JPH0869326A - Positioning controller - Google Patents

Abstract

PURPOSE: To control the positioning device to return a moving object to an original position in a short period accurately by accelerating and moving the moving object in a reverse direction to the restoring direction and decelerating the moving object into a stop to return the moving object to the original position after the stop. CONSTITUTION: Upon the receipt of an original position return command signal RET from a PC 40, a CPU 21 commands it to a pulse generating circuit 22 to accelerate a moving object 13 to the original position. The pulse generating circuit 22 increases gradually the frequency of a pulse signal CW to accelerate the moving object 13 from start speed to high speed. When an original position sensor 15 is turned on, the CPU 21 decelerates the moving object 13 and when the sensor 15 is deergized, the CPU 21 stops the moving object 13. Then the CPU 21 gives a command to the pulse generating circuit 22 to move the moving object 13 in a reverse direction to the restoration direction. The pulse generating circuit 22 increases gradually the frequency of a pulse signal CCW to accelerate and move the moving object 13 from low speed to high speed in the reverse direction to the original position restoration direction. Then the moving object 13 is decelerated till the original position sensor 15 is turned on and then deenergized and the CPU 21 stops the moving object 13 when the original position sensor 15 is turned OFF.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning controller for controlling a positioning device for positioning a moving body, and more particularly to controlling the origin returning operation of the moving body.

[0002]

2. Description of the Related Art In factory automation (FA), it is necessary to position a moving body with high accuracy. A positioning device that moves the moving body by a motor such as a stepping motor or a servo motor is used to position the moving body, and a positioning controller is used to control the positioning device.

The positioning controller generates a pulse signal corresponding to the moving speed and the moving distance of the moving body and gives the pulse signal to the positioning device. As a result, the motor moves the moving body at the moving speed corresponding to the frequency of the pulse signal by the moving distance corresponding to the number of pulses of the pulse signal.

At the start of the operation of such a positioning device, it is necessary to perform an origin returning operation for returning the moving body to a predetermined origin position. Conventionally, mainly two methods have been proposed to perform the origin return operation.

The first method is to control the origin return operation using a pre-origin sensor arranged near the origin position and an origin sensor arranged at the origin position. A method of returning to the origin using such two sensors is disclosed in, for example, Japanese Patent Laid-Open No. 59-144397.

FIG. 4 is a diagram showing the relationship between the position and speed of a moving body in the origin returning method using the front origin sensor and the origin sensor. In Fig. 4, the origin sensor is located at position XD.
It is assumed that the origin sensor is located at position X0. Further, it is assumed that the moving body is located at the position X1 when the return-to-origin command is given.

When a home return command is given, the mobile body is moved in the home return direction (direction closer to the home position X0) while being accelerated, and when the speed of the mobile body reaches a predetermined speed, the mobile body is driven at a constant speed. Move in the same direction. When the front origin sensor is turned on when the moving body reaches the position XD, the moving body is decelerated to a predetermined low speed and then moved in the same direction at a constant speed, and when the origin sensor is turned on, the moving body is stopped. Let In this way, the moving body stops at the origin position X0.

The second method is to control the origin returning operation using only the origin sensor arranged at the origin position. Such an origin returning method using only one sensor is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2-71313 and 2
No. 246796.

FIG. 5 is a diagram showing the relationship between the position and speed of the moving body in the origin returning method using only the origin sensor. In FIG. 5, the origin sensor is assumed to be located at the origin position X0. Further, it is assumed that the moving body is located at the position X1 when the return-to-origin command is given.

When the origin return command is given, the moving body is moved while accelerating in the origin returning direction, and when the speed of the moving body reaches a predetermined speed, the moving body is moved at the same speed in the same direction. Then, when the origin sensor is turned on, the moving body is decelerated and stopped. During this time, the origin sensor is turned on for a certain period of time and then turned off. In this case, the moving body stops at a position that has exceeded the origin position. Therefore, the moving body is moved at a constant speed in the opposite direction to the above-mentioned origin return direction at a low speed, and is stopped when the origin sensor is turned on and then turned off.

