JP2001275398A - Zero-point detection method and positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zero-point detection method that can detect a zero point of the reference position of the rotary position of a stepping motor at a fixed position, regardless of the fluctuations in the state of a load and the characteristics of the stepping motor, and a positioning device that prevents deviation in the zero point of the stepping motor, caused by the state of the load and the characteristics of the stepping motor. SOLUTION: A drive circuit 2 makes a stepping motor 3 subjected to microstep driving by a pulse signal from a control circuit 1. A position detection sensor 5 detects an instruction piece 4 of the stepping motor 3. When a specific excitation detection circuit 10 detects specific excitation pattern of the stepping motor 3, the output signal of a decision circuit 20 reaches an H level. When the output of the judgment circuit 20 reaches the H level, the control circuit 1 stops the pulse signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an origin detecting method for detecting an origin which is a reference position of a rotational position of a stepping motor used in industrial equipment, OA equipment, home electric appliances, and the like, and an object to be moved by the stepping motor. The present invention relates to a positioning device that controls a stepping motor so as to move a stepping motor to a target position.

[0002]

2. Description of the Related Art Conventionally, as a positioning device of this type, the one shown in FIG. 8 is known. In other words, the positioning device having the configuration shown in FIG. 8 drives the stepping motor 3 based on the control circuit 1 that outputs a pulse signal of a pulse number corresponding to a desired rotation angle and the pulse signal input from the control circuit 1. And a drive circuit 2. Here, FIG. 8 shows an example in which a two-phase stepping motor is used as the stepping motor 3.
Drives the stepping motor 3 by supplying an exciting current to each phase (A phase, inverted A phase, B phase, and inverted B phase) of the stepping motor 3 based on the pulse signal.

Incidentally, this type of positioning device is mechanically coupled to an output shaft (not shown) of the stepping motor 3 in order to detect an origin which is a reference position of the rotational position of the stepping motor 3. An indicator 4 that rotates together with the indicator 3 and a position detection sensor 5 that detects the indicator 4 when the rotational position of the output shaft of the stepping motor 3 is within a specified section including the origin. Here, the control circuit 1 is constituted by a computer or the like. For example, when power is turned on, the physical (mechanical) rotational position of the output shaft of the stepping motor 3 and the processing (that is, logically) by software are performed. FIG. 9 shows that the stepping motor 3 is rotated in a predetermined direction (direction for returning to the origin) in order to match both origins with the rotational position.
The driving circuit 2 is instructed by a pulse signal as shown in FIG. At this time, the drive circuit 2 starts rotating the stepping motor 3 in a predetermined direction based on the pulse signal from the control circuit 1. Then, when the position detecting sensor 5 detects the pointing piece 4, the output changes from the L level to the H level as shown in FIG. 9B. The control circuit 1 stops outputting the pulse signal immediately upon receiving the detection output (H level signal) of the position detection sensor 5. Therefore, the stepping motor 3 stops at the rotation position when the output of the position detection sensor 5 changes, and the origin of the physical rotation position is determined.

[0004]

However, when the stepping motor 3 is driven by microstepping in the drive circuit 2 of the conventional positioning device, that is, the exciting current of the drive circuit 2 is not changed digitally. When the basic step angle of the stepping motor 3 is driven by further subdividing it in an analog manner, if the load is heavy, the rotation of the stepping motor 3 based on the exciting current and the physical rotation of the stepping motor 3 match. In some cases, the physical rotation is slower and the logical origin position indicated by the excitation current is shifted.

[0005] To explain further, the stepping motor 3
Is ideally determined by the excitation position, and the physical position also coincides with the excitation position. However, when the pointing piece 4 physically reaches the detection position of the position detection sensor 5 as described above, Even when the pulse signal is stopped, the excitation position is in a position advanced in the rotation direction from the indicator 4 due to the load condition and the variation in the characteristics of the stepping motor 3, and further, the variation in the load and the variation in the characteristics of the stepping motor 3. As a result, there is a problem that the logical excitation position is not constant and the logical origin position is shifted. As an example,
Explaining with reference to FIG. 10, the excitation vector V is shifted between the case of FIG. 10A with a light load and the case of FIG. 10B with a heavy load. In FIG. 10, it is assumed that the pointing piece 4 has been rotated clockwise.

