JP3354179B2 - Moving body movement direction monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for monitoring the moving direction of a movable body such as a robot arm or a slide of a press machine.

[0002]

2. Description of the Related Art For example, in a factory or the like, when machines and humans work in a joint work space, safety measures for workers are extremely important. For example, when a human and a machine work in a common work space, an accident occurs when a part of a human body collides with a movable part of a machine. As an example, in a joint operation between a human and a robot, there is an accident such as a collision of a robot arm with a human body.

In this case, as a moving direction of a movable body such as an arm of a robot, a direction approaching a human body means danger to a human, and a direction away from the human body is not always dangerous. Similarly, in the operation of the slide of the press machine, the descent of the slide is dangerous, but the elevation of the slide means safety. Therefore, the moving direction of the movable body such as the robot arm or the slide of the press machine is monitored, and it is determined whether the moving direction of the movable body is safe or dangerous for the worker. Stopping immediately and operating the movable part as it is when the vehicle is in a safe direction is extremely useful for ensuring the safety of the worker and at the same time increasing the working efficiency of the machine.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a movable body movement monitoring device capable of monitoring the moving direction of a movable body and having a fail-safe configuration.

[0005]

For this reason, the movable body movement monitoring apparatus of the present invention generates an alternating signal that becomes low when a failure occurs in at least three phases or more in accordance with the movement of the movable body.
A polyphase signal generating means for generating the alternating signal with a phase difference in which at least one other alternating signal is in a high level state at the time of each of the alternating signals, and a falling detection signal of each of the sequentially falling alternating signals. The same number of the self-holding circuits as the number of the alternation signals are provided by self-holding with the signal of the high level state at that time to generate an output and no output is generated at the time of failure, and the falling order of the alternation signal varies according to the moving direction of the movable body. Moving direction determining means for outputting a moving direction determining signal for the movable body in accordance with the output state of the self-holding circuit based on.

[0006]

In this configuration, the multi-phase signal generating means generates at least three or more alternating signals in accordance with the movement of the movable body. The alternating signals have a phase difference such that at least one of the alternating signals is at a high level at the time of the falling of each of the alternating signals. Also, this alternating signal
The falling order differs depending on the moving direction of the movable body, and the output state of each self-holding circuit of the moving direction determining means differs depending on the falling order of the alternating signal. For example, when the moving direction of the movable body is a direction away from the person, it is a safe direction for the person, so it is not necessary to prohibit the movement of the movable body. The self-holding circuit is self-held and the output is continued, and a high-level output is generated from the moving direction determining means as a safe direction determining signal. On the other hand, when the moving direction of the movable body is in the direction approaching the person, the movement of the movable body must be stopped because it is a dangerous direction for the person. The output is stopped without the self-holding circuit being self-held, and the moving direction judging means generates a low-level output as a dangerous direction judging signal. As described above, the moving direction judging means outputs the judgment signal corresponding to the output state of the self-holding circuit, so that the moving direction of the movable body can be known.

The alternating signal from the multi-phase signal generator goes low when a fault occurs, and the self-holding circuit has a configuration in which no output is generated when the fault occurs.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 to 3 showing the configuration of the first embodiment of the present invention, as shown in FIGS. 2 and 3, a disk 1 is fixed to a movable body, for example, a shaft of a drive motor of a robot arm. A large number of slits 2 are formed in the disk 1 at equal intervals of the central angle θ. Further, three sets of photocouplers 3 to 5 each comprising a pair of light emitting elements 3A, 4A, 5A and light receiving elements 3B, 4B, 5B opposing each other with the disc 1 interposed therebetween.
Is provided. The positional relationship between the photocoupler 4 and the photocoupler 3 is shifted by θ / 3, and the photocoupler 5 is shifted by 2θ / 3 from the photocoupler 3.
Only in a position shifted in phase.

For this reason, the disk 1 is N
When the light receiving element 3B is rotated in the
(In this embodiment, when the light from the light emitting element is received by half or more of the light receiving element), and then when the disk 1 is rotated by 3 / θ, the output is output from the light receiving element 4B. Is generated, and when the disc 1 moves by 2θ / 3, an output is generated from the light receiving element 5B. Then, the output of each of the photocouplers 3 to 5 becomes an alternating signal in which a high level and a low level repeat every θ / 2.

