JPH0465702A - Method for searching origin of robot - Google Patents

Abstract

PURPOSE:To stably detect the z phase of an encoder by slowly moving an arm from the position of a limit switch in the reverse direction and deciding the origin of a robot when the number of pulses counted until the Z phase is detected is less than the number of pulses counted in one revolution of an encoder. CONSTITUTION:An incremental type encoder 1-1 for detecting the relative angle of a spindle of a motor 1-2 outputs 100 or 2,000 pulses e.g. and one z-phase pulse per revolution. A high speed arithmetic processor drives the motor 1-2 and moves the arm 1-4 up to position of the limit switch 1-5. When the number of pulses counted until the z-phase pulse is detected from the encoder at the time of slowly moving the arm 1-4 in the reverse direction is less than the number of pulses per revolution, a correct origin is decided. Consequently, the z phase of the encoder can be stably detected without receiving influence due to the restriction of the calculation accuracy of the high speed arithmetic proces sor or the like of the processor.

Description

[Detailed Description of the Invention] [Summary] In the robot origin search method of searching the origin of an encoder attached to the robot, the number of pulses required to detect two phases by slowly moving the limit switch in the opposite direction from the position of the limit switch is 1. The origin is set when the number of rotation pulses is smaller than the number of rotation pulses, and the aim is to stably detect the two phases of the encoder without being affected by limitations such as the accuracy of high-speed calculation processors. The motor is equipped with an encoder that detects the rotation angle to be driven and a limit switch that detects the position of the joint. After driving the motor at a predetermined speed and moving the joint until the limit position is detected by the limit switch, the motor is moved in the opposite direction. , count the pulses from the encoder at this time, and find the number of pulses until a two-phase pulse is detected (e.g., 3), ・The second pulse a is one revolution of Any'-2-da. When the number of pulses is smaller than the number of pulses, the position of the l phase is taken as the origin;
[Field of use by business owners] The present invention relates to a robot origin (; .

[Problems that the prior art and invention attempt to solve] The r-l box used for the T-field's navy standing production 9] teaches the six-movement repeatedly, and the Ihanok The robots of type 41 and -, which are common in type -, use an linear/cremental type encoder that detects relative angles, and have the property of not being able to maintain absolute angles when the power is turned off. For this reason, the user 1 of Robo7) immediately after turning on the power? , -The origin is set at the reference position of the absolute angle without moving the famous joint.
It is necessary to conduct V Ninohara Hezarch has each joint and
: Limit switch, which is installed! :Encoder 1
This is done by using two phases that output only one pulse per rotation (its width is 1/100 to 1/2000 of one rotation). This encoder is directly connected to the motor, and there is a reducer (1150 to 1/120) between the joints of the arm, so for example, the encoder is 2000 pulses, When the reduction ratio is 1/120, the rotation angle of the joint corresponding to the two-phase branch pulse is 0°0015° (360/ (2
000X120>).

On the other hand, if a digital high-speed computation processor (1) SP) is used to control this mechanism and 4@'s ノ'' == BO control is performed at the same time, the zangling period and 12. urns is the lower limit.In order to detect the two-phase Tsuma Jless Shinshichi with the Sani/Filini/G Shuho device of l m5, the rotational angular velocity of the joint is 145"/S.
The following is a-key, L7 kashi, joint snoring angle reach j,
□L450°/S, and due to the limitation of calculation accuracy, 1
．． 5"/s may be increased by 1 to the degree of elevation angle that can be realized) 8) In such a case, 1. The pulse width of the 7th phase is reduced due to the shadow of noise etc.) and the reference position. There was a problem in that two phases that were fairly certain at the origin were detected and the reference position was 1' apart.This will be briefly explained below with reference to FIG.

In Fig. 3, C and ■ move the limit switch in the direction of the specified speed.

04 people, limit switch now detects people - or smoothness I'l
l Separate. , If yes (if the joint of t: l bore is moved in the direction of the limit switch by knee/constant speed change and the ON signal from the limino 1 switch is detected), then the process of The origin point is completed by .

@ stops. Rice 1. teeth,@ ! J: Since I detected the 0 signal from the limit switch, I stopped J.