The present invention has been made in view of the above circumstances, and an object of the present invention is to determine the origin, which is the reference position of the rotation position of the stepping motor, when the stepping motor is driven by microstepping, and to determine the load state and the stepping state. An origin detection method that can detect the origin of the stepping motor at a fixed position regardless of variations in motor characteristics, and a positioning device that prevents the origin of the stepping motor from shifting due to variations in load conditions and stepper motor characteristics. To provide.

[0007]

According to a first aspect of the present invention, there is provided an apparatus for driving a stepping motor to return a stepping motor to a reference position based on a pulse signal output from a control means. When the stepping motor is rotated, the position detecting means detects that the rotation position of the stepping motor exists in a specified section including the origin which is the reference position, and the excitation pattern of each phase of the stepping motor is When the specific excitation detecting means detects that a specific excitation pattern for positioning the rotational position at the origin is obtained, it is determined that the rotational position of the stepping motor is at the origin, and the stepping motor is microstep-driven. In this case, the origin, which is the reference position of the rotation position of the stepping motor, is Regardless of the variations in the characteristics of the motor can be detected at a predetermined position, allowing accurate positioning.

According to a second aspect of the present invention, in the first aspect of the present invention, the specific excitation detecting means detects a combination of the values of the excitation currents of the respective phases of the stepping motor as a specific excitation pattern. .

According to a third aspect of the present invention, in the first or second aspect, the stepping motor is a two-phase stepping motor.

According to a fourth aspect of the present invention, in the first or second aspect, the stepping motor is a five-phase stepping motor.

According to a fifth aspect of the present invention, there is provided a control circuit for outputting a pulse signal having a pulse number corresponding to a desired rotation angle, and an exciting current flowing to each phase of the stepping motor based on the pulse signal input from the control circuit. A driving circuit for micro-step driving the stepping motor, position detecting means for detecting that the rotational position of the output shaft of the stepping motor is within a specified section including the origin which is a reference position, and A specific excitation detection circuit that detects a combination of the current values of the excitation currents of the respective phases of the stepping motor when the stepping motor is positioned as a specific excitation pattern, and the control circuit includes both a position detection unit and the specific excitation detection circuit. When it is determined that the stepping motor is at the origin, the output of the pulse signal is stopped. When both the position detection means and the specific excitation detection circuit determine that the stepping motor is at the origin, the pulse signal from the control circuit to the drive circuit is stopped. However, it is possible to prevent deviation due to variations in the load condition and the characteristics of the stepping motor, and accurate positioning can be performed.

According to a sixth aspect of the present invention, there is provided a control circuit for outputting a pulse signal having a number of pulses corresponding to a desired rotation angle, and an exciting current flowing to each phase of the stepping motor based on the pulse signal input from the control circuit. A driving circuit for micro-step driving the stepping motor, position detecting means for detecting that the rotation position of the output shaft of the stepping motor is within a specified section including the origin serving as a reference position, and counting the pulses of the pulse signal. And a specific excitation detection circuit for detecting a specific excitation pattern when the stepping motor is positioned at the origin.The control circuit determines that the stepping motor is at the origin by both the position detection means and the specific excitation detection circuit. The output of the pulse signal is stopped when it is performed, the position detection means and the specific excitation detection circuit In both cases, the pulse signal from the control circuit to the drive circuit is stopped when it is determined that the stepping motor is at the origin, so that the origin, which is the reference position of the rotation position of the stepping motor, depends on the load condition and the stepping motor. It is possible to prevent deviation due to variations in characteristics, and to perform accurate positioning.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) As shown in FIG. 1, a positioning device according to the present embodiment includes a control circuit 1 composed of a computer that outputs a pulse signal having a pulse number corresponding to a desired rotation angle. A drive circuit 2 for microstep driving the stepping motor 3 based on a pulse signal input from the control circuit 1; Here, the stepping motor 3 is a two-phase stepping motor, and the drive circuit 2 excites each phase (A phase, inverted A phase, B phase, and inverted B phase) of the stepping motor 3 based on the pulse signal. The ratio of the current is controlled as shown in FIG. 2, and the stepping motor 3 is driven by 1/8 microstep. In the example shown in FIG. 2, an operation of 1/8 of the basic step is possible with the electric rotation angle of 90 ° as the basic step (one step).

