JPH07952Y2 - Disconnection detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a wire breakage detection device, particularly an insulated wire bundle (hereinafter referred to as a harness) wired to an automatic machine such as an industrial robot.
The present invention relates to a disconnection detecting device capable of detecting the disconnection of a wire even in a semi-open state.

[Conventional technology]

Generally, in an automatic machine such as a robot, a harness composed of electric wires for transmitting various signals for driving and controlling is wired in order to operate the automatic machine or control the operation.

The contents of the control harness include, for example, a position detector,
Most of them are control signal lines for conducting the detection signals of the speed detector and other various sensors.

Such various harnesses may cause a wire break or a half wire break due to friction or bending while repeating a predetermined operation in an automatic machine such as a robot that frequently performs a rotating motion and a sliding motion. .

Here, as shown in FIGS. 6 (a) and 6 (b), the term “half-break wire” means that the conductor wire is in a conductive state as shown in FIG. It means a non-conductive state as shown in FIG. In the figure, one conductor wire 1 of a plurality of conductor wires constituting a harness is composed of a core wire 2 and a covering member 3 that covers the outside of the core wire 2. The core wire 2 has a semi-conducting wire portion 2a when used over time.
Has occurred. When the conducting wire 1 is bent, the semi-broken portion 2a forms a gap G to hinder the conducting state of the conducting wire 1 as shown in FIG. 6 (b).

As an example for detecting the wire breakage of a harness wire including such a half wire breakage, there is a wire breakage detecting device disclosed in Japanese Patent Laid-Open No. 60-111169. This disconnection detection device 11
Are provided in the servo control circuit 10 as shown in FIG. The control circuit 10 includes an error counter 4 in which a movement amount of a robot (not shown) is supplied to one input end as a command value, and a D / A conversion for converting an increase amount of the pulse counted by the counter 4 into an analog signal. Device 5, a motor drive circuit 6 that controls the drive of the motor 7 based on the analog output of the converter 5, and the actual rotational speed of the motor 7 supported by the motor 7 coaxially with the A phase and the B phase. Based on the rotary encoder 8 that feeds back as a pulse train of, and the pulse train supplied by the encoder 8, either the A phase or the B phase is used as the leading phase to determine whether the motor 7 is forward or reverse, and the other input to the counter 4. The phase discriminator 9 supplies a pulse train to the end.

The disconnection detection device 11 is connected to the input terminal of the phase discriminator 9, receives a pulse train of the A-phase and B-phase and performs a logical operation, and a logical operation based on the output of the counter 4 to perform a clock operation. An exclusive OR circuit 13 that outputs a pulse output, a first flip-flop circuit 14 that receives the output of the NAND circuit 12 as an input and receives the output of the OR circuit as a clock pulse, and an output of the first flip-flop circuit 14. And a second flip-flop circuit 15 which outputs a detection output by the clock pulse output of the OR circuit 13. The first and second flip-flop circuits 14 and 15 form a latch circuit 16.

With the configuration described above, when the motor 7 is operating normally, the detection output of the encoder 8 is advanced in any phase regardless of whether the motor 7 is rotating normally or reversely. Therefore, the output of the disconnection detecting device 11 is an alarm. Neither output nor disconnection detection signal is output.
However, if an abnormality such as a disconnection occurs somewhere in the motor 7 and the control circuit 10, the abnormality is irrelevant to the NAND circuit 12, the OR circuit 13 and the latch circuit 16 irrespective of fluctuations in the rotation speed of the motor 7.
Can be detected more accurately.

The above-mentioned conventional example is of a type that is incorporated into an automatic machine such as a robot, but as a commercially available device for detecting disconnection, various harness single-unit checkers such as a cable continuity tester and an electrical resistance tester have been proposed. ing. The cable continuity tester pre-inputs data regarding "conduction" or "non-conduction" between the input and output pins and compares these data with the detected value. Further, the electric resistance tester sets a constant resistance value in place of the conduction / non-conduction data, and compares the measured resistance value with the set resistance value to detect disconnection.

In addition, as a device that is installed in an actual machine of an automatic machine and detects disconnection when the power is off, a time domain reflectometer (Time do
main reflect meter) and frequency domain reflectometer (Frequency do
(main reflect meter) etc. The time-domain reflectometer applies a high-speed pulse to the cable and the frequency-domain reflectometer applies a high frequency to the cable, respectively, to detect the disconnection position by capturing the waveform reflected from the imbalance point of the cable. These reflectometers are often used for long cables, coaxial cables, etc., and are capable of instantaneously measuring the distance to a disconnection point.