■ is the lowest p degree in a certain direction, and rice 7. teeth,[
Stop at [phase]! , 7. Move slowly in the opposite direction at the lowest speed Lm.

■ Check whether the correct 1.2 phase is detected or not. 76. At ■, slowly move the limit switch in the reverse jj direction by 1 low speed '7', and apply 1 pulse per rotation from the encoder. It doesn't matter whether the output phase pulse is detected or not.If yes, then z41?
Therefore, stop and set the position F at this time as the origin (reference position), and set 1o, 2, and the following positions l:
Perform control, etc. 4 On the other hand, if the answer is no, repeat ■ and perform j7.

Also, the person who solves the above-mentioned problem: Meni, 4th Ei '1 (
(a) When the two-phase signal B is ], m s, use the circuit in Figure 4 (b) to trigger the rise of the pulse of z4i) = I-, 2rn S l
The pulse of Thor 1- is native (゛(41st flash (c)), 2
There is also a method that stabilizes the detection of phase pulses. With this method, if two high-frequency noises are added to the two-phase signal, the noise will be reduced as shown by U in Figure 4 (C). The output signal 5 is generated, and the reference position exceeded by -1 is detected!
-r 1. The problem is that it is not appropriate.

The present invention detects two phases by slowly moving the limit switch in the opposite direction from the position of the limit switch, and when the number of pulses of C' is smaller than the number of pulses of one rotation, the origin is determined 7, and high-speed calculation ``/'' 0 2. Without being affected by the limitations on the load-bearing phase of the processor. The purpose is to stably detect two phases of the encoder.

[Means to solve the problem]

Means for solving the problem will be explained with reference to FIG.

In FIG. 1, an encoder 1-1 is an incremental encoder that detects rotation angles of joints of a robot.

The motor 1-2 drives the joints of the robot.

The limit switch 1-5 detects the limit position of the joint of the robot.

[Effect]

In the present invention, as shown in FIG.
1 to move the joint until the limit position is detected by limit switch 1-5, then slowly move it in the opposite direction, count the pulses from encoder 1-1 at this time, and calculate the two-phase pulse. Measure the number of pulses until it is detected, and when this pulse number is smaller than the number of pulses per revolution of encoder 1-1, the position of the two phases is the origin, and when it is larger, try again. ing.

Therefore, the number of pulses counted until the joint is moved to the limit switch 1-5 position, slowly moved in the opposite direction, and two-phase pulses from encoder 1-1 are detected is smaller than the number of pulses in one rotation. By setting the correct origin (reference position W), high-speed calculation processor (DSP)
It becomes possible to stably detect the two phases of the encoder 1-1 without being affected by the limitation of measurement accuracy in 2).

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 and 2.

FIG. 1(a) shows an example of a joint mechanism of a robot.

FIG. 1(A) shows a front view of the joint mechanism of the robot. Here, the encoder 1-1 is directly connected to the shaft of the motor 1-2, and the encoder 1-1 is connected directly to the shaft of the motor 1-2. It is an incremental encoder that detects angles, and outputs, for example, 100 to 2000 pulses per revolution, and one two-phase pulse per revolution.

Here, the pulse positions of these two phases are searched and set as the origin.

The motor 1-2 drives the arm 1-4 via a reduction gear 1-6.

The limit switch 1-5 is a microswitch or the like for detecting the + limit position and the - limit position of the arm 1-4.

The speed reducer 1-6 reduces the rotation of the motor 1-2, e.g.
The speed is reduced by 150 to 1/120.

FIG. 1(A)-(B) shows a side view of the encoder 1-1 of FIG. 1(A)-(A). If the number of pulses generated per one rotation of the encoder 1-1 is, for example, 2000, then 360/2000=0. It becomes 18°.

FIG. 1(a)(C) shows a side view of the arm in FIG. 1(a)(A). Here, the angle corresponding to the two-phase pulse of the arm is the angle of the reducer 1-6. If the reduction ratio is 1/120, then 0.18/120=0.0015°, which is an extremely small angle.

FIG. 1(b) shows a system configuration diagram using a DSP. Here, the DSP is a high-speed arithmetic processor, and in this embodiment, servo control of four axes is performed simultaneously, and the sampling period is l m s.

