JPH0697877B2 - DC step motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a DC stepping motor realized by driving a DC servomotor stepwise, and in particular,
The present invention relates to an improvement in which only one equilibrium stationary point is provided for each minimum unit rotation angle that determines resolution.

<Prior Art> Conventionally, various DC stepping motors are known, and an example of the structure will be described with reference to FIG. That is, the reversible counter 1 whose set pulse train input terminal 1a is supplied with the set pulse train P1 is connected to the input terminal 3a of the pulse width modulation amplifier 3 via the digital-analog converter 2.
Forward rotation command pulse train terminal 3b, reverse rotation command pulse train terminal 3c
Respectively extend to the control terminals of the drivers 6 and 7 connected in series between the positive and negative power supplies 4 and 5,
A DC servomotor 9 is connected between the node 8 between 7 and the ground. The standard sine wave signal terminal 10a and the reference sine wave signal terminal 10b of the pulse encoder 10 which is interlocked with the DC servo motor 9 extend to the control circuit 11, and the addition / subtraction command signal terminal 11a of the control circuit is the control terminal of the reversible counter 1. 1b
And a feedback pulse train terminal of the control circuit 11
11b is connected to the feedback pulse train input terminal 1c of the counter 1.

In the configuration of such a conventional device, when the setting pulse train P1 is supplied to the setting pulse input terminal 1a, the reversible counter 1
Is supplied to the control terminal 1b, in response to the subtraction command signal S1 or the addition command signal S2 described later, from the cumulative value of the set pulse train P1, similarly subtracts the cumulative value of the feedback pulse train P2 described later,
Alternatively, it operates for each pulse of both pulse trains P1 and P2 so that the feedback pulse train P2 is added to the cumulative value of the set pulse train P1, and both pulses P of each pulse of both pulse trains P1 and P2 are supplied.
A digital error signal S3 representing the difference value or the sum value of the cumulative values of 1 and P2 is sent to the digital-analog converter 2. The digital-analog converter 2 converts the digital error signal S3 into an analog voltage and supplies it as an analog error signal S4 to the input terminal 3a of the pulse width modulation amplifier 3. In response to this, the amplifier outputs an analog error signal. When the error signal S4 represents a positive polarity value, a pulse train having a duty ratio substantially proportional to the absolute value of the signal S4 is output from the forward rotation command pulse train terminal 3b as a positive rotation forward command pulse train P3, while the error is signal
When S4 represents a negative polarity value, the reverse rotation command pulse train terminal
The reverse rotation command pulse train P4 of negative polarity is output from 3c alternatively.

Then, when the normal rotation command pulse train P3 is supplied to its control terminal, the driver 6 intermittently operates at the duty ratio of the pulse train P3 to pass a positive power source to the DC servomotor 9 to rotate it normally, and When the reverse rotation command pulse train P4 is supplied to its control terminal, the driver 7 operates in the same manner to connect the negative power source 5 to the motor 9 and reverse it.

In this way, the pulse encoder 10 also rotates in the same direction in conjunction with the direct-current servomotor 9 that rotates in the forward and reverse directions, and from the standard sine wave signal terminal 10a and the reference sine wave signal terminal 10b, a cycle is calculated for each unit rotation angle. The reference sine wave signal S5 and the reference sine wave signal S6 having a 90 ° phase difference from the standard sine wave signal S5 are output, and these signals S5 and S6 are supplied to the control circuit 11.

In response to this, the control circuit 11 compares the two signals S6 and S5 to determine whether the pulse encoder 10 is forward or reverse,
When the forward rotation is determined, the subtraction command signal S1 is supplied, and when the reverse rotation is determined, the addition command signal S2 is supplied from the addition / subtraction command signal terminal 11a to the control terminal 1b of the reversible counter 1, and at the same time, the reference sine signal is supplied. A feedback pulse train P2 composed of a pulse for each cycle of the wave signal S5 or the reference sine wave signal S6 is generated, and this feedback pulse train input terminal of the reversible counter 1 is generated.
Supply to 1c.

