JPH07129236A - Position deviation detecting device - Google Patents

Abstract

PURPOSE:To detect a position deviation due to the step-out, etc., of a motor without requiring any encoder. CONSTITUTION:A motor driver 2 sends operation pulses to a stepping motor 3 according to an operation command of a controller 1 and the operation pulses are fed back to the controller 1. The controller 1 integrates the operation pulses, and reads a stored operation pulse value, stored previously in a ROM 10, and compares it with the integrated operation pulse value once detectors 8 and 9 detect a specific position being reached. When the difference between the both is larger than a specific value, abnormality is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for moving a moving body using a motor controlled by operation pulses, and more particularly to a position shift detecting device capable of detecting a position shift due to step out of the motor.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration of a moving device for a moving body using a conventional stepping motor. The controller 21 sends an operation command to the motor driver 22 to operate the stepping motor 23. The stepping motor 23 includes a drive pulley 24 and a driven pulley 2
5, the moving body 27 by driving the drive mechanism including the belt 26
To move. Detectors 28 and 29 are provided at predetermined positions on both ends of the movement of the moving body 27. The rotation of the drive shaft of the stepping motor 23 is detected by the encoder 30.

[0003]

According to the configuration as shown in FIG. 2, the detector 2 in which the moving body 27 is arranged at both ends of the moving path is used.
High-accuracy positioning is possible by detecting with 8 and 29. However, if there is an unexpected load change, the stepping motor 23 loses synchronization and accurate positioning cannot be performed. Therefore, the encoder 30 attached to the drive shaft of the stepping motor 23 constantly sends a position signal to the controller 21. I try to give feedback. However, since the encoder 30 and the encoder signal processing system are generally delicate, they are likely to cause a failure or malfunction and are expensive.

Therefore, an object of the present invention is to provide a positional deviation detecting device which is highly reliable and can be constructed at low cost.

[0005]

In order to achieve the above object, the present invention provides an integrating means for accumulating operation pulses of a motor for moving a moving body, a detecting means for detecting the moving body at a predetermined position, and the predetermined means. The storage means for storing the operation pulse value in the normal operation at the position in advance is compared with the integrated operation pulse value and the stored operation pulse value at the predetermined position, and if there is a deviation of a predetermined value or more, it is determined to be abnormal The misregistration detection device is configured to have a comparison means.

[0006]

Since the present invention has the above-mentioned structure, it has the following effects.

According to the position shift detecting device of the present invention,
The integrating means integrates the operation pulses of the motor along with the operation. When the moving body reaches a predetermined position, the detecting means detects the moving body, and the comparing means compares the integrated operation pulse value with the stored operation pulse value during normal operation stored in advance in the storage means, and then sets the predetermined value. If there is the above deviation, it is determined to be abnormal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below.

FIG. 1 is a block diagram showing the configuration of an embodiment of the position shift detecting apparatus according to the present invention.

In FIG. 1, the controller 1 gives an operation command to the motor driver 2, and the motor driver 2 generates an operation pulse to operate the stepping motor 3. Further, the operation pulse is fed back to the controller 1. The fed back operation pulse value is integrated by the controller 1 in the forward-reverse count according to the forward and reverse rotation directions.

The stepping motor 3 drives the drive pulley 4 to move the moving body 7 fixed to the belt 6 stretched between the drive pulley 4 and the driven pulley 5. Moving body 7
Detectors 8 and 9 are respectively arranged at predetermined positions on both ends of the movement of, and the moving bodies 7 reaching the predetermined positions can be detected.

A ROM 10 is connected to the controller 1. The operation pulse value at a predetermined position of the moving body 7 is stored in the ROM 10. The controller 1
The operation pulse value stored in the ROM 10 can be read. A timer 11 is connected to the controller 1.

In the present embodiment, the abnormality detection is performed based on the comparison between the integrated operation pulse value and the stored operation pulse value. When the controller 1 gives an operation command to the motor driver 2, the motor driver 2 generates an operation pulse according to the operation command. Stepping motor 3 by operating pulse
Operates in the forward direction, and the moving body 7 moves to the right. The operation pulse is fed back to the controller 1, and the controller 1 accumulates the operation pulse value at any time to obtain the integrated operation pulse value.

When the moving body 7 reaches a predetermined position at the right end of the moving path, the detector 9 detects the moving body 7 and the controller 1
Send a signal to. The controller 1 reads the storage operation pulse value corresponding to the predetermined position at the right end from the ROM 10, and compares the read storage operation pulse value with the integrated operation pulse value. If there is a deviation of a predetermined value or more between the two, it is determined that the positional deviation has occurred due to step out or other abnormality,
Perform abnormal processing such as interrupting operation and issuing an alarm.

