JP2002318619A - Method for detecting obstacle for traveling vehicle and device for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically detect even the disconnection failure of a detecting circuit at the time of detecting that a traveling vehicle has bumped into another object by an A contact type sensor. SOLUTION: When a traveling vehicle 1 has bumped into another object, a pressurizing force is received by an A contact type sensor 12, and a detecting circuit 15 is closed, and first and second contacts 12a and 12b in the sensor 12 are serially connected so that a potential can be applied in this detecting circuit 15 for detecting an obstacle. In this case, a detecting point 14 of the detecting circuit 15 is allowed to generate different outputs according as the first and second contacts 12a and 12b are closed in a by-pass state, as the first and second contacts 12a and 12b are opened in a by-pass releasing state, and as the detecting circuit 15 is disconnected. Thus, it is possible to detect any object according to the judgment of the presence or absence of any obstacle by a person/obstacle judging means and the presence or absence of the disconnection of the detecting circuit 15 from the difference of the outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting an obstacle of a moving vehicle such as an automatic guided vehicle, which mainly detects an obstacle when the moving vehicle moves.

[0002]

2. Description of the Related Art Automated guided vehicles are used in warehouses, factories, clean rooms where semiconductors and liquid crystal substrates are manufactured and handled, and move in accordance with remote control or a predetermined traveling program. In addition to moving vehicles that move on a free route in a free order by remote control, even if the moving vehicle moves along a predetermined moving route according to a traveling program, the state of the device that transfers and transfers goods, the transportation around this device Since the arrangement state of the objects and the state of the worker who handles the apparatus change in various ways, the objects may collide with these conveyed objects or people and may hinder the moving vehicle. In addition, for a conveyed article or a person, a collision with a moving vehicle may cause damage or danger. For example, the moving speed of a moving vehicle that transports a liquid crystal substrate in a clean room can be up to four.
Although it is about 0 to 60 m / min, the weight is about 500 kg when the liquid crystal substrate is mounted, and about 1 t depending on the object, so that the collision is avoided for a moving vehicle, an expensive liquid crystal substrate, surrounding objects, and a person. Is an important issue.

[0003] Conventionally, a moving vehicle is provided with a fault detection sensor for detecting when it hits another vehicle, and when a fault is detected, a warning is issued so that the vehicle can respond immediately.

[0004]

However, the above-mentioned sensor for detecting a failure has to adopt a normally open A contact type which closes by pressing when hitting an obstacle and detects the contact thereof. The detection circuit for detecting that the sensor has been closed by contact with an object remains open in a normal state where the sensor is not pressed. For this reason, the detection circuit in the normal state is not particularly different from the disconnection state of the circuit, and even if there is a disconnection in the circuit, it cannot be automatically detected.

For this reason, the disconnection of the detection circuit cannot be known without checking whether the detection circuit operates by pressing the sensor by hand or the like. Even if the disconnection occurs while moving,
As a result, contact with an obstacle cannot be detected, and the safety of a moving vehicle, a conveyed object, surrounding objects, and persons cannot be guaranteed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for detecting a failure in a mobile vehicle, which can automatically detect a disconnection failure in a detection circuit for detecting a collision with another using an A contact type sensor. It is in.

[0007]

In order to achieve the above-mentioned object, a method for detecting a failure of a moving vehicle according to the present invention provides a method for detecting an output of a detection circuit depending on whether a sensor is being pressed by a moving vehicle hitting another. In the obstacle detection method for a moving vehicle that detects the presence or absence of an obstacle by being different, the closed state of the sensor,
An open state and a disconnection state of the detection circuit that detects the opening and closing of the detection circuits cause different outputs at the detection points of the detection circuit. One feature is to provide a determination by means and detect a failure.

In order to achieve this, a moving vehicle obstacle detecting device detects the presence or absence of an obstacle based on whether the output of a detecting circuit differs depending on whether the moving vehicle hits another and the sensor is pressed. In the obstacle detection device for a moving vehicle, a state where the sensor is pressed, a state where the sensor is not pressed, and a broken state of a circuit that detects the opening and closing of these sensors,
A detection circuit that produces different outputs at the detection points, and the presence or absence of an obstacle based on the difference in output from the detection circuit,
And a failure determination means for detecting the presence or absence of a disconnection.