Here, when the light emitting elements 3A, 4A, 5A are driven by an AC signal, when the slit 2 passes over the light receiving elements 3B, 4B, 5B with the rotation of the disc 1, the light receiving elements 3B, 4B, 5B are driven. An AC signal is generated from 4B and 5B. As long as the light emitting elements 3A, 4A, 5A and the light receiving elements 3B, 4B, 5B are normal, the light receiving element 3
Since B, 4B, and 5B output AC signals, if the presence of an AC signal is a logical value 1 (high level) and the absence of an AC signal is a logical value 0 (low level), the outputs of the light receiving elements 3B, 4B, and 5B are , A fail-safe binary logic signal that does not mistaken for at least a logic value 1 at the time of failure.

Therefore, the disk 1 and the three sets of photocouplers 3 to 5 allow at least 3
Polyphase signal generating means for generating an alternating signal with a phase difference in which at least one other alternating signal is in a high level state at the time of each falling of each alternating signal in a phase or more. The light receiving elements 3B, 4 of the photocouplers 3 to 5 are used.
As shown in FIG.
The signals are rectified by the signals 7 and 8, and become the alternating signals of a, b and c shown in FIG. The rectifier circuit 6,
At 7 and 8, the power supply voltage V _CC of AND gates 12, 13, and 14 described later is superimposed.

Each of the AND gates 12, 13, and 14 is composed of a conventionally known fail-safe window comparator that generates an output only when an input signal higher than the power supply voltage V _CC is input. The differential output of each of the falling differential circuits 9, 10, and 11, which detects the falling of each of the alternating outputs of the rectifier circuits 6, 7, and 8 and generates a positive differential output, is input to the other input terminal. In the AND gate 12, the output signal b of the rectifier circuit 7 is input, and
The gate 13 receives the output signal c of the rectifier circuit 8 and outputs
The D gate circuit 14 is configured to receive the output signal a of the rectifier circuit 6. In addition, each AND gate 12, 13,
Each of the outputs 14 is rectified through the respective rectifier circuits 15, 16 and 17 and is fed back to the input terminal side of the differential output of the falling differential circuits 9, 10, and 11, and the other input signal is supplied to the differential output. It is a configuration that is self-maintained at the high level. Therefore,
The AND gate 12 and the rectifier circuit 15, the AND gate 13 and the rectifier circuit 16, and the AND gate 14 and the rectifier circuit 17 constitute a self-holding circuit provided corresponding to each number of alternating signals. The output before rectification of these AND gates 12, 13, 14 is O
The OR gate 18 outputs a moving direction determination signal x for the movable body according to the output state of the AND gates 12, 13, and 14. Accordingly, the falling differentiating circuits 9, 10, 11; AND gates 12, 13, 14;
The moving direction determination means of the movable body is constituted by 6, 17 and the OR gate 18.

Next, the operation of the moving direction monitoring apparatus according to the present embodiment will be described with reference to the time chart of FIG. FIG.
, The alternating signals a, b, c are supplied to the respective rectifier circuits 6, 7, 8
, And the alternating signals Ma, Mb, Mc indicate the outputs of the AND gates 12, 13, 14. When the disk 1 moves in the N direction in FIG. 1 with the movement of the arm, the rectifier circuits 6, 7, 8 based on the outputs from the photocouplers 3, 4, 5 respectively.
As shown in FIG. 4, the alternating signals a, b, and c are generated out of phase by θ / 3, and fall in the order of the alternating signals a, b, and c. Therefore, when the alternating signal a falls, the alternating signal b is at a high level and the alternating signal c is at a low level. Similarly, when the alternating signal b falls, the alternating signal c is at a high level, the alternating signal a is at a low level, and when the alternating signal c falls, the alternating signal a is at a high level. There is a low level. That is, when any one of the three-phase alternating signals a, b, and c falls, the alternating signal whose phase is shifted by θ / 3 from the falling signal is in a high level state, and the alternating signal whose phase is shifted by 2θ / 3. Is in a low level state.

