JP5271499B2 - Robot system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a robot needs a safety guard fence (safety fence) fully covering the maximum working range of the robot and a fence of a wide area is needed even if a working range is small, and thereby flexible constitution of equipment is hindered. <P>SOLUTION: A monitor for the working range of the robot is independently provided as a robot control unit, whereby the working range of the robot is surely monitored with abnormalities of the control unit (such as noise and bugs). Since the robot control unit is independent, a robot system is also free from influence in a function of monitoring the working range if the robot control unit is modified or improved. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a robot control apparatus that multiplexly monitors and reliably limits the operation range of a robot.

Increasing the range of motion by reducing the limit of the robot's movable range increases the flexibility of the equipment to which the robot is applied, so efforts to increase the range of motion are made and implemented by each robot manufacturer. Has been. However, if the range of movement of the robot is expanded, malfunctioning due to operator error or external electrical noise, etc., may interfere with the operator due to interference or contact with the workers around the robot. It can be dangerous. Further, it is conceivable that the robot body or peripheral device is damaged due to interference or collision of the robot with the peripheral device.
Therefore, in order not to endanger the worker in particular, during the operation of the robot, the area including the movable range of the robot is surrounded by a safety protection fence, so that the operator cannot enter the movable range of the robot by intention or negligence. There are restrictions. In addition, during teaching of robot operation procedures, there is a teaching device equipped with an enabling device that allows the robot to operate only when it is operating, limiting the operation speed of the robot. Reductions are required and implemented in each standard.

FIG. 6 is a diagram for explaining a region where a general robot operates. In the figure, the maximum area 112 is obtained by adding an area that can be swept by the end effector 110 and the workpiece to an area defined by the manufacturer that can be swept by the movable part of the robot. In addition, a limited area 111 is a part of the maximum area that is limited by a limit device (such as a mechanical operation limiting device) that sets a limit that does not exceed any failure or malfunction of the robot system. . An area surrounded by a safety protection device 114 (such as a safety protection fence) including the maximum area 112 is referred to as a safety protection area 113. (Term definitions for maximum area 112, restricted area 111, and safeguard area 113 are excerpted from JIS B 8433-1993.)
The safe protection area 113 is surrounded by a safety protection device 114 (safety protection fence) or the like so that the worker cannot access the vicinity of the robot while the robot 101 is in operation, and the worker approaches the robot during teaching. The robot operation is permitted only when the enabling device is operating, and even if a robot operation that is not intended by the operator such as a malfunction occurs, the operator stops the operation of the robot by disabling the enabling device. Or, it is designed to operate at a safe driving speed or less capable of taking a danger avoidance action.

The robot performs trajectory calculation for moving the robot in accordance with a program (work program) set in advance, calculates a motion predicted position (prefetch position) based on this calculation, and drives the robot. In such a configuration of the trajectory calculation and operation of the robot, an arithmetic unit such as a CPU that performs an error in the trajectory calculation and the predicted motion position calculation (bug of the control program), a defect in the memory storing the work program, and a calculation is performed. In case of accidental failure of electrical equipment and electrical elements, for safety to workers, self-diagnosis is performed, for example, when power is turned on or periodically. I try to stop. In addition, various tests are conducted during development for defects in semiconductor elements such as CPUs (design defects: errata) and defects in control program development environments such as compilers used when creating CPU control programs (bugs in development programs). However, it is impossible to test (coverage rate 100%) in all cases. Therefore, depending on the timing of diagnosis for detecting an error or abnormality, it is impossible to deny the possibility that the robot performs an abnormal operation due to these.
Also, it is difficult to detect or avoid this as an error in the operation of the robot due to an error in the work program taught and set by the operator.

Hereinafter, the protection of the operator will be described while limiting the movable range of the robot to an area (operation range or maximum operation range) required for work.
To limit the robot operating range, it is equipped with a control device that partially limits the movable range of the robot based on detection signals using multiple photoelectric sensors. The movable range is set according to the installation space of the robot. A robot movable range limiting device that can be arbitrarily changed has been proposed (for example, Patent Document 1).
However, since this proposal uses a photoelectric sensor, it is necessary to adjust the optical axis in order to divide the operating area when installing the equipment, and it is necessary to install it securely so that the optical system does not shift during use. and it becomes necessary to confirm the regular optical system, in the production plant atmosphere dusty and oil mist products, for dirty the condenser lens or the like of the light emission portion and a light receiving unit, regular cleaning Such maintenance is necessary. As described above, a detector using light is not suitable except for a special environment such as a clean room.

