JPH02264307A - Position control device - Google Patents

Abstract

PURPOSE:To realize the position control of high speed and high reliability by detecting the current position of a stepping motor by an encoder and an electronic scale, and feeding it back. CONSTITUTION:In an initial state, the output of a second position instruction generating means 110 is inputted to a function generating means 111, and the input of the outputs from a position data correcting means 105 and an operating electric angle correcting means 109 is interrupted, and the stepping motor 101 is open-loop-controlled. The output of the encoder 102 connected directly to the stepping motor 101 is inputted to the electronic scale means 103, and becomes current position data. When an object to be controlled passes over a reference position, the position data correcting means 105 corrects the value of the electronic scale means 103 by the output of a reference position detecting means 104, and outputs an absolute position. At this state, the values of the operating electric angle correcting means 109 and the position data correcting means 105 are inputted to the function generating means 111, and closed-loop control based on a first position instruction generating means 106 is started.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a position control device, and more particularly to a position control device capable of high-speed and highly accurate positioning.

2. Description of the Related Art In recent years, the performance of information equipment has improved dramatically, and as a result, faster and more accurate position control devices are required as drive sources for magnetic disk drives, printers, and the like.

Conventionally, stepping motors have been widely used as drive sources for these devices, and a method of open-loop control of the stepping motors has been common.

Although the open-loop control method has the advantage of a simple control circuit, it is difficult to increase the speed because there is always a risk of the stepping motor stepping out. Furthermore, when stopping for positioning, it vibrates around the stopping point and takes time to settle. Furthermore, it is well known that there are many difficult problems in realizing a high-speed, high-precision position control device, such as the fact that there are limits to positioning accuracy.

Therefore, in recent years, a closed-loop control method has been proposed in which the angle and displacement of the stepping motor are detected using an encoder or the like, and the detected angle and displacement are configured to match the target position. In the closed loop control method, the phase of the excitation current of the stepping motor can be determined based on the signal output from the encoder. Therefore, it is possible to prevent the step-out phenomenon of the stepping motor as described above, and it is possible to speed up the positioning operation.

In addition, since the angle and displacement of the stepping motor can be detected at the same time, it is possible to shorten settling time and improve positioning accuracy (for example, Takashi Mishiro et al., "Basics and Applications of Stepping Motors", 1972, Sogo Denshi Shuppansha) ).

Problems to be Solved by the Invention However, in order to realize a closed-loop control type position control device using a stepping motor, it is necessary to determine the phase of the current to be passed through the stepping motor from the signal output from the encoder as described above. Must be. In other words,
It is necessary to be able to determine the electrical phase relationship between the rotor and stator of the stepping motor using an encoder. For this reason, for example, when the electrical phase relationship between the rotor and stator is in a specific phase relationship, there is a process of adjusting the mechanical phase of the encoder and stepping motor so that the encoder output becomes the corresponding output. It was necessary.

Furthermore, in order to increase the positioning resolution of the position control device, the number of poles of the stepping motor used therein must be increased, and as a result, the mechanical phase adjustment described above becomes extremely difficult.

The present invention was made in view of the above-mentioned problems, and it is possible to adjust the phase of a position detection encoder and a stepping motor without using mechanical means, which could not be achieved with a conventional position control device using a stepping motor. high speed·
The present invention provides a position control device capable of highly accurate positioning.

Means for Solving the Problems In order to solve the above problems, the position control device of the present invention includes a stepping motor, an encoder that outputs signals of multiple phases different from each other in accordance with the movement of the stepping motor, and an output of the encoder. electronic scale means for processing signals and outputting signals according to the operating position of the stepping motor; reference position detection means for detecting that the load driven by the stepping motor is at a reference position; position data correction means for receiving the output of the electronic scale means and outputting data obtained by correcting the output of the electronic scale means; first position command generation means for commanding the positioning position of the stepping motor; a comparison means for outputting deviation data according to the deviation between the position command data output by the command generation means and the current position data output by the position data correction means; and a comparison means for receiving the deviation data output from the comparison means as an operation amount for the stepping motor. an operating electrical angle data calculation means for computing operating electrical angle data; and receiving an output of the operating electrical angle data calculation means;
an operating electrical angle data correcting means for outputting data obtained by correcting the output of the operating electrical angle data calculating means; a second position command generating means for outputting position command data for causing the stepping motor to reach a predetermined reference position; A function generating means which inputs the position command data outputted by the second position command generating means or the output of the operation electrical angle data correcting means and outputs a multi-phase current command to the stepping motor; and a driving means for supplying a driving current to the stepping motor accordingly.

According to the present invention, with the above configuration, the operating electrical angle data correction means recognizes the relative relationship between the electrical phase relationship between the stator and rotor of the stepping motor and the phase of the electrical signal output from the encoder, and adjusts the operating electrical angle. Correction can be made to the output of the data calculation means.