For this reason, the AND gate 12 outputs the alternating signal a
Falls and the differential output is input, the alternation signal b is at a high level. Therefore, the differential output is self-held and the alternation signal Ma is generated until the alternation signal b falls. Similarly, since the alternating signal c is at a high level when the alternating signal b falls and its differential output is input, the AND gate 13 self-holds the differential output and maintains the alternating signal until the alternating signal c falls. Mb, and AND
The gate 14 self-holds the differential output and generates the alternating signal Mc until the alternating signal a falls because the alternating signal a is at a high level when the alternating signal c falls and its differential output is input. I do.

Therefore, the alternating signal Ma is output from the AND gate 12.
Occurs, the alternating signal Ma falls at the falling of the alternating signal b.
When falling, the alternating signal Mb is generated from the AND gate 13 based on the falling differential output of the alternating signal b, and when the alternating signal Mb of the AND gate 13 falls at the falling of the alternating signal c, When the alternating signal Mc is generated from the AND gate 14 based on the falling differential output of the alternating signal c and the alternating signal Mc of the AND gate 14 falls at the falling of the alternating signal a, the falling differential of the alternating signal a The alternating signal M is output from the AND gate 12 based on the output.
a occurs.

As described above, when the disk 1 rotates in the direction N of FIG. 1, the alternating signals Ma, Mb, Mc of the AND gates 12, 13, 14 are continuously generated one after another. O
The R gate 18 continuously generates a moving direction determination signal x of a high level (corresponding to a logical value of 1). On the other hand, when the disk 1 rotates in the R direction indicated by the dashed arrow in FIG.
The falling order of b and c is opposite to that described above, and the falling order of the alternating signals c, b and a occurs. in this case,
As is apparent from FIG. 4, when the alternating signal a falls, the alternating signal b is at a low level and the alternating signal c is at a high level. When the alternating signal b falls, the alternating signal c is at a low level. When the alternating signal a is at a high level and the alternating signal c falls, the alternating signal a is at a low level and the alternating signal b is at a high level. For this reason, any AND gate
Also in 12, 13, and 14, the alternating signals Ma, Mb, and Mc are not held by themselves, and the OR gate 18 generates a low-level (corresponding to a logical value of 0) moving direction determination signal x.

As described above, since the output state of the OR gate 18 varies depending on the rotation direction of the disk 1 corresponding to the movement direction of the arm, the movement direction of the arm can be determined.
It is possible to monitor the direction of movement of the arm. When the arm, which is a movable body, moves in the safe direction away from the worker, the disc 1 rotates in the N direction, and when the arm moves in the danger direction to approach the worker, the disc 1 moves in the R direction. If the moving body is configured to rotate and generates a moving direction determination signal x having a logical value of 1 when the movable body moves in the safe direction, and generates a moving direction determination signal x having a logical value of 0 when moving the dangerous body in the dangerous direction, When the output stops at the time of failure,
The output state of the moving direction determination signal x from the OR gate 18 becomes the same as the output state of the movable body in the dangerous direction movement, and in the event of a device failure, the movable body is determined to be in the dangerous direction movement and the movable body movement stop output is generated. By doing so, a fail-safe configuration can be achieved.

Next, a second embodiment of the present invention will be described. In the second embodiment, when one of the three-phase alternating signals falls, the other two alternating signals are in a high level state. For example, in this embodiment, the slit 2 of the disc 1 is
The interval is set to the central angle θ as in the first embodiment, and the width of the slit 2 is widened so that the ratio of the portion of the slit 2 to the portion without the slit 2 is 5: 1. Therefore, in one cycle (θ) of each of the alternating signals a ′, b ′, and c ′, as shown in FIG. 6, the high level state is 5θ / 6 and the low level state is θ.
/ 6.

FIG. 5 shows a circuit configuration in this case. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Referring to FIG. 5, in this embodiment, one of the input terminals of each of the AND gates 12, 13, 14 is provided with each of the alternating signals a ',
Similarly, the falling differential outputs of b 'and c' are input. However, the alternating signal c 'is input to the other input terminal of the AND gate 12, and the alternating signal a is input to the AND gate 13. ′ Is input, and the AND gate 14 outputs an alternating signal b ′.
Is configured to be input. Also, AND gate 1
Outputs 2, 13, and 14 are input to an adder circuit 20, and the sum of these outputs is output as a moving direction determination signal x.

