JPH1014292A - Step out detector for stepper motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step out detector for stepper motor, so as to detect step out without using a position detector, such as encoder. SOLUTION: The rotor of a stepper motor 1 is driven by supplying a pulse train to the stepper motor 1 from a shift instructing part 4, the number of pulses of the pulse train is counted by an instruction position counter 5, a switch element 11 is arranged at a position opposite to a previously fixed position in the path, wherein a table 3 shifts by the rotation of the rotor of the stepping motor 1, and the change of the output from the switch element 11, which is generated by sensing the magnetic flux of a magnet 10 provided on the table 3 when the table 3 passes through the opposing position of the switch element 11, is detected by a change-point detecting part 12. Then, the count value of the instruction position counter 5 is latched when the change point is detected by the change point detecting part 12, and when the position of the table 3 based on the latch count value is not within the sum of the arranged position value of the switch element 11 set by a change point position setting part 13 and a value based on the accuracy of the switch element 11 set by an operation accuracy setting part 14, step out is detected by a step-out detecting part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor out-of-step detecting device, and more particularly to a stepping motor for detecting step-out of a stepping motor in cooperation with a position detection signal of a moving body driven by the stepping motor. Out-of-step detection device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a table actuator 31 uses a stepping motor 1 as a drive motor, and drives a table 3A by a ball screw 2 which is driven to rotate by a rotor of the stepping motor 1. In this conventional table actuator 31, the stepping motor 1 is driven based on an instruction from the controller 30 composed of a computer to position the table 3A.

The controller 30 receives a movement command unit 4 for generating a command serial pulse, a command position counter 5 for counting output command serial pulses from the movement command unit 4, and an output command serial pulse from the movement command unit 4. A driving circuit 6 for converting the driving signal into a driving signal based on the number of phases and the number of exciting phases of the stepping motor 1; receiving an output pulse of an encoder 7 provided on a rotor shaft of the stepping motor 1 and counting the number of output pulses of the encoder 7. By table 3
A position detection counter 8 that substantially detects the position of A, and a step-out detection unit 9A that detects a step-out by comparing the count value of the command position counter 5 with the count value of the position detection counter 8 is functionally provided. I have.

The controller 30 constructed as described above
, The stepping motor 1 via the drive circuit 6 based on the command serial pulse output from the movement command unit 4
Is driven. The rotation angle of the rotor shaft of the stepping motor 1 is detected by an encoder 7, and a serial pulse based on the rotation angle is transmitted. This serial pulse is counted by a position detection counter 8, and the counted value of the command position counter 5 and the position detection counter 8 Is counted by the out-of-step detection unit 9A, and when the count values of both counters do not match, it is determined that step-out has occurred.

[0005]

However, in the case of the conventional step-out detection as described above, it is necessary to detect the position of the moving body using a position detector such as an encoder, and the volume of the position detector such as an encoder is reduced. Because of the large size, there is a problem that the volume of the entire stepping motor out-of-step detecting device becomes large even if the volume of the stepping motor is small.

Further, there is a problem that a position detector such as an encoder is expensive, and even if a stepping motor is inexpensive, a step-out detecting device for a stepping motor eventually becomes expensive.

Further, in the conventional controller for detecting step-out, step-out is judged by constantly comparing the position command value and the detected position, so that a controller having a high processing capability is required. Was complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stepping motor step-out detecting device capable of detecting step-out without using a position detector such as an encoder.

[0009]

A step-out detecting apparatus for a stepping motor according to the present invention comprises a driving pulse generating means for supplying a pulse train to the stepping motor to drive a rotor of the stepping motor, and counting the number of pulses in the pulse train. And a switch that is installed to face a predetermined position in the movement path of the moving body that moves in accordance with the rotation of the rotor, and that generates an output when the moving body passes through a position facing the installation position. Means, a change point position setting means for setting a value (α) corresponding to the installation position of the switch means, and an operation accuracy setting means for setting a value (β) corresponding to the output generation position accuracy of the switch means. A change point detecting means for detecting a change point of the output of the switch means; and a count value of the counter when the change point is detected by the change point detecting means. And step-out detection means for detecting whether or not the latched count value is within the value (α ± β) and transmitting a step-out detection signal when detecting that the count value is not within the value. Features.

