JPH0647239B2 - Power supply for robot encoders - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power supply device for a robot equipped with an encoder for absolute position detection, in which the encoder power supply is never interrupted.

[Conventional technology]

In conventional robots, especially industrial articulated robots, the rotation axes of each joint are controlled independently, and the absolute position of the moving parts connected by these rotation axes is managed by an encoder attached to the robot. Has become.

Therefore, by connecting an absolute position detection encoder to the motor that drives the robot movable part of the industrial robot around each axis, the current position around the axis of each robot movable part is calculated and stored as the absolute position of the corresponding drive motor. By reading this stored value, the movement control of the robot movable portion can be easily achieved. However, in the absolute position detection encoder that controls the drive motor of each robot movable part, once the power supply is cut off, all the absolute position data of each movable part stored in the storage unit of the encoder disappears. You will have to enter the data again.

Therefore, the encoder of such an industrial robot is connected to, for example, a backup power source (battery) installed in the robot body, and when the main power source line for operation control of the robot is cut off, The battery is used as a power source so that the absolute position of each movable portion, which is input to the storage unit of the encoder when the robot is assembled, is always held.

[Problems to be solved by the invention]

However, in general, the encoder of an industrial robot is attached to the movable part of the robot, the backup battery is installed on the robot body, and both are connected by a flexible communication cable. May be cut due to dynamic fatigue caused by the movement of the moving parts of the robot.

If the cable connecting the backup battery and the encoder is disconnected, or if the voltage drops due to the consumption of the backup battery, etc., the encoder's memory will be lost when the main power supply line for robot operation control is cut off. All disappear.

Therefore, it has been proposed to arrange the backup battery at a position where it is easy to replace the battery and the communication cable is not easily broken by the movement of the movable part of the robot.
0-91221) and a proposal to issue an alarm when the voltage from the backup battery drops (Japanese Patent Application No. 60-128072), but even with the former proposal, it is still possible to disconnect the communication cable. In the latter proposal, the operator may turn off the switch without noticing the alarm and shut off the main power supply line for controlling the operation of the robot.

[Means for solving problems]

The object of the present invention is to solve the above-mentioned problems, and when the voltage from the backup battery drops due to a cable disconnection or the like, even if the worker cuts off the main power supply for controlling the operation of the robot, the power supply of the encoder It is an object of the present invention to provide an excellent power supply device for a robot encoder, in which the data stored in the encoder is never lost without being interrupted.

The power supply device for a robot encoder of the present invention that achieves the above object connects an encoder that manages and controls the absolute position of each movable part of the robot to the main power supply for robot control when the robot is in operation, and this power supply is cut off. In the power supply device of the robot encoder that is connected to the backup power supply on the robot body side via the communication cable, the detection means for detecting the voltage of the backup power supply via the communication cable, and the detection means When the detected value is less than or equal to a predetermined value, a power supply holding means is provided so as not to cut off the main power supply even if the cutoff switch of the main power supply for robot control is operated.

[Work]

In the power supply device for the robot encoder of the present invention, the worker can operate when the communication cable connecting the backup battery and the encoder is disconnected, and when the voltage of the backup battery drops to the operating voltage of the encoder or lower for some reason. Even if the operation of cutting off the main power supply for controlling the operation of the robot is performed, the main power supply is not cut off and the power supply of the encoder is not cut off.

〔Example〕

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of an encoder provided with a power supply device for a robot encoder according to an embodiment of the present invention. Generally, there are an encoder of an incremental type and an encoder of an absolute type, but in this embodiment, an encoder having a mechanical unit of an incremental type having a simple mechanical unit and capable of substantially functioning as an encoder of an absolute type is provided. Are using.

In FIG. 1, the encoder is a mechanical unit 1 and a signal processing unit 2.
The signal processing unit 2 includes a power source 51 in the control device 5.
Alternatively, the voltage is supplied from the backup power source 4, more specifically, a battery such as a dry battery. The mechanical unit 1 includes a rotary code plate 11 fixed to a rotary shaft of an object to be detected and rotating with the rotation of the rotary shaft, and light emitting elements 12a and 12b and a light receiving element 13a, which are opposed to each other with the rotary code plate interposed therebetween.
It has 13b. The rotary code plate 11 is provided with a light-transmitting portion and a light-shielding portion along the circumference thereof.
Of the light emitted from the light emitting elements 12a and 12b as the light is rotated, the light that has passed through the transparent portion of the rotary code plate 11 is received by the light receiving element 1.
3a and 13b are detected as phase A and phase B signals 90 ° out of phase, that is, D _A and D _B.