Next, the operation of the second embodiment will be described with reference to the time chart of FIG. First, when the disk 1 moves in the N direction in FIG. 1 with the movement of the arm, each rectifier circuit 6, based on the output from each of the photocouplers 3, 4, 5
As shown in FIG. 6, the alternating signals a ', b', and c 'are generated out of phase with respect to the signals 7' and 8 ', and the alternating signals a', b ',
Falling in the order of c 'is the same as in the first embodiment.

From the circuit of FIG. 5, in this embodiment,
When the alternating signal a 'falls, the AND gate 12
The differential output is self-held by the alternating signal c ', and the alternating signal Ma' is generated until the alternating signal c 'falls.
Similarly, the AND gate 13 self-holds the differential output with the alternating signal a 'when the alternating signal b' falls, and the alternating signal a '
Is generated until the falling edge of the AND signal, and AND signal Mb 'is generated.
The gate 14 self-holds the differential output with the alternating signal b 'when the alternating signal c' falls, and generates the alternating signal Mc 'until the alternating signal b' falls.

Therefore, in this embodiment, when the disk 1 is rotating in the N direction, as shown in FIG.
Alternating signals Ma ', Mb', Mc 'of D gates 12, 13, 14
Is in a high-level output state, and the output of the AND gates 12, 13, and 14 is a logical value 1 when the level is high, and a logical value 0 when the level is low, the disk 1 in the N direction In this case, the output state of the moving direction determination signal x of the adder circuit 20 becomes the logical value 2.

On the other hand, when the disk 1 is rotating in the R direction opposite to the N direction, the fall order of the alternating signals a ', b', and c 'is the same as in the first embodiment. , The alternating signals c ', b', and a 'fall in this order. In this case, the falling edge of the alternating signal c 'is self-held by the alternating signal b', the alternating signal Mc 'is continued until the falling edge of the alternating signal b', and the falling edge of the alternating signal b 'is expressed by the alternating signal a'. The self-holding continues the alternating signal Mb 'until the falling of the alternating signal a', and the self-holding of the falling of the alternating signal a 'with the alternating signal c' causes the alternating signal Ma 'to fall to the falling of the alternating signal c'. Therefore, when the alternating signals a ', b', and c 'sequentially fall, a new self-holding output is sequentially generated, and at the same time, the self-holding output up to that time disappears sequentially. Gates 12, 13, 14
The output from the adder 20 is not the logical value 2, but becomes the logical value 1. The moving direction determination signal x from the adder circuit 20 indicates that the disk 1 has R When it is rotating in the direction, it is in a lower level state than when it is rotating in the N direction.

Therefore, also in this case, since the output state of the adding circuit 20 differs depending on the rotation direction of the disk 1 corresponding to the movement direction of the arm, the movement direction of the arm can be determined. Can be monitored, and the disk 1 rotates in the N direction when the arm moves in the safe direction away from the worker, and when the arm moves in the danger direction approaching the worker, the disk 1 If the configuration is such that the motor rotates in the direction and the danger direction is determined when the output is lower than the output corresponding to the logical value 2, a fail-safe configuration can be obtained as in the first embodiment.

FIG. 7 shows the circuit of the first embodiment shown in FIG. 1 as a countermeasure against backlash of the mechanical portion including the movable body and the like, even if the disc 1 returns slightly in the opposite direction, the output of the self-holding circuit does not stop. This is an example of a circuit in which hysteresis is made large. Note that the same elements as those in FIG. 7, in this embodiment, rectifier circuits 6 ', 7', and 8 'are newly provided, and the outputs of the photocouplers 3, 4, and 5 are branched to generate two rectified outputs. The outputs of the wired OR circuit 31 based on the alternating signals a and b, the outputs of the wired OR circuit 32 based on the alternating signals b and c, and the alternating terminals are connected to the input terminals of the AND gates 12, 13, and 14 which are not the differential output input terminals. Signals c and a
, The output of the wired-OR circuit 33 is input.