[Problems to be solved by the device]

Since the conventional disconnection detecting device is configured as described above in the one described with reference to FIG. 7, it detects a disconnection or a half disconnection only when an automatic machine such as a robot is operating. However, there is a problem in that reliability of disconnection detection is impaired.

In addition, since the configuration of the disconnection detecting device uses a large number of several logical operation elements, it becomes expensive, and it is not possible to provide this detecting device for each control or driving harness of the robot or the like. However, there is also a problem that it is not preferable in terms of manufacturing cost.

Furthermore, in the case of harness single checker and various measuring machines,
Not only are there many things that cannot detect half-breaks, but there are also problems that measurement and breakage detection cannot be performed while the actual machine is in operation, and that the device is expensive.

In addition, while various reflectometers are intended for long coaxial lines extending over several kilometers, a single line with a length of only a few meters, such as a robot harness, is not always optimal. In addition, the device is too expensive. Moreover, in the case of this type of reflectometer, even if the device is expensive, if it is necessary to measure the disconnection of each conductor of the harness, the measurement or disconnection during operation of the actual machine can be performed. No detection was possible.

The present invention has been made to solve the above problems, and a constant voltage source for measurement and a simple comparison / detection circuit having a simple structure are provided for each conductor of the harness. Accordingly, it is an object of the present invention to provide a low-cost disconnection detection device that has high reliability in detection operation, can perform rapid disconnection detection.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the disconnection detecting device according to the present invention is provided with potential raising means for generating a potential different from the normal potential when each of the plurality of single wires constituting the harness is broken, and each single wire is provided. A comparator is provided to detect disconnection by comparing the abnormal potential generated when the single wire is disconnected with a constant reference potential, and the disconnection detection output from this comparator is held by a holding circuit, and based on this holding output The disconnection status indicator displays a disconnection abnormality for each single line.

Further, according to the present invention, in the disconnection detecting device for detecting disconnection of the signal transmission harness consisting of a plurality of single wires drawn from the transmission circuit provided in the movable mechanism of the automatic machine, the movable mechanism is driven independently. A cable provided separately from the signal transmission harness, a plurality of single wires connected at the end of the harness, and a potential raising means for generating an abnormal potential higher than a normal signal potential when the single wire is broken, and each single wire. A constant reference potential having an intermediate value between the signal potential and the abnormal potential and the potential in the vicinity of the connection point of the potential raising means is input for each, and when the abnormal potential occurs, the output is compared with the comparator and the comparison is made. The present invention is characterized by including a holding circuit for holding that the device has generated an output, and a disconnection state indicator for displaying a disconnection abnormality for each single line based on the output of the holding circuit.

[Action]

Since the present invention is configured as described above, when an abnormal situation such as a break or a half break occurs in any one of the wires forming the harness, a high potential appears in the single wire through a high resistance. The comparator compares this with a reference potential and generates a disconnection detection output. The disconnection detection output is held by a holding circuit such as a flip-flop, and the disconnection abnormality is indicated by light emission or the like by a display such as a light emitting diode.

With the above-described configuration, it is possible to detect an abnormal state such as a disconnection for each single wire forming the harness, so that it is possible to ensure reliability with respect to disconnection detection, and it is possible to detect a disconnection or the like with a simple configuration. Therefore, the manufacturing cost can be reduced, and further, the disconnection can be detected during the actual operation of the automatic machine such as the robot.

Further, according to the disconnection detection device in which the movable mechanism is driven by a cable different from the signal transmission harness and the potential raising means is connected to the end of the harness, disconnection detection of the power line can be particularly easily performed. it can.

〔Example〕

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

FIG. 1 is a block diagram showing the construction and usage of one embodiment of the present invention.

In FIG. 1, a harness 28 provided on the movable arm 20 on the machine body side, for example, on the transmission circuit 21 side such as an encoder,
For example, a disconnection detection circuit 30 connected to the reception circuit 23 provided in the controller 22 such as a motor drive circuit by connectors 27 and 24 is provided. In this embodiment, the harness is divided into an inner harness 25 on the main body side and an outer harness 28 on the outer side of the relay mounting member 26 for convenience. In this example, the internal harness 25 is composed of single wires 25A, 25B, 25C. Reference numeral 29 is a cable that connects the detection device 30 and the controller-side connector 24.