Therefore, the process of adjusting the mechanical phase of the encoder and stepping motor is unnecessary. Furthermore, the phase of the current that should be passed through the stepping motor in order to obtain a certain torque is determined by an electronic scale means that processes the output of the encoder.
Alternatively, since the output can be uniquely determined from the output of the position data correction means that corrects the output, the stepping motor can be efficiently driven without fear of causing step-out even in a transient state.

Further, by performing differential compensation using the operation electrical angle data calculation means, electrical damping can be applied to the stepping motor, so that the stepping motor can be quickly stabilized. Further, by performing integral compensation, steady deviation between the target position and the actual position can be eliminated, so highly accurate positioning is possible.

Therefore, the present invention can provide a position control device that can achieve high speed and high positioning accuracy.

Embodiment An embodiment of the position control device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a first embodiment of the position control device of the present invention.

A stepping motor 101 is a two-phase rotary stepping motor in this embodiment.

102 is an encoder, and a stepping motor 101
It outputs a two-phase sinusoidal signal, EaSEb, in response to the rotation of the stepping motor 101. 1
03 is an electronic scale means, and an encoder 102
It receives the output from the stepping motor 101 and outputs data Xo proportional to the rotation angle of the shaft of the stepping motor 101. Reference numeral 104 denotes a reference position detection means, which detects the output Z when the load driven by the stepping motor 101 is at the reference position, for example, in the case of a magnetic disk device, when the magnetic head is on a certain reference track on the magnetic disk. becomes active.

Reference numeral 105 denotes a position data correction means, which outputs the output Xo of the electronic scale means 103 and the output Z of the reference position detection means 104.
, and outputs current position data X which becomes zero at the reference position. 106 is a first position command generating means, which generates position command data R1 to determine the position of the stepping motor 101, that is, the stepping motor 10.
gives a position command to the load driven by 1. 107 is a comparison means, and the first position command generation means 1
By comparing the position command data R1 output by the position command data R1 and the current position data X output by the position data correction means 105, deviation data E corresponding to the deviation of the current position data X with respect to the position command data R1 is output.

Reference numeral 10B denotes an operation electrical angle data calculating means, which calculates the value of torque that the stepping motor 101 should generate from the deviation data E. Reference numeral 109 denotes an operating electrical angle data correction means, which corrects the data output from the operating electrical angle data calculating means 108 based on the electrical phase relationship between the rotor and stator of the stepping motor 101 and the relationship with the current position data X. do. 110 is a second position command generation means;
In an initial state before the correction data of the position data correction means 105 and the operation electrical angle data correction means 109 are determined, position command data R2 for driving the stepping motor 101 to move the load to the reference position by open loop control is generated. Occur. Reference numeral 111 denotes a function generating means, which generates a torque command V output from the operation electrical angle data correction means 109;
Alternatively, the position command data R2 generated by the second position command generation means 110 is converted into a current command Ss indicating the value of the current to be applied to each of the two-phase windings of the stepping motor 101.
, Sc. Reference numeral 112 is a driving means that supplies a driving current to the stepping motor lot based on the current commands Ss and Sc.

Next, the main elements constituting FIG. 1 will be explained.

FIG. 2 is a block diagram showing one embodiment of the electronic scale means of the present invention. 2 output from encoder 102
The phase signals Ea and Eb are amplified by amplifiers 201a and 201b, and the two-phase carrier signals Ca, Cb outputted from the carrier generation circuit 204 are sent to a modulation circuit 2 using a multiplier, respectively.
02a, 202b. The modulated signals are added by an adder 203.

Here, the signals obtained by these processes will be explained. Two-phase signal EaSE output from encoder 102
If the rotation angle of the shaft of the stepping motor 101 is θ, b is Ea=E-cow(2gθ/θP) (1)
Eb=E-sin(2gθ/θP) (2)
It is expressed as Here, θP is the rotation angle corresponding to one period of the sine wave output from the encoder 102, and E is the amplitude of the sine wave.0th order, the carrier signals Ca and Cb generated by the carrier generation circuit 204 are out of phase with each other. The signals differ by 90 degrees, Ca= cos (2z f c-t) ・−・−・・
-...<3) Cb=sin (2x f c-t)
・−・・・−・・・(4) Represented by: fc is the frequency of the carrier signal, and this electronic scale means 103
Since the output from the carrier signal is obtained every signal period (1/fc) of the carrier signal, a sufficiently high frequency is selected.The signal Comp obtained by adding the signals modulated by the output signal of the encoder 102 for each carrier signal is as follows:Comp= Ea-Ca+Ea-Cb=E-cos2x(f c-t-θ/θI))
...(5). From Part 2 (5), it can be seen that if the above processing is performed, the carrier signal is subjected to phase modulation according to θ by the signal output from the encoder 102.

