JP4680492B2 - Robot controller - Google Patents

Description

According to the present invention, in a control device for driving a motor, when the drive energy supply is cut off, that is, when the drive power supply is cut off, the stored energy is released or not released based on the output of the power failure detection circuit. More specifically, the present invention relates to a robot control device .

  In a slider or turntable for supplying parts to a processing machine to which a single-axis motor is applied, there are cases where an operator attaches a part to an attachment jig or removes a processed part. Also in an industrial robot to which a plurality of motors are applied, particularly, an operator attaches a component to a mounting jig or removes a processed component. Furthermore, during teaching to register and edit work programs for industrial robots, the teaching operator operates the pendant in the vicinity of the robot to move the robot to the desired position and register or change the position. Perform teaching work. In this way, an operator may approach the operating range or the vicinity of a processing machine or an industrial robot to which a motor is applied. In order to ensure the safety of the operator against unintended operations caused by external noise or a motor drive device component failure, the motor drive power is shut off automatically or by operation.

Further, details of the control device for driving the motor will be described with reference to the drawings, taking an industrial robot as an example. FIG. 7 is a diagram showing a configuration of a conventional robot control apparatus and system.
In the figure, reference numeral 1 denotes a robot, which is connected to a robot control device 2. A work tool for performing work is attached to the tip of the wrist of the robot 1. The robot control device 2 is connected to a pendant 3 and is provided with an enable device 9 that can turn on and off the motor power by a hand operation of the operator 7 during teaching. While the robot 1 is working, it is surrounded by a protective fence (not shown) so that the worker 7 does not enter the operating range. Reference numeral 8 denotes an external operating device, which is connected to the robot control device 2 and gives signals such as an emergency stop, a motor power-on command, an operation start command, and a stop command to the robot control device 2. Reference numeral 5 denotes a work table including a turntable 6 that is turned by a motor, and is connected to the robot control device 2.

The operator 7 attaches the work 4 to be processed to the work table 5 or removes the work 4 after the work by the robot 1 from an opening of a protection fence (not shown). At this time, the operator 7 may directly touch the turntable 6, and at least a part of the body of the operator 7 may enter the movable range of the robot 1. In order to ensure the safety of the operator 7, these setup operations are performed after the motor drive power of the robot 1 and the work table 5 is shut off by operating the emergency stop button of the external operation device 8 or the like. The worker 7 evacuates from the operating range of the robot 1 and the work table 5 after the setup work, and works by turning on the motor drive power by inputting the motor power on command of the external operation device 8 and inputting the operation start command. The operation based on the program is started and the work for the work 4 is performed.

Further, the worker 7 approaches the robot 1 during the teaching work and operates the robot 1 by operating the pendant 3. However, if the operator 7 performs an erroneous operation on the pendant 3, the robot 1 Unintended operation will be performed. This unintended operation of the robot 1 has a problem that the peripheral equipment of the robot may be damaged or the teaching operator may be harmed. For this reason, the pendant 3 is provided with an enable device 9, and when the pendant 3 is released from the gripping state, the driving power of the robot 1 is cut off, so that the robot 1 is completely stopped and the aforementioned problems are reduced. Yes.
Thus, the drive power supply is frequently turned on and off during operation or teaching.

On the other hand, in the maintenance work of the motor drive unit and the robot control unit housed in the robot control device 2, the power supply is cut off by the power cut-off means such as a breaker provided in the robot control device 2 to surely stop the motor. This is performed after releasing (discharging) the charge energy accumulated in the robot controller 2 and eliminating the risk of electric shock.
There are various types of robots such as vertical multi-joint type, horizontal multi-indirect type, and cylindrical coordinate type, but the torque output of the drive shaft stops because the power supply is cut off, and its arm falls in the direction of gravity. In order to prevent this, each drive shaft is provided with a cage such as an electromagnetic brake.