Thus, in response to each pulse of the set pulse train P1 having the predetermined number of pulses supplied to the set pulse input terminal 1a of the reversible counter 1, the DC servomotor 9 is normally rotated by the predetermined number of pulses per unit rotation angle. , Meanwhile, reversible counter 1
Is the stored content, that is, the set pulse train P1 for each one of the feedback pulse trains P2 supplied in response to the subtraction command signal S1 for each actual rotation of the unit rotation angle of the motor 9.
When 1 is subtracted from the accumulated value of 0 and the stored content of the counter becomes zero, the motor 9 stops, but on the other hand, the motor 9 causes the rotation angle position set by the set pulse train P1 of the predetermined number of pulses to be stopped for some reason. When the normal rotation is exceeded, the stored content of the reversible counter 1 has a negative polarity and the negative digital error signal S3 is output. Therefore, the motor 9 rotates in the reverse direction, and the reversible counter 1 outputs the addition command signal S2 during that time. In response to each of the feedback pulses, while adding to the stored content,
Continue reversing the motor until it reaches zero, eventually
The motor 9 is driven to a rotation angle position set by a set pulse train of a predetermined number of pulses and stopped.

By the way, FIG. 5 is a block diagram showing the internal configuration of the pulse width modulation amplifier 3 in the above embodiment.
Is a first whose input terminal is commonly connected to the input terminal 3a,
The second integrators 3A and 3B and the respective integrators 3A and 3B are followed by a reference power source 3C having a positive polarity and a reference power source having a negative polarity at the reference voltage terminals thereof.
3D and first and second comparators 3E and 3F connected to each other, and each reset terminal of the integrator is connected to a clock oscillator (not shown) via the first and second clock pulse terminals 3d and 3f. The output terminals of the comparator are connected to the drivers 6 and 7 via the forward rotation command pulse train terminal 3b and the reverse rotation command pulse train terminal 3c.
Is connected to each control terminal.

When the analog error signal S3 arriving at the input terminal 3a has a positive polarity (FIG. 6 (a) a), the first integrator 3A executes the integrating operation in response to this. , The integrated output voltage is increased with a gradient proportional to the voltage value of the error signal S3 (FIG. 6 (b) b), and the first reset pulse as the first clock pulse (FIG. 6 (C)). The output voltage is reset every time the reset voltage is received by the reset terminal (FIG. 6 (b) c).

The integrated output voltage (FIG. 6 (B)) of the first integrator 3A thus obtained is received at its input terminal, and the subsequent first comparator 3E receives the output voltage and its reference voltage. The magnitude relationship with the positive reference voltage (VR in FIG. 6 (B)) received by the terminal is compared and discriminated, so that the output voltage shifts to the positive polarity only while the reference voltage is exceeded. To generate a pulse train (W1 in FIG. 6 (D)) whose pulse width is modulated, and forward this through the forward rotation command pulse train terminal 3b.
Output as P3.

Next, when the voltage value of the analog error signal S4 is halved (FIG. 6 (A) d, b), the rising slope of the integrated output voltage in the first integrator 3E is also halved (FIG. 6 (B) e). The pulse width of the forward rotation command pulse train P3 is also halved (W2 in FIG. 6 (D)).

Further, when the voltage value of the analog error signal S4 becomes zero (Fig. 6 (A) f), the rising slope of the integrated output voltage becomes zero (Fig. 6 (B) g), but if this is done, When the balance is stationary, the command pulse train disappears, and various inconveniences arise from the fact that the DC servomotor 9 is not energized at all. To avoid this, a bias input is internally applied to the integrator. , Even when the error signal S4 is zero, integration is performed with a gradient reaching the reference voltage (VR in FIG. 6 (B)) in a little less than one cycle of the first reset pulse (FIG. 6 (C)) which is the first clock pulse. Increase the output voltage (Fig. 6 (B))
h), a scissor signal (Fig. 6 (D) i) having a minute pulse width is usually generated when the error signal S4 is zero.

