JPH10118977A - Controller for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormal action in varied kinds of robots by providing type instructing means set in compliance with the type of the robot, detecting the type of the robot on the basis of a status signal outputted from a rotary encoder itself, and determining whether the type corresponds to the instructed type instructed by the type instructing means. SOLUTION: A controller is provided with a selection switch by which recognition whether a rotary encoder to be used is a full absolute type one or a semi absolute type one is obtained. When a power source is turned on, it is determined whether a preset status signal is outputted or not, and then, an actually used type is detected. If the full absolute type is designated by means of the selection switch in a step S1 when the power source is turned on, a preset status signal is read in a step S2, and a signal level is determined in a step 3. It is determined whether a comparison between the setting based on the selection switch and the type detected by means of the preset status signal shows correspondence or not, and if correspondence is not obtained, an error display is carried out and a robot is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller for detecting the rotational position of a motor for driving a movable body such as an arm by a rotary encoder and controlling the operation of the movable body based on the rotational position information of the rotary encoder. In particular, the present invention relates to an apparatus capable of supporting a plurality of types of rotary encoders.

[0002]

2. Description of the Related Art Potentiometers, resolvers, rotary encoders, and the like are used as sensors for detecting the position of a robot. In many cases, a rotary encoder is used. The rotary encoder is provided in a motor that drives a movable body such as an arm, and detects a rotational position of the motor.
Then, the control device of the robot detects the operation position of the movable body based on the rotation position information of the rotary encoder, and performs control based on the operation program.

[0003] There are an incremental type and an absolute type in the rotary encoders generally used. Each type of rotary encoder outputs a pulse signal indicating the direction of rotation and the amount of rotation, and the position detection circuit of the robot controller transmits a pulse of the amount of rotation output from the rotary encoder to the rotation. The rotational position of the motor, that is, the current position of the movable body is detected by counting up or down according to the direction.

Incidentally, an absolute type rotary encoder outputs absolute position information even when the motor is stopped. Therefore, even if the power of the robot is turned off and the up / down counter of the position detection circuit is cleared, if the power is turned on again, the controller immediately returns the absolute current position of the rotary encoder with respect to the origin. Can be read.

On the other hand, in the incremental type rotary encoder, one pulse is output every one rotation in order to detect a specific position within one rotation.
It does not output absolute position information. Therefore, when the power of the robot is turned off and the up / down counter is cleared, the position detection circuit loses the memory of the absolute rotational position of the rotary encoder. The absolute rotational position of the encoder cannot be recognized.

Therefore, a robot using an incremental type rotary encoder performs a home return operation when the power is turned on, and starts counting the number of pulses by an up / down counter from the home position. The absolute rotational position of the encoder can be recognized.

As described above, in the increment type rotary encoder, since it is necessary to perform the home return operation when the power is turned on, it takes a long time to start up the robot. On the other hand, in the absolute type rotary encoder, since there is no need for the home position return operation, the start-up time of the robot can be reduced, but on the other hand, it is more expensive than the incremental type. Therefore, recently, a simple absolute rotary encoder intermediate between an increment type and an absolute type has been developed. In the following description, a conventional absolute-type rotary encoder is referred to as a full-absolute-type rotary encoder, and a simple absolute-type rotary encoder is referred to as a semi-absolute-type rotary encoder.

The above-described semi-absolute type rotary encoder is configured to output absolute position information at several points within one rotation. For this reason, semi-absolute type rotary encoders are less expensive than full absolute type rotary encoders, and when the power of the robot is turned on, if the rotary encoder rotates the motor to the position where absolute position information is output, the control device Since the absolute rotation position of the rotary encoder can be recognized by the user, the so-called return-to-origin operation can be minimized and the startup time can be reduced.

As described above, there are three types of rotary encoders, and depending on the type of the rotary encoder used, the home return operation is required or not required. Therefore, conventionally, a dedicated control device has been manufactured according to the type of the rotary encoder used.

[0010]

The necessity of the home position return operation depends on the type of the rotary encoder used. However, in any type of rotary encoder, the position detection after the control device recognizes the absolute rotation position is performed by detecting the rotation amount pulse output from the rotary encoder every time the motor rotates by a certain minute angle. This is performed by counting with an up / down counter.

In other words, the control device has the same configuration as that of the rotary encoder except that the home return operation is performed when the power is turned on. Therefore, in order to reduce the cost, the control device must be manufactured as a common type for the full absolute type and the semi-absolute type, or for the full absolute type and the increment type. A selection switch that outputs a different signal according to the type of rotary encoder to be provided, and when the power is turned on, the control device detects an output signal of the selection switch and makes a determination on software based on the detection result. It is possible.