According to the stepping motor out-of-step detecting device according to the present invention, the rotor of the stepping motor is driven to rotate based on the pulse train output from the driving pulse generating means, and the moving body is driven in accordance with the rotation of the rotor. Is done. The switch generates an output when passing through a position opposite to the position where the switch is installed while the moving body is moving. When the output of the switch means is generated, it is also detected by the change point detecting means. On the other hand, the pulse train is counted by a counter, and the counted value corresponds to the position of the moving body. The time when the switch means generates an output is when the moving body passes through a position facing the installation position of the switch means, and at this time, the count value of the counter is latched.

However, the latched count value corresponds to the position where the moving body is opposed to the installation position of the switch means. When the moving object is not out of synchronization, the latched count value is (α ±
β). However, when the latched count value is (α
If it is detected that it is not within ± β), it means that the stepping-out occurs, and when the moving object does not reach the position within (α ± β) due to the step-out, Is detected, and a step-out detection signal is transmitted. When the latched count value is within (α ± β), it is determined that there is no step-out.

In the stepping motor step-out detecting device according to the present invention, the value (α) set in the change point position setting means is a value of a position at which the switch means generates an output when the moving body is moved. There is a feature.

The value (α) set in the change point position setting means
Is the position value when the switch means generates an output when the moving body is moved, the count value of the counter when the switching means generates the output by driving the moving body is defined as a value (α). This makes it easy to set the value of the change point position setting means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A step-out detecting device for a stepping motor according to the present invention will be described with reference to an embodiment.

FIG. 1 is a block diagram showing a configuration of a step-out detecting device for a stepping motor according to an embodiment of the present invention.

In the stepping motor step-out detecting device according to one embodiment of the present invention, the same components as those of the conventional example shown in FIG. 4 are denoted by the same reference numerals.

A table actuator 21 to which the stepping motor out-of-step detecting device according to the present embodiment is applied uses a stepping motor 1 as a driving motor and a ball screw 2 which is rotationally driven by a rotor of the stepping motor 1. Table 3 is driven.

A magnet 10 is mounted on the table 3.
In addition, a switch element 11 that generates an output when it faces the magnet 10 and that generates an on / off output, for example, is formed of a magnetoresistive element or the like. It is installed at a predetermined position. Here, switching means is formed by the magnet 10 and the switching element 11.

In the table actuator 21, the stepping motor 1 is driven based on an instruction from the controller 20 composed of a computer to position the table 3.

The controller 20 receives a movement command section 4 for generating a command serial pulse, a command position counter 5 for counting output command serial pulses from the movement command section 4, and an output command serial pulse from the movement command section 4. A drive circuit 6 for converting to a drive signal based on the number of phases and the number of excitation phases of the stepping motor 1, a change point detecting unit 12 for receiving a change from the switch element 11 and detecting a change point of the output from the switch element 11, The count value of the position command counter 5 is latched by the detection signal from the point detection unit 12, the latched count value, the change point position information set in the change point position setting unit 13 described later, and the operation accuracy setting unit 14 described later. Step-out detecting unit 9 for detecting a step-out based on the operation accuracy information set in the above.

Here, the movement command section 4 corresponds to the drive pulse generating means, the change point detecting section 12 corresponds to the change point detecting means, and the change point position setting section 13 corresponds to the change point position setting means. The accuracy setting unit 14 corresponds to an operation accuracy setting unit,
The step-out detecting section 9 corresponds to the latch means and the step-out detecting means.

