JPS61147306A - Safety device of robot - Google Patents

Abstract

PURPOSE:To ensure sufficiently the safety of a worker at a time such as teaching job by supervising a combined speed value of a robot tip, an operating speed command of of each axis and a real operating speed of each axis so as to limit and stop the robot when they exceed a reference value. CONSTITUTION:When the combined speed at the robot tip operated based on an operating command of a multi-axis robot exceeds a reference combined speed stored in advance in a memory 12, the operating position command is changed while taking the over amount into account. The present value is subtracted from the operating position command to obtain the operating speed command Dv, and when the operating speed command Dv exceeds a reference operating speed Dr at each axis during operation, an output of the 1st comparator 24 limits to voltage level of an operating speed command voltage signal Sv. When the speed of a robot axis exceeds the reference axial speed going to be runaway, the 2nd comparator 25 discriminates it, a magnetic contactor 29 is excited to open a normally closed contact 29a, thereby shutting off a power supply for each servo amplifier and the system comes to an emergency stop immediately.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a safety device for a robot.

[Prior Art] - Normally, a robot control device is provided with an operating speed #limiting circuit 1 as shown, for example, surrounded by a broken line in FIG.

To explain this simply, when the switch 2 in this circuit 1 is turned off, the deviation counter 3 sequentially generates the position command pulse CP and the robot axis driving motor 4.
Deviation (accumulation amount) ΔS&D from the position feedback pulse FP from the pulse generator 5 attached to the output shaft of
The speed command signal ΔV obtained by digital/analog conversion by the /A converter 6 is output to the servo amplifier 7 via the amplifier consisting of a resistor and an operational amplifier in the circuit 1, and the motor 4 is thereby attached to its output shaft. It rotates while receiving speed feedback from the tough generator 8.

On the other hand, when the switch 2 in the circuit 1 is turned on, the Zener diode 9 becomes effective, so that even if the speed command signal ΔV tries to exceed the set voltage determined according to the Zener voltage, it will be clamped to the set voltage. Become,
This limits the operating speed of the robot axis moved by the motor 4.

Note that although only one axis is shown in the figure, the same applies to the other axes.

[Problem that the invention seeks to solve]

However, in the prior art as described above, the speed command signal ΔV for each axis of the robot is clamped to a set voltage determined according to the Zener voltage of each Zener diode S.

This method was effective for robots that only move in a straight line, such as Cartesian robots, but it is effective for robots where it is difficult to predict the movement speed of the robot tip, such as multi-axis (multi-joint) robots with polar or cylindrical coordinate systems. Because it is not possible to limit the movement speed below the required value, unexpected accidents may occur during teaching work.

Further, even though the speed command signal ΔV is limited, no safety measures are taken in case the robot's axes run out of control for some reason, which poses a problem in terms of ensuring the safety of the workers.

This invention attempts to solve the above problems.

[Means for solving problems]

Therefore, in the robot safety device according to the present invention, as shown in FIG. A first determination means B that determines whether or not the operating speed command value of each axis of the multi-axis robot exceeds the reference operating speed value of each axis. means, C, a third determining means for determining whether the actual operating speed of each axis of the multi-axis robot exceeds the reference actual speed of each axis, and the first determining means B. The first limiting means E limits the composite speed value or its operation command when it is determined that the speed value exceeds the reference composite speed value, and the second determining means C controls the operation speed command value of each axis. A second limiting means F limits the corresponding operating speed command value when it is determined that any one exceeds the corresponding reference operating speed value, and a third determining means controls the actual operating speed of each axis. A stop means G is provided to stop the operation of each axis of the multi-axis robot when it is determined that any of the axes exceeds the corresponding reference actual speed.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 2 to 5 of the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention.

In the figure, reference numeral 10 denotes a central control unit constituting a robot control device for a multi-axis (for example, 6-axis) robot, and a central processing unit (CPU) 11. Memory (ROM, RAM)12.
The microcomputer includes input/output interfaces 13 and 14, and a teach data memory 15 for storing tee and teach data for each axis.

