which the vehicle travels at the constant speed set by the driver. From e ₁ and the vehicle speed signal S, the following mode is set to follow the vehicle ahead.
The throttle actuator 13 is controlled in each mode. Now, when it is detected that "fog" has occurred, the fog detection signal f
Is input to the automatic drive control circuit 12, and the automatic drive control circuit 12 stops automatic control of the throttle actuator 13. Therefore, the automatic constant speed traveling of the vehicle is released, and the vehicle travels at a speed corresponding to the degree of depression of the accelerator pedal of the occupant.

Further, in the second embodiment described above, the auto drive is canceled by detecting fog, but instead of canceling the auto drive, the set speed can be automatically reduced to a safe speed.

Also, it is not limited to the automatic drive device, but by fog detection,
You may make it light a fog lamp automatically.

〔The invention's effect〕

As described above, according to the present invention, the presence of fine particles (rain, fog, snow, etc.) floating in the air can be accurately detected. Therefore, based on this information, it is possible to apply to various traveling controls of the vehicle, for example, and it is possible to improve safety when the vehicle is traveling.

[Brief description of drawings]

1 is a control block diagram of the first embodiment of the present invention, FIG. 2 is a waveform diagram of each signal in the block diagram shown in FIG. 1, FIG. 3 is a partial detailed block diagram of FIG. 1, and FIG. , Fig. 5,
FIG. 6 is a flow chart of the microcomputer shown in FIG. 3, and FIG. 7 is a control block diagram of the second embodiment of the present invention. 1 ... Pulse drive circuit, 2 ... Pulse semiconductor laser, 5 ... Photodetector, 6 ... Amplifier, 7 ... Peak detection circuit, 8 ... Distance data generation frequency, 9 ... Vehicle speed detection circuit, 10 ... Determination circuit, 11 ... Display device .

Claims (2)

[Claims] 1. A light sending means for sending light of a predetermined wavelength corresponding to the size of fine particles floating in the air to be detected in a detection area outside the vehicle, and the sent light by a reflector. Light detection means for receiving the reflected light reflected, and the time required to receive the light by the light detection means after the light is sent from the light sending means, and the distance data to the reflector in the detection area. Distance data calculating means for calculating the traveling speed of the vehicle, and a speed detecting means for outputting a vehicle speed signal, the vehicle speed signal of the speed detecting means and distance data from the distance data calculating means, When the vehicle speed signal indicates a traveling state of a predetermined value or more, and the content of the distance data continues for a predetermined short distance for a predetermined time or more, there are particles floating in the air in the detection area. A suspended particulate matter detection device comprising: a determination unit that determines whether the particle is present. 2. The suspended particle detecting device according to claim 1, wherein the particles suspended in the air are fog.