In such a configuration, a state in which the sensor is pressed by the moving vehicle hitting an obstacle, a state in which the sensor does not hit the obstacle due to no contact with the obstacle, and a state in which the detection circuit is disconnected. Therefore, different outputs are automatically obtained at the detection points of the detection circuit, and the presence or absence of an obstacle and the presence or absence of a disconnection of the detection circuit can be determined by a person or determination means to detect a failure based on the difference between the outputs. it can.

[0010] The obstacle detecting method for a mobile vehicle according to the present invention further comprises:
In the obstacle detection method for a moving vehicle in which an A-contact type sensor receives a pressing force when a moving vehicle hits another and closes a detection circuit to detect an obstacle, the first and second contacts in the sensor are connected in series. The first and second detection circuits
At the time of bypass when the contacts are closed, when the bypass is open when the first and second contacts are open, and when the detection circuit is disconnected, different outputs are generated at the detection points of the detection circuit,
Another feature is that the difference between the outputs is used to determine whether there is an obstacle or not and whether there is a disconnection in the detection circuit by a person or a determination unit to detect the failure.

In a moving vehicle obstacle detecting device which achieves such a method, an A contact type sensor receives a pressing force when a moving vehicle hits another, and closes a detecting circuit to detect an obstacle. In the obstacle detection device for a moving vehicle, the detection circuit includes a series circuit unit that connects the first and second contacts of the sensor in series to always provide a potential, and a first circuit and a second contact of the series circuit. A potential detection point, wherein the first and second contacts are closed, the first and second contacts are opened, the bypass is opened, and the detection circuit is disconnected. It is sufficient to provide a failure determining means for determining the presence or absence of an obstacle and the presence or absence of a disconnection from the difference in the potentials, and detecting a failure.

In such a configuration, the sensor is an A-contact type, and when the moving vehicle is pressed against another, the state changes from the open state to the closed state.
In a series circuit section that applies a potential by connecting the second contacts in series, a detection point that outputs a potential between the first and second contacts determines when the first and second contacts are short-circuited and when the first and second contacts are closed. A different output is obtained between a non-short circuit in which the second contact is open and a disconnection of the detection circuit. Based on the difference between the outputs, the presence or absence of an obstacle and the presence or absence of a disconnection are automatically determined. Can be automatically detected.

If the judging means is a circuit and a plurality of judging means are provided for one detecting circuit, even if one of the circuits which often has a faulty element or the like of the judging means has a fault, the other means may be replaced by another. Since the judgment means is working, the safety of the moving vehicle, the transported object, the surrounding objects, and the people can be secured without stopping the movement of the moving vehicle, and the repair can be performed during the normal stop.

The output can be viewed as a voltage as an example, and it is easy to obtain the different output by providing a resistor at an appropriate position in the series circuit section.

When the automatic stop means or the common or individual warning means is activated by the output of the obstacle detection and the output of the disconnection detection, the automatic stop means may cause the mobile vehicle to automatically stop in a state where it hits another. Thus, strong contact and collision can be avoided. Depending on the warning means, it is possible to know the occurrence of a failure and to stop it manually without an automatic stop means, or to know the failure including the case of automatic stop and take an early action.

The warning means gives a visual or audible warning, but the visual warning is suitable for a loud place or the like, and the audible warning is provided at a place where an operator is away or obstructed by an object. It is suitable when there is.

There are a plurality of sensors, each of which detects the presence or absence of an obstacle and the presence or absence of a disconnection by an independent detection circuit, and at least displays which sensor corresponds to the output of the disconnection according to the difference in the detection circuit. Then, while enabling the detection of a hit or a disconnection with another at a plurality of places of the moving vehicle by a plurality of sensors and a detection circuit, at least for the detection of the disconnection of the detection circuit, the detection circuit corresponding to any sensor Since this is displayed externally, the repair target is clarified, and it is possible to easily respond at an early stage.

Further features and operations of the present invention will become apparent from the following detailed description and drawings. Each feature of the present invention is solely as much as possible,
Alternatively, various combinations can be used in combination.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for detecting a failure of a moving vehicle according to an embodiment of the present invention will be described in detail with reference to FIGS.

The mobile vehicle according to the embodiment of the present invention is an example of a mobile vehicle that unmannedly transports a liquid crystal substrate housed in a cassette along a predetermined route according to a preset program for handling a liquid crystal substrate in a clean room. It is. However, the present invention is not limited to this, and the present invention is effective not only for a mobile vehicle that moves on a free route in a free order by remote control, but also for a mobile vehicle where a person rides in some cases, Both belong to the category of the present invention.