As schematically shown in FIG. 2A, the change point position setting section 13 changes the signal output from the switch element 11 by the movement of the table 3 at the change points corresponding to the table positions a and b. Point position information is set. The gap between the table positions a and b at this change point corresponds to the operation clearance of the switch element 11. This is because the operation of the switch element 11 has an operation clearance,
This is because the position of the table 3 when the output changes from off (open) to on (closed) differs from the position of the table 3 when the output changes to off after being turned on.

As schematically shown in FIG. 2B, the operation accuracy setting section 14 sets a value corresponding to the accuracy of the output generation position of the switch element 11, that is, when a change in the output signal of the switch element 11 occurs. Are set based on the variation in the position of the table 3 in the table 3, and the values Δa / 2 and Δb / 2 are set at the table positions a and b, respectively.

Here, the step-out detection by the step-out detection unit 9 is performed by detecting the position of the table 3 based on the count value of the command position counter 5 when the output from the change point detection unit 12 is generated (hereinafter, the total value of the command position counter 5). The position of the table 3 based on the numerical value is also simply referred to as the count value of the counter 5) and (a ± Δa
/ 2) and the position of the table 3 based on the count value is not within (a ± Δa / 2) or the count value of the command position counter 5 when the output from the change point detection unit 12 is generated. The position of the table 3 based on the counted value is compared with the position of the table 3 based on (b ± Δb / 2), and
If it is not within b / 2), it is detected as a step-out. Therefore, a step-out is detected in the hatched portion in FIG.

The operation of the stepping motor out-of-step detecting device according to the embodiment of the present invention configured as described above will be described.

In the table actuator 21 configured as described above, a command serial pulse is generated from the movement command unit 4 on the table 3 based on a drive command. A drive pulse is generated based on the number of phases and the number of excitation phases of the stepping motor 1 in the drive circuit 6 that has received the command serial pulse output from the movement command unit 4, and the stepping motor 1 receives the output from the drive circuit 6 and receives the output. Driven. Immediately before the generation of the command serial pulse, the count value of the command position counter 5 is cleared, and subsequently, the command serial pulse is counted by the command position counter 5.

The rotation of the rotor of the stepping motor 1 based on the output from the drive circuit 6 drives the ball screw 2 to rotate.
Is moved. By moving the table 3, the magnet 10
Is close to the switching element 11 or the switching element 1
Move away from 1.

The output of the switch element 11 changes from the OFF state to the ON state due to the proximity of the magnet 10 to the switch element 11, and the output of the switch element 11 changes from the ON state to the OFF state when the magnet 10 moves away from the switch element 11. Changes to When there is a change in the output of the switch element 11, the change point detection unit 12
Is detected (step S).
1).

When the change point detector 12 detects a change in step S1, the count value of the command position counter 5 is latched (step S2). Therefore, step S
2 is executed, the position of the table 3 when the output of the switch element 11 changes is detected,
The position is temporarily stored in the storage device of the controller 20.

Subsequent to step S2, the position of the table 3 based on the latched count value of the command position counter 5 is compared with (a ± Δa / 2), and the counted value of the latched command position counter 5 is calculated. The position of the table 3 based on (a
It is checked whether it is within ± Δa / 2) (step S3). In step S3, when it is determined that the position of the table 3 based on the count value of the latched command position counter 5 is within (a ± Δa / 2), it is detected as normal, and the count value of the command counter 5 is determined. The latch is released, and the next operation is performed (step S4).

If it is determined in step S3 that the position of the table 3 based on the count value of the latched command position counter 5 is not within (a ± Δa / 2), the total of the latched command position counter 5 is counted. The position of the table 3 based on the numerical value is compared with (b ± Δb / 2) to determine whether the position of the table 3 based on the latched count value of the command position counter 5 is within (b ± Δb / 2). Is checked (step S5).