Usually, the origin sensor has a hysteresis characteristic, or the mechanical part for moving the moving body may have a backlash, so that the origin sensor is in the ON state while the moving body is moving in the direction of returning to the origin. The position of the moving body when changing from the OFF state to the OFF state is different from the position of the moving body when the origin sensor changes from the OFF state to the ON state while the moving body is moving in the direction opposite to the home return direction. Therefore, the stop position of the moving body is a position slightly passing the origin position X0. Therefore, the moving body is moved again in the above-described origin returning direction at a predetermined low speed, and stopped when the origin sensor is turned on. In this way, the moving body moves to the origin position X0.
Stop at

[0012]

In the origin return method using the pre-origin sensor and the origin sensor, if the return speed of the moving body is increased, the speed of the moving body becomes sufficiently low after the pre-origin sensor is turned on. The origin sensor will be turned on before. In that case, the moving body cannot stop at the origin position and passes through the origin position and stops. As a result, the stop position of the moving body deviates from the origin position.

Therefore, if the front origin sensor is arranged at a position sufficiently distant from the origin sensor, the speed of the moving body becomes sufficiently low at the time when the origin sensor is turned on, even if the returning speed of the moving body is increased. However, since it takes a long time for the moving body to move at a low speed after the origin sensor turns on until the origin sensor turns on, there is a problem that it takes time for the moving body to return to the origin position. Further, every time the speed pattern of the moving body is changed, it is necessary to change the position of the pre-origin sensor so that the speed of the moving body becomes sufficiently low when the origin sensor is turned on.

On the other hand, in the origin returning method using only the origin sensor, when the deceleration time of the moving body in the direction of returning to the origin is long, or when the returning speed of the moving body at a constant speed is high, the moving body moves to the origin position. The distance overshooting becomes longer. In that case, since the moving body must be returned at a low speed by the distance that has passed too much, there is a problem that it takes time for the moving body to return to the origin position. Further, even if the distance overshooting is short, if the moving body must be returned at a lower speed, it takes time for the moving body to return to the origin position.

An object of the present invention is to provide a positioning controller capable of controlling the positioning device so as to accurately return the moving body to the original position in a short time.

[0016]

[Means for Solving the Problems]

(1) First Invention A positioning controller according to the first invention controls a positioning device that includes an origin detection unit that detects that a moving body is at a predetermined origin position and that positions the moving body. The positioning controller includes command means for commanding a moving direction and moving speed of the moving body, and pulse generating means for giving a pulse signal for driving the moving body to the positioning device in response to a command from the command means. Prepare When the origin return command is given, the command means instructs the pulse generating means to move the moving body in the direction of returning to the origin position, and decelerates the moving body in response to the detection of the moving body by the origin detecting means. The pulse generator is instructed to stop, and after stopping the moving body, in order to return the moving body to the origin position, the moving body is accelerated in a direction opposite to the return direction and then decelerated to stop the pulse. Command generation means.

(2) Second invention In the positioning controller according to the second invention, in the configuration of the positioning controller according to the first invention, the command means moves the moving body from the time when the moving body is detected by the origin detecting means. The switching timing between the acceleration movement and the deceleration movement in the direction opposite to the return direction is calculated on the basis of the number of pulses of the pulse signal generated by the pulse generation means before the stop.

(3) Third Invention A positioning controller according to a third invention is the positioning controller according to the first or second invention, wherein the moving body is decelerated in a direction opposite to the returning direction. Then, the command means generates a pulse so that the moving body is moved in the direction of returning to the origin position at a predetermined low speed after stopping after passing the origin position by the, and the moving body is stopped when the moving body is detected by the origin detecting means. It is a command to the means.

[0019]

In the positioning controller according to the first to third inventions, when the origin return command is given, the moving body is moved in the returning direction to the origin position and responds to the detection of the moving body by the origin detecting means. The moving body is decelerated and stopped. In this case, since the stop position of the moving body is a position which has passed the origin position too much, the moving body is returned in the direction opposite to the above-mentioned returning direction. When moving in the opposite direction, after the moving body is accelerated,
It is decelerated and stopped. Therefore, the moving body can be accurately returned in a short time by the distance that has passed from the origin position.

