JPS61273603A - Turning device of articurated robot - Google Patents

Abstract

PURPOSE:To enable an operator to teach a robot easily by attaining the input of the same position information only to the same point even in case each rotary shaft has >=1 rotations. CONSTITUTION:When servo motors 6, 18 and 25 are revolved, the 1st arm 14, the 2nd arm 38 and a tool shaft 42 are turned respectively. Thus the signals equivalent to these turning quantity are produced from encoders 7, 17 and 23. Here the number of pulses produced from the encoders 7-23 increase more than its upper limit value. In such a case, those encoders are reset to set the number of pulses at '0'. Then the addition is carried out again from '0'. While the number of pulses decrease less than its lower limit value. In such a case, the number of these pulses is reset to the upper limit value. Then the subtraction is carried out again from the upper limit value. Thus it is possible to supply the same position information only to the same point even in case each rotary shaft has >=1 rotations. This facilitates an easy teaching job to a robot having a turning shaft which turns at >=360 deg..

Description

Detailed Description of the Invention (Technical Field) The present invention provides first
The present invention relates to an articulated robot having an arm and a second arm.

(Prior art) Conventionally, for example, in an articulated robot, the rotation range of the arm was limited to 3
Utility Model Application Publication No. 59-160182 has an angle of 60° or more. This is achieved by doubling the rotation axis of the first arm and the axis for rotationally driving the second arm, and by providing the second arm drive motor on the fixed part on the same side as the first arm drive motor. This allows one arm to rotate over 360 degrees without interfering with other members.

Currently, in many cases, the position of a robot is measured by counting signals such as pulses from a sensor such as a rotary encoder connected to a motor shaft. Then, if the arm is structured to rotate more than 360' and the arm position measurement method is as described above, as in the above-mentioned Utility Model Application Publication No. 59-160182, if the arm rotates more than 360 degrees, it will cause a certain point in the work area of the robot to be detected. The rotational position of the motor will be multiple times in a single point. In other words, each time the arm rotates n times around a point and the arm tip returns to the same point, n pieces (n types) of position information are generated for the same point, which makes it difficult to teach the robot the position. Depending on the movement of the arm, different data must be input for the same point. This has the problem that the work becomes complicated when the operator teaches the robot, and that the rotation angle of the arm is limited if the storage capacity of the position information of the robot control device is small.

(Purpose) The present invention has been made based on the above-mentioned conventional problems. An object of the present invention is to provide a rotation device for an articulated robot that can solve the above problems by making it possible to input only the same position information for the same point even if the robot rotates one or more times. .

(Structure) In order to achieve the above object, the present invention includes a first arm rotation shaft supported on a fixed base, a second arm rotation shaft supported on the tip of the first arm, and a tool shaft provided on the tip of the second arm. The servo motors for driving the first arm rotation axis, second arm rotation axis, and tool axis are each equipped with an encoder that generates a signal according to the rotation amount, and each axis is rotated more than 1 rotation. Reset the pulses generated when rotating to zero, add them again from zero, and when the number of generated pulses decreases to zero and further decreases from zero, subtract the decreased number of pulses from the number of pulses generated by one rotation. The invention is characterized in that it includes means for counting so as to

Hereinafter, a detailed explanation will be given based on an example. In FIG. 1, a first arm rotation shaft 2 is supported by a bearing 3 on the cylindrical upper part of a fixed base 1. As shown in FIG. Said rotation axis 2
A pulley 4 is connected to the lower end of the . The fixed pedestal 1
A servo motor 6 equipped with an encoder 7 is fixed to a flange portion 5 formed on the side surface of the motor 6.
A reduction gear 9 is connected to the shaft 8 . Reducer 9
An output shaft of the fixed base 1 is connected to a shaft 11 supported by a bearing 10 provided on the flange portion 5 of the fixed base 1.

A pulley 12 is fixed to the shaft 11, and the pulley 12 and the pulley 4 are connected to the timing belt 1.
Connected by 3. The upper end of the rotation shaft 2 is formed into a flange shape, and the base of the first arm 14 is fixed thereto. The rotating shaft 2 is formed hollow, and a shaft 16 is supported by a bearing 15 in the hollow portion.

The lower end of the shaft 16 is connected to the shirts 1 to 1 of a servo motor 18 equipped with an encoder 17 provided on the fixed base 1.
9 via a coupling 20. A pulley 21 is fixed to the upper end of the shaft 16. Further, a flange 22 is formed on the cylindrical upper part of the fixed base 1, and a motor 25 including an encoder 23 and a speed reducer 24 is provided. A pulley 27 is pivotally supported by a bearing 26 at the upper end of the cylindrical upper portion of the fixed base 1 .

The lower part of the pulley 27 and the output shaft 28 of the motor 25
A pulley 29 fixed to is connected by a timing belt 30. At the tip of the first arm 14, a first
An arm rotation shaft 31 is supported by a bearing 32.