On the other hand, during this period, the second integrator 3B also performs the integration operation (FIG. 6 (E) j), but the reference voltage of the subsequent second comparator 3F has a negative polarity. The reverse rotation command pulse train P4 does not appear (Fig. 6 (G) k).

When the error signal S4 becomes zero (Fig. 6 (A))
f), the negative integrated output voltage of the second integrator 3F reaches the negative reference voltage (Fig. 6 (E) e), and the comparator 3F
From the above, a negative-polarity scissor signal is generated and output for each time point of the second reset pulse which is the second clock pulse (FIG. 6 (G) m).

Furthermore, when the analog error signal S4 turns negative (the sixth
(A) n), the integrated output voltage of the integrator 3B is the signal S4
Of the negative polarity inversion command pulse train P4 (the sixth negative polarity) of the pulse width corresponding to the negative reference voltage of the comparator 3F and reaching the negative reference voltage of the comparator 3F. (G) W2) is generated and output.

<Problems to be Solved by the Present Invention> In such a conventional device, the DC servomotor 9 is rotated forward or backward by a unit rotation angle in response to each pulse of the set pulse train P1, and the predetermined pulse train is set. Although for the time being driven to the rotation angle position corresponding to the number of pulses, the rotation angle position to be driven was set as a rotation angle band with an indefinite region over the unit rotation angle.

That is, the DC servo motor 9 in the conventional device is reliably driven up to the rotation angle band corresponding to the set pulse train P1 of the predetermined number of pulses, but the position within the rotation angle band is indefinite, so that it is used as a step motor. However, there is a problem in that the ability to analyze the unit rotation angle cannot be substantially exhibited and the positioning accuracy is poor.

<Means for Solving the Problems> The present invention addresses the problem of poor positioning accuracy during step operation due to a unit rotation angle being a rotation angle band with an indefinite region in a conventional device. In view of this, a positive reference half-wave signal obtained by rectifying the reference sine wave signal from the pulse encoder to the positive half-wave and a reference sine wave signal with a 90 ° phase difference from the reference sine wave signal to the negative half-wave. The above-mentioned problems are solved by supplying each of the rectified negative reference half-wave signal to the first and second input terminals of the pulse width modulation amplifier.

<Operation> Therefore, as shown in FIG. 1, the configuration of the present invention is arranged such that each unit rotation angle from the pulse encoder 10 that rotates in association with the rotation of the DC servomotor 9 by the unit rotation angle is changed. Periodic reference sine wave signal S5 and 90 ° to this
Receiving the reference sine wave signal S6 of the phase difference, the rectifier circuit 14
The former is half-wave rectified to the positive side to generate the positive reference half-wave signal S8, and the latter is half-wave rectified to the negative side to form the negative reference half-wave signal.
S9 is generated, these both signals are supplied to the signal switching circuit 13,
The switching circuit responds to the zero detection signal S7 from the zero detection circuit 12 which has detected the zero of the reversible counter 1 when the motor is in a stationary state, and outputs the standard half-wave signal S8 and the reference half-wave signal S9 to the pulse width modulation amplifier. 3'is supplied to the first and second input terminals, whereby the standard half-wave signal S8 and the reference half-wave signal S9 have equal polarities, and the signals from the first and second integrators in the amplifier are supplied. It acts to drive the DC servomotor 9 to a unique point position in a unit rotation angle band in which both integrated output voltages have equal polarities.

<Embodiment> The construction and operation of an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the output terminal of the reversible counter 1 branches and extends to the input terminal of the zero detection circuit 12, and two switching circuits are provided in the signal switching circuit 13 driven by the zero detection signal S7 in the detection circuit 12. The switches 13A and 13B are included.
The movable contacts A and 13B are connected to the first of the pulse width modulation amplifier 3 ',
The break contacts of the switches 13A and 13B are connected to the second input force terminals 3a and 3g, respectively, and are commonly connected to the output terminal of the digital-analog converter 2.