The signal processing unit 2 includes amplifiers 21a and 21b for converting the A-phase and B-phase signals D _A and D _B into rectangular waves, and a phase difference between output signals from the amplifiers, for example, A when the rotary code plate 11 is positively rotated. The direction of rotation of the rotary code plate 11 is detected based on the fact that the phase signal leads the B-phase signal by 90 °, and the A-phase signal lags the B-phase signal by 90 ° in the case of reverse rotation.
It has a rising / falling detection circuit 22 that outputs a rising pulse S _U or a falling pulse S _D , and an up / down counter 23 that counts an increase / decrease according to the pulse S _U or S _D. The up / down counter 23 is the rotary code plate 11.
If is a normal rotation, the count value is increased, and if it is a reverse rotation, the count value is decreased. The rotation position of the rotation code plate 11 is updated in the up-down counter 23 in this way,
It may provide an output similar to an absolute type encoder. The value of the up / down counter 23 is output from the output drivers 27a and 27b via the transmission circuit 26 when the request signal REQ from the control device 5 is received. In the example of FIG. 1, the output signals of the A-phase and the B-phase are output in opposite phases, that is, as a pair of signals SA ₁ , SA ₂ and SB ₁ , SB ₂ having a relationship of high level and low level. . That is, the output drivers 27a and 27b are differential drivers.

The differential outputs SA ₁ and SA ₂ are differential amplifiers 52 in the control device 5.
It is accepted by a and used by the control device 5 as a position signal. The differential outputs SB ₁ and SB ₂ are received by the differential amplifier 52b.

The signal processing unit 2 is provided with a rotation ratio detector 24 and a clock generation circuit 25 that changes a clock cycle by the output of the rotation ratio detector. The rotation ratio detector 24 detects the count rate with respect to the time of the up / down counter 23, and when the count rate is low, that is, when the rotation of the rotary code plate 11 is slow, the clock period is increased to reduce the power consumption in the signal processing unit 2 and the like. However, it is not directly related to the present invention. The light emitting elements 12a and 12b are turned on in response to the clock signal from the clock generation circuit 25.

Since the encoder operates simultaneously with the operation of the control device 5, it receives DC power from the power supply unit 51 in the control device 5. The power supply unit 51 is connected to an AC power supply (usually 200 V) via the switch 6 and generates a direct current necessary for the encoder. Reference numeral 6 denotes a switch which is turned off in conjunction with the cutoff switch 7 of the main power supply for controlling the robot being turned off. The power supply unit 51 is connected to the signal processing unit 2 via the diode 28.

As it is, the switch 6 is turned off and the signal processing unit 2 does not operate and the memory of the encoder is lost. Therefore, the signal processing unit 2 is flexible via the diode 29 having the cathode connected to the cathode side of the diode 28. It is connected to the backup battery 4 installed on the robot body by a communication cable 41. Since the voltage of the battery 4 is set slightly lower than the voltage from the power supply unit 51, the diode 29
When the power is supplied from the power supply unit 51 to the signal processing unit 2 by the action of, the power from the battery 4 is not supplied, and the power from the battery 4 is supplied from the switch 6
This is done only when is turned off.

The communication cable 41 connects the terminal T ₂ of the signal processing unit 2 and the terminal T _{3 of the} battery 4 to each other.
There is a risk of disconnection in 1. When the communication cable 41 is broken and when the battery 4 is exhausted, the voltage at the terminal T ₂ drops. Therefore, in the present invention, the voltage detector 3 is connected to the terminal T _2, the voltage of the terminal T ₂ is always monitored.

The voltage detector 3 is set with a lower limit voltage value at which the memory of the encoder is not lost, and when the detected voltage value is below this set value, the voltage holder 8 connected to the voltage detector 3 is set.
And a signal is output to the alarm device 9.
When a signal is received from the voltage detector 3, the alarm device 9 displays so that the operator can know that the power supply system of the backup battery 4 is abnormal, and the voltage holder 8 shuts off the main power supply for robot control. Even if the switch 7 is turned off, the power supply unit 51 is prevented from being disconnected from the AC power supply. In this embodiment, a switch 81 is provided in parallel with the switch 6, and when the voltage holder 8 receives a signal from the voltage detector 3, the switch 81 is turned on.

Therefore, when the voltage detector 3 detects that the voltage of the terminal T ₂ has dropped due to the disconnection of the communication cable 41 or the voltage drop of the battery 4, the alarm device 9 notifies the abnormality and the voltage holder 8 switches. Since 81 is turned on, even if the operator overlooks the abnormal display of the alarm device 9 and turns off the cutoff switch 7 and turns off the switch 6 in this state, the power supply unit 51 is connected to the AC power source through the switch 81. Therefore, there is no fear that the memory of the encoder will be lost.

What has been described above is the conceptual configuration of the power supply device for the robot encoder of the present invention. Next, an example of a more specific configuration of the device of the present invention will be described with reference to FIG. The description of the components other than the power supply unit shown in FIG. 1 is omitted here.

In FIG. 2, a factory power supply 100 (for example, AC200
A start switch (ON switch) 71 for the main power supply for robot control and a magnet contact MCC connected in series to this are provided between V) and the ground GND. Further, a normally-closed cutoff switch (OFF switch) 7 and the magnet contact M are provided between the connection point of the start switch 71 and the magnet contact MCC and the power supply 100.
A circuit in which a contact MCC1 that is turned on by energizing CC is connected in series, and a circuit in which a contact K1 that is turned on by energizing an alarm 9 and a relay K described later are connected in series are provided.