However, when a robot provided with a semi-absolute type or an incremental type rotary encoder is mistakenly combined with a control device in which a selection switch is set to use a full absolute type rotary encoder, Since the home position return operation is not performed, the control device starts the operation of the robot without recognizing the absolute current position of the rotary encoder. As a result, the robot may perform an unexpected operation.

Particularly, in order to reduce the manufacturing cost of the motor, if the shapes and colors of the rotary encoders are not the same depending on the type but are all the same, any type of rotary encoder can be used depending on the shape and the color of the motor. Is not known, the possibility of mistaken combination with the control device is further increased.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to cope with a plurality of types of rotary encoders with one type of control device, and to use different types of rotary encoders. An object of the present invention is to provide a control device for a robot that can avoid a risk of causing an abnormal operation of the robot in such a case.

[0015]

According to a first aspect of the present invention, a rotary position of a motor for operating a movable body such as an arm is detected by a rotary encoder, and information on the rotational position is obtained. Controlling the operation of the movable body based on the type of the rotary encoder, the type indication means being set to a state corresponding to the type of the rotary encoder, and the rotary encoder by a status signal output to notify the state of the rotary encoder itself Determination means for detecting the type of the rotary encoder, and determination means for determining whether or not the type of the rotary encoder detected by the determination means matches the type set by the type instruction means. The apparatus is characterized in that an error state is set when the means judges that they do not match.

That is, the rotary encoder outputs a status signal to notify its current state.
One of the status signals output by the full-absolute type and semi-absolute type rotary encoders is a preset status signal output when the absolute position information is output. This preset status signal
In the case of a full absolute type rotary encoder, the output is performed at the same time as the power is turned on. However, in the case of the semi-absolute type rotary encoder, a preset status signal is hardly output at the same time as the power is turned on. By reading the status signal output from the rotary encoder in this way, it is possible to determine what kind of rotary encoder is.

Therefore, according to the first aspect of the present invention, the type of the rotary encoder to be combined is set in advance by the type indicating means, and the type of the actually combined rotary encoder is detected by the status signal. be able to. If the type of the rotary encoder set by the type indicating means is different from the type of the actually combined rotary encoder, an error state is set, and the danger that the robot will cause abnormal operation is avoided.

Further, the means for stopping the movable body when the movable body deviates from the set movable area, and for canceling the stop function of the stop means are provided. An operating means is provided.

In the robot, in order to prevent the arm from colliding with, for example, other equipment, a movable region is set in advance, and when the arm moves out of the movable region, the drive motor for the arm is urgently stopped. Is configured.
On the other hand, during repairs and inspections, it may be necessary to manually move the arm out of the movable range.However, with a robot using a full-absolute rotary encoder, the current position of the arm is recognized when the power is turned on. If the arm is moved out of the movable region by manual operation, the motor is immediately stopped, and as a result, the arm cannot be moved out of the movable region. However, according to the means described in claim 2, since the stopping function of such a stopping means can be canceled, even a robot using a full absolute type rotary encoder can be moved out of the movable area. It is.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4, the robot includes a robot main body 1 and a control device 2 for controlling the robot main body 1. The robot body 1 of this embodiment is
For example, it is configured as a horizontal articulated type,
A first arm 4 pivotally provided on the base 3, a second arm 5 pivotally provided on the first arm 4,
A wrist shaft 6 is provided on the second arm 5 so as to be vertically movable and rotatable, and a hand 7 is provided on the wrist shaft 6. The turning operation of the first and second arms 4 and 5 as a movable body, the up-down operation and the rotation operation of the wrist shaft 6 are performed using the motors 8 to 11 as driving sources. FIG. 4 shows only the turning motor 8 of the first arm 4.

On the other hand, as shown in FIG. 3, the control device 2 for controlling the robot body 1 includes a CPU 12 as a control unit,
A drive circuit 13 and a position detection circuit 14 are provided. The CPU 12 is connected to a ROM 15 storing a system program of the entire robot and a RAM 16 storing an operation program of the robot main body 1 as storage means. The CPU 12 has an input / output port 17.
The teach pendant 18 is connected as an external operation device via the.