The output operation of the AND gate in such a configuration will be described with reference to FIG. FIG. 8 shows only the output operation of the AND gate 12. If the disc 1 is slightly returned in the R direction while moving in the N direction, AN
In the D gate 12, an output is generated at the fall of the alternating signal a. Thereafter, when the disk 1 rotates in the reverse direction in the R direction, the wired OR output of the alternating signals a and b is input, so that even if the alternating signal b disappears, until the alternating signal a disappears, The self-holding output is maintained as it is. That is,
If the movement of the disk 1 in the reverse direction is within θ / 2, the output of the AND gate 12 is not reset and the output is continued.

Although not shown, the same applies to the AND gate 13. When an output is generated at the falling edge of the alternating signal b and the disk 1 rotates in the reverse direction R, the alternating signals b and c are output.
By inputting the wired-OR output of the above, even if the alternating signal c disappears, until the alternating signal b disappears,
The self-holding output is maintained as it is. In the AND gate 14, after the output is generated at the falling edge of the alternating signal c, when the disk 1 rotates in the reverse direction in the R direction, the wired-OR output of the alternating signals c and a is input. By doing so, even if the alternating signal a disappears, the self-holding output is maintained until the alternating signal c disappears. In the circuit of the first embodiment shown in FIG. 1, the self-holding output is not stopped if the movement in the reverse direction is within θ / 6.

In this embodiment, a rotating disk such as a motor is provided with a disk having a slit to monitor the moving direction of the movable member based on the rotating direction of the rotating member. It is needless to say that it is possible to apply the present invention to the monitoring of the direction of the movable body that reciprocates by providing a plate member with a slit on the side. Further, although the light from the photocoupler is used for detecting the moving direction, magnetic means, for example, a method in which a magnet is embedded in a movable body to detect a DC magnetic field may be used. Further, in this embodiment, the movable body is described as an example of a robot arm. However, the present invention is not limited to this, and is also applicable to monitoring of a moving direction of a slide of a press machine and a moving direction of a train at a railroad crossing. it can.

[0029]

As described above, according to the present invention, the direction of movement of the movable body can be determined, the movement of the movable body with respect to the person in the safe direction can be detected by a high level output, and the movement in the dangerous direction can be performed. Is detected by the output of the low level state, when the output becomes the low level at the time of the device failure, the judgment output of the danger direction side movement is made, and the fail safe configuration can be realized.

Therefore, the movement of the movable body is permitted when the person is moving in the safety direction, and the movement of the movable body is stopped only when the person is moving in the danger direction. In addition to improving work efficiency in the work system, fail safety can be ensured and safety can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a polyphase signal generating means according to the first embodiment;

FIG. 3 is a side view of the polyphase signal generating means of FIG. 2;

FIG. 4 is a time chart for explaining the operation of the first embodiment;

FIG. 5 is a circuit diagram of a second embodiment of the present invention.

FIG. 6 is a time chart for explaining the operation of the second embodiment;

FIG. 7 is a circuit diagram of a third embodiment of the present invention.

FIG. 8 is a main part time chart for explaining the operation of the third embodiment;

[Explanation of symbols]

 1 Disc 2 Slit 3, 4, 5 Photocoupler 6, 7, 8 Rectification circuit 9, 10, 11 Falling differentiation circuit 12, 13, 14 AND gate 15, 16, 17 Rectification circuit 18 OR gate 20 Addition circuit

Continuation of the front page (56) References JP-A-48-5450 (JP, A) JP-A-61-250563 (JP, A) JP-A-3-12515 (JP, A) JP-A-5-80066 (JP) , A) Hikaru Hei 4-19997 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16P 3/00 G01P 13/04

Claims (1)

(57) [Claims] An alternating signal which becomes low when a failure occurs in at least three phases or more with the movement of a movable body, and at least one other alternating signal becomes high when each of the alternating signals falls. A polyphase signal generating means for generating the alternating signal with a certain phase difference; and a self-holding a falling detection signal of each sequentially falling signal with a high-level state signal at that time to generate an output. The number of the self-holding circuits that does not include the same number as the number of the alternating signals, and the movement that outputs the moving direction determination signal of the movable body according to the self-holding circuit output state based on the fall order of the alternating signal that differs according to the moving direction of the movable body A moving direction monitoring device for a movable body, comprising: a direction determination unit.