As to reduce the load of regular maintenance, such as the optical system detector, define the virtual safety barrier for limiting the movable range of the robot in the memory of the control unit, motion prediction position of the robot, including a tool the virtual There has been proposed a robot operation restriction device that stops the movement of the robot arm when it is determined that the safety fence is exceeded (for example, Patent Document 2).
If the position of each axis of the robot is detected instead of the motion predicted position of Patent Document 2, it is determined whether the detected position data is within the operable range, and if it is determined that the position is out of the motion range. There is also a proposal of a robot runaway prevention device that stops the operation of the robot or issues an alarm (for example, Patent Document 3).

  In addition to the CPU that controls the robot, a CPU that constantly monitors the state of the robot is provided, and the operable range monitored in Patent Document 2 or Patent Document 3 is monitored by this monitoring CPU. The robot control CPU and the monitoring CPU The minimum necessary communication is performed between the robots, and the robot is stopped when an abnormality is detected (for example, Patent Document 4). In such a configuration, both the robot control CPU and the monitoring CPU can monitor the robot and the other CPU, so that the robot is stopped even if a single component failure occurs. You can be in a safe direction.

In the conventional robot control apparatus, efforts are made to make the operation restriction more reliable with the configurations of Patent Documents 1 to 3. However, as a general design requirement for robots, “the safety function will not fail even if any one of all components (electrical, electronic, mechanical, pneumatic and hydraulic) fails within a predictable range. It is requested that “the robot system should be designed, manufactured and installed so that the robot system is not affected and can be kept safe even if affected” (extracted from Japanese Industrial Standard B843-1993). ing. In order to meet this requirement, there are several points where there are accidents and failures of components (manufacturing failures, operation failures, errata, etc.) and problems that must be eliminated as much as possible in the control program development environment. Monitoring these issues solves these problems.

JP 2000-6083 A JP 2004-322244 A JP 63-102892 A JP-A-60-25893

  FIG. 7 is a diagram illustrating an operation area of the installed robot. In the robot 101, a work program is created by the operator from the pendant 103 before being operated, and is stored in the robot control device 102. The work program is configured to perform a predetermined work on the work 105 with the work tool 104 attached to the wrist of the robot 101. If the shape of the workpiece 105 is small in this way, when the robot 101 is working on the workpiece 105, the operation area 106 of the robot 101 is within the maximum area of the robot 101, and the operation area 106 is surrounded by a safeguard fence. In addition, the worker's safety is ensured by restricting the worker from entering the operation area 106 of the robot 101 while the robot 101 is in operation. However, it is conceivable that the robot moves beyond the operation area 106 due to external electrical noise or a failure of a robot or a part of the robot controller.

As a customer who introduces a robot and a supplier of the robot, there are some who obtain authentication by a third-party organization as a means for proving safety of the robot so that the robot can be used with confidence. This certification takes a long time to acquire, and for example, the procedure for updating the certification is troublesome every time the control program is revised or the hardware is improved. There is a problem that rapid revision and improvement are difficult.
The present invention has been made in view of such problems, and eliminates as much as possible accidents and failures of components (manufacturing failures, operation failures, errata, etc.) and failures and mistakes hidden in the control program development environment. Another object of the present invention is to provide a robot system capable of reducing labor and time required for renewal of authentication by a third party organization.

In order to solve the above problem, the present invention is configured as follows.
According to the first aspect of the present invention, there is provided a driving unit that controls driving of a robot including a plurality of motors based on rotational position data output from an encoder, and an operation region of the robot in which control points of the robot are set in advance. And a controller that outputs a control signal to a power shut-off means so as to shut off the driving power of the robot when a deviation is detected, the robot control device comprising: a controller for each axis of the robot; receiving the rotational position data from said encoder for detecting the position, on the basis of the preset mechanism portion data and the rotational position data, obtains the current position of the control point of the robot, preset of the current position is the robot First operation area monitoring means for detecting a deviation of the operation area defined by the operated area data, and the current position is the operation A first monitoring section for outputting a control signal to the first shut-off means so as to shut off the driving power of the robot based on the output of the first motion area monitoring means when detecting a deviation from the area; and each axis of the robot receiving the rotational position data from said encoder for detecting the position, on the basis of the preset mechanism portion data and the rotational position data, obtains the current position of the control point of the robot, advance the current position of the robot A second motion region monitoring means for detecting a deviation of the motion region defined by the set motion region data; and when the current position detects a deviation from the motion region, the second motion region monitoring means is based on the output of the second motion region monitoring means. separately with the second monitoring unit and the control unit and the driving unit of the position monitoring unit having a to output a control signal to the second shut-off means to cut off the driving power source of the robot Before asked dynamic power is characterized in that the front Symbol power-off means and the first shut-off means and said second shut-off means is connected to the motor via a series-connected line.

According to a second aspect of the present invention, the first monitoring unit or the second monitoring unit includes a CPU, and the CPU sequentially outputs encoder selection signals from the plurality of encoders of the robot. The rotation position data of the encoder selected by the encoder selection signal is sequentially acquired by serial communication, and the current position of the control point of the robot is obtained based on the rotation position data of the plurality of encoders of the robot. To do.

According to the first aspect of the present invention, the monitoring point of the robot is monitored by the two monitoring units independent of the control of the robot, and when the robot deviates from the operation area, the electromagnetic contactor is opened to supply power to the driving unit. Since the supply is cut off, it is possible to reliably detect that the robot deviates from the operation range due to malfunction or runaway due to a problem in the control of the robot, and at that time, the drive power supply can be cut off and stopped .
According to the second aspect of the present invention, the position signal is obtained by scanning the position signal sequentially for the plurality of encoders that detect the position of the robot. The number of circuits or elements to be converted can be reduced, the shape of the position monitoring unit can be reduced, and the cost can be reduced .

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

  FIG. 1 is a block diagram of a robot system to which the present invention is applied. In the figure, reference numeral 1 denotes a robot, which is a combination of a plurality of motors 10 and encoders 11, drives a plurality of joints to operate an arm, and moves a work tool 104 to a target position (only one set is shown in the figure). ing). Reference numeral 3 denotes a pendant. When teaching, the operator operates the robot 1 to a target position to register the position and register or edit a work program for the work 105. Also, the robot mechanism information is input and the operation range 106 is set. Further, the pendant 3 is provided with a display (not shown), displaying a list of work programs, displaying mechanism data as mechanism information, displaying operation area data, displaying an abnormality, displaying other data necessary for installing the robot, Displays the status. Reference numeral 2 denotes a robot control device, which is a control unit 20 that controls the robot operation, a drive unit 21 that drives the motor 10 based on the operation command of the motor 10 obtained by the control unit 20, a work program, mechanism unit data, and an operation area. A storage unit 22 that stores data and other data or programs necessary for robot control is configured as a main element. In the present invention, a position monitoring unit 23 is provided.

The driving power source for operating the robot 1 is a commercial power source 25, an electromagnetic contactor 24-1 that is controlled to open and close by the control unit 20, and an electromagnetic contactor 24-2 and 24-- that are controlled to open and close by the position monitoring unit 23. 3 contacts are connected in series and connected to the drive unit 21. That is, both of the control unit 20 and the position monitoring unit 23 closes the contact of the electromagnetic contactor 24-1, 24-2, 24-3 at the time to allow the operation of the robot 1, power supply 25 is supplied to the drive unit 2 1 It is, when the operation of the robot 1 is not allowed, either contact of the electromagnetic contactor 24-1, 24-2, 24-3 is adapted to the power supply open circuit to the driving unit 2 1 is blocked Yes. Incidentally, a factor that prohibits the non-contact of the electromagnetic contactor 24-1, 24-2, and 24-3, for example, the operation of the emergency stop contacts and other robots between the power supply 25 and the drive unit 2 1 Although the contact is inserted, it is omitted in this figure.

The control unit 20 and the position monitoring unit 23 are connected by an information transmission path such as serial communication. However, the mechanism unit data and the operation area data are set in the position monitoring unit 23, and the state and abnormality information of the position monitoring unit 23 are displayed. by transmitting to the control unit 20, equipment installation time and recovery abnormality have the purpose of information transmission for performing rapid, motion control of the robot 1 at the time of normal operation of the robot 1 (reproducing the operating program) There is no need for information transmission.

  FIG. 2 is a block diagram of the position monitoring unit 23. In the figure, 31 is a first monitoring unit and 41 is a second monitoring unit. Since the 1st monitoring part 31 and the 2nd monitoring part 41 are the same structures, a 1st monitoring part is demonstrated. The first monitoring unit 31 and the second monitoring unit 41 employ CPUs having different architectures, so that CPU errata and control program development device failures (compiler bugs, etc.) can be detected at the same location in both monitoring units. It eliminates the opportunity to get in and monitors each other independently. Moreover, each of the 1st monitoring part 31 and the 2nd monitoring part 41 drives the operation coil of the electromagnetic contactors 24-2 and 24-3.

Position signals of a plurality of axes from the encoder 11 provided in the motor 10 of each joint of the robot 1 are input to the drive unit 21 and servo-controlled, and are connected in parallel to the position monitoring unit 23. 2 are further branched and input to the monitoring unit.
Position signals from the plurality of encoders 11 input to the first monitoring unit 31 are read into the CPU 33 via the receiver 32. The CPU 33 performs forward conversion 35 from the position data of each joint of the robot 1 input from the encoder 11 to the position data of the coordinate system of the robot 1 based on the mechanism part data 37 of the robot 1 stored in the storage unit 34. . By this forward conversion, position data in the coordinate system of the control point of the robot 1 is obtained.
The control point is a representative point of the end effector to which the work tool is attached (see FIG. 5) or a representative point of the attached work tool (for example, in arc welding, the wire tip of the welding torch attached to the end effector (work Point)).
The receiver 32 in this figure is an interface circuit or element that receives a position signal from the encoder and temporarily stores it as position data in a counter or a register. The position data may be acquired by the CPU 33.

The obtained position data of the coordinate system is compared with the operation area data 38 stored in the storage unit 34. If the position data is inside the operation area data, the operation coil of the electromagnetic contactor 24-2 is driven. Close the contact and open the contact if it is outside the operating area data.
FIG. 3 is a drive circuit diagram of the electromagnetic contactor 24-2. The magnetic contactor conducts and interrupts the current to the operation coil 24-5, so that the two normally open main contacts 24-6 are opened / closed and the one normally closed auxiliary contact 24-7 is closed / open. Operates in conjunction. When the CPU 33 of the first monitoring unit 31 determines that the position data is outside the operation area data, the CPU 33 cuts off the power supply to the operation coil 24-5 via the output interface 40-1 and opens the main contact 24-6. To do. When it is determined that the position data is within the operation area data from the state where the main contact 24-6 is open, the operation coil 24-5 is energized via the output interface 40-1, and the main contact 24- 6 and the auxiliary contact 24-7 are opened. Before the operation coil 24-5 is energized, the state of the auxiliary contact 24-7 is read via the input interface 40-2 and the circuit is closed. Check. This confirmation of the state of the auxiliary contact 24-7 corresponds to confirmation that no contact welding has occurred on the main contact 24-6.

  The first monitoring unit has an invalid input 39 in case the robot deviates from the operation area 106 for some reason while the robot is operating. When the invalid input becomes active, the first monitoring unit invalidates the monitoring of the operation area and closes the main contact 24-6 or closes the main contact 24-6 of the electromagnetic contactor 24-2. It is supposed to be. That is, when the invalid input 39 is activated when the robot moves from the position deviating from the operation area 106 to the position inside the operation area 106 by operating the pendant, even if the robot deviates from the operation area 106, The drive power can be turned on. The invalid input 39 is input by, for example, a momentary switch. The invalid input may be transmitted through the information transmission path from the control unit 20.

Since the second monitoring unit 41 has the same configuration as the first monitoring unit 31, detailed description thereof is omitted.
Note that the motion area data forms a rectangular parallelepiped on the robot coordinate system, for example. That is, a maximum value and a minimum value are set in advance for each of the X, Y, and Z axes via the information transmission path. If the current position is between the maximum and minimum values for each of the X, Y, and Z axes, it is determined that it is inside the motion area, and if it is between the maximum and minimum values, the robot motion area is determined to be a departure. To do.

As described above, the position monitoring unit 23 of the robot control device 2 monitors the position of the robot independently from the control unit 20 and the drive unit 21. When the position deviates from the preset operation region 106, the electromagnetic contactors 24-2 and 24- The operation of the robot 1 is prohibited by opening the contact point -3 and shutting off the power supply to the drive unit 21. Then, the state data at this time is sent to the control unit 20, and the control unit appropriately displays the state data on a display (not shown) provided in the pendant 3, or outputs it from the output unit (not shown) to the outside of the robot controller 2. It is used for investigation of the cause of abnormality and maintenance work.

  In the robot control apparatus 2, the control unit 20 obtains the operation trajectory of the control point of the robot 1 for each control period, and performs the motion control of the robot 1 along the operation trajectory. Therefore, for example, when there is a failure in some data of the work program stored due to malfunction or failure of the storage unit 22, before the operation of the robot 1 at this stage, The deviation of the operation area 106 can be detected, and the robot 1 can be prohibited from operating by opening the contact of the electromagnetic contactor 24-1.

  Due to such a configuration, unlike the Patent Documents 2 to 4, the control unit 20 and the first monitoring unit 31 and the second monitoring unit 41 of the position monitoring unit 23 monitor the robot operation area in triplicate. It can be surely limited. Since the position monitoring unit 23 is independent of the control unit 20, the position monitoring can be performed without being affected by the robot operation control, so that the robot operation area deviation can be reliably monitored. Therefore, it is possible to install a safety protection fence suitable for the operation area, especially when the operation area of the robot is narrow due to work on small workpieces, etc. Can also be specified.

  Since the position monitoring unit 23 performs position monitoring independently of the control unit 20 and the drive unit 21, even if there is an improvement matter of the control unit 20 or the drive unit 21 after obtaining authentication by a third party organization, the position monitoring unit 23 Since it does not affect the unit 23, it is not necessary to update authentication.

FIG. 4 is a diagram showing the configuration of the first monitoring unit of the second embodiment. In the figure, 51 is a first monitoring unit, which replaces the first monitoring unit 31 of FIG. Position signals from the plurality of encoders 11 are guided to the first monitoring unit 51 and input to the selector 52. The CPU 33 outputs an encoder selection signal 53 to the selector, selects one axis from the position signals from the plurality of encoders 11, and outputs it to the receiver 32. The receiver 32 receives the position signal of the selected encoder 11 as the position data of the corresponding axis, and the CPU acquires this position data and selects the encoder to obtain the position data from the encoder 11 of the next axis. Step signal 53.
In this way, after acquiring the position data of all axes of the robot 1, forward conversion 35 is performed to the position data of the coordinate system of the robot 1. By this forward conversion, position data in the coordinate system of the control point of the robot 1 is obtained, and the obtained position data of the coordinate system is compared with the operation area data 38 stored in the storage unit 34, and the position data is operated. If it is inside the area data, the operation coil of the electromagnetic contactor 24-2 is driven to close the contact, and if outside the operation area data, the contact is opened.

Since the second monitoring unit is the same, illustration and description are omitted. The configuration of the second monitoring unit is not limited to the configuration of the second embodiment, and the configuration of the first embodiment may be used.
In the configuration of the second embodiment, this encoder signal is sent from the encoder 11 by serial communication so that the receiver 32 obtains the position in units of a single axis.
Further, although the position data acquisition timing for each axis is different, the difference in the acquisition of position data is, for example, 100 microseconds, even if the maximum speed of the robot is assumed to be 2 meters / second, it is 0. Since the difference is about 2 millimeters, it is not a problem in practice.

  In this way, since the configuration is such that the position data of each axis is acquired in order, the number of receivers can be reduced within a range that does not substantially pose a problem in the control point position calculation of the robot. It is possible to expect the effect of downsizing the monitoring unit shape and further to reduce the cost.

FIG. 5 is a configuration diagram of a vertical articulated robot 200 according to the third embodiment. In the figure, the robot arm has a first Takashi Seki to rotate (pivot) in a horizontal plane, a first arm 202 connected to the first joint, the second joint 203 is attached to an end of the first arm 202 ing.
A second arm 204 connected to the second joint 203 and a third joint 205 are attached to the end of the second arm 204. A wrist 208 is attached to the end of the third arm 206 via a fourth joint 207.
In this case, the horizontal to the XY plane, when the sky direction + Z direction, the third arm 20. 6, the posture of the robot, the operation, the end portion of the third arm 20 6, when most operating region is wider is there.
That is, it is necessary to compare the current position of the third joint 205 or the fourth joint 207 with the motion region.
The current position of the third joint 205 or the fourth joint 207 can be obtained from forward conversion and will not be described in detail. It is also possible to obtain by inverse transformation from the position of the control point 209 to the fourth joint 207 or the third joint 205.

Since it is designed to be performed independently of the robot control, it is easy to receive certification from a third-party accredited organization for monitoring the robot motion range, and even if improvements and improvements related to robot motion control are implemented, Renewal of certification is not required because it does not interfere with the scope of certification already acquired.
The present invention is effective without exposing the user to danger, and can be applied to an automatic machine such as a numerical control machine that operates with a drive source such as a motor.

Block diagram of a robot system to which the present invention is applied Block diagram of the position monitoring unit of the first embodiment Driving circuit diagram of magnetic contactor Block diagram of the first monitoring unit of the second embodiment Configuration diagram of vertical articulated robot of third embodiment Diagram explaining the area where a general robot operates Diagram explaining the operating area of the installed robot

Explanation of symbols

1, 101, 200 Robot 2, 102 Robot control device 3, 103 Pendant 10 Motor 11 Encoder 20 Control unit 21 Drive unit 22 Storage unit 23 Position monitoring unit 24 Electromagnetic contactor 31, 51 First monitoring unit 32 Receiver 33 CPU
34 Storage section 35 Forward conversion 36 Comparison 37 Mechanism section data 38 Operation area data 41 Second monitoring section 52 Selector 53 Encoder selection signal 104 Work tool 105 Work 106 Operation area 111 Restriction area 112 Maximum area 113 Safety protection area 114 Safety protection device

Claims (2)

A driving unit that drives and controls a robot having a plurality of motors based on rotational position data output from the encoder; and a driving power source for the robot when a deviation from the robot operating region in which the control points of the robot are set in advance is detected In a robot system comprising a robot controller having a control unit that outputs a control signal to a power shut-off means so as to shut off
The robot controller is
Receiving the rotational position data from said encoder for detecting the position of each axis of the robot, based on a preset mechanism portion data and the rotational position data, obtains the current position of the control point of the robot, the current position The first motion region monitoring means for detecting a deviation of the motion region defined by the preset motion region data of the robot, and the first motion region monitoring means when the current position detects a deviation from the motion region. A first monitoring unit that outputs a control signal to the first shut-off means so as to shut off the driving power of the robot based on the output;
Receiving the rotational position data from said encoder for detecting the position of each axis of the robot, based on a preset mechanism portion data and the rotational position data, obtains the current position of the control point of the robot, the current position The second motion area monitoring means for detecting a deviation of the motion area defined by the preset motion area data of the robot, and the second motion area monitoring means when the current position detects a deviation from the motion area. A second monitoring unit for outputting a control signal to the second shut-off means so as to shut off the driving power of the robot based on the output;
A position monitoring unit having a separate from the control unit and the drive unit ,
Robot system and wherein the pre-listen dynamic power, the previous SL and the power supply cut-off means and said first blocking means and the second shut-off means is connected to the motor via a series-connected line. The first monitoring means or the second monitoring means includes a CPU, and the CPU
By sequentially outputting the encoder selection signal, the rotational position data of the encoder selected by the encoder selection signal from the plurality of encoders of the robot is sequentially acquired by serial communication,
The robot system according to claim 1, wherein a current position of a control point of the robot is obtained based on the rotational position data of the plurality of encoders of the robot.

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