Further, the positioning device of the present embodiment is mechanically connected to an output shaft (not shown) of the stepping motor 3 to detect an origin which is a reference position of the rotational position of the stepping motor 3. An indicator piece 4 that rotates together with the motor 3, a position detection sensor 5 that detects the indicator piece 4 when the rotation position of the output shaft of the stepping motor 3 is within a specified section including the origin, and a position where the stepping motor 3 is located at the origin. Stepping motor 3 when making
And a specific excitation detection circuit 10 for detecting a combination of the exciting current values of the respective phases as a specific excitation pattern. In the present embodiment, the pointing piece 4 and the position detection sensor 5 constitute a position detection unit that detects that the rotation position of the output shaft of the stepping motor 3 exists in a specified section including the origin.

The specific excitation detection circuit 10 includes four current detection circuits 11 for detecting excitation currents from the drive circuit 2 to each phase of the stepping motor 3, and each current detection circuit 11.
And four comparison circuits 12 each outputting a signal of a predetermined level (for example, H level) when the detected current value and the specific excitation current value are compared and matched with each other, and each of the comparison circuits 12
And a matching circuit 13 that outputs an H level signal when all the output signals are at H level. Here, the output of the matching circuit 13 and the output of the position detection sensor 5 are input to a determination circuit 20 composed of an AND element, and the output signal of the determination circuit 20 is input to the control circuit 1. On the other hand, when the output of the determination circuit 20 changes from the L level to the H level, the control circuit 1 stops outputting the pulse signal to the drive circuit 2.

Hereinafter, a method of detecting the origin, which is the reference position of the rotation position of the stepping motor 3, will be described.

The control circuit 1 moves the stepping motor 3 in a predetermined direction (to the origin) in order to match the origin of the physical rotational position of the output shaft of the stepping motor 3 with the rotational position in processing (logically) by software. The rotation is directed to the drive circuit 2 by a pulse signal as shown in FIG. At this time, the driving circuit 2
Based on the pulse signal from the control circuit 1, the stepping motor 3 starts rotating in a predetermined direction (direction for returning to the origin). Then, when the position detecting sensor 5 detects the pointing piece 4, the output changes from the L level to the H level as shown in FIG. On the other hand, the specific excitation detection circuit 10
FIG. 3 shows that when a combination of the exciting current values of the respective phases of the stepping motor 3 when returning the stepping motor 3 to the origin is detected as a specific exciting pattern, the output is as shown in FIG.
The level changes from the L level to the H level as shown in FIG.
Then, since the output of the determination circuit 20 changes from the L level to the H level, the control circuit 1 stops outputting the pulse signal to the drive circuit 2.

In short, in the present embodiment, when the driving circuit 2 as the driving means rotates the stepping motor 3 in the direction of returning to the reference position of the rotation position based on the pulse signal output from the control circuit 1 as the control means. In addition, the position detecting means detects that the rotational position of the stepping motor 3 exists within the specified section including the origin, which is the reference position, and the excitation pattern of each phase of the stepping motor 3 indicates the rotation of the stepping motor 3. When the specific excitation detection circuit 10 serving as a specific excitation detection unit detects that a specific excitation pattern for positioning the position at the origin is obtained,
It is determined that the rotational position of the stepping motor 3 is at the origin. Note that the stepping motor 3 generates a specific excitation pattern at a plurality of positions during one rotation. However, since the logical output of the detection output of the specific excitation detection circuit 10 and the detection output of the positioning sensor 5 is taken, the origin is determined. It can be detected reliably.