When the driving power supply for driving is cut off, the conventional motor driving device forcibly discharges the electric charge converted into direct current and charged in the smoothing capacitor, or displays the charging state of the smoothing capacitor (for example, patents). Reference 1 and Patent Reference 2).
As described above, the conventional motor drive device forcibly discharges the electric charge charged in the smoothing capacitor when the motor drive power is cut off, and even if the motor drive device is directly touched for maintenance and inspection, an electric shock accident may occur. It is preventing. In addition, by displaying the charge, the operator is cautioned about electric shock.
JP-A-9-37562 Japanese Patent Application Laid-Open No. 10-225583

Conventional motor drive devices control the discharge of the smoothing capacitor when the power supply to the motor drive device is cut off, and work machines that frequently turn on and off the drive power represented by machine tools and industrial robots There were the following problems in the application.
(1) Since the electric charge charged in the smoothing capacitor is forcibly discharged by the discharge resistor when the drive power supply is cut off, the discharge resistor may be overheated and burned if the frequency increases.
(2) The temperature of the smoothing capacitor is increased and the life of the smoothing capacitor is shortened.
(3) When the driving power supply is turned on after discharging the smoothing capacitor, charging of the smoothing capacitor to generate an appropriate torque for the motor requires a charging time of several hundred milliseconds, which is an obstacle to increase the tact time. .
Further, when displaying the state of charge of the smoothing capacitor, it was necessary to wait until the display was turned off and there was no risk of electric shock when performing maintenance and inspection. In order for the voltage across the smoothing capacitor to be below the dangerous voltage for the human body (for example, DC 30V), the charged charge depends on the natural discharge and the leakage current of the drive circuit components. is necessary. Relying on this forced discharge by the operator's operation has been problematic because forgetting the operation will impede safety.
In addition to shutting off the drive power supply during setup, in addition to ensuring the safety for the above-mentioned workers, it also saves power when the machine tool is not in operation, which has the effect of saving energy and has been increasingly demanded.

  The present invention has been made in view of such problems, and by not cutting the smoothing capacitor forcibly only by shutting off the driving power source, the capacity of the discharging resistor can be reduced and the life of the smoothing capacitor can be shortened. In addition to shortening the charging time of the smoothing capacitor when the motor drive power is turned on for continuing work, the smoothing capacitor is turned off when the entire power supply of the control device is cut off, that is, when the control power supply is turned off. It is an object of the present invention to provide a control device that can perform maintenance and inspection safely without delay and without causing an electric shock accident by forcibly discharging the charged electric charge.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 is a smoothing capacitor which stores power when power is supplied from a power source through a contact of a circuit breaker connected in series and a contact of a relay, and the contact of the circuit breaker and the contact of the relay are closed A drive power supply unit comprising: a drive unit that receives power supply from the drive power supply unit and drives a motor via a drive circuit; and is connected between the contact of the circuit breaker and the contact of the relay, and stops the supply of the power And a power failure detection circuit that outputs a power supply stop signal and energy release means for releasing excess energy due to regeneration from the motor and releasing energy stored in the smoothing capacitor when the motor decelerates. in the robot control apparatus, when the power failure detection circuit outputs the power failure detection signal to the smoothing capacitor by the energy release means Performs opening of the obtained energy, the relay in a state from a state in which the power is supplied to the drive power supply portion via the contact of the relay and the contacts of the circuit breaker from said power source, contact of the circuit breaker was closed If the power failure detection circuit does not output the power supply stop signal when the power supply to the drive power supply unit is cut off by opening the contact of the power supply, the energy stored in the smoothing capacitor is released by the energy release means It is characterized by performing natural discharge without performing the above.

According to the invention described in claim 1, a robot control device when the drive power shutdown of the motor, from the power failure detection circuit, the forced discharge causes a charge energy power supply stop signal is accumulated in the capacitor if it is not output If the power supply stop signal is output, the charge energy stored in the capacitor can be forcibly discharged, extending the life of the capacitor and discharge means components, and continuing the operation with minimum waiting time at the time of input. . Furthermore, an electric shock accident can be prevented during maintenance. Furthermore, it is possible to eliminate obstacles such as shortening of parts even in a production machine where the operator enters the robot operation area and the drive power is turned on and shut off frequently.