The shared memory 3 writes commands from the personal computer main body 4 and causes the DSP 2 to execute the commands,
This is for writing the angle of the encoder 1-1 from the DSP 2 and importing it into the personal computer main body 4.

The personal computer main body 4 writes the robot's lll11m command in the shared memory 3, and causes the DSP 2 to perform origin search, assembly work, etc.

The console 5 is used to input various data into the personal computer main body 4 to control the robot, display the results, and so on.

Next, the operation of the configuration shown in FIG. 1 will be explained in detail using FIG.

In Figure 2, ■ moves the limit switch in a certain direction at a constant speed, which means that the DSP 2 in Figure 1
-2 to move the arm 1-4 in the direction of the limit switch 1-5.

Note that this DSP control corresponds to the personal computer main body 4 supplying a control current to the robot's motor 1-2 to put it in a servo control state, and then writing a command to stop the operation when, for example, a + limit is detected. Then, do it.

(2) determines whether or not a limit has been detected.

If yes (when the DSP 2 detects, for example, an ON state from the limit switch 1-5), the process from 0 onwards is performed, and if no, the process (2) is repeated.

■ Stops. Since the limit position has been detected, the motor 1-2 is stopped and stopped.

[Phase] stores the encoder value (A). this is,
The current position value of encoder 1-1 at the limit position is stored.

[Phase] moves in a constant direction at the lowest speed, this is the direction opposite to the direction toward limit switch 1-5 (return direction)
The motor 1-2 is driven at the lowest speed. Furthermore, this DSP
Control No. 2 is performed in response to the personal computer main body 4 writing a command to the shared memory 3 to stop the operation when two phases are detected.

[Phase] determines whether two phases are detected. If yes, stop at ■ and perform [phase]; if no, repeat ■.

[Phase] stores the encoder value (B). this is,
[Phase] Yes, we detected two-phase pulses from encoder 1-1, so we counted the pulses sent from encoder 1-1 when we memorized it as [phase] and then moved it in a fixed direction at the lowest speed! (B) is memorized.

[Phase] is! It is determined whether A-Bl is less than the number of pulses per encoder revolution. If yes, the number of pulses counted from the limit position to the position where two-phase pulses are detected is less than the number of pulses in one rotation of the encoder, so it is determined that the origin is correct and the process is stopped. On the other hand, if No, the number of pulses counted from the limit position to the position where two-phase pulses were detected is greater than the number of pulses in one rotation of the encoder, so it is determined that the origin is incorrect, and [
[phase] to move the limit switch to position (A), and repeat steps from ■.

〔Effect of the invention〕

As explained above, according to the present invention, the pulses counted until the joint is moved to the position of the limit switch 1-5, slowly moved in the opposite direction, and two-phase pulses from the encoder 1-1 are detected. Since the system uses a configuration that determines the correct origin when the number of pulses per revolution is smaller than the number of pulses per revolution, the encoder's two-phase detection can be performed stably without being affected by limitations on the calculation accuracy of high-speed arithmetic processors. be able to. This stabilizes the origin search and makes it possible to guarantee that the robot will repeat the movement as taught even if the power is turned off midway through.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of one embodiment of the present invention, Fig. 2 is an origin search method and flowchart according to the present invention, Fig. 3 is a conventional origin search method and flowchart, and Fig. 4 is an explanatory diagram of the prior art. . In the figure, l is a robot, 1-1 is an encoder, 12 is a motor, l-4 is an arm, 1-5 is a limit switch, 1-
6 is a reducer, 2 is a DSP (high-speed arithmetic processor), 3 is a
4 represents a shared memory, 4 represents a personal computer body, and 5 represents a console.

Claims (1)

[Claims] A robot origin search method for searching the origin of an encoder attached to a robot, comprising an encoder (1-1) that detects a rotation angle for driving a joint of the robot by a motor (1-2), and a limit position of the joint. After driving the motor (1-2) at a predetermined speed and moving the joint until the limit position is detected by the limit switch (1-5), Move the encoder (1-1) slowly in the opposite direction and count the pulses from the encoder (1-1) at this time to find the number of pulses until the z-phase pulse is detected. A robot origin search method characterized in that when the number of rotation pulses is smaller than the number of rotation pulses, the position of the two phases is set as the origin, and when the number is larger, a retry is made.