The vehicle according to the present embodiment has a vehicle body 1 having running wheels (not shown) at the bottom as shown in FIG.
A drive section 2 for driving the running wheels and a storage section 3 for storing a liquid crystal substrate are integrally provided at a lower portion and an upper portion of the mobile vehicle body 1. The storage unit 3 is provided with a side window 5 having a transparent opening / closing shutter 4 and a transfer mechanism (not shown) for exchanging the liquid crystal substrate with another while the liquid crystal substrate is stored in a cassette through the window 5. The transfer mechanism is normally in a retracted state in which the cassette is retracted into the storage section 3. By extending the window mechanism to the outside through the window 5, a cassette can be received from an external device or the like and retracted into the storage section 3 for storage. The cassette received and stored in the cassette can be taken out through the window 5 and transferred to another device. The moving vehicle body 1 receiving and storing the cassette can close the window 5 with the opening / closing shutter 4 and hermetically close the window 5 to transport the cassette to the destination while maintaining a clean state. On the upper surface of the mobile vehicle body 1, an antenna 6 for steering according to a preset program and an alarm lamp 7 for notifying an abnormality are provided.

A detachable operation panel 8 is provided on the rear surface of the mobile vehicle body 1 and connected by a cable 9. The operation panel 8 is held in a hand to operate the mobile vehicle body 1 in various ways. And a transfer mechanism can be operated. Bumpers 11 are provided on the front, rear, and lower and upper sides of the drive unit 2 of the mobile vehicle body 1, and when the mobile vehicle body 1 hits another inside the bumpers 11, an obstacle is detected as an obstacle. A detection sensor 12 is provided. As a result, the mobile vehicle body 1 can detect obstacles at a total of eight locations, that is, up and down two locations in four directions,
It can respond to contact with various obstacles. However, even if the sensor 12 is provided at only one location, it is effective in principle.

As shown in FIG. 4, the sensor 12 is a so-called A-contact type, and the first and second contacts 12a and 12b are normally open.
In the related art, a detection circuit detects that a contact circuit closes when receiving a pressure as shown in FIG.
However, this alone cannot detect the disconnection of the detection circuit as described above and cannot detect the obstacle.

Therefore, the method for detecting a failure of a mobile vehicle according to the present embodiment uses an output of a detection circuit 15 as shown in FIG. 1 depending on whether or not the mobile vehicle body 1 hits another and the sensor 12 is pressed. In order to detect the presence or absence of an obstacle due to the difference, the closed state of the sensor 12, the open state, and the disconnection and contact state of the detection circuit 15 for detecting the open / close state of the sensor 12 correspond to the detection point 14 of the detection circuit 15, respectively. A different output is automatically generated, and a difference between the output and the person or fault determination means 16 is determined.
The presence or absence of an obstacle and the presence or absence of a disconnection are determined to detect a failure. In the case of a person, the output state of the detection point 14 can be determined by monitoring the output state of the detection point 14 with an analog instrument or an appropriate display means and displaying it externally. In the case of the determination means, the output state of the detection point 14 can be input to various determination devices. Can be automatically determined.

The obstacle detecting device for a mobile vehicle according to the present embodiment detects a state where the sensor 12 is pressed, a state where the sensor 12 is not pressed, and an open / close state of the sensor for detecting the obstacle. A detection circuit 15 that produces a different output at the detection point 14 depending on the disconnection state of the circuit; and a failure determination that determines the presence or absence of an obstacle and the presence or absence of a disconnection based on the difference in output from the detection point 14 of the detection circuit 15. Means 16.

As described above, the state in which the sensor 12 is pressed when the mobile vehicle body 1 hits an obstacle, the state in which the sensor 12 is not pressed because there is no contact with the obstacle, and the state in which the detection circuit 15 is disconnected. The detection point 1 of the detection circuit 15
4. When different outputs are automatically obtained for each of the four, the presence or absence of an obstacle is determined by the obstacle determination means 16 or the like based on the difference between the outputs.
In addition, it is possible to automatically determine the presence or absence of disconnection of the detection circuit 15 and detect a failure.

In order to obtain the three output states, in the present embodiment, in particular, the first and second contacts 12 of the sensor 12 are used.
a and 12b are connected in series to apply a potential to the series circuit unit 1
At 3a, the first and second parts are pressed by the hit against others.
The detection point 14 of the detection circuit 15 differs between the bypass point where the contacts are closed, the bypass state where the first and second contacts 12a and 12b are open without being pressed, and the disconnection state of the detection circuit 15. The output is generated automatically. Specifically, the detection circuit 15 includes a series circuit unit 13a that connects the first and second contacts 12a and 12b of the sensor 12 in series to always provide a potential, and a circuit between the first and second contacts of the series circuit unit 13a. And the detection point 14 for the potential of the above-mentioned potential, the detection circuit 15 is constituted.

Thus, when the first and second contacts 12a and 12b are opened without being pressed, the series circuit portion 13a is in a state where the first and second contacts 12a and 12b are connected in series, and the pressing is performed. When the first and second contacts are closed upon receiving, the series circuit portion 13a is in a bypass state at the first and second contact portions, and no current flows even if a disconnection occurs in any portion of the series circuit portion 13a. . That is, the circuit state of the detection circuit 15 differs between when the sensor 12 receives the pressure, when the sensor 12 does not receive the pressure, and when the detection circuit 15 is disconnected, and a different output corresponding to each is obtained at the detection point 14.

That is, the series circuit section 13a is electrically connected in series while maintaining the A contact type sensor 12 itself in a mechanically normally open state, and is formed into a B contact so that the detection circuit 15 is kept closed. When the detection circuit 15 has a disconnection, the detection circuit 15 is opened for the first time, so that the output of the detection point 14 becomes 0 V and the disconnection is detected. The sensor 12 remains connected in series at the serial circuit section 13a unless there is a disconnection, but when the first and second contacts are closed by being pressed, the series circuit section 13a is bypassed and the sensor 12 is not pressed. 1. When the second contact is open, the output to the detection point 14 can be made different by utilizing the fact that the bypass of the series circuit portion 13a is opened and the overall resistance state changes.

The output can be viewed as a voltage as an example, and there is an advantage that the output can be easily adjusted by providing resistors 21 and 22 at appropriate places in the series circuit section 13a.
22 makes it possible to increase the difference in output at the detection point 14 due to the difference in the circuit state. Now, the resistance value of the first and second contacts 12a and 12b of the sensor 12 is 0,
Assuming that the resistance values of the first and second circuits are equal, the series circuit unit 1
The output V1 at the detection point 14 in a state where the first and second contacts 12a and 12b are open and there is no disconnection is V / 2, and the first and second contacts 12a have no disconnection. , 12b are closed, the output V2 (= V) of the detection point 14 is determined by the resistance 21 of the series circuit 13a.
Since V2> V / 2 because of being bypassed by the second contacts 12a and 12b, the output V3 (= 0) of the detection point 14 in a state where the disconnection occurs in the detection circuit 15
V3 <V / 2 because no current flows through a. An example of this is shown in the graph of FIG.

Such three output states can be obtained by, for example, a difference in resistance during energization depending on whether or not a pressure sensor using conductive rubber or the like is pressed, and a state in which energization is stopped due to disconnection.

The fault judging means 16 uses two comparators 23 and 24 for one sensor 12 in response to viewing the difference in output from the detection point 14 by voltage. Actually, it is considered that the three outputs at the detection point 14 vary, so that the comparator 23 outputs the output V (V) at the time of hit and the output 1/2 V at the normal time.
(V), a fault is detected by detecting an output of 3/4 V (V) or more with a margin, and a comparator 24 outputs a normal output 1/2 V (V) and an output during disconnection. A disconnection is determined by detecting an output of 1/4 V (V) with a margin near both 0 (V) to detect a failure. Thus, it is possible to avoid erroneous detection even if there is a variation in output.

In the circuit of FIG. 1, the output of the detection point 14 is input to comparators 23 and 24. Comparator 23
Input the reference voltage 3/4 V (V) to the positive side and input the output to the negative side. When the output exceeds the reference voltage, the photo MOS relay 32 is connected through a line to ground.
Of the current flowing to the comparator 23 to detect a failure. At this time, the photo MOS relay 32 changes from the on state to the off state, and at the same time as the display lamp 33 including an LED or the like is turned on, the relay coil 34 as an example of an automatic stop means for turning on the power of the mobile vehicle body 1. Is turned off. Further, a display lamp 3 composed of an LED or the like provided corresponding to the comparator 23 is provided.
5 also lights up.