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

  FIG. 1 is a connection diagram of a power supply circuit showing a first embodiment of the present invention. In the figure, reference numeral 21 denotes a circuit breaker, which disconnects the power supply 20 to the control device. Branching from the circuit breaker 21, one side supplies power for control from the power supply device 22 to the drive power supply control circuit 24, and a power failure detection circuit 23 detects a power failure of the power source 20 or power interruption by the circuit breaker 21. A power supply stop signal is output to the drive power supply control circuit 24. A drive power-on command is input to the drive power control circuit 24 from a control unit (not shown) to control power-on / off of the drive power-supply unit 35. The power supply device 22 has a voltage holding time equivalent to a forced discharge time of the smoothing capacitor 33 described later. The other is connected to the drive power supply unit 35 via the relay 25 and relays the power supply 20 to the rectifier 26 based on a command from the drive power supply control circuit 24. The rectifier 26 is a diode array that converts alternating current into direct current. Reference numeral 27 denotes a resistor, 28 denotes a relay, 29 denotes a voltage detection circuit, 30 denotes a regeneration control circuit, 31 denotes a transistor, 32 denotes a regeneration resistor, 33 denotes a smoothing capacitor, and 34 denotes a drive circuit.

The resistor 27 is intended to suppress inrush current. When the voltage across the smoothing capacitor 33 is equal to or lower than a predetermined voltage, the relay 28 is opened, the relay 25 is closed, and the current converted into DC by the rectifier 26 is passed to the smoothing capacitor 33. The current is limited by the resistor 27 so that the charging current is not excessive. When the voltage detection circuit 29 detects that the voltage across the smoothing capacitor 33 has become a predetermined voltage, the relay 28 is closed and charged directly.
Further, when the motor decelerates, the regenerative energy is returned from the drive circuit 34 from the motor, and the voltage across the smoothing capacitor 33 becomes high. In order to prevent the circuit components from being burned out and the circuit from being broken down by this high voltage, the voltage detection circuit 29 Is detected to be higher than a predetermined overvoltage, a result is output to the regenerative control circuit 30. The regenerative control circuit 30 drives the transistor 31 to transfer the electric charge stored in the smoothing capacitor 33 to the regenerative resistor 32. To discharge through. The regenerative resistor 32 is also used when the energy stored in the smoothing capacitor 33 is forcibly discharged. That is, when a forced discharge signal is output from the drive power supply control circuit 24 to the regeneration control circuit 30, the regeneration control circuit 30 drives the transistor 31 to convert the charge energy stored in the smoothing capacitor 33 into the regeneration resistor 32. Use to forcibly discharge.

The drive circuit 34 is connected to a motor (not shown), and drives the motor based on a command from a control circuit (not shown). In order to drive the multi-axis motor, there are a configuration including a plurality of drive power supply units 35 and a configuration including a plurality of drive circuits 34 in parallel with the smoothing capacitor 33. In the practice of the present invention, one-axis control is possible regardless of the configuration. This will be described with reference to FIG.

The operation of the present invention will be described below. When the circuit breaker 21 is closed and the power supply 20 is relayed, the power supply device 22 supplies necessary drive power to the drive power supply control circuit 24, and the power failure detection circuit 23 sets “power supply normal” to the drive power supply control circuit 24. Output to.
Next, the motor drive power is turned on by inputting the motor power on command of the external operating device 8.
When a drive power on command is input to the drive power control circuit 24, a drive power on signal is output to the relay 25, the relay 25 is energized and energized, the contact is closed, and power is supplied to the rectifier 26.