The input/output interface 13 includes a robot control panel 16 and a teaching pendant 17, and the input/output interface 14 includes a servo circuit 18 for the first axis of a multi-axis robot (not shown), and servo circuits and magnets for each axis of other robots (not shown). Two contactors are connected respectively.

Note that the configuration and operation and effect of the servo circuits for each axis of the other robots (not shown) are the same as those for the first axis, so in the following explanation, the explanation of the servo circuit 18 for the first axis will be used for the other robot axes. This will replace the description of each axis of the robot.

The central control unit 10 allows the CPU 11 to execute a program to be described later and various programs whose explanations will be omitted, thereby teaching/playing the first determination function, first restriction function, and robot according to the present invention. Performs various functions in back drive control.

The robot control panel 16 includes a power switch, speed magnification setting volume, robot operation mode, operation cycle setting,
and various switches for selecting work programs, etc., and a programming keyboard.

Various data display devices and a manual switch for emergency stop are provided, and data is transferred via an input/output interface 13 in the central control unit 10.

The teaching pendant 17 includes a setting volume for setting the speed multiplier for determining the combined speed of the robot tip and the movement speed of each axis of the robot, push buttons for individually driving each axis of the robot, and buttons for moving the tip of the robot in a three-dimensional orthogonal coordinate system. Push buttons that drive in the coordinate axes (X, Y, Z) directions, switches that perform confirmation playback, edit switches that change, add, or delete teach data, various data displays, and manual switches for emergency stops, etc. It is provided,
Again, data is transferred via the input/output interface 13.

The servo circuit 18 for the first axis is as shown in Figure 1 (D/A converter 19, sample hold circuit 20° servo amplifier 21
．． Current value detection circuit 22. Reference speed register 23. First comparator 24. and a second comparator 25.

The D/A converter 1 converts the operating speed command value Dv for the first axis output via the input/output interface 14 of the central control unit 10 into digital/analog and outputs it as an operating speed command voltage signal Sv. .

The sample hold circuit 20 includes a first comparator 2 which will be described later.
When the comparison judgment result a in step 4 is 0'', the internal switch is closed and the D/A converter samples the operating speed command voltage signal Sv from the 1st day and outputs the sampled operating speed command voltage signal Sv as it is. When the comparison result a is 1, the internal switch is opened to enter the hold mode, and the operation speed command voltage signal Sv sampled and held immediately before the internal switch is opened continues to be output.

Note that this sample hold circuit 20 immediately makes its output Sv zero when the input Sv becomes zero in the sampling mode.

The servo amplifier 21 receives an operating speed command voltage signal Sv from the sample hold circuit 20 and an actual operating speed indicating the actual operating speed of the first axis from a tacho generator 27 attached to the output shaft of a motor 26 that drives the first axis. A drive current is applied to the motor 26 according to the deviation from the voltage signal Svv.

The current value detection circuit 22 sequentially detects the current position of the first axis by counting up or down the position wave pack pulse signal FP from the pulse generator 28 attached to the output shaft of the motor 26 depending on the rotational direction of the motor 26. The detected value is output to the input/output interface 14 of the central control unit 10 as the current value PP.

Above D/A converter 1 day, sample hold circuit 20.
Servo amplifier 21. and each part of the current value detection circuit 22,
By interaction with the central control unit 10 that performs position feedback control using the current value PP from the current value detection circuit 22, the second One axis moves according to instructions from the central control unit 10.

A reference operating speed value Dr for the first axis outputted via the input/output interface 14 of the central control unit 10 is written in the reference speed register 23 .

The first comparator 24, which is a digital comparator, outputs the operating speed command value Dv for the first axis via the input/output interface 14 of the central control unit 10.

By comparing the reference operating speed value Dr for the first axis written in the reference speed register 23, Dv>D
It is determined whether or not r, and if Dv≦Dr, the comparison determination result a is set to 0", and if Dv)Dr, the comparison determination result a is set to 1".

That is, this first comparator 24 constitutes the second determination means according to the present invention, together with the comparators of each part 1 in each servo circuit for each axis of the other robots (not shown).

The sample-and-hold circuit 20, which switches between the sampling mode and the hold mode as described above, operates at an operating speed when a==1'' in Dv)Dr based on the comparison judgment result a of the first comparator 24. The signal level S v k of the command voltage signal Sv according to Dv=Dr;
It acts to limit.

