JPH0123279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial robot, and particularly to an industrial robot in which a movable part of the robot is provided with an incremental encoder, and the movable part is servo-controlled to a target posture using the detection output of the incremental encoder.

In an industrial robot in which an incremental encoder is provided on a robot movable part, such as an arm or a hand, and the movable part is controlled to a target posture by its detection output, the incremental encoder is used to control the relative position of the movable part. Since the encoder only detects the absolute orientation of the robot, the origin orientation of the encoder corresponds in advance to the absolute origin orientation of the movable part, and then the operation of the industrial robot is started and the robot movable part is controlled to the target position. .

As mentioned above, in this type of industrial robot, it is necessary to adjust the home position of the incremental encoder in advance, but conventionally, this home position adjustment is done visually using a spirit level, etc. However, since the origin position alignment error due to individual differences among operators cannot be avoided, and the origin position alignment is performed by the operator's direct operation, the safety of the operator cannot be sufficiently ensured. .

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an industrial robot that can accurately, safely and automatically perform the origin position alignment.

In order to achieve the above object, the present invention includes an incremental encoder provided in a robot movable part to detect the amount of drive of the robot movable part, and uses the output of the encoder as a feedback signal to change the posture of the robot movable part to a target posture. In an industrial robot equipped with a servo control system that performs servo control, the robot movable part is equipped with an inclination angle detector that detects the current posture of the robot movable part. The present invention is characterized in that the robot movable part is set to the original position based on the deviation of the detected position.

Hereinafter, preferred embodiments of the industrial robot according to the present invention will be described based on the drawings.

FIG. 1 shows a state in which the movable part of the robot of this embodiment is controlled in attitude, and FIG. 2 shows a state in which the movable part is in the original position.

A cylindrical post 12 is erected on the base 10, and a rotating frame 14 is rotatably supported on the top of the post 12 so as to be rotatable in a plane (XY plane) perpendicular to the axial direction (Z-axis direction) of the post 12. ing. An inner arm 16 is pivotally supported on this rotating frame 14 so as to be pivotable in a plane orthogonal to the plane of rotation of the rotating frame 14, and an outer arm 16 is rotatably supported on the tip of this inner arm 16 in a plane that is pivotable in the plane of rotation of the inner arm 16. An arm 18 is pivotally supported. Further, a rotation shaft 20 is rotatably supported at the tip of the outer arm 18 so as to be rotatable around the axis.
A first wrist frame 22 is fixed to the tip of the wrist. Further, a second wrist frame 24 is provided to grip the first wrist frame 22, and the second wrist frame 24 can rotate within a plane perpendicular to the rotation plane of the first wrist frame 22. A rotary shaft 26 is rotatably supported on the base of the second wrist frame 24 so as to be rotatable around the direction of extension thereof, and a fifth wrist frame 28 is fixed to the tip of the rotary shaft 26. Furthermore, a hand 30 for gripping tools, parts, etc. is provided at the tip of the third wrist frame 28.

As described above, since the movable part of this embodiment has six joints, the hand 30 can be set to any position and posture.

As described above, in the present invention, the above-mentioned movable parts are provided with inclination angle detectors for detecting the current posture of the movable parts. , a first one on the side of the third wrist frame 22, 24, 28,
Second, third, fourth, fifth, and sixth tilt angle detectors 3
2A, 32B, 32C, 32D, 32E, 32F
is installed.

The tilt angle detector 32 is located at a predetermined position of each movable part,
For example, the angle of inclination from the vertical can be detected.

Note that the inclination angle detected by the detector 32 corresponds to the current posture of each movable part.

In addition, the post 12 and the rotating frame 14 include
A marking 100 for positioning the rotating frame 14 is formed.

FIG. 3 shows the configuration of a servo control system for each movable part (hereinafter simply referred to as an arm) of the industrial robot in this embodiment.