Particularly, in the positioning controller according to the second aspect of the present invention, the command means accelerates in the opposite direction based on the number of pulses generated from the time when the origin detecting means detects the moving body to when the moving body stops. By calculating the switching timing between the movement and the deceleration movement, it is possible to switch between the acceleration movement and the deceleration movement at an appropriate timing according to the overshoot distance.

Further, in the positioning controller according to the third aspect of the invention, the moving body passes through the origin position and stops after decelerating movement in the direction opposite to the returning direction, and then the moving body moves in the returning direction to the origin position. By moving at a predetermined low speed and stopping the moving body when the moving body is detected by the origin detecting means,
Even when the origin detecting means has a hysteresis characteristic, or when the mechanical portion for moving the moving body has a backlash, the moving body can be accurately stopped at the origin position.

[0022]

1 is a diagram showing the configuration of a positioning system using a positioning controller according to an embodiment of the present invention. The positioning system in FIG. 1 includes a positioning device 10, a positioning controller 20, a motor driver 30, and a programmable controller (hereinafter referred to as a PC) 40.

In the positioning device 10, the ball screw 12 is rotated by the rotation of the stepping motor 11. As a result, the moving body 13 fitted in the ball screw 12 moves in the direction indicated by the arrow X along the guide 14. Here, the stepping motor 11 is clockwise (CW direction).
When it is rotated to the right, the moving body 13 moves to the right on the paper surface,
It is assumed that when the stepping motor 11 rotates counterclockwise (CCW direction), the moving body 13 moves leftward on the paper surface.

An origin sensor 15 is arranged at a predetermined origin position within the moving range of the moving body 13. Also,
The stepping motor 11 rotates clockwise to move the moving body 1.
The limit sensor 16 is arranged at the limit position when 3 moves to the right of the paper, and the limit sensor 16 is placed at the limit position when the stepping motor 11 rotates counterclockwise and the moving body 13 moves to the left of the paper. 17 are arranged. The origin sensor 15 turns on when detecting the moving body 13,
The detection signal OLS is generated. Also, limit sensor 1
6 and 17 turn on when the moving body 13 is detected, and generate limit signals CWL and CCWL, respectively.

The stepping motor 11 is provided with a rotary encoder 18 that generates a Z-phase pulse (zero-phase pulse) ZER for each rotation from the reference position. The positioning controller 20 includes a CPU (central processing unit) 21 and a pulse generation circuit 22. The CPU 21 detects the detection signal OLS from the origin sensor 15, the limit sensor 16,
In response to the limit signals CWL, CCWL from 17, the Z-phase pulse ZER from the rotary encoder 18, the home-return command signal RET and the operation command signal OP from the PC 40, a command is given to the pulse generation circuit 22. In response to a command from the CPU 21, the pulse generation circuit 22 generates a pulse signal CW for rotating the stepping motor 11 clockwise or a pulse signal CCW for rotating the stepping motor 11 counterclockwise, To the motor driver 30. The motor driver 30
The stepping motor 11 is driven in response to the pulse signals CW and CCW from the pulse generation circuit 22.

Next, the origin return operation in the positioning controller 20 of FIG. 1 will be described. FIG. 2 is a diagram showing the relationship between the position and speed of the moving body 13 and the state of the detection signal OLS from the origin sensor 15 in the origin returning operation. Also, FIG.
3 is a flowchart showing an origin returning operation of the positioning controller 20.

In FIG. 2, the origin sensor 15 is assumed to be located at the origin position X0. Further, it is assumed that the moving body 13 is at the position X1 when the return-to-origin command is given.

When the origin return command signal RET is given from the PC 40 (step S1), the CPU 21 causes the moving body 1 to move.
Pulse generator circuit 22 to accelerate 3 in the direction of return to origin.
Command. Here, in the home-return direction, the stepping motor 11 is rotated clockwise in FIG.
Let 3 be the direction to move to the right of the paper.

The pulse generation circuit 22 generates the pulse signal CW and gradually increases its frequency to accelerate the moving body 13 from the starting speed of the low speed P1 to the high speed P2 (step S2). After that, the pulse generation circuit 22 keeps the frequency of the pulse signal CW constant and moves the moving body 13 in the same direction at a constant speed until the origin sensor 15 is turned on (step S3).