That is, this sample hold circuit 20.

Together with each sample hold circuit in each servo circuit for each robot axis (also not shown), this constitutes the second limiting means according to the present invention.

Note that the comparison determination result a of the first comparator 24 is also input to the central control unit 10 and is used as recognition data as to whether or not restriction processing is to be performed.

The second comparator 25, which is an analog comparator, receives the first axis actual operating speed voltage signal Svv from the first axis tacho generator 27 and the first axis reference written in the reference speed register 23. 5vv) by comparing the operating speed value Dr with a reference actual speed voltage signal Sr corresponding to the voltage level obtained by converting the operating speed value Dr with a D/A converter (not shown).
It is determined whether or not Sr, and if Svv≦Sr, the comparison judgment result is set to 0", and if Svv>Sr, the comparison judgment result is set to 1". The comparison and determination results are then input to the input/output interface 14 of the central control unit 10.

That is, this second comparator 25 constitutes the third determination means according to the present invention, together with the comparators of each part 2 in each servo circuit for each robot axis (not shown).

Next, the magnetic contactor 2 is connected to the input/output interface 14 of the central control unit 10 via a driver circuit (not shown).
However, if an input is received from any of the second comparators of each axis, including the second comparator 25 for the first axis, the driver circuit immediately excites the Open the closed contact 29a, thereby cutting off the power supply (3-slide power g in the figure) to each servo amplifier of each servo circuit including the servo amplifier 21 in the servo circuit 18 for the first axis.
Stop the movement of each axis of the robot.

That is, this magnetic contactor constitutes a stopping means according to the present invention.

The comparison result of 1" input to the input/output interface 14 is directly input to the magnetic contactor driver circuit, but this comparison result also causes an interrupt to cpUll of the central control unit 10. ,
As a result, necessary emergency stop processing is performed.

In reality, when this magnetic contactor 29 is energized and its normally closed contact 29a opens, the non-excited brakes provided on the drive parts of each axis of the robot are also activated, thereby changing the posture of the robot. Fixed.

Next, the operation of this embodiment configured as described above will be explained in the 31st section!
This will be explained with reference to the flowcharts shown in FIGS.

First, with reference to the flowchart in FIG. 3, the operation when the teaching pendant 17 is used to individually teach each axis of the robot will be explained in detail.

When the axis drive push button on the teaching pendant 17 is operated (one or more at the same time), the CPU
1 reads the current value PP from the current value detection circuit of the robot axis corresponding to the operated push button, and also reads the operating position command value (read current value) for a predetermined inching operation according to the operating direction indicated by the operated push button. [obtained by adding or subtracting the inching movement amount to PP] is set in the register.

Next, the operating position command value set in the register and the current value P
After calculating the positional deviation from P (equal to the above-mentioned inching movement amount), calculate the calculated target operating speed command value of the robot axis from the positional deviation based on a predetermined required function formula, and The calculated target operating speed command value is multiplied by the speed multiplier (common to each axis) set by the setting volume on the teaching pendant 17 to obtain the final target operating speed command value 6. Then, the calculated target operating speed command value is calculated. A composite speed value at the tip of the robot is calculated by subjecting the motion speed command value to a required coordinate transformation process determined by the robot.

Note that this composite speed value is actually a value obtained by dividing the movement amount of the robot tip by the movement time, which is obtained by applying the required coordinate transformation to the current value PP of each axis and the operation position command value, respectively.
What it means is that it indicates the average value of the moving speed of the robot tip when the robot axis actually moves, regardless of whether there is one axis to be driven or multiple axes.

Next, the obtained composite speed value of the robot tip and the memory 12
By comparing with the reference composite speed value stored in advance, it is determined whether the obtained composite velocity value exceeds the reference composite velocity value, and if it does not, the operating position command value set in the register is changed. If the operation position command value is not exceeded, the operation position command value is changed by decreasing the operation position command value by a predetermined value or a value selected in consideration of the amount of excess.