In step S5, when it is determined that the position of the table 3 based on the count value of the latched command position counter 5 is not within (b ± Δb / 2), step-out is detected and step-out detection is performed. A signal is sent (step S
6). In step S5, the position of the table 3 based on the latched count value of the command position counter 5 is (b ± Δ
When it is determined that it is within b / 2), it is detected as normal, and the latch of the count value of the command position counter 5 is released (step S4), and the next operation is executed.

Here, a method of obtaining change point position information set in the change point position setting section 13 will be described. The change point position information set in the change point position setting unit 13 is obtained by moving the table 3 at a very low speed, detecting the ON / OFF change position of the switch element 11 during the movement, and converting the information based on the change point into the change point. What is necessary is just to set as positional information. Further, a change point position setting unit 13 is provided in the controller 20 to drive the table 3 as described above, and to detect the ON / OFF change position of the switch element 11 during the movement of the table 3, and When the output is turned on and off, the count value of the command position counter 5 can be used as the change point position information.

In the above description, in the case of the ideal switch element 11 having no gap between the operations, the output from the switch element 11 changes at one point where the switch element 11 and the magnet 10 face each other. Thus, the change point position setting unit 13 sets only one point, for example, information of a, and the operation accuracy setting unit 14 only needs to set Δa. However, in reality, the switching element 11 has an operation clearance. Therefore, the step-out device for a stepping motor according to the embodiment of the present invention described above is advantageous.

In the step-out device for a stepping motor according to the embodiment of the present invention, step S3 is performed.
Since step S5 is executed, it is not necessary to detect the moving direction of the table 3. On the other hand, the moving direction may be detected in the table 3 and step S3 or step S5 may be executed based on the moving direction.

As the switch element 11, a proximity switch, a photo micro switch, a micro switch having a mechanical contact, or the like can be used.

[0037]

As described above, according to the stepping motor out-of-step detecting apparatus of the present invention, step-out of the stepping motor can be detected without using an encoder, and the switch means for detecting the table position can be used. 1
By arranging one, it is possible to obtain an effect that the configuration is simplified.

Further, the step-out detection of the step-out motor step-out detection device according to the present invention detects whether or not step-out has occurred when the output of the switch means for detecting the table position changes. It is not necessary to monitor the movement position of the step, and it is sufficient to interrupt the step-out detection means for detecting whether or not step-out occurs when the output of the switch means is generated, and the processing capability of the step-out detection means is reduced. There is.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a step-out detection device for a stepping motor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a setting value of a change point position setting unit showing a configuration of a stepping motor out-of-step detecting device according to an embodiment of the present invention;

FIG. 3 is a flowchart for explaining an operation of the stepping motor out-of-step detecting device according to the embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a step-out device for a conventional stepping motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Ball screw 3 Table 4 Movement command part 5 Command position counter 6 Drive circuit 9 Step-out detection part 10 Magnet 11 Switch element 12 Change point detection part 13 Change point position setting part 14 Operation accuracy setting part 20 Controller 21 ... Table Actuator

Claims (2)

[Claims] 1. A driving pulse generating means for supplying a pulse train to a stepping motor to drive a rotor of the stepping motor, a counter for counting the number of pulses of the pulse train, and a moving path of a moving body moving in accordance with the rotation of the rotor. And a switch means for generating an output when the moving body passes through a position facing the installation position, and a value (α) corresponding to the installation position of the switch means. Change point position setting means to be set, operation accuracy setting means to set a value (β) corresponding to the output generation position accuracy of the switch means, and change point detection means to detect a change point of the output of the switch means Latch means for latching the count value of the counter when the change point is detected by the change point detection means, and whether the latched count value is within a value (α ± β) And a step-out detecting means for transmitting a step-out detection signal when the step-out is detected. 2. The stepping motor step-out detecting device according to claim 1, wherein the value (α) set in the change point position setting means is a position at which the switch means generates an output when the moving body is moved. A step-out detection device for a stepping motor.