The position detecting circuit 14 is for detecting the positions of the arms 4, 5 and the wrist shaft 6. The position detecting circuit 14 includes rotary encoders 19 to 22 provided for the motors 8 to 11, respectively. It is connected. Note that FIG.
Here, the arms 4 and 5 and the wrist shaft 6 are collectively shown as a movable body in one block, and the motors 8 to 1
1. The rotary encoders 19 to 22 are also collectively shown in one box. Then, the position detection circuit 14 uses the signals input from the rotary encoders 19 to 22 to rotate the motors 8 to 11, that is, the arms 4,
The current position of the wrist shaft 5 and the wrist shaft 6 is detected, and the current position information is given to the CPU 12.

The CPU 12 supplies a drive signal to the drive circuit 13 based on the operation program, and the drive circuit 13 supplies a current corresponding to the drive signal to the motors 8 to 11 to drive the motors 8 to 11, 4,5 and wrist axis 6
To work. At this time, the CPU 12 compares the current position and the target position with respect to each of the arms 4, 5 and the wrist shaft 6 using the position detection signal of the position detection circuit 14 as a feedback signal, and sends a drive signal corresponding to the deviation to the drive circuit 13. Is configured to give.

The control device 2 is a rotary encoder 1
Regardless of whether a full-absolute type or a semi-absolute type is used as 9 to 22, it is configured to cope with this. In this case, the control device 2
Have rotary encoders 19 to 22 of motors 8 to 11
A selection switch 23 is provided as a type indicating means for causing the CPU 12 to recognize which type of rotary encoder is used, of the full absolute type and the semi-absolute type.

The selection switch 23 is composed of a jumper wire connected between a power supply and a ground line and connected to a resistor and a direct current. If the jumper wire is not cut, its output voltage is, for example, high level. When the jumper wire is disconnected, the output voltage is set to a low level. In this embodiment, when a full absolute type rotary encoder is used for the rotary encoders 19 to 22, the jumper wire is not cut,
When a semi-absolute type is used, the jumper wire is cut.

The CPU 12 determines whether the rotary encoders 19 to 22 are of the full absolute type or the semi-absolute type based on the output level of the selection switch 23. If the CPU 12 determines that the rotary encoders 19 to 22 are of the semi-absolute type, It is programmed to execute the home return operation and to omit the home return operation when it is determined that the type is the full absolute type.

On the other hand, the rotary encoders 19 to 22
In either case of the full-absolute type or the semi-absolute type, it outputs a position signal and a status signal for notifying its current state. It is assumed that the packet structure of the position signal and the status signal is common to both full-absolute type and semi-absolute type rotary encoders. The position signal includes
Data indicating the absolute position of the rotary encoder is included. This absolute position signal is valid data for the full-absolute type without returning to the home position after turning on the controller.However, for the semi-absolute type, the absolute position is established until the home position is returned. Is not valid data.

The status signal includes a signal indicating whether the power supply voltage of the rotary encoders 19 to 22 is normal, a signal indicating whether the internal circuits of the rotary encoders 19 to 22 are normal, and an absolute position. It includes a signal indicating whether or not it has been determined. A signal indicating whether or not the absolute position has been determined is called a preset status signal.
Becomes low level when the absolute position signal is output (when the absolute position is determined), and goes high when the absolute position signal is not output (when the absolute position is not fixed).

Therefore, the preset status signal before the home return operation is always at a low level when the rotary encoders 19 to 22 are of a full absolute type, and is always at a high level when the rotary encoders 19 to 22 are of a semi-absolute type. By the way, even the semi-absolute type,
If the rotation is stopped at the rotational position where the absolute position signal is output by chance before the home position return operation, the absolute position signal is output, and thereafter, the preset status signal becomes low level. This probability is 9 to 10% according to experiments.

The CPU 12 detects whether or not the preset status signal is output from the rotary encoders 19 to 22 when the power is turned on, so that the actually used rotary encoders 19 to 22 are of the full absolute type or the semi-absolute type. It is possible to detect the type (determination means). Further, the CPU 12 compares the type of the rotary encoders 19 to 22 set by the selection switch 23 with the type of the rotary encoders 19 to 22 detected from the preset status signal to determine whether or not the two match. (Determination means). This will be described below.

First, the control device 2 is set to the full absolute type rotary encoder specification by setting the selection switch 23 to a state in which full absolute type rotary encoders 19 to 22 are used (jumper wires are not cut). The case will be described. That is, as shown in the flowchart of FIG. 1, when the power of the robot is turned on, the CPU 12 selects the selection switch 2 in step S1.
It is determined whether the output signal of No. 3 is at a high level, in other words, whether the rotary encoders 19 to 22 are designated to be of the full absolute type (set type decoding means). When the output signal of the selection switch 23 is at a high level,
The CPU 12 determines "YES" in the step S1, that is, determines that the rotary encoders 19 to 22 are specified to use the full absolute type, and shifts to the next step S2.