A shaft 33 is pivotally supported on the second arm 14 by a bearing 34 above the cough bearing 32 . A pulley 35 is formed on the upper part of the shaft 33, and is connected to the pulley 21 by a timing belt 36. The lower end of the shaft 33 is connected to a reducer 37, and the output shaft of the reducer 37 is connected to the second arm rotation shaft 31. The pivot shaft 31 is connected to the base of the second arm 38 at its lower end. Also, the first arm 14
A pulley 39 is supported by a bearing 40 coaxially with the second arm rotating shaft 31 at its tip, and the upper part of the pulley 39 and the upper part of the pulley 27 are connected by a timing belt 41. At the tip of the second arm 38, a tool shaft 42 having a hand 44 at its lower end is supported by a bearing 43. A pulley 45 is formed on the upper part of the tool shaft 42 and is connected to the lower part of the pulley 39 by a timing belt 46. First arm 14. Second arm 38. The hand 44 is capable of turning more than 360° on each rotation axis.

Next, the operation will be explained with reference to FIG.

When the servo motor 6.1.8.25 is rotated, the first arm 14. Second arm 38. The tool shafts 42 each rotate, and a signal corresponding to the amount of rotation is sent to the encoder 7.
．． Occurs from 1.7.23.

For example, if you use an incremental type encoder 7.17.23, the signal generated will be a pulse train,
In this case, assuming that the reduction ratio of the reducer 9, 24°37 is good, the number of pulses generated when the arm makes one rotation (=360°) is NXE. In UNIT ■, the pulse (NXE
) is transmitted by T (T is an integer), and this pulse is converted into two outputs of UP (addition) + DOWN (subtraction) from the rotation direction, and the UP.

The two outputs of DOWN are UNIT ■ and C0UNTER
It is input to the CPU via UNIT. UNIT ■ detects the signal, and the pulse (NX
EXT) upper and lower limit values are detected, and only at this time UNIT■
It outputs a signal to. In UNIT■, C0U
When the upper limit value (NXEXT) signal is input at NT UP, C0UNTERUN will be input at the next C0UNT UP.
At this time, C0U in IT should be loaded with the lower limit value from CLE A, R or memory.
Do not input the C0UNT UP signal to NTERUNIT), or lower limit value (0) at C0WNT DOWN.
When the signal input is received, the upper limit value (NXEXT) is LO at C0UNTERUNIT at the next C0WNT DOWN.
AD (at this time, C0UNTER has C0U
(Do not input the NT DOWN signal).

Not limited to this circuit configuration, when the number of pulses generated from the encoder increases and reaches the upper limit value and increases further, it is reset to 0 and the number of pulses decreases again so that it starts from 0 again. When it reaches the lower limit value (0) and decreases further, it can be reset to the upper limit value and subtracted from the upper limit value again. Only location information can be input.

(Effects) In the present invention, the first arm rotation shaft is pivotally supported on the fixed base, the second arm rotation shaft is pivotally supported on the tip of the first arm, the tool shaft is pivotally supported on the tip of the second arm, and the second arm rotation shaft is pivotally supported on the tip of the second arm. The servo motors for driving the 1st arm rotation axis, 2nd arm rotation axis, and tool axis are each equipped with an encoder that generates a signal according to the amount of rotation, and the pulse generated when each axis rotates more than 1 rotation is reset. Set it to zero, add it again from zero, and the number of generated pulses decreases to zero,
Since it is equipped with a counting means to subtract the reduced number of pulses from the number of pulses generated by one rotation when the number of pulses further decreases from zero, even if the first arm, second arm, and tool shaft rotate more than one rotation, The position information stored by the robot control device is one-to-one for each point in the robot work area.
Therefore, it becomes easier to teach a robot having a rotation axis that rotates over 360 degrees, and there is no restriction on the rotation angle of the arm. In the above embodiment, an incremental type rotary encoder is used as a sensor for detecting the rotation angle of the motor, but an absolute type or other resolver type sensor may be used instead.

Also, when using the reducer by changing the output and increasing the speed,
The speed ratio N and sensor resolution E are H = n (n is an integer)
If this condition is satisfied, it is accurate because there is no deviation in the reset signal when the arm rotates once. Further, in the above embodiment, the motor is decelerated using a speed reducer, but the motor may directly drive the rotating shaft without using the speed reducer.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention, and FIG. 2 is a block diagram for explaining the operation. 1... Fixed pedestal 2... First arm rotation axis 6.18.25... Servo motor 7.17.23... Encoder 14... First arm 31... Second arm rotation Axis 38...Second arm 42...Tool axis

Claims (1)

[Claims] A first arm rotation shaft is pivotally supported on the fixed base, a second arm rotation shaft is pivotally supported on the first arm tip, a tool shaft is pivotally supported on the second arm tip, and the first arm rotation shaft and the second arm rotation shaft are pivotally supported on the fixed base. The servo motors for driving the 2-arm rotation axis and the tool axis are each equipped with an encoder that generates a signal according to the amount of rotation, and when each axis rotates more than one rotation, the generated pulse is reset to zero, and then added again from zero. Furthermore, the rotation device for an articulated robot is provided with a means for counting so that when the number of generated pulses decreases to zero and further decreases from zero, the decreased number of pulses is subtracted from the number of pulses generated by one rotation. .