If the operating position command value has not been changed, the previously determined final target operating speed command value is used as is, while if the operating position command value has been changed, the final target operating speed command value is newly determined based on that command value. After calculating the target operating speed command value, calculate the current value from the operating position command value set in the register by multiplying the target operating speed command value by the predicted speed gain determined by the capabilities of the servo circuit and robot axis. P
The operating speed command value Dv is obtained by sequentially adding the value obtained by subtracting P and the value obtained by multiplying the position correction gain.

In addition to outputting it to the D/A converter of the servo circuit corresponding to the operated pushbutton, the reference operating speed value Dr of each axis part obtained by, for example, reverse calculation from the reference composite value (a predetermined value may also be used) Servo processing is performed to write the value to the reference speed register of each servo circuit.

Thereby, for example, if the fully operated push button is a push button for the first axis, the D/A converter 19 in the servo circuit 18
By the action of each part from to the current value detection circuit 22, the first
The shaft moves in the required direction and at the required speed.

Then, when the operating position command value and the current value PP become equal, the target operating speed command value is reset to zero and Dv is set to zero, but if the push button being operated at that time is not released. , without resetting the target operating speed command value, performs a process of adding or subtracting the operating position command value again by the inching operation movement amount, and continues outputting the operating speed command value Dv.

In this way, while the push button is being operated, the corresponding robot axis continues to move so that the composite speed of the robot tip does not exceed the reference value, and if Dv>Dr during the operation, the first comparator Since the comparison result a becomes 1'', the voltage level of the operating speed command voltage signal Sv is immediately suppressed to a level corresponding to the reference operating speed value Dr, and thereby the robot axis also moves so as not to exceed the reference value.

Despite these double checks, if for some reason the robot axis attempts to exceed the standard actual speed and run out of control, the second comparator will detect this and provide a comparison result. Immediately sets the current to 1#, so the magnetic contactor 29 is energized and its normally closed contact 29. opens, which cuts off the power to each servo amplifier and immediately brings each axis of the robot to an emergency stop.

Therefore, the safety of the workers is ensured even in such a case.

Note that instead of the process of changing the operating position command value shown in the flowchart in Figure 3, the obtained composite speed value is limited and the required operating position command value for each axis is calculated backwards from the limited composite velocity value. Alternatively, the target operation speed command value itself may be limited.

Next, with reference to the flowchart in FIG. 4, the operation when the teaching pendant 17 is used to perform a teaching operation on the tip of the robot in a desired coordinate axis direction will be described in detail.

When the above operation push button on the teaching pendant 17 is operated, the CPU 1l first reads the speed magnification set by the setting volume and calculates the operation speed value Vx by multiplying the read speed magnification by a required value.

Next, the trajectory control step time Tx stored in advance in the memory 12
is read out and the Tx is multiplied by the previously calculated Vx to calculate the increment distance ml (synthetic movement movement distance m>Lx).

Then, from this increment distance Lx, the movement angle (travel amount) of each axis of the robot is calculated, and from the calculated movement angle of each axis, the target operating speed command value of each axis (the movement angle is subtracted by Tx) is calculated. value).

Then, the operating position command value of each shaft section is determined from the current value pp of the movement angle of each shaft section, and the above-mentioned servo processing ( (including linear interpolation processing).

As a result, each axis of the frontage bot whose push button is pressed moves so that the robot tip moves in the direction of the coordinate axis indicated by the push button.

However, in this case, the reference operating speed value Dr of each shaft portion written in each reference speed register of each servo circuit is a value determined from the operating speed value Vx.

Also during such a teaching operation, the first . The second comparator and sample-and-hold circuit as well as the magnetic contactor function in exactly the same way as in the previous case, thereby ensuring the safety of the operator.

Note that when the robot tip is moved in the direction of the required coordinate axes, the operation speed value initially determined can be appropriately determined, so the determination process of one composite speed value is not performed, but it is of course possible to perform it.

Finally, with reference to the flowchart in FIG. 5, the operation when each axis of the robot is operated for playback will be explained in detail.

When playback is activated, cpul 1 first reads the position data Pn from the teach data memory 15 and the average speed data VVx (movement time data is written to the memory), which is an operation command for moving to the position indicated by the position data Pn. If there is, the difference between the position data Pn-+ and Pn is divided by the travel time data).