The origin sensor 15 is turned on to detect the detection signal OLS.
Rises to a high level (step S4), the CPU
21 commands the pulse generation circuit 22 to decelerate the moving body 13. As a result, the pulse generation circuit 22
By gradually reducing the frequency of the pulse signal CW, the moving body 13
Is decelerated from the high speed P2 (step S5). During this time,
The origin sensor 15 is turned on for a fixed time and then turned off. When the speed of the moving body reaches the low speed P1 (step S6), the generation of the pulse signal CW is stopped to stop the moving body 13 (step S7). The stop position of the moving body 13 at this point is X2. In this case, the moving body 13 has gone too far by the distance from the origin position X0 to the stop position X2.
During this time, the CPU 21 controls the pulse generation circuit 22 from the time when the origin sensor 15 is turned on to the time when the moving body 13 is stopped.
The number of pulses of the pulse signal CW generated by is counted.

Next, the CPU 21 commands the pulse generation circuit 22 to move the moving body 13 in the direction opposite to the above-mentioned return direction (step S8). As a result, the pulse generation circuit 22 generates the pulse signal CCW and gradually increases its frequency to accelerate the moving body 13 from the low speed −P3 to the high speed −P4 in the direction opposite to the above-described origin return direction ( Step S9).

The CPU 21 determines whether the moving body 13 is between the stop position X2 and the origin position X0 based on the number of pulses from the time when the origin sensor 15 is turned on to the time when the moving body 13 is stopped in the deceleration movement of step S5. The number of pulses of the pulse signal CCW required to return to the intermediate position X3 is calculated. Then, when the number of pulses of the pulse signal CCW generated by the pulse generation circuit 22 reaches the above-mentioned required number of pulses after the start of the movement of the moving body 13 in the direction opposite to the home-return direction, the CPU 21 moves the moving body. The pulse generation circuit 22 is instructed to decelerate 13 (step S10). As a result, the pulse generation circuit 22 gradually decreases the frequency of the pulse signal CCW and decelerates the moving body 13 until the origin sensor 15 turns on and then turns off (step S1).
1).

When the origin sensor 15 is turned off (step S
12), the CPU 21 commands the pulse generation circuit 22 to stop the moving body 13. Thereby, CPU2
1 stops the generation of the pulse signal CCW and stops the moving body 13 (step S13). In this case, if the origin switch 15 has a hysteresis characteristic, or if the fitting portion between the ball screw 12 and the moving body 13 has backlash, the moving body 13 is moving in the home return direction. The position of the moving body 13 when the origin switch 15 changes from the off state to the on state and the moving body when the origin switch 15 changes from the on state to the off state while the moving body 13 is moving in the direction opposite to the home return direction. 13 is out of position. Therefore, the moving body 13 stops at the position X4 which has slightly passed the origin position X0.

Next, the CPU 21 causes the pulse generating circuit 2 to move the moving body 13 again in the above-mentioned origin returning direction.
2 is instructed (step S14). As a result, the pulse generating circuit 22 generates the pulse signal CW and keeps its frequency constant, and moves the moving body 13 at a low speed P1 at a constant speed in the above-described origin returning direction until the origin sensor 15 is turned on (step S15). ).

The origin sensor 15 is turned on to detect the detection signal OLS.
Rises to a high level (step S16), CP
U21 commands the pulse generation circuit 22 to stop the moving body 13. As a result, the pulse generation circuit 22
Stops the generation of the pulse signal CW and stops the moving body 13 (step S17). In this way, the moving body 1
3 returns to the origin position X0.

In the positioning controller 20 of the above embodiment, when the moving body 13 is returned from the stop position X2 to the origin position X0, the moving body 13 is accelerated once and then decelerated, so that the moving body 13 is moved. The time for returning the distance from the stop position X0 to the excessive distance is shortened.

