JPH07260618A - Probe for determining direction of fume source and searching method therefor - Google Patents

Abstract

PURPOSE:To determine the direction of a fume source accurately in a short time by disposing a wind direction sensor and a plurality of gas sensors on a movable truck. CONSTITUTION:A prism 3 is disposed on a truck 1 and four wind direction sensors 4 are arranged oppositely on the side face thereof. Four semiconductor gas sensors 5 corresponding to the sensors 4 are arranged above the prism 3. The truck 1 incorporates an A/D converter 6 connected with the sensors 4, 5 and a microcomputor(MPU) 7 interconnected therewith. The MPU 7 is connected with a motor control circuit 8 for driving the wheel 2 of the truck 1. The sensor 4 determines the direction of wind at the unit of 90 deg. and the outputs from two sensors, arranged vertically to the direction of wind, are compared with each other. The direction of a fume source is then determined through combination of the wind direction detected by the sensor 4 and the direction of increasing concentration detected by the sensor 5. The truck is moved while repeating the operation thus locating a fume source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an odor source direction determination probe used in an autonomous mobile odor source detection system and an odor source detection method using the same.

[0002]

2. Description of the Related Art Conventionally, as a technical research on the detection of odor sources, the inventors of the present application have already proposed Japanese Patent Application No. 5-149.
There is one proposed as No. 375. That is, in an autonomous mobile odor detection system that detects the source of odors, a probe that determines the direction by comparing the gas concentrations of the movable body and the front and back sides of a plate placed on this body using a semiconductor gas sensor. A first drive means for rotating the probe in a direction parallel or orthogonal to the direction of the odor flow; a gas concentration detection means connected to the probe; and an odor connected to the gas concentration detection means. A direction discriminating means for discriminating the flowing direction of the electric field and a second driving means for moving the main body in the discriminating direction by the direction discriminating means are provided.

[0003]

However, in the above-mentioned conventional odor source detection system, in the probe, the plume (spread of the ejected ethanol) end portion is erroneously determined to be leeward, and the threshold plate. There is a problem in that it takes time because it is necessary to change the direction of and judge twice.

A problem with the flow probe is that it takes time to reach the odor source. One of the causes is that the time constant of the measurement system is large and it takes a long time for the response of the gas sensor to stabilize. Such a long recovery time is considered to be due to gas remaining in the suction pipe, the sensor cell, and the Teflon tube connecting them. When the semiconductor gas sensor is placed directly in the air flow and the sensor response is measured, the time constant is improved because it is not rate-controlled by the residual gas. Such a measurement system will be called an open system.

An object of the present invention is to provide a odor source direction determination probe and a odor source detection method using the same, which eliminates the above problems, shortens the determination time, and has high reliability.

[0006]

According to the present invention, in order to achieve the above object, an odor source direction determination probe is provided with a wind direction sensor and a plurality of gas sensors mounted on a movable carriage. Is. Also, in the odor source detection method using the odor source direction determination probe,
The wind direction sensor mounted on the movable carriage determines the wind direction, and based on the wind direction, the direction of the odor source is determined by multiple gas sensors mounted on the movable carriage, and the odor is determined according to the determination result. It is designed to move the source detection cart.

Furthermore, in Odor method using the odor source direction determination probe, it sets the angle alpha ₀ predetermined from the windward, and advanced toward the truck from the該風to angle alpha ₀ only displaced direction , If all the gas sensor responses exceed the threshold, it is judged that the plume has been entered, and then the vehicle advances from there.
When all the gas sensor responses fall below the threshold value, it is determined that the plume has exited, from which the truck turns from the windward in the direction of the angle -α ₀ , returns to the plume, and repeats the above steps.

[0008]

According to the present invention, unlike the conventional probe, the gas does not remain in the suction pipe, the sensor cell, and the Teflon tube connecting them, that is, the so-called measurement system is an open system, and the gas sensor is directly connected. The time constant can be improved by placing it in an air stream so that it is not rate-controlled by the residual gas.