In FIG. 3, the attitude command 102 output from the attitude command circuit 34 is sent to the D/A via the comparator 36.
is supplied to a converter 38 and converted into an analog quantity;
The signal is supplied to the servo driver 40. The servo driver 40 can drive the motor 42 provided at the joint in accordance with the analog-converted comparison output 104 of the comparator 36. The drive amount of this motor 42 is determined by the incremental encoder 4.
4, and at this time its detection output 106
is a pulse train whose number corresponds to the amount of drive of the arm driven by the motor 42. The detection output 106 of this encoder 44 is the pulse counter 4
6, and the count value 108 of the pulse counter 46 is supplied to the other comparison input of the comparator 36. Here, pulse counter 4
The count value 108 of 6 is reset to zero at the start of the home alignment work, and becomes a value corresponding to the current posture according to the relative movement of the arm.
can determine the deviation of the count value 108 with respect to the command 102 and obtain a comparison output corresponding to the deviation. In the device of this embodiment, the arm is driven until the comparison output of the comparator 36 becomes zero, so the arm is servo-controlled to a posture corresponding to the command 102.

The detection output 110 of the tilt angle detector 32 is supplied to one comparison input of a comparator 48. Since the reference voltage 112 is supplied from the origin attitude reference voltage generation circuit 50 to the other comparison input of the comparator 48, the deviation 114 of the tilt angle detection attitude of the movable part from the origin attitude is obtained by this comparator 48. be able to.

The deviation 114 is supplied to the attitude command circuit 34.

As shown in FIG. 4, in this embodiment, the attitude command circuit 34 includes a presettable digital integrator 52 that outputs the command 102, and the deviation 114.
is supplied, a limiter 54 outputs a speed command of zero when the deviation 114 falls within a predetermined range, and outputs a speed command of a predetermined value when it does not fall within the predetermined range, converting the speed command output from the limiter 54 into a digital value. It is composed of an AD converter 56 for conversion.

Since the presettable digital integrator 52 is reset to zero at the start of origin alignment, the integrator 5
2 is a command 102 corresponding to the posture of the robot movable part.
can be output. Therefore, this Directive 1
The robot movable part is servo-controlled to a posture according to 02.

Also, when the origin alignment is performed, the detector 3
Deviation 1 of the output 110 of 2 from the reference voltage 112
14 is supplied to the limiter 54. At this time, if the value of the deviation 114 is larger than a predetermined value, a predetermined speed command is supplied to the presettable integrator 52 via the AD converter 56. And the integrator 52 is
A relative position command 102 integrated with the speed command from the AD converter 56 can be output, and the comparator 36
Then, the deviation between the command 102 and the current value 108 is calculated. The deviation is converted by the DA conversion 38 and becomes a speed command 102, which is supplied to the servo driver 40 to drive the arm. The robot movable part is driven at a speed corresponding to the value of the speed command, thereby shifting the deviation 114 of the comparator 48 to zero. As a result, when the deviation 114 approaches zero and falls within a predetermined range, a speed command with a value of zero is output from the limiter 56, the drive of the robot movable part is stopped, and the robot movable part returns to the origin. Stop is controlled.

As described above, the servo control system shown in FIGS. 3 and 4 can servo control the posture of the robot movable part to the target posture corresponding to the command 102, and
When aligning the origin, the robot movable part is set to the origin position based on the deviation 114 of the tilt angle detection attitude (corresponding to the current attitude) 110 output from the inclination angle detector 32 with respect to the reference voltage (corresponding to the origin attitude) 112. At this time, in this embodiment, the robot movable part is driven at a predetermined speed.

A preferred embodiment of the present invention has the above configuration,
The effect will be explained below.

When shipped from the factory, the post 12 shown in FIGS. 1 and 2 is laid down horizontally, and the reference voltage 112 at this time is
The motor 42 is driven based on the deviation 114 of the detection output 110 of the inclination angle detector 32 relative to the tilt angle detector 32, and the rotating frame 14 is controlled to stop at the original position. In this state, the marking 100 is formed on the post 12 and the rotating frame 14.