Further, the switching timing between the acceleration movement and the deceleration movement when returning from the stop position X2 to the origin position X0 is calculated based on the number of pulses generated until the moving body 13 passes the origin position X0 and stops. Origin position X
Even if the distance from 0 to the stop position X2 is not constant,
It is possible to accurately control the speed of the moving body 13 at the time of returning to the origin position X0 to a predetermined low speed-P3 by switching between the acceleration movement and the deceleration movement at an appropriate timing. Therefore, the moving body 13 can be accurately returned to the origin position X0 in a short time.

In the above embodiment, the speed gradient in step S9 is the same as the speed gradient in step S2, and the speed gradient in step S11 is the same as the speed gradient in step S5. The velocity gradient and the velocity gradient in step S11 may be set separately from the velocity gradient in step S2 and the velocity gradient in step S5, respectively.

In the above embodiment, the velocity gradient in step S9 and the velocity gradient in step S11 are symmetrical with respect to the intermediate position X0.
The inclination of the speed in 9 and the inclination of the speed in step S11 do not have to be symmetrical, and the switching position between them may not be the intermediate position X3 between the origin position X0 and the stop position X2.

In these cases, the inclination of the speed in step S9 and step S11 can be set arbitrarily within the range in which the motor of the positioning device can follow the change in speed, and the acceleration movement of step S9 and step S1 can be performed.
The switching timing for the deceleration movement of 1 is calculated based on the number of pulses generated in step S5.

The speeds P1 and P2 and step S5
The speed-P4 may be calculated from the speed slope in step S9, or the speed slope in step S9 may be calculated.

[0042]

As described above, according to the first to third aspects of the invention, the moving body is moved in the returning direction to the origin position, and the moving body is accelerated when returning the moving body by the distance that has passed too far from the origin position. Since the moving body is decelerated after being moved, the moving body can be accurately returned to the origin position in a short time.

In particular, according to the second aspect of the present invention, even when the distance overshooting from the origin position is different, the acceleration movement and the deceleration movement can be switched at an appropriate timing. Further, according to the third invention, even when the origin detecting means has a hysteresis characteristic or the mechanical portion for moving the moving body has a backlash, the moving body can be accurately stopped at the origin position.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a positioning system using a positioning controller according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a position and a speed of a moving body and a state of a detection signal by an origin sensor in an origin returning operation by the positioning controller of FIG.

FIG. 3 is a flowchart showing an origin returning operation in the positioning controller of FIG.

FIG. 4 is a diagram showing the relationship between the position and speed of a moving body in a conventional origin returning method using a front origin sensor and an origin sensor.

FIG. 5 is a diagram showing a relationship between a position and a speed of a moving body in a conventional origin returning method using only an origin sensor.

[Explanation of symbols]

 10 Positioning Device 11 Stepping Motor 13 Moving Object 15 Origin Sensor 20 Positioning Controller 21 CPU 22 Pulse Generation Circuit 30 Motor Driver 40 PC In addition, the same reference numerals in each drawing indicate the same or corresponding parts.

Claims (3)

[Claims] 1. A positioning controller for controlling a positioning device for positioning a moving body, the positioning controller including origin detecting means for detecting that the moving body is located at a predetermined origin position. And a pulse generating means for giving a pulse signal for driving the moving body to the positioning device when a command is given from the command means, and the command means is an origin point. When a return command is given, the pulse generating means is instructed to move the moving body in the returning direction to the origin position, and the moving body is decelerated in response to the detection of the moving body by the origin detecting means. To the pulse generating means, and after stopping the moving body, in order to return the moving body to the origin position, the moving body is applied in a direction opposite to the return direction. A positioning controller for instructing the pulse generating means to move at a high speed, then decelerate and stop. 2. The returning means based on the number of pulses of a pulse signal generated by the pulse generating means from the time when the moving body is detected by the origin detecting means to the time when the moving body is stopped. 2. The positioning controller according to claim 1, wherein a switching timing for accelerating movement and decelerating movement in the opposite direction is calculated. 3. The instructing means sets the moving body in a returning direction to the origin position after the moving body has passed through the origin position and stopped by decelerating in a direction opposite to the returning direction. 3. The positioning controller according to claim 1, wherein the pulse generation means is instructed to move at a low speed and stop the moving body when the origin detecting means detects the moving body.