Therefore, θ, that is, position information of the stepping motor 101 can be obtained from the phase difference between the signal Comp and the carrier signal Ca. Signal Comp is low pass filter 2
05, the waveform shaping circuit 206 converts the signal into a digital signal having only phase information. This low-pass filter 205 has the effect of removing the influence of harmonics contained in the carrier signal. Therefore, the carrier signal may be a rectangular wave, and signals having phases different by 90° from each other can be easily generated using a digital circuit. A phase difference counter 207 detects the phase difference between the output of the waveform shaping circuit 206 and the carrier signal generated by the carrier signal generation circuit 204. Specifically, the counter value, which is counted from zero at the rise of the carrier signal, is latched at the rise of the output of the waveform shaping circuit 206 and output as digital data. The frequency of the clock signal of the counter that detects this phase difference is selected to be higher than the frequency of the carrier signal because it determines the resolution of phase difference detection. 2
Day 0 is a carry detection circuit. The phase difference that can be detected by the phase difference counter 207 is co
As can be seen from the fact that the s function repeats at 2π, θ is changed to θp
It is the phase difference for the remainder divided by . Therefore, θp
Information about θ exceeding If the output crosses zero while decreasing, a down-count pulse is output, and if the output crosses zero while increasing, an up-count pulse is output.

The up/down counter 209 counts up and counts down in response to these count pulses. As a result, the output of the up/down counter 209 provides information about θ that exceeds θp.

The synthesis circuit 210 synthesizes the output of the up/down counter 209 and the output of the phase difference counter 207 to obtain the output XO of the electronic scale means 102. With the above configuration, the angle of the stepping motor can be detected over the entire movable range of the stepping motor 101 with a resolution equal to or less than the pitch of the encoder.

FIG. 3 is a block diagram showing the configuration of the position data correction means 105 of the present invention. The position data correction means 105 is composed of a data latch 301 and a subtracter 302. The data latch 301 is connected to the output Z of the reference position detection means 104.
The output of the electronic scale means 103 is latched at the timing of the signal. A subtracter 302 subtracts the value latched by the data latch 301 from the output Xo of the electronic scale means, and outputs the result as position data X, which is the output of the position data correction means 105.

FIG. 4 is a block diagram showing the configuration of the comparison means 107 and the operation electrical angle data calculation means 10B of the present invention. The comparison means 107 is a subtracter, and the first position command generation means 1
The position data X output by the position data correction means 105 is subtracted from the position command data R1 output by the position data correction means 105 to obtain the deviation data E. The operation electrical angle data calculation means 108 is a proportional element calculation unit 4 that calculates an operation amount proportional to the deviation data.
01, a differential element calculator 402 that calculates a manipulated variable proportional to the differential value of the deviation data E, and an integral element calculator 403 that calculates a manipulated variable proportional to the integral value of the deviation data E, and add these outputs. The adder 404 includes an adder 404.

The configuration shown in Figure 4 is the PI in classical control theory.
Since it is the same as controller D, detailed explanation will be omitted.

FIG. 5 is a block diagram showing the configuration of the operation electrical angle data correction means 109 of the present invention. The operation electrical angle data correction means 109 includes a data latch 501 and a settling detection means 50.
3 and an adder 502.

The settling detection means 503 assumes that the stepping motor 101 has settled to the target position when the output of the comparison means 107 and the deviation data become equal to or less than a preset value, and its output becomes active. The data latch 501 latches the output data of the adder 502 at the timing of the output signal of the settling detection means 503. In the adder 502, a data latch 50 is applied to the output Vo of the operation electrical angle data calculation means 108.
The latched data is added to 1 and the output of the operation electrical angle data correcting means 109 is obtained.

FIG. 6 is a block diagram showing the configuration of the function generating means 111 of the present invention.

Before explaining the operation of the function generating means 111, the torque generated by the stepping motor will be briefly explained. Figure 7 (
a) is a diagram schematically depicting a stepping motor.
The rotor 702 is a permanent magnet field and rotates around a rotating shaft 703. Armature coil 701a, 7
A rotor 702 located on the stator side moves around a rotating shaft 703 under the action of magnetic fields from armature coils 701 a and 701 b.

The torque generated in the rotor 702 is determined by the combination of armature currents flowing through the two coils, and can be easily understood by introducing the concept of a magnetomotive force vector due to armature currents. In other words, the magnetic field generated by the armature current is expressed as a vector with magnitude and direction. FIG. 7(b) is a vector representation of the magnetic field inside the stepping motor of FIG. 7(a).

The field and the magnetic field generated by the armature are expressed by two vectors.