In this embodiment, when both the position detection sensor 5 and the specific excitation detection circuit 10 determine that the stepping motor 3 is at the origin, the pulse signal from the control circuit 1 to the drive circuit 2 is output. Since the rotation is stopped, the excitation position corresponding to the origin, which is the reference position of the rotation position of the stepping motor 3, can be prevented from being shifted due to the load state or the variation in the characteristics of the stepping motor 3, and accurate positioning can be performed. . In the present embodiment, the position of the excitation vector V at the excitation position is the same in the case of FIG. 4A with a light load and the FIG. 4B with a heavy load. In FIG. 4, it is assumed that the pointing piece 4 has been rotated clockwise.

(Embodiment 2) As shown in FIG. 5, the positioning device of this embodiment outputs a pulse signal of a pulse number corresponding to a desired rotation angle, and a control circuit 1 which inputs the pulse signal. Stepping motor 3 based on pulse signal
And a drive circuit 2 for micro-step driving. Here, the stepping motor 3 is a two-phase stepping motor, and the drive circuit 2 controls each phase (A phase, inversion A) of the stepping motor 3 based on the pulse signal.
The stepping motor 3 is driven by １ ／ microstep by controlling the ratio of the exciting current to the phase, the B phase, and the inverted B phase as shown in FIG. 2 described in the first embodiment.

The positioning device of the present embodiment is mechanically connected to an output shaft (not shown) of the stepping motor 3 to detect an origin which is a reference position of the rotational position of the stepping motor 3. An indicator piece 4 that rotates together with the motor 3, a position detection sensor 5 that detects the indicator piece 4 when the rotation position of the output shaft of the stepping motor 3 is within a specified section including the origin, and a position where the stepping motor 3 is located at the origin. A specific excitation detection circuit 10 for detecting a specific excitation pattern at the time of activation. In addition,
In the present embodiment, the pointing piece 4 and the position detection sensor 5 constitute a position detecting means for detecting that the rotation position of the output shaft of the stepping motor 3 exists in a specified section including the origin.

The specific excitation detection circuit 10 counts the pulses of the pulse signal output from the control circuit 1 and indirectly detects a specific excitation pattern for positioning the stepping motor 3 at the origin. . Here, the specific excitation detecting circuit 10 is a counter having eight outputs Q1 to Q8, and each time one pulse of the pulse signal output from the control circuit 1 is input, Q1 → Q2 →.
The output becomes H level in the order of Q8, and after Q8, Q1 again
The output goes high. In the present embodiment, the stepping motor 3 is positioned at the origin on software by outputting nine pulses, and the H level of the Q1 output is associated with the specific excitation pattern.
The Q1 output of the specific excitation detection circuit 10 and the output of the position detection sensor 5 are input to a determination circuit 20 including an AND element,
The output signal of the determination circuit 20 is input to the control circuit 1. On the other hand, when the input from the determination circuit 20 changes from the L level to the H level, the control circuit 1 stops outputting the pulse signal to the drive circuit 2.

Hereinafter, a method of detecting the origin, which is the reference position of the rotation position of the stepping motor 3, will be described.

The control circuit 1 controls the stepping motor 3 in a predetermined direction (direction for returning to the origin) in order to match the origin between the physical rotational position of the output shaft of the stepping motor 3 and the logical (software) rotational position. 6A is instructed to the drive circuit 2 by a pulse signal as shown in FIG. At this time, the driving circuit 2
Starts rotating the stepping motor 3 in a predetermined direction (a direction to return to the origin) based on the pulse signal from the controller. Then, when the position detecting sensor 5 detects the pointing piece 4, the output changes from the L level to the H level as shown in FIG. On the other hand, when the specific excitation detecting circuit 10 counts the number of pulses when the stepping motor 3 is positioned at the origin, the Q1 output changes from the L level to the H level as shown in FIG. 6C. Then, the output of the determination circuit 20 changes from the L level to the H level.
Is configured to stop the output of the pulse signal to the drive circuit 2.

In short, in the present embodiment, when the drive circuit 2 serving as the drive unit rotates the stepping motor 3 in the direction of returning to the reference position of the rotation position based on the pulse signal output from the control circuit 1 serving as the control unit. In addition, the position detecting means detects that the rotational position of the stepping motor 3 exists within the specified section including the origin, which is the reference position, and the excitation pattern of each phase of the stepping motor 3 indicates the rotation of the stepping motor 3. When the specific excitation detection circuit 10 serving as a specific excitation detection unit detects that a specific excitation pattern for positioning the position at the origin is obtained,
It is determined that the rotational position of the stepping motor 3 is at the origin. Note that the stepping motor 3 generates a specific excitation pattern at a plurality of positions during one rotation. However, since the logical output of the detection output of the specific excitation detection circuit 10 and the detection output of the positioning sensor 5 is taken, the origin is determined. It can be detected reliably.

In this embodiment, when both the position detection sensor 5 and the specific excitation detection circuit 10 determine that the stepping motor 3 is at the origin, the pulse signal from the control circuit 1 to the drive circuit 2 is output. Since the rotation is stopped, the excitation position corresponding to the origin, which is the reference position of the rotation position of the stepping motor 3, can be prevented from being shifted due to the load state or the variation in the characteristics of the stepping motor 3, and accurate positioning can be performed. . In the present embodiment, the position of the excitation vector V at the excitation position is the same in the case of FIG. 7A with a light load and the FIG. 7B with a heavy load. In FIG. 7, it is assumed that the pointing piece 4 is rotated clockwise.

In each of the above embodiments, a two-phase stepping motor is used as the stepping motor 3.
A five-phase stepping motor may be used. Further, the micro-step driving is not limited to 1/8 step.

[0028]

According to the first aspect of the present invention, when the driving means rotates the stepping motor in the direction of returning to the reference position of the rotational position based on the pulse signal output from the control means, the rotational position of the stepping motor is changed. Is detected by the position detecting means, and the excitation pattern of each phase of the stepping motor has a specific excitation for positioning the rotation position of the stepping motor at the origin. When the specific excitation detecting means detects that the pattern becomes a pattern, the rotation position of the stepping motor is determined to be at the above-mentioned origin, so that when the stepping motor is driven by microstepping, the origin which is the reference position of the rotation position of the stepping motor is determined , Detection at a fixed position regardless of the load condition or the variation in the characteristics of the stepping motor Bets can be, there is an effect that it is possible to accurate positioning.

According to a fifth aspect of the present invention, there is provided a control circuit for outputting a pulse signal having a number of pulses corresponding to a desired rotation angle, and an exciting current flowing to each phase of the stepping motor based on the pulse signal input from the control circuit. A driving circuit for micro-step driving the stepping motor, position detecting means for detecting that the rotational position of the output shaft of the stepping motor is within a specified section including the origin which is a reference position, and A specific excitation detection circuit that detects a combination of the current values of the excitation currents of the respective phases of the stepping motor when the stepping motor is positioned as a specific excitation pattern, and the control circuit includes both a position detection unit and the specific excitation detection circuit. When it is determined that the stepping motor is at the origin, the output of the pulse signal is stopped. When both the constant excitation detection circuit and the stepping motor determine that the stepping motor is at the origin, the pulse signal from the control circuit to the drive circuit is stopped, so that the origin, which is the reference position of the rotation position of the stepping motor, is It is possible to prevent deviation due to variations in the state and the characteristics of the stepping motor, and it is possible to perform accurate positioning.

According to a sixth aspect of the present invention, there is provided a control circuit for outputting a pulse signal having a pulse number corresponding to a desired rotation angle, and an exciting current flowing to each phase of a stepping motor based on the pulse signal input from the control circuit. A driving circuit for micro-step driving the stepping motor, position detecting means for detecting that the rotation position of the output shaft of the stepping motor is within a specified section including the origin serving as a reference position, and counting the pulses of the pulse signal. And a specific excitation detection circuit for detecting a specific excitation pattern when the stepping motor is positioned at the origin.The control circuit determines that the stepping motor is at the origin by both the position detection means and the specific excitation detection circuit. When this is done, the output of the pulse signal is stopped, and both the position detection means and the specific excitation detection circuit step. When it is determined that the stepping motor is at the origin, the pulse signal from the control circuit to the drive circuit is stopped, so that the origin, which is the reference position of the rotation position of the stepping motor, depends on the state of the load and variations in the characteristics of the stepping motor. There is an effect that the displacement can be prevented and accurate positioning can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a positioning control device according to a first embodiment.

FIG. 2 is an explanatory diagram of micro-step control in the above.

FIG. 3 is an operation explanatory view of the above.

FIG. 4 is an operation explanatory diagram of the above.

FIG. 5 is a schematic configuration diagram of a positioning control device according to a second embodiment.

FIG. 6 is an operation explanatory view of the above.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is a schematic configuration diagram of a conventional positioning control device.

FIG. 9 is an operation explanatory view of the above.

FIG. 10 is an operation explanatory view of the above.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control circuit 2 drive circuit 3 stepping motor 4 indicator piece 5 position detection sensor 10 specific excitation detection circuit 20 determination circuit

Claims (6)

[Claims] When the driving unit rotates the stepping motor in a direction for returning to the reference position of the rotational position based on a pulse signal output from the control unit, the rotation position of the stepping motor is the origin which is the reference position. Is detected by the position detecting means to be in the specified section including
Further, when the specific excitation detecting means detects that the excitation pattern of each phase of the stepping motor becomes a specific excitation pattern for positioning the rotation position of the stepping motor at the origin, it is determined that the rotation position of the stepping motor is at the origin. An origin detection method characterized by determining. 2. The method according to claim 1, wherein the specific excitation detecting means detects a combination of the values of the excitation currents of the respective phases of the stepping motor as a specific excitation pattern.
Origin detection method described. 3. The method according to claim 1, wherein the stepping motor is a two-phase stepping motor. 4. The method according to claim 1, wherein the stepping motor is a five-phase stepping motor. 5. A control circuit for outputting a pulse signal having a number of pulses corresponding to a desired rotation angle, and an exciting current flowing to each phase of the stepping motor based on the pulse signal input from the control circuit, thereby controlling the stepping motor by a microcontroller. A drive circuit for step driving, position detecting means for detecting that the rotational position of the output shaft of the stepping motor is present in a specified section including the origin which is a reference position, and a driving circuit for positioning the output shaft of the stepping motor at the origin. A specific excitation detection circuit that detects a combination of the current values of the excitation currents of the respective phases of the stepping motor as a specific excitation pattern, and the control circuit uses the position detection means and the specific excitation detection circuit to set the stepping motor at the origin. A positioning device, wherein the output of the pulse signal is stopped when it is determined that there is a pulse signal. 6. A control circuit for outputting a pulse signal having a number of pulses corresponding to a desired rotation angle, and an exciting current flowing to each phase of the stepping motor based on the pulse signal input from the control circuit, thereby controlling the stepping motor by a microcontroller. A drive circuit for step driving, position detecting means for detecting that the rotational position of the output shaft of the stepping motor is within a specified section including the origin which is a reference position, and counting the pulses of the pulse signal to control the stepping motor. A specific excitation detection circuit for detecting a specific excitation pattern when the stepping motor is located at the origin, when the stepping motor is determined to be at the origin by both the position detection means and the specific excitation detection circuit. A positioning device for stopping output of a pulse signal.