Further, between the power source 100 and the ground GND, there is provided a circuit in which a power source unit 51 for generating DC 5V and a contact MCC2 which is turned on by energizing the magnet contact MCC are connected in series. The power supply unit 51 is connected to the diode 28 via the terminal T ₁ , and supplies DC power to the signal processing unit after the contact MCC2 is turned on by turning on the start switch 71.

On the other hand, in the power supply system from the backup battery 4, the circuit from the terminal T ₂ on the signal processing unit side to the diode 29 is connected to the comparator 30. The comparator 30 is provided with a reference voltage V by a battery 31, for example.
₀ (V ₀ << battery voltage) is given, and a signal is output when the voltage at the terminal T ₂ falls below this reference voltage V ₀ . A relay K is connected to the output of the comparator 30 via an amplifier 32. The relay K turns on the contact K1 by energizing.

In the power supply device for the robot encoder configured as described above, since the magnet contact MCC is energized when the start switch 71 is turned on, the contact MCC1 and the contact MCC2
And turn on. Since the shutoff switch 7 is normally closed,
After the MCC1 is turned on, even if the start switch 71 is turned off, the magnet contact MCC is kept energized. Further, when the contact MCC2 is turned on, the direct current from the power supply unit 51 is supplied to the signal processing unit.

When the cutoff switch 7 is turned off, the magnetic contact
Since the power supply to the MCC is stopped, the contacts MCC1 and MCC2 are both turned off, and the direct current supply from the power supply unit 51 to the signal processing unit is also stopped. At this time, the signal processing unit is connected to the backup battery 4 through the diode 29 and the connecting cable and receives the direct current from the battery 4, so that the memory of the encoder is retained.

When the start switch 71 is turned on in this state, the direct current from the power supply unit 51 appears at the terminal T ₁ as described above, and here also (voltage of terminal T ₁ )> (voltage of terminal T ₂ ). Therefore, the supply of direct current from the battery 4 stops,
Direct current from the power supply unit 51 is supplied to the signal processing unit.

The above is the operation of the power supply device for the robot encoder in a normal state. At this time, whether the direct current supplied to the signal processing unit is from the power supply unit 51 or from the battery 4, since the voltage of the battery 4 is applied to the terminal T ₂ , the input voltage value of the comparator 30 is Much larger than its reference voltage value, the comparator 30 does not output a signal.

However, when the flexible communication cable 41 is cut due to dynamic fatigue due to the movement of the movable portion of the robot, or when the voltage of the battery 4 drops extremely due to leakage or consumption, the voltage at the terminal T ₂ is Greatly reduced. At this time, the input voltage value of the comparator 30 falls below the reference voltage value, and an output signal is output to the comparator 30.

This signal is amplified by the amplifier 32 and the relay K is energized. The contact K1 is turned on by energizing the relay K, and the alarm 9
Is energized to notify the operator of an abnormality in the power supply circuit of the backup battery 4. The operator may notice the abnormality by the operation of the alarm device 9, but if not noticed, the cutoff switch 7 is turned off at the end of the work.

However, in the power supply circuit of the present invention, even if the cutoff switch 7 is turned off, the magnet contact MCC is
Since the contact MCC2 is connected to the power supply 100 via the contact K1, the ON state of the contact MCC2 is maintained and the power supply unit 51 continues to supply DC to the signal processing unit, so that the stored contents of the encoder are not lost.

〔The invention's effect〕

As described above, according to the present invention, when there is an abnormality in the backup power supply circuit, the encoder power is not turned off even if the main power cutoff switch is turned off. (Location information) is not lost.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a power supply device for a robot encoder of the present invention, and FIG. 2 is a circuit diagram of another embodiment. 1 ... Mechanism part, 2 ... Signal processing part, 4 ... Backup battery, 5 ... Control device, 7 ... Break switch, 3
0 ... Comparator, 41 ... Communication cable, 51 ... Power supply unit, 70 ... Startup switch, 100 ... Power supply, MCC
…… Magnet contact, K …… Relay, MCC1, MCC
2, K1 ... contact point.

Claims (2)

[Claims] 1. An encoder for managing and controlling the absolute position of each movable part of a robot is connected to a main power supply for robot control when the robot is in operation, and when the main power supply is cut off, a robot body is connected via a communication cable. In the power supply device for the robot encoder connected to the backup power supply on the side, the voltage of the backup power supply is detected through the communication cable, and the detection value of the detection means is equal to or less than a predetermined value, A power supply device for a robot encoder, which is provided with a power source holding unit that does not shut off the main power source even when a shutoff switch of the main power source for robot control is operated. 2. The power supply device for a robot encoder according to claim 1, wherein said detection means is provided with alarm means for notifying the outside when the detected voltage value is below a predetermined value. .