When this device is installed after shipping, the marks 100 formed on the post 12 and the rotating frame 14 are first aligned, and the rotating frame 14 is positioned. Therefore, at this time, there is no need to lay down the post 12 horizontally, and the detector 32A can also be removed.

Next, the inner arm 16 is erected. At this time, since the inclination angle detector 32B detects the inclination angle of the inner arm 16 with respect to the vertical direction, the inner arm 16 is accurately controlled to stand upright in the vertical direction.

Then, the outer arm 18 is erected. At this time, as in the case of the inner arm 16, the inclination angle detector 32c detects the inclination angle of the outer arm 18 with respect to the vertical direction. Therefore, the outer arm 18 is also accurately controlled to stand upright.

Next, the outer arm 18 is rotated 90 degrees to be horizontal, and the first wrist frame 22 is rotationally driven, and the deviation 11 obtained by the inclination angle detector 32D is
4 becomes zero, that is, when the reference tilt direction of the tilt angle detector 32D coincides with the vertical direction, the first wrist frame 22 is controlled to stop.

Then, the first outer arm 18 is rotated 90 degrees and rotated back in the vertical direction, and the second wrist frame 24 is rotated and stopped in the vertical direction where the deviation 114 obtained by the inclination angle detector 32E becomes zero. controlled.

Furthermore, the outer arm 18 is turned 90 degrees to make it horizontal, and then the third wrist frame 28 is rotationally driven, so that the deviation 114 obtained by the inclination angle detector 32F of the third wrist frame 28 is zero. The stop is controlled to a certain position.

Finally, the outer arm 18 is turned 90 degrees and returned to the vertical direction.

When the above operations are completed, the movable part of the robot assumes the original position as shown in FIG. When the movable part is set to the original position in this way, the data corresponding to the original position of each arm is taught to the main robot, and thereby the correspondence between the relative original position of the incremental encoder 42 and the absolute original position is established. is taken.

Thereafter, when the robot starts operating, the arm of the robot is servo-controlled to a posture corresponding to the posture command 102 based on the relative origin posture corresponding to the above-mentioned absolute origin, and the predetermined process is performed by the robot. .

As explained above, according to the present invention, the robot itself controls its movable parts to stop at the home position, so there is no need to visually align the relative position and absolute position with the home position as in the past. Therefore, this origin alignment can be performed accurately.

Furthermore, according to the present invention, the operator does not directly operate the arm of the robot to perform the origin alignment, and does not have to approach the robot.
Operator safety can be ensured.

In the above-mentioned embodiment, it is preferable that each detector 32 can be removed from the movable part during operation, and that they be assembled to the original position at a uniform relative mounting position when re-aligning the origin. be.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of a robot movable part in an embodiment of the present invention, and FIG.
3 is a perspective view of a robot movable part, FIG. 3 is a block diagram of a servo control system according to an embodiment of the present invention, and FIG. 4 is a block diagram of a posture command circuit in FIG. 3. 12...Post, 14...Rotating frame, 16
...Inner arm, 18...Outer arm,
22, 24, 26...Wrist frame, 32...Inclination angle detector, 34...Attitude command circuit, 36...Comparator, 44...Incremental encoder, 4
8... Comparator.

Claims (1)

[Claims] 1 Industrial equipment equipped with a servo control system that includes an incremental encoder installed in a robot movable part to detect the amount of drive of the robot movable part, and uses the output of the encoder as a feedback signal to servo control the posture of the robot movable part to a target posture. In the robot for use, the robot movable part is provided with an inclination angle detector for detecting the current posture of the robot movable part,
The servo control system sets the robot movable part to the original position based on the deviation of the detected tilt angle from the original position of the robot movable part. An industrial robot characterized by: