KR0155896B1 - Origin return control method and device of robot - Google Patents

Abstract

According to the present invention, the conveying part 21 is moved toward the second limit sensor means 24 at the initial homing speed V0, and when the sensor dock 22 is detected by the second limit sensor means 24, the conveying part ( A first moving step of stopping 21); When the conveying part 21 is moved to the speed limit V1 toward the 1st limit sensor means 23, and the conveying part 21 is moved by the pulse which generate | occur | produces in the encoder past the predetermined index point P1 by the predetermined distance. A second moving step of stopping the transfer unit 21; A third moving step of moving the transfer section 21 toward the index point P1 at a speed V2 and stopping the transfer section 21 when the transfer section 21 reaches the index point P1; There is provided a robot homing control method and apparatus comprising a fourth moving step of rotating the driving means (M) to move the conveying part (21) at a speed (V3) until reaching the index point (P1). The present invention has the advantage that the error is minimized in micro units because the home position is returned through the second or more deceleration process using the encoder pulse.

Description

Method and device for homing control of robot

1 is a schematic state diagram for a robot homing device according to the prior art.

Figure 2 is a schematic state diagram for the robot home return apparatus according to the present invention.

3 is a flow chart showing a method of returning the origin of the robot shown in FIG.

* Explanation of symbols for main parts of the drawings

11,21: transfer unit 12,22: sensor dog

13,23: 1st limit sensor 14,24: 2nd limit sensor

15: home sensor M: drive motor

C: Controller P1, P2: Index Point

The present invention relates to a robot homing control method and apparatus, and more particularly to a robot homing control method and apparatus using an encoder pulse index point of the robot drive motor.

The basis for controlling the robot with high accuracy is the stopping accuracy at the time of home return. If the position error is included in the return to origin, it is impossible to control the accuracy of the system, and it is inconvenient to compensate the offset to overcome this error.

Robots that typically linearly reciprocate use a home sensor for home return. This method is a method in which the sensor dog installed in the transfer part of the robot is homed by detecting the position of the home sensor.

1 is a state diagram schematically showing a robot homing apparatus according to the prior art. In general, the robot reciprocating linearly controls the ball screw (T) rotated by the drive motor (M), the transfer part (11) coupled to the ball screw (T) and reciprocated, and the driving of the motor (M). The controller C is provided. A sensor dock 12 is attached to the transfer unit 11, and the sensor dock 12 includes a first limit sensor 13, a second limit sensor 14, and a home sensor 15 attached to a predetermined position of the robot frame. Is detected by).

The origin control method of the robot having the above configuration is as follows. First, when power is input and an origin return command is input, the transfer unit 11 unconditionally moves toward the second position sensor 14 regardless of the current position. If the transfer unit 11 is positioned between the first limit sensor 13 and the home sensor 15 when the home return command is input, the transfer unit 11 may be moved until the sensor dock 12 is detected by the home sensor 15. Move toward the second limit sensor 14. When the sensor dock 12 is detected by the home sensor 15, the drive motor M stops and the stop position is set to the origin. In addition, if the transfer unit 11 is positioned between the home sensor 15 and the second limit sensor 14 when the origin command is issued, the transfer unit 11 moving toward the second limit sensor 14 is the sensor dock 12. When it detects this 2nd limit sensor 14, it stops. Thereafter, the driving motor M rotates in reverse to move the transfer part 11 toward the first limit sensor 13. When the sensor dock 12 of the conveying part 11 which moved toward the 1st limit sensor 13 is detected by the home sensor 15, the drive motor M will stop and set the position as an origin. In addition to the embodiment shown in FIG. 1, there is a robot employing a linear motor as the driving means, but only the driving method is different, and the configuration and control method of the homing device using the limit sensor and the home sensor are different from those of FIG. same.

The homing device and method as described above have the following problems. First of all, due to the structure of the sensor itself, an error inevitably occurs. As the enlarged view of the home sensor 15 of FIG. 1, the sensor has a width L of at least about 0.025 mm, and the width L of such a sensor causes an error. That is, when the sensor dock 12 moves between the first limit sensor 13 and the home sensor 15 and returns to the home position, the sensor dock 12 stops at the point indicated by the sign 16 of the home sensor 15, while the home sensor 15 is stopped. ) And when returning to the home position, the motor stops at the point indicated by reference numeral 17 of the home sensor 15.