The comparator 24 inputs the reference voltage 1/4 V (V) to the minus side, inputs the output to the plus side, and when the output falls below the reference voltage, flows to the photo MOS relay 32 through a line to ground. The current that has flowed to the comparator 24 determines the disconnection and detects a failure. At this time, the photo MOS relay 32 changes from the on state to the off state, and at the same time as the display lamp 33 including an LED or the like is turned on, the current of the relay coil 34 for turning on the power of the mobile vehicle body 1 is cut off. You. In addition, a display lamp 36 formed of an LED or the like provided corresponding to the comparator 24 is also turned on. Indicator lamps 35, 36
Which of the two comparators 23 and 24 worked, that is, the difference between the detection of the contact and the disconnection can be visually recognized from the outside, and depending on the display lamp 33, the fact that the detection circuit 15 having the sensor 12 has hit or detected the disconnection. It can be seen from outside.

The outputs of the comparators 23 and 24 are monitored, that is, by detecting the signals at the judgment output points 37 and 38, it is possible to determine that the detection circuit 15 has detected a hit or a disconnection.

In the above, instead of turning off the power, a partial operation such as a movement or a drive stop of the transfer mechanism can be stopped. The display lamps 33, 35, 36 and the like have a small output, and are suitable to be mounted on the failure determination means 16 itself on the failure detection board 41 to grasp the circuit state. It is preferable that the alarm lamp 7 is shared, a dedicated lamp is provided, or the operation panel 8 is used, and the output of the hit or disconnection failure detection is displayed as a signal as a warning. The warning display can also be individually displayed externally depending on the type of the obstacle, that is, whether an obstacle due to a collision with another is detected or a disconnection is detected. Further, the automatic stopping means can be omitted.

Visually displaying the warning as described above is preferable in a place where the sound is noisy, while displaying an audible warning is preferable in a case where the worker is away or is in a place where an object is obstructed. . Therefore, it is most preferable to use both the visual warning display and the audible warning display.

In this embodiment, furthermore, as shown in FIG. 1, one sensor 12 and one detection circuit 15 obtain different outputs due to the above-mentioned hit and disconnection. And a fault is detected in each case. As a result, the failure determination means 16 is likely to be an electric circuit having a semiconductor element or the like which is susceptible to failure due to static electricity or the like.
Even if there is such a failure in the circuit 6, since the other failure determination means 16 is working, the moving vehicle main body 1, the conveyed object, the surroundings,
In addition, the safety of humans can be ensured, and the disconnection can be repaired during a normal stop. If necessary, three or more can be provided. Further, the outputs of the plurality of fault determination means 16 are compared (L
A comparison by a person based on the lighting state of the EDs 33, 35, and 36 or an automatic comparison by an additional circuit may be used. ), It is possible to detect a failure of the failure determination unit 16 itself.

Further, there are eight sensors 12 as described above. Thus, even if there are a plurality of sensors 12, as shown in FIG.
5 and the obstacle determination means 16 detect the presence or absence of an obstacle and the presence or absence of a disconnection, and the detection status can be externally displayed by individual display lamps 33, 35 and 36. Since the corresponding detection circuit 15 and system can be visually recognized, the detection state can be understood, and it is easy to cope with a disconnection or the like.

[0040]

According to the method and apparatus for detecting an obstacle of a moving vehicle according to the present invention, as is apparent from the above description, the difference between the state in which the sensor is pressed when the moving vehicle hits the obstacle and the obstacle is determined. Different outputs are automatically obtained at the detection points of the detection circuit in a state in which the sensor is not pressed due to no contact and a state in which the detection circuit is disconnected. And the presence or absence of disconnection of the detection circuit can be determined to detect a failure.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a method and an apparatus for detecting a failure of a mobile vehicle according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between three outputs of a detection circuit in the circuit of FIG.

FIG. 3 is a perspective view showing a specific example of a moving vehicle to which the obstacle detection method and device of FIG. 1 are applied.