In step S2, the CPU 12 reads the preset status signals output from the rotary encoders 19 to 22. Then, the next step S
In step 3, the CPU 12 determines whether the preset status signal is at a low level, in other words,
Reference numeral 22 determines whether or not the absolute positions are determined when the motors 8 to 11 are stopped. If the preset status signal is at the low level, the CPU 12 determines “YES” in the step S3, and shifts to a normal routine of the next step S4.

In this normal routine, the CPU 12 executes a mode in which the operation program is executed without executing the home return operation when the rotary encoders 19 to 22 are instructed by the selection switch 23 to be the full absolute type. . In this case, the absolute type is actually used for the rotary encoder full 19 to 22 even without executing the home position return operation, and the CPU 12 can recognize the absolute rotational position at the same time when the power is turned on.
There is no possibility that the robot body 1 will cause an abnormal operation.

On the other hand, when the preset status signal read in step S2 is at a high level, the CPU 1
No. 2 determines “NO” in step S3, and proceeds to step S5. Then, in step S5, the CPU 12 instructs the control device 2 or the display (not shown) of the teaching pendant 18 to display a character indicating an error of "WRONG ENCODER". To

As described above, in spite of the fact that all or part of the rotary encoders 19 to 22 are actually of the semi-absolute type in spite of the fact that the control device 2 is of the full absolute type rotary encoder specification,
U12 displays an error state, that is, displays an error, and keeps the robot body 1 stopped. As a result, the operator has to install the motors 8 to 11 having the full absolute type rotary encoders 19 to 22, but has erroneously installed the motors having the semi-absolute type or incremental type rotary encoders. Be aware of this and replace it with the correct motor.

On the other hand, by setting the selection switch 23 to a state in which a semi-absolute type rotary encoder is used for the rotary encoders 19 to 22 (cutting a jumper line), the control device 2 is set to a semi-absolute type rotary encoder specification. When the power is turned on, the CPU 12 determines "NO" in the step S1, and proceeds to the step S4 for executing the normal routine.

When the control device 2 is of the semi-absolute type rotary encoder specification, the step corresponding to step S3, that is, whether the rotary encoders 19 to 22 are actually of the semi-absolute type or the full absolute type is performed. I do not judge. The reason is that, even if the full absolute type is used for the rotary encoders 19 to 22, when the CPU 12 shifts to the normal routine of step S4, the CPU 12 first performs the home return operation. However, even if an attempt is made to perform the home return operation, a signal indicating the absolute position is immediately input from the rotary encoders 19 to 22, so that the CPU 12 does not actually perform the home return operation, but only the arms 4, 5 and the wrist shaft. 6 and the like do not operate abnormally.

Of course, if "NO" is determined in the step S1, the preset status signals output from the rotary encoders 19 to 22 are read, and then the preset status signals are set to the high level (the rotary encoders 19 to 22 are semi-absolute). Is determined, and if the level is high, the process proceeds to step S4 where the normal routine is executed. If the level is low, the process proceeds to step S5.
And the error display may be performed, and the operation of the robot may be stopped as it is.

When the robot unit 1 using the semi-absolute type as the rotary encoders 19 to 22 is combined with the control device 2 set to the full absolute type rotary encoder specifications as described above, an error is displayed and the robot body 1 is displayed. Is stopped, the controller 2 of the full-absolute type rotary encoder specification is erroneously provided to the control device 2 at the robot assembly factory or at the time of replacement of the motors 8 to 11 by the user thereafter. Even if a motor provided with a rotary encoder is mounted, the error can be reported. For this reason, a motor installation error is immediately noticed, and the motor is replaced with a proper motor, so that the danger of the robot body 1 operating abnormally can be avoided. Note that the control device 2 may be configured so as to be able to be set to a full absolute type rotary encoder specification or an increment type rotary encoder specification.

When the robot is actually used in a factory or the like, the operation areas of the arms 4, 5 and the wrist shaft 6 are set in consideration of the relationship with other equipment and workers, and the operation area is set. Do not operate beyond (non-operating area). During the operation of the robot, the CPU 12 repeatedly executes the operation monitoring routine as an interruption routine every predetermined short time, and when the arms 4, 5 and the wrist shaft 6 move to the non-operation region, the motors 8 to 11 are emergency. Stop.