In addition, there is a problem that the origin return error due to the inertia of the transfer unit 11 cannot be avoided. In general, when the home return command is input, the feed speed of the feed unit 11 is maintained at a low speed, but slip occurs due to the inertia of the feed unit itself, and this slip causes an error. In order to reduce such an error, an error may be removed or an offset correction may be attempted through a separate program, but the setting method itself is very inconvenient.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a robot homing control device with improved accuracy.

Another object of the present invention is to provide a robot homing control method with improved accuracy.

In order to achieve the above object, according to the present invention, the drive means including an encoder; Drive force transmission means; Control means for controlling the drive means; A conveying unit reciprocating by the driving means; A sensor dock attached to the transfer unit; In the home return method of a robot having first and second limit sensor means, the initial home return speed in which the conveying unit is decelerated at a steady state conveying speed to 1/10 to 2/10 toward the second limit sensor means. A first moving step of moving V0 and stopping the conveying unit when the sensor dock is detected by the second limit sensor means; The transfer unit is moved toward the first limit sensor means at a speed V1 in which the initial homing speed V0 is reduced to 1/2 to 2/3, and the transfer unit is arbitrarily set by a pulse generated from the encoder. A second moving step of stopping the conveying part when it is moved by a predetermined distance past the index point P1; Moving the feeder to the index point PI at a speed V2 in which the speed V1 is reduced by 1/10 and stopping the feeder when the feeder reaches the index point P1; 3 moving steps; And a fourth moving step of rotating the driving means in the opposite direction to the third moving step to move the feeder to the index point P1 at the lowest speed V3 of the driving means. A home return control method of is provided.

According to another feature of the present invention, in the first moving step, the point where the transfer unit is stopped by being detected by the second limit sensor means is set as a reference point, and in the second moving step, the transfer unit passes the index point P1. The predetermined distance to stop is measured from the said reference point.

According to another feature of the invention, the predetermined distance is 10 mm.

According to another feature of the invention, the steady state feed speed of the transfer part is a speed generated when the rotation speed of the drive means (M) is 3,000 rpm.

According to the present invention there is also provided a drive means comprising an encoder; Drive force transmission means; Control means for controlling the drive means; A conveying unit reciprocating by the driving means; A sensor dock attached to the transfer unit; In the robot home return device provided with first and second limit sensor means, home return control device is provided by the home return control method of claim 1.

Hereinafter, the present invention will be described in more detail with reference to an embodiment shown in the accompanying drawings.

2 shows a robot homing apparatus according to the present invention. The robot includes a ball screw T that is rotated by the drive motor M, and a transfer part 21 that reciprocates as the ball screw T rotates. The sensor dock 22 is attached to the transfer part 21, and the first limit sensor 23 and the second limit sensor 24 are attached to the frame of the robot. The sensor dock 22 is detected by the limit sensors 23 and 24, and the controller C controls the drive motor M according to the detected signal.

The drive motor M, which is typically used as a driving means of the robot, includes an encoder for controlling the position and speed of the robot. The encoder generates a pulse signal every one revolution in the case of the servo-type motor shown in FIG. 2, and the index point can be arbitrarily set by calculating the number of the pulse signals. The first index point P1 and the second index point P2 shown in the drawing are set as above. Not only the servo type motor but also a linear motor which can be employed as the robot driving means of the present invention can generate an encoder pulse to set an index point at an arbitrary point.

The zero point return method according to the present invention will be described with reference to the flowcharts shown in FIGS. 2 and 3.

When the home return command is input, the transfer unit 21 moves toward the second limit sensor 24. The initial homing speed V0 is set lower than the normal robot running speed. The speed of the robot transfer part 21 is determined by the rotation speed of the motor which is the drive source of a moving shaft. In normal operating conditions, the rotational speed of the drive motor is typically 3,000 rpm, and the initial homing speed (V0) is a speed generated at a motor speed of 300 to 600 rpm, which is about 1/10 to 2/10 of the normal speed. Is preferred. When the sensor dock 22 is detected by the second limit sensor 24, the movement of the transfer part 21 is stopped, and the position at this time is set as the reference point.

Next, the drive motor M reversely rotates to move the feeder 21 toward the first limit sensor 23. The moving speed V1 at this time is a speed | rate decelerated by 1/2 thru | or 2/3 than the said original homing speed V0. Therefore, it is preferable that the speed is generated when the rotation speed of the drive motor is about 150 to 400 rpm. After reaching the first index point P1 set at an arbitrary point, the transfer part 21 stops after further moving a predetermined distance toward the first limit sensor 23. The distance that the transfer section 21 moves to the first limit sensor 23 past the index point P1 is preferably about 10 mm. As such, the distance that the transfer unit 21 moves past the index point may be measured from the reference point set above.

Next, the conveying part 21 is conveyed toward the 1st index point P1 again. At this time, the feed speed V2 should be slower than the feed speed V1. It is preferable that the feed speed V2 is decelerated by about 1/10 of the feed speed V1, and therefore, the speed at which the rotational speed of the drive motor is generated at 15 to 40 rpm is preferable. When it is detected that the transfer section 21 has reached the first index point P1, the transfer is stopped. At this time, even if the transfer part 21 is detected as having reached the first index point P1, the position of the transfer part 21 does not substantially coincide exactly with the first index point P1. This is because slip occurs due to the inertia of the conveying part 21, and even if the conveying part is detected, it is inevitable that the conveying part 21 exceeds the index point P1. At this time, the distance from the conveying section 21 to the index point (P1) is approximately 1 to 2 micrometers.

In order to avoid the error due to the inertia as described above, the conveying part 21 is reversed until it is detected to reach the index point P1 again by reversing the direction of rotation of the drive motor M and at the lowest decelerated moving speed V3. Move). It is preferable that the moving speed V3 at this time is the speed which generate | occur | produces in the minimum rotation speed of a drive motor, and is a speed near zero. As described above, the transfer unit 21 reaches the index point by deceleration over three orders, thereby completing the homing.

The robot home return control method and apparatus according to the present invention has an advantage that the error is minimized in micro units because the home return is performed through a second or more deceleration process using an encoder pulse. In addition, the use of a home sensor and the like used in the prior art is excluded, the device can be simplified / cheaper and there is an advantage that the home return program is simplified.

Claims (5)

Drive means (M) including an encoder; Drive force transmission means (T); Control means (C) for controlling said drive means (M); A transfer part 21 reciprocating by the driving means M; A sensor dock 22 attached to the transfer part 21; In the method of homing of a robot having first and second limit sensor means (23, 24), the conveying portion (21) is set at a feed rate in a steady state toward the second limit sensor means (24). A first moving step of moving to an initial homing speed V0 decelerated to 2/10 and stopping the transfer part 21 when the sensor dock 22 is detected by the second limit sensor means 24; The transfer unit 21 is moved toward the first limit sensor means 23 at a speed V1 in which the initial homing speed V0 is reduced to 1/2 to 2/3, and the transfer unit 21 A second moving step of stopping the transfer part (21) when the pulse generated by the encoder is moved by a predetermined distance past an arbitrarily set index point (P1); When the transfer part 21 moves to the index point P1 at a speed V2 in which the speed V1 is reduced by 1/10, the transfer part 21 reaches the index point P1. A third moving step of stopping the transfer part 21; The drive means M is rotated in the opposite direction to the third moving step to move the transfer part 21 at the minimum speed V3 of the drive means M until it reaches the index point P1. Robot home return control method comprising a fourth moving step. According to claim 1, wherein the transfer point is set to a reference point where the transfer section 21 is stopped by the second limit sensor means 24 in the first moving step, and the transfer unit 21 in the second moving step A method for controlling the homing of a robot, characterized in that a predetermined distance for stopping past an index point (P1) is measured from the reference point. The robot homing control method according to claim 1 or 2, wherein the predetermined distance is 10 mm. The robot home return control method according to claim 1, characterized in that the steady state feed speed of said transfer part (21) is a speed generated when the rotation speed of said drive means (M) is 3,000 rpm. Drive means (M) including an encoder; Drive force transmission means (T); Control means (C) for controlling said drive means (M); A transfer part 21 reciprocating by the driving means M; A sensor dock 22 attached to the transfer part 21; In the robot home return device having first and second limit sensor means (23,24), home return control device is characterized in that the home return control is performed by the home return control method of claim 1. .