The voltage across the smoothing capacitor 33 is monitored by a voltage detection open circuit 29. The relay 28 is opened below the voltage set for overcurrent prevention, and the voltage from the rectifier 26 to the smoothing capacitor 33 via the resistor 27 is opened. Charged. When the voltage detection open circuit 29 detects a voltage exceeding the voltage set for overcurrent prevention, the relay 26 is closed.
FIG. 2 is a both-ends voltage graph when the smoothing capacitor 33 is turned on from the completely discharged state. It takes about 250 milliseconds for the smoothing capacitor 33 to be fully charged from the discharged state and to have a voltage necessary for driving the motor without any trouble.

  FIG. 3 is a voltage graph across the smoothing capacitor 33 when only the drive power supply is cut off without turning off the control power supply. The drive power-on command to the drive power control circuit 24 is turned off and the relay 25 is opened. Since no power supply stop signal is output from the power failure detection circuit 23, no forced discharge signal is output from the drive power supply control circuit 24 to the regeneration control circuit 30, and as a result, the transistor 31 is not driven and is stored in the smoothing capacitor 33. The charged energy is not discharged through the regenerative resistor 32. In this state, the charge is still accumulated in the smoothing capacitor 33 and spontaneous discharge is caused by the leakage current of the circuit. Therefore, it takes several minutes to several tens of minutes to discharge the charge accumulated in the smoothing capacitor 33. Note that if the drive power supply is cut off while the motor is operating, the motor is decelerated and the regenerative energy may be returned to increase the voltage of the smoothing capacitor 33. This overvoltage is detected by the voltage detection circuit 28, and the output is The transistor 31 is driven based on the command of the connected regenerative control circuit 30 and discharged by the regenerative resistor 32 so that the voltage across the smoothing capacitor 33 is controlled not to become higher than a predetermined voltage that is an overvoltage.

  FIG. 4 is a both-ends voltage graph when the drive power supply is turned on during the natural discharge from the smoothing capacitor 33 after the drive power supply cut-off of FIG. In the upper part, the entire drive power supply is turned on at 10 S / div after the drive power supply is cut off, and in the lower part, the enlargement at the time of drive power supply is 100 mS / div. The drive power supply is turned on about 60 seconds after the drive power supply is cut off. Based on the drive power supply command, the relay 25 is closed and the power supply 20 is supplied to the drive power supply unit 35. The rectifier 26 converts the supplied alternating current into direct current and accumulates electric charge in the smoothing capacitor 33. However, since the smoothing capacitor 33 is not completely discharged, it is charged to a voltage necessary for driving the motor without any trouble. Such time is much shorter than several 60 milliseconds and about 250 milliseconds of the charging time in FIG.

  FIG. 5 is a voltage graph across the smoothing capacitor 33 when the power supply is stopped and the drive power supply is shut off. When the circuit breaker 21 is opened, a power supply stop signal is output from the power failure detection circuit 23, and a control unit (not shown) cuts off the drive power. When the drive power supply command is turned off, the drive power supply control circuit 24 turns off the drive power supply signal and opens the relay 25. Since the power supply stop signal is output, a forced discharge signal is output from the drive power supply control circuit 24 to the regeneration control circuit 30. As a result, the transistor 31 is driven, and the charge energy accumulated in the smoothing capacitor 33 is regenerative resistor. Forcible discharge is performed via 32. The discharge time at this time is about 100 milliseconds.

FIG. 6 is a both-ends voltage graph when the power supply is stopped during the natural discharge from the smoothing capacitor 33 after the drive power supply is cut off in FIG. When the power supply is stopped, the power failure detection circuit 23 detects this, and outputs a power supply stop signal to the drive power control circuit 24. The drive power supply control circuit 24 outputs a forced discharge signal to the regeneration control circuit 30, and the regeneration control circuit 30 drives the transistor 31 to forcibly discharge the electric charge accumulated in the smoothing capacitor 33 via the regeneration resistor 32. In the control device in which the motor driving device and the control unit are housed, the charging unit is housed in the enclosure in order to protect workers and the like from electric shocks, and when the enclosure is opened for maintenance, the circuit breaker 21 is used to supply power. A configuration for shutting off is required by a standard related to machine safety (for example, JIS B 843 3 ). In FIGS. 5 and 6, it is clear that this requirement is met.