Further, as described above, the direction of the odor source is determined by combining the wind direction sensor and the gas sensor for measuring the odor / gas concentration, and according to the determination result,
By moving the autonomous mobile odor source detection truck, the odor source can be detected quickly and accurately.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. According to the present invention, in an odor source direction determination probe, a sensor capable of measuring the wind direction and a plurality of gas sensors are mounted on a movable carriage. As the wind direction sensor, a plurality of wind speed sensors may be arranged first, but in addition to this, a tandem type probe and a split film type probe may be used.

More specifically, a columnar body is provided on a movable carriage, and a wind direction sensor and a plurality of gas sensors are arranged on the columnar body. For example, a prism is provided as a columnar body, and a wind speed sensor is arranged on each side surface of the prism. Further, the columnar body is a quadrangular prism, four wind speed sensors are arranged on each side surface of the quadrangular prism, and four semiconductor gas sensors are arranged above the quadrangular prism.

Hereinafter, a more specific odor source direction determination probe showing an embodiment of the present invention will be described. FIG. 1 is a side view of an odor source direction determination probe showing an embodiment of the present invention, FIG. 2 is a plan view of the odor source direction determination probe, and FIG. 3 is a schematic view of a wind tunnel for determining the odor source direction.

Reference numeral 1 is a trolley, 2 is a wheel of the trolley 1, 3 is a prism provided on the trolley 1, and 4 is four wind speed sensors (for example, manufactured by Shibaura Electronics Co., Ltd.) which are arranged to face the side surfaces of the prism 3. Air flow sensors, F6201-1), 5 are four semiconductor gas sensors provided above the prism 3 so as to correspond to the four wind speed sensors 4. In addition, an A / D connected to the wind speed sensor 4 and the semiconductor gas sensor 5 in the carriage 1.
A converter 6 and a microcomputer 7 connected to this A / D converter 6 are mounted.

Further, a motor control circuit 8 is connected to the microcomputer 7, and by this motor control circuit 8,
The wheels 2 that move the carriage 1 are driven. Here, as shown in FIG. 3, for example, the height z (35 cm) and the width x (80
cm) and a depth y (70 cm), a nozzle 12 is provided in a rectangular wind tunnel (wind tunnel) 11.
A pyramid-shaped chimney is provided on the side opposite to it, and a discharge port 14 having a suction AC fan 13 is provided at the tip thereof. In the wind tunnel 11, an autonomous mobile odor / gas source detection cart (not shown) having the odor source direction determination probe of the present invention is set. Then, the saturated ethanol is sent from the nozzle 12 through the valve 15 together with the air. Then,
The diffusion rate of odor and gas is very slow, and odor and gas are mainly carried by the wind.

In this embodiment, the wind direction at that location is detected by the four wind speed sensors 4, the target odor / gas concentration is detected by the semiconductor gas concentration sensor, and the odor source is moved upwind. It is possible to detect odors and gas sources by approaching to. The odor source direction determining probe of the present invention will be described in more detail.
It has a size of (W) × 3 cm (D) × 5 cm (H), and four wind speed sensors 4 are arranged so as to correspond to the side surfaces of the prism 3, respectively, and correspond to these wind speed sensors 4. Thus, the four semiconductor gas sensors 5 were mounted on the prism 3. Since the output of the wind speed sensor 4 behind the prism 3 is small and a characteristic pattern can be obtained depending on the direction of the wind, the wind direction can be determined, and the wind speed sensor 4 with the smallest response can be determined to be leeward. , 90 ° unit can be determined.

Further, the response pattern in 45 ° units is stored in the memory (not shown) of the microcomputer 7, and the squared error from the measured sensor response pattern is calculated to determine the closest pattern. ° Unit can be judged. Although the output voltage of the hybrid IC (corresponding to the A / D converter 6 and the microcomputer 7 in FIG. 1) to which the wind speed sensor 4 is connected is non-linear, it can be regarded as substantially linear in the wind speed range used in this embodiment. Therefore, the response V _i of the sensor i can be obtained by the following equation (1).

V _i = V _out −2.51 [V] (1) V _i : Response of sensor i V _out : Voltage output of hybrid IC Here, 2.51 V is the output voltage when the wind speed is 0. is there.
The response vectors of the four wind speed sensors composed of these sensor responses were standardized using the following equation so that the magnitude becomes 1.

[0018]

[Equation 1]

Using this sensor response pattern,
The result as shown in FIG. 4 was able to be obtained. That is,
FIG. 4A shows the case where wind comes from the front of the probe. The sensor response V _{N1 of the} sensor A receiving this wind from the front is the largest at about 0.8, and then the sensors B and D arranged on both sides. It can be seen that the sensor response V _N2 is about 0.4, and the sensor response V _{N3 of the} sensor C arranged on the back side is the smallest.

FIG. 4B shows the case where the wind comes from the diagonal direction of the probe, and the sensor response V _N2 of the sensor D on the wind direction side.
Is about 0.7, the sensor response V _N1 of the sensor A on the wind side is about 0.6, and the sensor response V _N3 of the sensors B and C on the back side is
It can be seen that is low, about 0.2. Where ◇ is AC
The fan voltage is 100 V (about 20 cm / sec), and the open circle is the AC fan voltage 50 V (about 12 cm / sec).

As shown in this figure, from 10 cm / sec to 2
Almost the same output pattern was obtained for a wind speed of 0 cm / sec, and the wind direction could be determined regardless of the wind speed. This probe is mounted on a trolley 1 having wheels 2 controlled by a motor control circuit 8 in response to a command from a microcomputer 7, and moves autonomously according to the determined direction.

A specific odor source detection experiment example will be described below. The simplest odor source detection algorithm using this probe is as follows. First, the wind direction is determined in 90 ° units from the output pattern of the wind speed sensor 4, and then the outputs of the two semiconductor gas sensors 5 arranged perpendicularly to the wind direction are compared.

Therefore, the direction of the odor source is determined by combining the wind direction obtained by the wind velocity sensor 4 and the direction in which the concentration is increased obtained by the semiconductor gas sensor 5, and the odor is moved by repeating this determination, thereby making the odor. The source can be reached. For example, if the wind direction is to the left with respect to the front of the bogie and the one with higher concentration is to the front, the vehicle moves on the assumption that there is an odor source in the front left 45 ° direction.

This can be summarized as a flow chart in FIG. (1) First, the microcomputer 7 determines the wind direction based on the outputs from the plurality of wind speed sensors 4 (step S1). (2) Next, based on the wind direction, the microcomputer 7 compares the outputs from the plurality of semiconductor gas sensors 5 to determine the direction of the odor source (step S2).

(3) Next, in accordance with a command from the microcomputer 7, the motor control circuit 8 drives the wheels 2 in the direction of the odor source to move the carriage 1 (step S).
3). (4) The above steps are repeated until the odor source is reached, and when the odor source is reached, the process ends (step S4).

FIG. 6 shows the result of actually detecting the odor source. The height of the ethanol source was adjusted to the height of the gas sensor, the ethanol source was placed at (x, y, z) = (70, 35, 20.5), and jetting was performed at a flow rate of 150 ml / min. The voltage of the AC fan was 100V. The movement speed was 1.1 cm / sec. The arrival time is 240 seconds (33 steps) in the case of FIG.
In the case of (b), it was shortened to 234 seconds (25 steps).

Next, the source detection in the continuous movement odor will be described. In order to further speed up the odor source detection, it is desirable to use an algorithm that continuously moves while measuring the sensor response without stopping the carriage 1 in order to wait for the sensor to stabilize or to measure the average value. Therefore, the zigzag approach method shown in FIG. 7 was tried. In this zigzag approach, a predetermined angle α ₀ is set from the windward (step S11),
The truck 1 is rotated in a direction displaced from the windward by an angle α ₀ (step S12), and until the plume is reached, for example,
It moves forward at 1.8 mm / sec (step S13). A threshold S _th1 is used to determine that the plume has been entered. That is, it is determined whether or not all gas sensor responses are S ≦ S _th1 (step S14).