In addition, the reference sine wave signal terminal 10 of the pulse encoder 10
a, the reference sine wave signal terminal 10b is also connected to the rectifier circuit 14,
In the rectifier circuit, the reference sine wave signal S5 is folded back to the positive side to generate a reference half-wave signal S8, which is fed to the reference half-wave signal terminal 14a.
To the first half-wave rectifier circuit (not shown) and the reference sine wave signal S6 to the negative side to generate a reference half-wave signal S9, which is output to the reference half-wave signal terminal 14b. Half-wave rectification circuit (not shown) is included, and the terminals 14a, 1
4b is a changeover switch 13 in the signal changeover circuit 13, respectively.
It is connected to each make contact of A and 13B.

The other constituent elements are the same as those indicated by the same reference numerals in FIG.

FIG. 2 shows the internal structure of the pulse width modulation amplifier 3'in FIG. 1, in which the input terminals of the first and second integrators 3A and 3B are respectively the first and second input terminals. It differs from the configuration of FIG. 5 only in that it is connected to the input terminals 3a and 3g.

In the above configuration, since the contents stored in the reversible counter 1 are not zero during the process of driving the DC servomotor 9 to the rotation angle position set by the set pulse train P1 having the predetermined number of pulses, the zero detection circuit 12 outputs the zero detection signal. Without outputting S7, the movable contacts of the changeover switches 13A and 13B in the signal changeover circuit 13 are in contact with the respective break contacts.
The configuration shown in the figure is realized, and as a result, operations equivalent to those of the incoming device are ensured.

Then, when the DC servo motor 9 completes the rotation to the set rotation angle position and is in equilibrium stationary state in which it is driven into the unit rotation angle band, the stored content of the reversible counter 1 becomes zero. The zero detection circuit 12 detects and outputs the zero detection signal S7, and the changeover switch 13 in the signal changeover circuit 13
Drive A and 13B together and switch this to the make contact side.

Then, the reference half-wave signal terminal 14a and the reference half-wave signal terminal 14b of the rectifier circuit 14 are connected to the first and second input terminals 3a and 3g of the pulse width modulation amplifier 3'via the changeover switches 13A and 13B, respectively. , The configuration of the main part operates.

That is, the rectifier circuit near the equilibrium stationary state of the servomotor 9.
In FIGS. 3 (A) and (B) showing each one cycle of the standard half-wave signal S8 and the reference half-wave signal S9 at 14, the rotation angle position (unit rotation angle) corresponding to the peak value of X1 and Y1 is temporarily assumed. When the motor 9 stands still (in the band), in the pulse width modulation amplifier 3 ', the first integrator 3A integrates the peak value X1 and the subsequent first
Comparator 3E of the first clock pulse (Fig. 3 (A)
(A)) a wide positive polarity forward rotation command pulse train P3 (Figs. 3 (A) and (b)) is generated and output, while the second integrator is output.
3B integrates the peak value Y1 and the subsequent second comparator 3F
For each clock pulse (Fig. 3 (B) (a)), a narrow negative polarity reverse rotation command pulse train P4 (Fig. 3 (B) (b)) is generated and output, and both command pulse trains P3, P4 are generated. It is supplied to the flow step motor 9 via the drivers 6 and 7 at the same time (although accompanied with the phase difference between the first and second clock pulses). Then, in response to the relatively wide forward rotation command pulse, the motor 9 rotates in the forward direction, and when its rotation angle position eventually rotates to a point position corresponding to the peak values X2 and Y2, Since the high values X2 and Y2 are equal in reversibility, the pulse widths of the forward rotation command pulse train P3 (Figs. 3 (A) and (c)) and the reverse rotation command pulse train P4 (Figs. 3 (B) and (c)) are equal. The value becomes a value, and the motor 9 stops at this point position. If, for some reason, the motor 9 excessively rotates in the normal direction and rotates to a point position corresponding to the peak values X3 and Y3, the peak value Y3 is the peak value.
Since it becomes relatively larger than X3, this time, a wide reverse rotation command pulse train P4 (Figs. 3 (B) and (d)) and a narrow forward rotation command pulse train P3 (Figs. 3 (A) and (d)) Are simultaneously supplied, and the motor 9 is driven by a relatively wide reverse rotation command pulse train.
In response to P4, it starts reversing and heads to the stationary point position corresponding to the peak values X2 and Y2.

Further, if the DC servo motor 9 enters the rotation angle position corresponding to the area where both peak values are zero (FIG. 3 (A) Z, FIG. 3 (BZ), the first and second integrations are performed. Since the devices 3A3B both integrate the zero voltage, they operate in the same manner as in the conventional device, and the positive scissor signal (third part) is supplied to the motor.
Figures (A) and (e)) and a negative scissor signal (Figure 3 (B)).
(E)) is simultaneously supplied (although accompanied with the phase difference between the first and second clock pulses), and as a result, the motor 9 is in a region where both peak values are zero (see FIG. ) Z, (B) Z in the figure, it is experimentally confirmed to rotate to a rotation angle position that leaves the rotation angle position region.

Then, when the motor 9 rotates in the normal direction and moves out of the region, the peak value X4 becomes relatively larger than the peak value Y4 remaining at zero, as exemplified by the peak value X4Y4. After entering the area, the forward rotation operation described above continues and the motor 9
Is driven to the point position corresponding to the peak value X2Y2.

On the other hand, when the motor 9 reverses and goes out of the area, the peak value Y4 enters the area where the peak value X4 is larger than the peak value X4 which remains zero, as illustrated by the peak value X5Y5. The above-described reverse rotation operation continues, and the motor 9 causes the reference sine wave signal S5 to have an equivalent peak value X6Y6 of the next adjacent cycle.
Is driven to the stationary point position corresponding to.

Thus, at the time of equilibrium standstill, the motor 9 is always driven to rest by being driven to the only standstill point in the unit rotation angle band. However, in the configuration described above, the motor 9
However, if it happens to occupy the rotation angle position corresponding to the area of both peak values zero, which of the two peaks of adjacent two cycles of the reference sine wave signal S5, in other words, the two adjacent peak values. It is uncertain which position of the stationary point in one unit rotation angle band will be driven in. To avoid this,
As illustrated in FIG. 3, the positive polarity scissor signal in the forward rotation command pulse train P3 (FIGS. 3 (A) and (e)) is the negative polarity scissor signal in the reverse rotation command pulse train P4 (third rotation). Figure (B)
It may be formed relatively wide with respect to (e).

Then, the motor 9 always settles at the stationary point position corresponding to the equivalent peak value X2Y2 in the cycle.

<Effect> As described above, according to the present invention, the reference sine wave signal having a cycle for each unit rotation angle and the reference sine wave signal having a 90 ° phase difference are positively interlocked with the DC servo motor. It rectifies so as to fold back to the negative side and the positive side reference half-wave signal and the negative reference half-wave signal is generated and output by the rectifier circuit. This is detected, the signal switching circuit is activated, and the reference half-wave signal and the reference half-wave signal are separately supplied to the pulse width modulation amplifier, where the peak values of both half-wave signals are responded to. A normal rotation command pulse train of positive polarity and a reverse rotation command pulse train of negative polarity having a pulse width to be generated are generated and are supplied to the motor at the same time. The motor rotated to the specified rotation angle position, In addition, it corresponds to the only stationary point position within the unit rotation angle band that determines the positioning resolution, that is, the only waveform position in one cycle in which the standard half-wave signal and the reference half-wave signal have exactly opposite polarities. Since it stops for the first time after being driven to the rotation angle position, as in the conventional device, when the DC servo motor is driven into the unit rotation angle band, due to the undefined region in the unit rotation angle band, , It is possible to always perform the positioning for each unit angle that determines the resolution without suffering from the positioning inaccuracy resulting from the fact that it is unknown at which position in the angle band the arm is stationary. The excellent effect of being markedly improved is exhibited.

[Brief description of drawings]

1 to 3 relate to an embodiment of the present invention. FIG. 1 is a block circuit diagram thereof, FIG. 2 is a block circuit diagram of a main portion thereof, and FIG. 3 is a waveform of a main portion thereof. It is a figure.
4 to 6 relate to the prior art, FIG. 4 is a block circuit diagram thereof, FIG. 5 is a block circuit diagram of a main portion thereof, and FIG. 6 is a waveform diagram of a main portion thereof. 1 ... Reversible counter 2 ... Digital-analog converter 3 ... Pulse width modulation amplifier 4, 5 ... Power supply, 6, 7 ... Driver 9 ... DC servo motor 10 ... Pulse encoder 11 ... Control circuit, 12 …… Zero detector circuit 13 …… Signal switching circuit, 14 …… Rectifier circuit

Claims (1)

[Claims] 1. A setting pulse train P1 is supplied to a setting pulse input terminal 1a, a feedback pulse train P2 is supplied to a feedback pulse train input terminal 1c, and in response to a subtraction command signal S1, a feedback pulse P2 is generated from the cumulative value of the setting pulse P1. Is subtracted, the digital error signal S3 corresponding to the difference is output, and the addition command signal is added.
In response to S2, the cumulative value of the feedback pulse P2 is added to the cumulative value of the setting pulse P1, and the reversible counter 1 that outputs the digital error signal S3 corresponding to the sum value is responsive to the digital error signal S3. Then, the digital-analog converter 2 that outputs the analog error signal S4 of positive and negative polarities corresponding to the digital error signal and the positive analog error signal S4 are received at the first input terminal 3a thereof, and the signal S4 is received. Generates a positive polarity forward rotation command pulse train P3 having a pulse width according to the absolute value of the negative polarity, receives a negative polarity analog error signal S4 at its second input terminal 3g, and outputs the signal S4.
A pulse width modulation amplifier 3'which generates a negative polarity reverse rotation command pulse train P4 having a pulse width according to the absolute value of P2 and selectively outputs both pulse trains P3 and P4, and a normal rotation command pulse train P3 DC servo motor 9 that normally rotates in response to the reverse rotation command pulse train P4, and the reference sine wave signal S5 for each unit rotation angle and 90 ° with respect to the reference sine wave signal in conjunction with the DC servo motor 9. Based on the pulse encoder 10 which outputs the reference sine wave signal S6 of the phase difference and the standard sine wave signal S5 and the reference sine wave signal S6, when the DC servomotor 9 is in the normal rotation, the subtraction command signal S1 is supplied to the motor. During reverse rotation, the addition command signal S2 is alternatively generated and output, and the feedback pulse train for each unit rotation angle of the pulse encoder 10 is based on either the standard sine wave signal S5 or the reference sine wave signal S6. Generate and output P2 In the DC stepping motor and a control circuit 11, a reference sine wave signal S5 half-wave rectification to the positive polarity reference half-wave signals
Rectifier circuit 14 that generates and outputs S8, and performs half-wave rectification of the reference sine wave signal S6 to generate and output the negative reference half-wave signal S9.
And a zero detection circuit that detects that the digital error signal S3 or the analog error signal S4 has become zero and outputs the zero detection signal S7.
12 in place of the analog error signal S4 supplied to the first and second input terminals 3a, 3g of the pulse width modulation amplifier 3'in response to the zero detection signal S7. In the input terminal 3a,
The reference half-wave signal S8 of positive polarity is supplied to the second half of the amplifier 3 '.
A DC stepping motor having a signal switching circuit 13 for supplying a negative reference half-wave signal S9 to its input terminal 3g.