The disconnection detection device 30, the detection single wire 31 consisting of each single wire 31A, 31B, 31C, and one end is connected to each single wire, the other end is 18V
Pull-up resistors 32A, 32B, 32 of several MΩ connected to the voltage source
A voltage generator 32 composed of C, a comparison circuit 33 composed of comparators 33A, 33B, and 33C in which the connection point of the resistance to each detection single wire is connected to one side, and each comparator 33A of the comparison circuit 33. 3
A reference voltage generator 34 that supplies a reference voltage V _R to the ten side of 3C,
A flip-flop circuit 35 that receives each comparison output of the comparators 33A to 33 and holds that the comparison output is in the "1" state, and one of the single wires 25A to 25C of the harness 25 based on this comparison output. A disconnection abnormality indicator 36 including light emitting diodes 36A, 36B, and 36C that light-emits that a disconnection abnormality has occurred. As the flip-flop circuit 35, an RS (set / reset) flip-flop is usually used.

In addition, each single wire 25A of the internal harness of the main body side movable arm 20
Zener diodes 38A, 38B, and 38C that perform a clipping action so that the signals transmitted to these single lines do not exceed a predetermined value are connected to 25C to 25C, respectively. If the upper limit of the signal voltage value is guaranteed, such a clipping circuit is unnecessary.

FIG. 2 is a block diagram showing a state in which the disconnection detecting device 30 according to the present invention is attached to an automatic machine such as a robot. In the figure, each reference numeral indicates each member shown in FIG. According to the figure, it is clear that the disconnection detection device 30 and the connection cable 29 are connected between the external harness 28 and the controller 22.

Next, the operation of the above embodiment will be described with reference to FIG. Each pull-up resistor 32A to 32C constituting the voltage generator 32 of FIG. 1 is connected to a high voltage power source of 18V at one end thereof, but the pull-up resistor has a large value of several MΩ, so that the transmitter circuit side. The current flowing to is very small and does not affect the output signal of the oscillator circuit. Further, the reference voltage is applied to one input terminal of each of the comparators 33A to 33C forming the comparison circuit 33.
A voltage of 16 to 17 V is constantly supplied as V _R. Also, the voltage of the control signal conducted to each single wire 25A to 25C is usually about 15V, so in a normal state where no disconnection occurs in each of the harnesses 25, 28, a comparison is made. The units 33A to 33C do not generate an abnormality detection output,
Therefore, none of the light emitting diodes 36A to 36C emits light.

This state is shown in the period T _A in FIG. Note that FIG. 3A shows the case where the output of the transmission circuit 21 is a digital waveform, and FIG. 3B shows the case where the output is an analog waveform.

Here, if, during the period T _B , a half-break occurs in the two single wires 25A and 25B, the detected voltage 40A at the connection point 39A
Is as shown in FIG. That is, during the period T _B in which the half-breakage occurs, the current from the high potential does not flow to the transmitting circuit and does not flow to the receiving circuit side that has high impedance, so that the potential at the connection point 39A is the high voltage source. It pulled and reach 18V exceeds the reference potential V _R by. This voltage is compared with the reference potential by the comparator 33A, and since it is higher than the reference potential, a detection output is generated. This detection output is held by the flip-flop circuit 35, and the light-emitting diode 36A is turned on by this flip-flop circuit output. This holding state is maintained even if the half-breakage state is resolved. In this way, disconnection of the single wire 25A is reliably detected.

Further, the detection of the disconnection as described above is similarly performed on the single wire 25B through which the analog signal flows, as shown in FIG. 3 (b). That is, when a disconnection of the single wire 25B is generated in a period T _B, the detection voltage of the node 39B is increased, a voltage of about 18V which is supplied through the resistor 32B and are detected, disconnection abnormality by lighting of the light emitting diode 36B The condition will be detected. In this way, the disconnection abnormality can be detected digitally or analogically.

In the above-described embodiment, the disconnection detection device 30 includes the transmitter circuit 21 of the movable arm on the main body side and the receiver circuit of the controller.
Although it has been described as being interposed between the inner harness 25 and the outer harness 28 that connect the 23 and the cable 29, the present invention is not limited to such a configuration, for example,
A disconnection measuring method as shown in FIG. 4 is possible. That is, the controller 22 has a specially prepared connection cable 41
Relay box provided on the main body side movable arm 20 via
Connected to 42. Further, the disconnection detection device 30 is connected to the movable arm 20 on the main body side via the outer harness 28 and the inner harness 25.
It is connected to the. Furthermore, the harness inside the movable arm 20
A clip circuit box 44 is provided in the middle of 43. In this measurement method, the movable arm is driven by the controller.
It is performed from 22 without using a harness.