When the plume is entered in step S14, the next step is to move out of the plume. That is, it is determined whether or not all the gas sensor responses are S> S _th1 (step S15). In step S15, when the vehicle 1 exits the plume, the trolley 1 turns from the windward in the direction of the angle -α ₀ and advances to return to the plume (step S16).

By repeating this, the trolley 1 heads upwind so that it does not stick out from the plume. When the odor source is approached, the width of the plume becomes narrower and the zigzag amplitude becomes smaller, so that the location of the odor source can be identified. In this zigzag approach method, the concentration gradient is detected by moving, and it is not necessary to detect the concentration gradient by comparing the responses of the gas sensors in proximity.

Actually, due to the meandering of the plume, the turn may be repeated at the end of the plume, and the plume may be lost. Therefore, when the response of all the gas sensors becomes a value larger than the threshold value S _th2 for determining that the plume has been lost, the route that came has been returned. New detection is started when the response of all the gas sensors becomes a value smaller than S _th1 .

By adding this process, the reliability of odor source detection is greatly improved. Here, the wind direction is determined in units of 45 °, and α ₀ = 60 °, S _th1 = 0.5, S _th2 =
It was set to 0.7. There is a maximum error of 22.5 ° in the determined wind direction, and the angle α ₀ is set so that the windward direction does not occur even at this time. The threshold was set so as not to hit the wall as much as possible.

The result of actual detection is shown in FIG.
The AC fan voltage was 50 V (average wind speed 12 cm / sec), the ethanol ejection rate was 75 ml / min, and the moving speed was
It was set to 1.8 mm / sec. As shown in FIG. 8 (a), when starting from the center of the plume, it is easy to reach the odor source, but as shown in FIG. 8 (b), the average sensor response at the start point is more than S _th1 . When starting from a large point, it takes a long time to wander near the starting point.

It took 678 seconds in the case of FIG. 8A and 1013 seconds in the case of FIG. 8B to reach the odor source. FIG. 9 shows the time required when detection is performed from the same point as in FIG. 8B under various conditions. That is, when the gas ejection amount is 150 ml / min, the AC fan voltage is 100 V.
242 seconds, AC fan voltage 50V for 249 seconds, and gas ejection rate 112.5 ml / min, AC fan voltage 5
029V for 1229 seconds, gas ejection rate 75ml / min, A
A C fan voltage of 100 V is 1460 seconds, and an AC fan voltage of 50 V is 1013 seconds.

As described above, the smaller the ejection amount, the longer the time required, but the ethanol source could be almost reached. As described above, the wind direction was determined using the wind speed sensor, and based on this wind direction, the concentration gradient obtained from the gas sensor was combined to obtain a probe for determining the direction of the odor source.

Therefore, by using the wind speed sensor, the certainty of the determination is increased, and the detection time can be shortened from several hours to several minutes. Moreover, the zigzag approach method was proposed as a method of detecting the odor source while moving continuously.
Incorporating a countermeasure when the plume is lost into the algorithm greatly improves the certainty of detection.

In the above embodiment, the gas sensor is
Although the semiconductor gas sensor is used, the present invention is not limited to this, and a crystal oscillator gas sensor, a SAW (Surface) are used.
An Acoustic Wave) gas sensor, an electrochemical gas sensor, or the like can be used as well, and can be changed depending on the type of gas to be detected. Also,
Although the wind speed sensor and the gas sensor are four in the above embodiment, the number may be two at the minimum, or four or more, for example, eight, may be arranged to more accurately detect the direction of the odor source. You may do it.

Further, by the autonomous mobile odor source detection system using the probe of the present invention, detection of gas leak, detection of drugs (drugs etc.), dangerous substances, detection of dangerous gas at semiconductor factory or tunnel factory site, etc. The unmanned exploration of can be surely performed. The present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0038]

As described in detail below, according to the present invention, the following effects can be obtained. (1) Like a conventional probe, a suction tube, a sensor cell,
And the so-called measurement system is an open system in which gas does not remain in the Teflon tube connecting them,
The time constant can be improved by placing the gas sensor directly in the air stream so that it is not rate-limited by the residual gas.