In the embodiment of the present invention shown in FIG. 1, the power failure detection circuit 23 and the power supply device 22 are configured separately, but these units have common parts in power reception, internal control voltage supply, and internal circuit configuration. As a result, it is possible to improve the reliability because the size of the control device can be reduced, the interconnections can be simplified, and the number of components can be reduced.

The present invention differs from Patent Document 1 and Patent Document 2 in that, when only the motor drive power is cut off, the charge charged in the smoothing capacitor is not forcedly discharged but is spontaneously discharged and the control power supply is cut off. In the case, it is a part provided to forcibly discharge the electric charge charged in the smoothing capacitor.

  As described above, when the drive power supply is shut off, the power failure detection circuit 23 detects whether or not the power supply is interrupted due to a power failure or the circuit breaker 21 being interrupted, and is stored in the smoothing capacitor 33 only at the time of the power failure. Since the charge energy is forcibly discharged, frequent turning on and off of the drive power prevents heating of the discharge resistor, prevents burnout, and shortens the life of the smoothing capacitor by reducing charging and discharging. In addition, since the charging time can be shortened, the tact time does not increase, and the electric discharge accident can be prevented because the discharge is completed within a short time during maintenance.

INDUSTRIAL APPLICABILITY The present invention is effective for a machine tool that turns on and off a drive power source with a control device that drives a motor, and can also be applied to uses such as a numerical control device, a slider, and a turntable control device.

Connection diagram of power supply circuit of control apparatus showing first embodiment of the present invention Smoothing capacitor both-ends voltage graph at the time of driving power supply from the smoothing capacitor full discharge state in the first embodiment of the present invention Smoothing capacitor both-ends voltage graph at the time of driving power supply cutoff in the first embodiment of the present invention Smoothing capacitor both-ends voltage graph at the time of driving power supply from the smoothing capacitor undischarged state in the first embodiment of the present invention Smoothing capacitor both-ends voltage graph when power supply is stopped in the first embodiment of the present invention Smoothing capacitor both-ends voltage graph at the time of power supply stop from the smoothing capacitor undischarged state in the first embodiment of the present invention Outline diagram of workpiece machining system by robot

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot 2 Robot control device 3 Pendant 4 Work 5 Worktable 6 Turntable 7 Worker 8 External operation device 9 Enable device 20 Power supply 21 Circuit breaker 22 Power supply device 23 Power failure detection circuit 24 Drive power supply control circuit 25, 28 Relay 26 Rectifier 27 Resistor 29 Voltage detection circuit 30 Regenerative control circuit 31 Transistor 32 Regenerative resistor 33 Smoothing capacitor 34 Drive circuit 35 Drive power supply unit

Claims (1)

A drive power supply unit comprising a smoothing capacitor that is supplied with power via a contact of a circuit breaker and a contact of a relay connected in series from a power source, and stores energy when the contact of the circuit breaker and the contact of the relay are closed;
A drive unit that receives power supply from the drive power supply unit and drives a motor via a drive circuit;
A power failure detection circuit that is connected between the contact of the circuit breaker and the contact of the relay and detects the supply stop of the power and outputs a power supply stop signal;
In a robot control apparatus comprising: energy release means for releasing surplus energy due to regeneration from the motor during deceleration of the motor and releasing energy stored in the smoothing capacitor;
When the power failure detection circuit outputs the power failure detection signal, the energy release means releases the energy stored in the smoothing capacitor,
From the state in which power is supplied from the power source to the drive power supply unit via the contact of the circuit breaker and the contact of the relay, the contact of the circuit breaker is opened while the contact of the circuit breaker is closed. If the power failure detection circuit does not output the power supply stop signal when the power supply to the unit is interrupted, the energy release means performs a natural discharge without releasing the energy stored in the smoothing capacitor. A robot controller characterized by the above.

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