4 is a circuit diagram of FIG. 1 and a cross-sectional view of a bumper including a sensor in the mobile vehicle of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving vehicle main body 7 Alarm lamp 11 Bumper 12 Sensor 12a 1st contact 12b 2nd contact 13a Series circuit part 14 Detection point 15 Detection circuit 16 Failure judgment means 21,22 Resistance 23,24 Comparator 33,35,36 Display lamp 34 Relay coil

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Yoshikazu Nakamura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. 3F333 AA01 AB20 FA11 FA13 FA20 FE03 FE09 5H301 AA01 BB05 GG06 LL01 LL02 LL08 LL08 LL11

Claims (15)

[Claims] 1. An obstacle detection method for a moving vehicle for detecting the presence or absence of an obstacle by differentiating an output of a detection circuit depending on whether or not the sensor is being pressed by the moving vehicle hitting another. In the received state, the state in which no pressure is applied, and the disconnection state of the detection circuit that detects the difference between these states, different outputs are generated at the detection points of the detection circuit. A method for detecting a failure of a mobile vehicle, wherein the determination is made by a person or a determination means as to whether or not there is a disconnection, and whether or not a disconnection has occurred. 2. An obstacle detecting method for a moving vehicle in which an A-contact type sensor receives a pressing force when a moving vehicle hits another and closes a detection circuit to detect an obstacle. Are connected in series and a potential is applied to the detection circuit, when the first and second contacts are closed, when the bypass is open when the first and second contacts are open, and when the detection circuit is disconnected. In each, a different output is generated at the detection point of the detection circuit, and the presence or absence of an obstacle based on the difference in the output is provided to a person or a determination unit for the presence or absence of a disconnection of the detection circuit to detect a failure. To detect obstacles in moving vehicles. 3. The method for detecting a failure of a mobile vehicle according to claim 1, wherein the failure determination means is a circuit, and a plurality of failure determination means are provided for one detection circuit. 4. The method according to claim 1, wherein the output is a voltage. 5. The mobile vehicle according to claim 1, wherein an output of the obstacle detection and an output of the disconnection detection activate an automatic stop means or a common or individual warning means. Failure detection method. 6. The method according to claim 5, wherein the warning means issues a visual or audible warning. 7. A plurality of sensors, each of which detects the presence or absence of an obstacle and the presence or absence of a disconnection by an independent detection circuit, and displays which sensor corresponds to at least the output of the disconnection to the outside by a difference in the detection circuit. The method for detecting a failure of a mobile vehicle according to claim 1. 8. An obstacle detecting device for a moving vehicle, wherein an output to a detecting circuit is different depending on whether the sensor is being pressed by the moving vehicle hitting another, and the presence or absence of an obstacle is detected. A detection circuit that produces different outputs at the detection points of the detection circuit in a state where the sensor receives pressure, a state in which no pressure is received, and a disconnection state of the detection circuit that detects a difference between these states, A failure detection device for a mobile vehicle, comprising: failure determination means for determining the presence or absence of an obstacle and the presence or absence of a disconnection from a difference in output from a detection circuit to detect a failure. 9. A fault detecting device for a moving vehicle, wherein when a moving vehicle hits another, an A-contact type sensor is pressed to close a detecting circuit and detect an obstacle, wherein the detecting circuit includes the sensor A serial circuit unit that connects the first and second contacts in series to provide a constant potential, and a potential detection point between the first and second contacts of the series circuit unit,
When the first and second contacts are closed and when the first and second contacts are closed.
Failure determination means for determining the presence or absence of an obstacle and the presence or absence of a disconnection based on a difference in output at the detection point between when the contact point is open and when the detection circuit is disconnected and when the detection circuit is disconnected is provided. An obstacle detecting device for a mobile vehicle, characterized in that: 10. The fault detecting device for a mobile vehicle according to claim 8, wherein the output is a voltage. 11. The mobile-vehicle fault detecting device according to claim 8, wherein a plurality of fault determining means are provided for one sensor. 12. The mobile-vehicle fault detecting device according to claim 11, wherein a fault of the fault determining means itself is detected by comparing outputs of the plurality of fault determining means. 13. An automatic stopping means or an alarming means, wherein an output of an obstacle detection and an output of a disconnection detection actuate the automatic stopping means and / or a common or individual warning means. The obstacle detection device for a mobile vehicle according to any one of claims 1 to 7. 14. The apparatus according to claim 13, wherein the warning means issues a visual or audible warning. 15. A plurality of sensors, each of which detects the presence or absence of an obstacle and the presence or absence of a disconnection by an independent detection circuit, and displays which sensor corresponds to at least the output of the disconnection to the outside by a difference in the detection circuit. The obstacle detection device for a mobile vehicle according to any one of claims 8 to 14, further comprising a display unit that performs the operation.