Therefore, it is possible to provide an odor source direction determination probe with a short determination time and high reliability. (2) The wind direction can be confirmed by the wind direction sensor, and the gas source can be detected quickly and accurately by the gas sensor. (3) Further, the autonomous mobile odor source detection system with a probe for determining the direction of the odor source according to the present invention detects gas leaks, drugs (narcotics, etc.), dangerous substances, semiconductor factories, tunnel factories, etc. The unmanned exploration such as the detection of dangerous gas can be swiftly and surely performed.

[Brief description of drawings]

FIG. 1 is a side view of an odor source direction determination probe showing an embodiment of the present invention.

FIG. 2 is a plan view of an odor source direction determination probe showing an embodiment of the present invention.

FIG. 3 is a schematic view of a wind tunnel for determining an odor source according to the present invention.

FIG. 4 is a diagram showing an output pattern of a wind speed sensor by the odor source direction determination probe of the present invention.

FIG. 5 is a flowchart showing an example of an odor source detection method of the present invention.

FIG. 6 is a diagram showing an odor source detection result by the odor source direction determination probe of the present invention.

FIG. 7 is a flowchart of a zigzag approach method using the odor source direction determination probe of the present invention.

FIG. 8 is a diagram showing an odor source detection result by the zigzag approach method by the odor source direction determination probe of the present invention.

FIG. 9 is a diagram showing the time required for odor source detection by the odor source direction determination probe of the present invention.

[Explanation of symbols]

 1 trolley 2 wheel 3 prism 4 wind speed sensor 5 semiconductor gas sensor 6 A / D converter 7 microcomputer 8 motor control circuit 11 wind tunnel (wind tunnel) 12 nozzle 13 AC fan 14 exhaust port 15 valve

Claims (9)

[Claims] 1. An odor source direction determination probe comprising a wind direction sensor mounted on a movable carriage and a plurality of gas sensors. 2. An odor source direction determination probe comprising (a) a columnar body provided on a movable carriage, and (b) a plurality of wind speed sensors and a plurality of gas sensors provided on the columnar body. 3. The odor source direction determination probe according to claim 2, wherein the columnar body is a prism, and each side surface of the prism has a wind speed sensor. 4. The odor source direction determination probe according to claim 3, wherein the columnar body is a quadrangular prism, and four wind speed sensors are provided on each side surface of the quadrangular prism. 5. The odor source direction determination probe according to claim 4, further comprising four semiconductor gas sensors above the quadrangular prism corresponding to the wind speed sensor. 6. An odor source detection method using an odor source direction determination probe, wherein (a) the wind direction is determined by a wind direction sensor mounted on a movable carriage, and (b) movement is possible based on the wind direction. A method for detecting an odor source, characterized in that the direction of the odor source is determined by a plurality of gas sensors mounted on the trolley, and (c) the odor source detection trolley is moved according to the determination result. 7. The method of detecting an odor source according to claim 6, wherein the direction of the odor source is determined by comparing the outputs of gas sensors arranged perpendicularly to the wind direction. 8. Odor method using the odor source direction determination probes, (a) set the angle alpha ₀ predetermined from the windward direction displaced by an angle alpha ₀ from the (b)該風Forward toward the carriage and when all the gas sensor responses exceed the threshold value, it is determined that the plume has been entered, (c) when the vehicle moves forward, and when all the gas sensor responses fall below the threshold value, it is determined that the plume has exited, and (d) From there, the dolly turns from upwind in the direction of the angle -α ₀ and returns to the plume,
A method for detecting an odor source, characterized by repeating the above steps. 9. The odor source detecting method according to claim 6, wherein the wind direction sensor comprises a plurality of wind speed sensors, and the wind direction is determined by comparing the outputs of these wind speed sensors.