However, for some reason, it may be desired to set the robot to the manual operation mode and move the arms 4, 5 and the wrist shaft 6 to the non-operation area by remote control using the teaching pendant 18. In such a case, if the incremental type rotary encoder is used, the CPU 12 does not determine the absolute positions of the arms 4 and 5 and the wrist shaft 6 unless the origin return operation is performed. Even if the robot moves to the non-operation area, there is no emergency stop.

However, the rotary encoders 19 to
In the case of using the full absolute type as the CPU 22, the CPU 12 immediately turns on the arms 4 and 5 and the wrist shaft 6 when the power is turned on.
When the arm return end flag is set to "1" and the arms 4, 5 and the wrist shaft 6 are moved to the non-operation area by remote control using the teaching pendant 18 thereafter, The CPU 12 immediately detects this and stops. In this case, arms 4,5,
The wrist shaft 6 cannot be moved to the non-operation area, which is inconvenient.

Therefore, in this embodiment, when the origin return end flag is set to "1", the CPU 12 enters the execution of the operation monitoring routine shown in FIG. 2, and the mechanical limit flag is set to "1". Is determined (step S
2) shall be. The mechanical limit flag is configured to be reset to “0” by operating a predetermined switch of the teaching pendant 18 as an operation means (cancellation of the stop function of the stop means).

If the mechanical limit flag is "1", C
The PU 12 determines “YES” in the step S2, and determines in a next step S3 whether the arms 4, 5 and the wrist shaft 6 are within the movable range. And arm 4,5, wrist axis 6
Is within the movable range, "YE" is determined in step S3.
S ", and returns to the main routine as a return to continue the operation of the robot body 1.

When the arms 4 and 5 and the wrist shaft 6 move out of the movable range and move to the non-operation area, the control device 2
Determines "NO" in step S3, shifts to step S4, performs error processing such as urgently stopping the motors 8 to 11, and keeps the robot body 1 in a stopped state (stop means).

As described above, the CPU 12 normally executes the above-described operation monitoring routine every predetermined short time, so that when the robot main body 1 goes out of the operation area, the robot main body 1 is urgently stopped. For this reason, even if it is desired to manually move the arms 4, 5 and the wrist shaft 6 to the non-operation area, the robot main body 1 cannot be manually operated as it is.

In this case, the teaching pendant 1
The predetermined limit switch 8 is operated to reset the mechanical limit flag to "0". Note that the rotary encoder 19
When ２２22 is a semi-absolute type or an increment type, if the home return operation is not performed when the power is turned on and the home return end flag is not set to “1”, the operation monitoring routine of FIG. , CPU 12
Becomes "NO" in step S1 and returns to continue the normal routine. Therefore, there is no need to operate a predetermined switch of the teaching pendant 18 to reset the mechanical limit flag to "0".

Thus, the mechanical limit flag is set to "0".
When the CPU 12 enters the operation monitoring routine, the CPU 12 determines "NO" in step S1 and returns to the main routine to continue the operation of the robot. Wrist axis 6
Can be moved to the non-operation area.

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications or extensions are possible. The type of the robot body 1 is not limited to the horizontal articulated type. The operation means for resetting the mechanical limit flag is not limited to the teaching pendant, but may be an external operation panel.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a flowchart showing control contents when power is turned on.

FIG. 2 is a flowchart showing control contents during operation monitoring.

FIG. 3 is a block diagram showing a hardware configuration.

FIG. 4 is a perspective view showing a schematic configuration of a robot.

[Explanation of symbols]

In the figure, 1 is a robot main body, 2 is a control device, 8 to 11 are motors, 12 is a CPU (determination means, determination means), 13 is a drive circuit, 14 is a position detection circuit, 18 is a teach pendant (operation means), 19 to 22 are rotary encoders, 2
Reference numeral 3 denotes a selection switch (type instruction means).

Claims (2)

[Claims] 1. A rotary encoder detects a rotational position of a motor for operating a movable body such as an arm,
Controlling the operation of the movable body based on the rotation position information, wherein a type indicating means set to a state corresponding to the type of the rotary encoder; and a status output by the rotary encoder to notify its own state Determining means for detecting the type of the rotary encoder by a signal; determining means for determining whether the type of the rotary encoder detected by the determining means matches the type set by the type indicating means A control device for controlling the robot, wherein an error state is set when the judgment means judges that they do not match. 2. When the movable body deviates from a set movable area, stop means for stopping the operation of the movable body, and operation means for canceling a stop function of the stop means are provided. The control device for a robot according to claim 1, wherein: