JP3491048B2 - Robot rotational position detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot rotary position detecting device for accurately detecting a rotation angle in a work motion of a robot installed in a factory or the like, and particularly in a rotary motion.

[0002]

2. Description of the Related Art Conventionally, in a robot that works by rotating, a limit switch is used as a means for detecting whether or not the robot has reached a specific rotation angle. There is a device which is mounted at the position of and stops the rotation of the robot when the robot reaches the rotation start point or the rotation end point and turns on the limit switch. In the rotational position detecting device using this limit switch, the position of the rotation start point and the rotation end point can be detected, but the rotation angle in the middle cannot be known.

Therefore, conventionally, there is a robot in which an encoder is attached, a relative angle from the origin position is detected, and a rotation angle is calculated based on this information. Further, there is a robot whose resistance value is changed by rotation. There is a method in which the rotation angle is calculated by changing the resistance value of the tension meter.

[0004]

By the way, in the above-mentioned one that detects the rotation angle using the encoder, since the encoder is not fail-safe, an erroneous signal is generated due to the failure of the encoder or the influence of noise, and the robot is Causes a malfunction, and if the encoder causes a position shift, the robot operates at an unexpected location.

Further, when the rotation angle of the robot is detected by using the potentiometer described above, there is a problem that the slider is worn and cannot be used for a long time.

[0006] The present invention is intended to St. solve the problems described above, it is an object of the that electromagnets to move along with the turning of the robot the magnetic sensor sequentially one by one arranged around the robot Another object of the present invention is to provide a rotational position detecting device for a robot which is turned on and detects the rotational position of the robot by changing the resistance value of a resistor connected to each magnetic sensor.

[0007]

The robot rotational position detecting device of the present invention is intended to achieve the above-mentioned object.
The means of claim 1 includes: a plurality of magnetic sensors arranged along a turning path of a robot; resistors connected in series to each of the magnetic sensors; Electromagnetic that sequentially turns on the sensor
The magnetic sensor is turned on by the movement of the stone and the electromagnet.
The rotation angle of the robot due to the change in the resistance value when
Degree, and at a specific timing,
Turn off the power and intentionally disable the output voltage at this time
And a detection circuit for determining whether or not to change.

The means of claim 2 is the same as that of claim 1.
Further , by setting the resistors of the detection circuit to have the same resistance value, the output voltage from the detection circuit is linearly proportional to the turning angle of the robot.

The means of claim 3 is the same as that of claim 1 described above.
In addition, the detection circuit includes resistors for voltage division RH, Rw, and R.
By connecting s'and Rs, the output voltage from the detection circuit is made different during normal operation and during failure.

The means of claim 4 is the same as that of claim 1.
In addition, the magnetic sensor is a power reed switch that is highly durable and is less likely to malfunction due to electromagnetic noise or the like.

The means of claim 5 is the same as that of claim 1 described above.
In addition, the magnetic sensor is magnetically shielded so that malfunction does not occur due to magnetic force from the outside.

The means of claim 6 is the same as that of claim 1.
In addition, at least the magnetic sensor is shielded so that it cannot be turned on by operating it from the outside.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a rotary position detecting device for a robot according to the present invention will be described below with reference to the drawings. 1 to 3 show a swivel portion of a work robot, FIG. 1 is a perspective view of the swivel portion, FIG. 2 is an enlarged perspective view of a main part of FIG. 1, and FIG.
Shows an enlarged plan view of the main part.

In the figure, 1 is a rotating member, 2 is an electromagnet fixed to the rotating member 1 via an arm 1a , 3
Is fixed to the floor or the like as a fixing member. Reference numeral 4 denotes a ring-shaped table projecting from the fixing member 3 in a brim shape.
Is a magnetic sensor that is fixed to the surface of the table 4 at regular intervals in the radial direction, and is turned on and off sequentially with the rotational movement of the magnet 2 to prevent malfunction due to electromagnetic noise and the like. It consists of a highly durable power reed switch, reed switch, or Hall element.

Reference numeral 41 denotes a cover plate made of a non-magnetic material that covers the upper surface of the magnetic sensor 5, and is attached for the purpose of preventing invasion of magnetic powder and the like. The researchers of the present invention adopted the power reed switch in the experiment, but the effects of the present invention can be obtained even if the above-mentioned ordinary reed switch or Hall element is adopted. Further, in the experiment, 72 magnetic sensors were fixed to the table 4 at intervals of 5 degrees. Further, although an electromagnet was used as the magnet 2 in the experiment, the effect of the present invention can be obtained even if a permanent magnet is used.

FIG. 4 shows a circuit block for detecting the rotation angle of the rotating member 1 by turning on and off the magnetic sensor 5 described above, and E is a DC power source and R1 to R7.
Reference numeral 2 denotes a carbon film resistor (hereinafter, simply referred to as a resistor) connected in series to the DC power source E, and the magnetic sensors S1 to R72 are provided at connection points between the resistors R1 to R72. One end of S72 is connected.

The other ends of the magnetic sensors S1 to S72 are connected to the connection point between the resistors R1 and R72. Further, Rs is a resistor for generating a signal output, and is set to the expression 1 so that a measurement error does not occur due to its existence. Further, in this circuit, in order to generate a voltage linearly proportional to the turning angle across the resistor Rs, the resistance value is set to R1 = R2 = ... = R72.

[Equation 1]

6 is a programmable controller (hereinafter,
PLC) to energize and de-energize the magnet 2 which is the electromagnet (for example, energize once every 10 seconds), and both ends of the DC power source E are connected to the DC power source E. The voltage is constantly monitored, and further the voltage Vs (sensor output) across the resistor Rs is monitored.

Next, in explaining the operation based on the configuration described above, now, in a state where the energized electromagnets 2, the electromagnetic <br/> stone 2 is rotated with the rotation of the rotary member 1, Fig. 1 shown in 4
When one of the magnetic sensors Sx is turned on, the current flowing in the circuit of FIG. 4 becomes I >> i because of the equation 2, so that the output voltage of the formula (1) is generated across the resistor Rs.

[Equation 2]

[0020]

[Equation 3] However, Vs is the voltage across the resistor Rs, E is the power supply voltage, and is given by equation (4).

[Equation 4]

By the way, in the circuit shown in FIG. 4, the following problems occur when the following failures occur. (B) If a disconnection occurs at the position "A" in FIG. 4, Vs =
It becomes 0. On the other hand, Vs = 0 even when the switch S72 is activated, and the two cannot be distinguished. (B) If a disconnection occurs at the position of “B” in FIG. 4, Vs =
It becomes E. On the other hand, when the switch S1 is activated, V is approximately
Since s = E, the two cannot be distinguished. (C) In the circuit of FIG. 4, when the magnetic sensor Sx has a poor contact, Vs = 0. On the other hand, when a disconnection occurs at the portion “A” in FIG. 4, Vs = 0, and the two faults are distinguished. Can not.

Therefore, the rotational position detection circuit of FIG. 5 is proposed as a solution to the above problems. In this circuit, the reed switch S72 is installed by installing the resistor Rw.
At the time of operation, the potential difference of Vw in FIG. 5 is generated between the potential and the potential 0, and the problem of the above (a) is solved. Further, by installing the resistor RH, a potential difference of VH in FIG. 5 is generated between the reed switch S1 and the potential E when the reed switch S1 is operated, thereby solving the problem (b). Further, a resistor Rs' is provided in parallel with the reed switch, so that Vs = R between the reed switch and the potential 0 when the reed switch has a poor contact.
A potential difference of s · E / (Rs + Rs ′) is generated to solve the problem (c).

From the above, the signal output Vs is given by the following equation. (A) When normal

[Equation 5]

[Equation 6] (B) Poor contact of reed switch, magnet falling off Vs = RsE / (Rs + Rs') (3) (c) Breaking of resistance Rn (including peripheral wiring) When x <n Vs = E ( 4-1) When x ≧ n Vs = 0 (4-2) (d) When the resistor RH (including peripheral wiring) is disconnected Vs = 0 (5) (e) Resistor Rw (including peripheral wiring) When the wire breaks Vs = E (6)

FIG. 6 is a conceptual diagram of the signal output Vs when the circuit of FIG. 5 is used. Here, the following conditions are required for ΔH and ΔL in FIG. 3 in order to clearly distinguish the normal output and the fault output. ΔH = (E-V1)> ε (7) ΔL = (V72−VF)> ε (8) where V1 is x = 1 in the equation (2) and V72 is x = 72 in the equation (2). It is the value of Vs. Also, ε (> 0)
Is the minimum value required to significantly distinguish E and V1, V72 and VF.

FIG. 7 shows actual measurement results when the rotational position detection circuit is normal and when it fails. As is clear from FIG. 7, when the circuit is normal, the signal signal Vs is linearly proportional to the turning angle. Also, the contact failure of the magnetic sensor, the resistor R
When n is disconnected, resistor RH is disconnected, and resistor Rw is disconnected, the signal output Vs has different values, so that the failure can be identified. As described above, since the output voltage at the time of normal operation and the output voltage at the time of failure are clearly distinguished, it is possible to identify whether or not the operation is normal. Also, if the contact of the magnetic sensor is poor, +1
Since V and 0 become 0 or + EV when the resistor is disconnected, it is possible to identify the failure of both.

In the above-described operation, when the operator intentionally turns on the specific magnetic sensor 5 by using the permanent magnet, the device is invalidated, which causes a problem in work. Therefore, in the present invention, the following measures are taken to prevent the above-mentioned problems from occurring.

[0027] Sunawa Chi, electromagnets specific timing (e.g., periodically such as once in operation at the start and a few seconds of the robot) to interrupt the energization of the electromagnet than PLC6, the output of this time the Vs When the voltage is the predetermined voltage, it can be determined that the invalidation by the permanent magnet has not occurred.

Next, the entire operation of the PLC 6 will be described with reference to the flowchart of FIG. 8 including the invalidation by the worker. First, the PLC 6 determines whether or not the voltage of the DC power source E is normal (step S1), and if there is an abnormality, operates so that the robot cannot be operated (step S2). When the DC power supply E is determined to be normal in the above determination, the PLC 6 energizes the electromagnet 2 and drives the rotating member 1 of the robot to rotate the electromagnet 2 (step S3).

Next, the rotation angle is detected by calculating the equation (2) with respect to the position of the magnetic sensor 5 which is turned on with the movement of the electromagnet 2 (step S4). During this detection operation, the PLC 6 monitors whether a preset time, for example, 10 seconds has elapsed (step S5). When it is determined that the time has elapsed, the power supply to the electromagnet 2 is cut off (step S6).

In this state, the calculation of the equation (3) is executed (step S7), and it is judged whether or not the voltage value of the execution result is the same as the voltage value obtained in advance (step S).
8). When the energization of the electromagnets 2 is cut off, all the magnetic sensors 5 are turned off and the value of the formula (3) is obtained, but the operator intentionally turns on any one of the magnetic sensors 5 with a permanent magnet. In this case, the value of the equation (3) is different and becomes the same as the value obtained by the equation (2). Therefore, it is determined to be invalid and the driving of the robot is stopped (step S9).
For safety.

If it is determined in step S8 that the rotating member 1 is normal, the electromagnet 2 is energized again (step S10), and then the process returns to step S4 to repeat the above-described operation to rotate the rotary member 1. The rotation angle is determined, and whether or not the operator has made invalidation is determined.

By the way, in step S6 described above, when the voltage of the output Vs after the power supply to the electromagnet 2 is cut off and the equation (3) is calculated, the power supply to the electromagnet 2 is cut off. Since a time lag occurs in the time until the electromagnet 2 is completely demagnetized, the voltage of the output Vs is detected at the timing shown in FIG.

First, a case will be described in which the timing at which the power supply to the electromagnet 2 is cut off by the PLC at regular intervals is once every 10 seconds. Now, in FIG. 9, (a)
Indicates that the electromagnet 2 is energized by a command from the PLC 6, and the voltage generated at the output Vs is the PLC 6 when the desired magnetic sensor is in the ON state.
Is input to the PLC 6, and the PLC 6 monitors the rotation angle of the rotary member 1 by performing the calculation of the equation (2).

Then, in (b), when the PLC 6 sends a command to cut off the energization of the electromagnet 2, the electromagnet 2 is demagnetized, but due to the residual magnetism of the electromagnet 2, the completely demagnetized state shown in (c). There will be a time lag until. Therefore, the PLC 6 delays the reading of the output Vs by the period (b) to (c), and then reads the output Vs during the period (c) to (d) until the electromagnet 2 is energized again. Done, this read output V
The PLC 6 executes the calculation of equation (3) for s, and makes the determination in step S8.

Then, when the energization to the electromagnet 2 is started again as shown in (d) after the cutoff time to the electromagnet 2 by the PLC 6 has elapsed, the electromagnet 2 is completely magnetized as shown in (e). Since a time lag occurs until the state is reached, the PLC 6 delays the reading of the output Vs by the time of (d) to (e), reads the output Vs again at (e) after the delay time, Step S4 described above
The operation from is performed.

In the above-described embodiment, the case of determining whether or not the invalidation has been electrically performed has been described, but as shown in FIG. 10, at least the magnetic sensor 5 is brought close to the outside. It may be covered with a magnetic shield plate 7 so as not to be turned on by a magnetic line of force such as a permanent magnet.

Further, in the above-described embodiment, the case where the magnetic sensor 5 is a power reed switch which is turned on / off by a magnetic force line or a normal reed switch has been described, but the resistance value changes due to a magnetic force line such as a Hall element. In the case of a magnetic sensor, a resistor is not necessary, or a resistor for correction due to variations in Hall element may be connected.

Further, in the above-mentioned embodiment,
Although the magnetic sensor 5 is attached to the upper surface of the table 4 in the above description, the magnetic sensor 5 may be attached to the peripheral surface of the table 4 and the magnet 2 may be moved on the peripheral surface of the table 4.

[0039]

As described above, according to the present invention, a resistor is connected in series to each of a large number of magnetic sensors arranged along the turning path of the robot, and the magnetic sensor is moved by the turning of the robot. since it is configured from the detection circuit for detecting the rotation angle of the robot by the change in resistance in the state in which the magnetic sensor is turned on by sequentially moving the electromagnets shall be the oN state, to accurately detect the rotational position of the robot when the output of from said detecting circuit makes it deviates from a predetermined range Ki out to suddenly stop the robot, also energization of the electromagnet at a specific time
The output voltage from the detection circuit at this time.
I decided to intentionally invalidate it.
Reliable detection of the intentional disabling of
Can be made. .

Further, since the voltage dividing resistor is connected to the detection circuit so that the output voltage from the detection circuit is different between the normal time and the failure time, it is easy to distinguish the normal time and the failure time of the robot. It can be done.

Further, since the magnetic sensor is a power reed switch that is hard to cause malfunction due to electromagnetic noise and has high durability, there is no malfunction due to disturbance,
And the service life is also long.

Further, the magnetic sensor is magnetically shielded so as to prevent malfunction due to magnetic force from the outside, and at least the magnetic sensor is shielded so that it cannot be turned on by being operated from the outside. This has the effect of being able to reliably prevent intentional invalidation.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of a rotational position detecting device for a robot according to the present invention.

FIG. 2 is an enlarged perspective view of a main part of the above.

FIG. 3 is a plan view of the above table viewed from above.

FIG. 4 is a circuit configuration diagram of a rotational position detecting device for a robot according to the present invention.

FIG. 5 is a circuit configuration diagram of a rotational position detecting device according to another embodiment.

FIG. 6 is a conceptual diagram of a signal output Vs when the above circuit is used.

FIG. 7A is a measurement result showing an output voltage with respect to a turning angle in a normal state, and FIG. 7B is a measurement result showing an output voltage with respect to a turning angle at a contact failure of the reed switch Sx and a disconnection of the resistor RH or Rw. , (C) are actual measurement results showing the output voltage with respect to the turning angle when the resistor Rx is disconnected.

8 is a flowchart showing the operation of the circuit of FIG. 4 or FIG.

FIG. 9 is a timing chart showing an operation when power supply to the electromagnet is cut off.

FIG. 10 is a perspective view showing another embodiment.

[Explanation of symbols]

1 Rotating Member 2 Magnet 3 Fixed Member 4 Table 41 Cover Plate 5 Magnetic Sensor 6 Programmable Controller (Detection Circuit) 7 Magnetic Shield Plates S1 to S72 Magnetic Sensors R1 to R72 Resistors RH, Rw, Rs Voltage Dividing Resistors

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenjiro Hamada Inventor, Kenjiro Hamada 2-13-1, Nishinomiya-shi, Fukuoka Yasukawa Control Co., Ltd. (56) Reference JP-A-58-58368 (JP, A) Flat 3-115814 (JP, U) Actual Open 61-30708 (JP, U) Actual Open 1-148806 (JP, U) Actual Open 54-76757 (JP, U) Actual Open Sho 58-66319 (JP , U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34

Claims (6)

(57) [Claims] 1. A large number of magnetic sensors arranged along a turning path of a robot, resistors connected in series to each of the magnetic sensors, and a magnetic sensor which is moved as the robot turns to move the magnetic sensors sequentially. An electromagnet to be turned on , and
When the magnetic sensor is turned on by the movement of the electromagnet
The rotation angle of the robot is detected by the change in the resistance value at the time
In addition, the power to the electromagnet is interrupted at a specific timing.
The output voltage at this time to determine if it is intentionally disabled.
A rotational position detection device for a robot, comprising: a detection circuit for performing a determination . 2. The rotation of the robot according to claim 1, wherein the output voltage from the detection circuit is linearly proportional to the turning angle of the robot by setting the resistors of the detection circuit to have the same resistance value. Position detection device. 3. The voltage dividing resistors RH, R are provided in the detection circuit.
2. The rotational position detecting device for a robot according to claim 1, wherein the output voltage from the detection circuit is made different between a normal state and a fault by connecting w, Rs' and Rs. 4. The rotation position detecting device for a robot according to claim 1, wherein the magnetic sensor is a power reed switch which is less likely to malfunction due to electromagnetic noise and has high durability. 5. The rotational position detecting device for a robot according to claim 1, wherein the magnetic sensor is magnetically shielded so as to prevent malfunction due to a magnetic force from the outside. 6. The rotational position detecting device for a robot according to claim 1, wherein at least the magnetic sensor is shielded so that it cannot be turned on by being operated from the outside.