The same is true when moving from a predetermined position at the right end to a predetermined position at the left end, and the controller 1 integrates operation pulses for operating the stepping motor 3 in the reverse direction,
When the detector 8 detects the moving body 7, the storage operation pulse value corresponding to the predetermined position at the left end is read from the ROM 10 and stored in the ROM 10.
Read from and compare with the integrated operation pulse value. If the difference between the two is greater than or equal to a predetermined value, it is determined that a position difference has occurred.

As described above, according to the positional deviation detecting apparatus of the present embodiment, the presence or absence of positional deviation is determined by comparing the stored operation pulse value and the integrated operation pulse value at a predetermined position without the need for an encoder. can do.

Further, the operating time T of the stepping motor 3
It is also possible to know the operation interruption state of the stepping motor 3 due to step-out by observing. The relationship between the speed and the position of the moving body 7 is as shown in FIG. 3, and the detectors 8 and 9 detect the moving body 7 at the beginning and the end of the movement, respectively. The controller 1 can measure the time from when one detector detects the moving body 7 to when the other detector detects it by the timer 11. If the operation is normal, the operating time T is substantially equal to the predetermined time stored in the ROM 10 in advance. However, if the operation is interrupted midway due to step-out, the operating time T greatly exceeds the predetermined time.
Therefore, the controller 1 can know that there is a step out.

Further, the operation time can be shortened by changing the speed pattern according to the integrated operation pulse value.

FIG. 4 shows an embodiment of the position shift detecting apparatus according to the present invention applied to the lifting mechanism of the transfer fork. A fork 13 is projectingly provided on a table 12 fixed to a belt 6 that is wound around a drive pulley 4 and a driven pulley 5. The fork 13 transfers the work W placed on the work receiver 14.

When the work W is scooped by the fork 13, the table 12 moves from the lower end position 12L to the upper end 1L.
Raise to the 2H position. In this case, as shown in the diagram representing the speed-position relationship, the table 12 rises from the position of the lower end 12L at a high speed H to just before the work receiving position P, then decelerates to a low speed L, and at a low speed L. Passes through the receiving position P. The acceleration / deceleration in this process (the process of empty load) is limited according to the operating capacity of the drive system.

By contacting the work W with the fork 13 at a low speed L, the impact on the lifting mechanism including the fork 13 and the work W can be minimized. Low speed L
Is limited by an allowable impact value when the work W and the fork 13 are in contact with each other.

After the work W is scooped by the fork 13 at the work receiving position P, the table 12 is accelerated again to the high speed H, decelerated before the upper end 12H, and stopped. The acceleration / deceleration in this process (actual load process) is limited by the allowable acceleration of the conveyed object. Therefore, the acceleration / deceleration may be more limited than in the empty process according to the operating capacity of the drive system.

Even when the work W placed on the fork 13 is placed on the work receiver 14, the table 12 is lowered from the upper end 12H to the lower end 12L by the same speed pattern.

Such operation can be easily realized by performing the operation of the stepping motor 3 for driving the drive pulley 4 based on the position detection based on the operation pulse integrated value. In addition, the movement control as in the present embodiment,
This is particularly advantageous when there are a plurality of transfer levels (positions) of the conveyed product and the movement stroke is large.

The embodiment of the present invention has been described above.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be appropriately modified within the scope of the gist of the present invention.

[0026]

As described above, according to the position shift detecting apparatus of the present invention, the stored operation pulse value and the integrated operation pulse value are compared at a predetermined position without requiring an expensive and low-reliability encoder. By doing so, it is possible to determine whether or not there is a positional deviation due to an abnormality such as step-out of the motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a positional deviation detecting device according to the present invention.

FIG. 2 is a block diagram showing a configuration of an example of a conventional positional deviation detecting device.

FIG. 3 is a diagram showing a speed-position relationship in the embodiment of FIG.

FIG. 4 is a diagram showing another embodiment of the positional deviation detecting device according to the present invention.

[Explanation of symbols]

 1 Controller 2 Motor Driver 3 Stepping Motor 7 Moving Object 8, 9 Detector 10 ROM

Claims (1)

[Claims] 1. An accumulating means for accumulating operation pulses of a motor for moving a moving body, a detecting means for detecting a moving body at a predetermined position, and an operation pulse value in a normal operation at the predetermined position are stored in advance. The storage means and the integrated operation pulse value and the stored operation pulse value at a predetermined position are compared,
A positional deviation detecting device having a comparing means for judging an abnormality when there is a deviation of a predetermined value or more.