Next, if this playback operation is an operation based on an instruction from the teaching pendant 17, the speed magnification set by the setting volume in the teaching pendant 17 is read.

If the operation is based on an instruction from the robot control ff 116, the speed magnification set by the setting volume on the robot control panel 16 is read.

Then, the previously read average speed data V V x is multiplied by the read speed magnification to calculate an operating speed value (composite speed value).

Next, by reading the reference composite speed value from the memory 12 and comparing the read value with the operating speed value calculated earlier, it is determined whether the calculated operating speed value exceeds the reference composite speed value. It is determined whether or not the calculated operating speed value is exceeded, and if the calculated operating speed value is not exceeded, the obtained operating speed value is used as is, and if it is exceeded, processing is performed to limit the obtained operating speed value to, for example, a reference composite speed value.

Then, the target operating speed command value for each axis of the robot is obtained from the unrestricted operating speed value or the restricted operating speed value by coordinate transformation, and the operating position command value for each axis of the robot is also calculated from the position data Pn. Obtain by conversion.

Then, by executing servo processing based on each command value obtained, each axis of the robot is controlled so that the combined speed of the robot tip does not exceed the reference value.

Moreover, the playback operation is performed so that the operating speed of each axis does not exceed the respective reference value Dr (each reference value Dr at this time is a value obtained from the reference composite speed value).

During this playback operation, even if the actual operating speed of any of the robot's axes exceeds the reference actual speed and goes out of control, each axis of the robot will be immediately stopped by the second comparator and magnetic contactor. Since the playback operation is stopped, the safety of the operator is ensured during the playback operation (particularly during the playback operation for confirming the teaching data based on instructions from the teaching pendant 17).

Incidentally, in the above embodiment, an example was described in which the second determination means was configured by hardware using the first comparator 24;
Of course, software configuration is also possible.

Furthermore, in the above embodiment, an example has been described in which the operating speed command value (voltage signal) that is D/A converted by the sample and hold circuit 20 is limited.

The command value before D/A conversion may be limited.

〔Effect of the invention〕

As described above, the robot safety device according to the present invention monitors the composite speed value of the robot tip, the operating speed command value of each robot axis, and the actual operating speed of each robot axis to obtain a composite speed value. When the and operating speed command value each exceed the reference value, they are each restricted, and when the actual operating speed exceeds the reference value, each axis of the robot is stopped, so multi-axis ( Even with robots such as multi-jointed robots whose tip movement speed is difficult to predict, worker safety can be sufficiently ensured during teaching work.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. 3 to 5 are flow diagrams of programs executed by the CPU 1 of FIG. 2, respectively. FIG. 6 is a block circuit diagram for explaining the prior art. 10... Central control unit 11... Central processing unit (CP
U) 12...Memory (ROM, RAM) 13.1
4... Input/output interface 15... Teach data memory 16... Robot control panel 17... Teach pendant 18... Servo circuit 20... Sample hold circuit (second limiting means)
24... first comparator (second determining means) 25...
Second comparator (third determining means) 26...Motor
27...Tacho generator 2nd...Pulse generator

Claims (1)

[Scope of Claims] 1. In a control device for a multi-axis robot, a first determination for determining whether a composite velocity value of the robot tip calculated based on a motion command of the multi-axis robot exceeds a reference composite velocity value. a second determining means for determining for each axis whether or not the operating speed command value of each axis of the multi-axis robot exceeds a reference operating speed value for each axis; third determining means for determining for each axis whether or not the operating speed exceeds the reference actual speed for each axis; and the first determining means determines whether the composite speed value exceeds the reference composite speed value. a first limiting means that limits the composite speed value or its operation command when it is determined that the composite speed value or its operation command is determined by the second determination means, and one of the operation speed command values for each axis corresponds thereto; A second control that limits the operating speed command value when it is determined that the operating speed command value exceeds the reference operating speed value.
and limiting means for controlling the motion of each axis of the multi-axis robot when the third determining means determines that any of the actual operating speeds of the respective axes exceeds the corresponding reference actual speed. A safety device for a robot, characterized in that it is configured to include a stopping means for stopping the robot.