Each specific circuit in this embodiment is substantially the same as that in the first embodiment, but as shown in FIG. 5, the clip circuit in FIG. 1 is an independent detachable box. Is different. Since signal exchange of the control system is performed without passing through the harness to be inspected, disconnection detection is performed without signal exchange with the controller. Therefore, it is possible to easily realize a clip circuit even for a power line through which a large amount of power flows, and it is less susceptible to noise or the like during measurement.

[Effect of device]

As described above in detail, according to the disconnection detection circuit according to the present invention, when the single wire is broken in each of the plurality of single wires forming the harness, the potential of the single wire is set to a potential higher than the normal signal potential. Since there is a pulling means for pulling up and the risen potential is detected by the comparator, an abnormal situation such as disconnection or semi-disconnection is simple and individual single wires that compose the harness with low manufacturing cost. Each disconnection can be detected reliably and accurately.

In addition, since it is designed to be directly connected to an actual machine such as a robot, it is possible to detect abnormalities such as disconnection even when the actual machine is operating, and perform flexible disconnection detection operations. Therefore, the reliability of the operation can be improved.

Furthermore, since each single wire forming the harness has a detection circuit, there is an effect that the disconnection of each single wire can be surely detected even for a harness which is not a coaxial cable.

Further, according to the configuration in which the power line is separated, it is less likely to be affected by noise and a clip circuit for the power line can be easily realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a wire breakage detecting device according to the present invention, FIG. 2 is a schematic block diagram showing a mounting state of the device of this embodiment, and FIGS. 3 (a) and 3 (b) show this. FIG. 4 is a signal waveform diagram for explaining the operation of one embodiment, FIG. 4 is a schematic block diagram for explaining one embodiment of the disconnection detecting method according to the present invention, FIG. 5 is a schematic circuit diagram thereof, and FIG. (A)
FIG. 7B is a partially enlarged cross-sectional view for explaining a general half-breakage state, and FIG. 7 is a schematic block configuration diagram for explaining an example of a conventional breakage detection device. 25 …… Internal harness, 25A, 25B, 25C …… Single wire, 32A, 32B, 3
2C: resistance for potential generation, 33A, 33B, 33C ... comparator, 35 ...
… Flip crop circuit, 36 …… Disconnection status indicator, 38A, 38
B, 38C ... Zener diode.

Claims (3)

[Scope of utility model registration request] 1. A disconnection detecting device for detecting disconnection of a signal transmission harness composed of a plurality of single wires drawn from a transmission circuit provided in a movable mechanism of an automatic machine, wherein a plurality of the single wires are provided at an end portion of the harness. Connected to each of the single wires, a potential raising means for generating an abnormal potential higher than a normal signal potential when the single wire is broken, and one side is connected for each single wire in the vicinity of the connection point of the potential raising means, and the other side A constant reference potential having an intermediate value between the signal potential and the abnormal potential is input to, a comparator that generates an output when an abnormal potential occurs, and that the plurality of comparators generate an output. A wire breakage detection device comprising: a holding circuit that holds the wire; and a wire breakage status indicator that displays a wire breakage abnormality for each single wire based on the output of the holding circuit. 2. The disconnection detection device according to claim 1, wherein each single wire of the harness in the movable mechanism is provided with a clip means for preventing the signal potential from exceeding a predetermined value. 3. A disconnection detecting device for detecting disconnection of a signal transmission harness consisting of a plurality of single wires drawn from a transmission circuit provided in a movable mechanism of an automatic machine, wherein the movable mechanism is driven independently. A cable provided separately from the signal transmission harness, a plurality of single wires connected at the end of the harness, and a potential raising means for generating an abnormal potential higher than a normal signal potential when the single wire is broken, For each of the single wires, a potential near the connection point of the potential raising means and a constant reference potential having an intermediate value between the signal potential and the abnormal potential are input, and an output is compared when the abnormal potential occurs. A disconnection circuit including a holding circuit for holding that the comparator has generated an output and a disconnection state indicator for displaying a disconnection abnormality for each single line based on the output of the holding circuit. Line detector.