In general, the torque generated by a stepping motor is proportional to sin φ, where φ is the electrical phase difference between the field vector due to the field and the magnetomotive force vector due to the armature current. In other words, if the generated torque is T, then T = Φ lm5inφ = Φ ・ lm5in (φ, -φ, ) ...
・Represented by (6). Here, φ is the electrical phase angle of the magnetomotive force vector, and φ is the electrical phase angle of the field vector. Φ is the magnitude of the magnetic flux of the field, and Im is the magnitude of the magnetomotive force vector due to the armature current.

Controlling the torque generated by the stepping motor is achieved by controlling the electrical phase angle φ of this magnetomotive force vector. Once the torque to be generated is determined, φ is
It can be determined from the relationship in equation (b). Since φ is determined by the electrical phase relationship between the rotor and stator that generate the field magnetic field, it can be detected from the rotation angle of the stepping motor by the method described later. Therefore, φ, is φ
,=φ ten φf ・・・・・・・・・・・・・・・
...It can be obtained using (7). That is, if the armature is excited with a phase angle φ obtained by adding φ corresponding to the torque to be generated to the electrical phase angle φf of the field vector, that torque can be generated.

Next, when φ is determined as above, consider the current that should be passed through each phase of the stepping motor.

The armature current i, , 11 in a two-phase stepping motor must satisfy the following conditions.

1, = 7i, + t, ......
... (8) jan φm-1b / l l
I ・・・・・・・・・・・・(9) The condition given by equation (8) is necessary to make the generated torque T of the stepping motor depend only on φ, and the condition given by equation (9) ) is necessary for the phase angle of the magnetomotive force vector generated by 11, tb to be φ.
8) From formula (9), il and ib are: i, -1・cos φ-・・・・・・・・・・・・
・・0ωi,=I ・sin φ1 ・・・・・・
・・・・・・・・・aO.

FIG. 6 will be explained in accordance with the above explanation. The adder 601 adds the output V of the operation electrical angle data correction means 109 and the current position data X output from the position data correction means 105. This corresponds to adding φ and φ to obtain φ. In other words, the operation electrical angle data correction means 109
The output represents the magnitude of the torque to be generated, and the current position data X represents the electrical phase angle φ of the field.

The switch 602 uses the load driven by the stepping motor 101 as a reference in the initial state until the correction data of the 0 position data correction means 105 which switches the input of the address data generation means 603 and the operation electrical angle data correction means 109 is determined. When moving to a position, the input of the address data generating means 603 is connected to the second position command generating means 110 via the switch 602, and its output R2 is inputted.

After the load moves to the reference position, the output of adder 601 is
The address data is input to address data generating means 603.

Address data generating means 603 generates address data for the ROM, which is a table of sine wave and cosine wave values. The sine wave table ROM2O3 and the cosine wave table ROM2O3 output the function data stored at the address specified by the address data. The relationship between address data and function data is a sine wave function and a cosine wave function, respectively. Note that since both the sine wave function and the cosine wave function are periodic functions, there is no need to tabulate data that exceeds one period. The range of address data that can be expressed with a certain number of bits is exactly one of these functions.
Address data generating means 603 generates upper data exceeding the bits of data output from adder 601, matching the period.
If rounded down, the address data for the sine wave table ROM2O3 and the cosine wave table ROM605 will fall within this range, and a table for one cycle will suffice.

The operation of the position control device of the present invention configured as above will be explained.

The position control device of the present invention has an initialization operation for determining correction data in each correction means, and a steady operation for performing a positioning operation based on a position command generated by the first position command generation means 106. The initialization operation is performed when the power is turned on or when the position of the load driven by the stepping motor 101 becomes unknown or the correction data changes due to some kind of failure. Therefore, the process from power-on to the final positioning operation will be explained step by step.

When the power is turned on, the rotation angle of the stepping motor 101 is considered to be indefinite, so the output of the electronic scale means 103 has no meaning. Therefore, when the power is turned on, the stepping motor 1 is controlled by open loop control.
01 to move the load to the reference position. Then, by recording the output of the electronic scale means 103 at the reference position and then comparing the output of the electronic scale means 103 with the data at the reference position, the position of the stepping motor 101, that is, the load, can be detected. Make it.

In order to do this, function generating means 11 shown in FIG.
The output from the second position command generation means 110 is coupled to the input of the address data generation means 603 by the first switch 602 . The second position command generation means 110 outputs position command data that monotonically increases with time. Address data generating means 603 converts the position command data into address data that increases in a constant direction within one cycle. The sine wave table ROM 604 and the cosine wave table ROM 2O3 then output current command data based on this address data.

S c = cosωt11111・e・・1・ψ−1
G21SS=sinωtT1...1111...l
-103) The driving means 112 is the stepping motor 101
When a current is supplied to the stepping motor 101, a rotating magnetomotive force vector is generated within the stepping motor 101. 2〇'lJ, ω on the second side is the rotation speed of the magnetomotive force vector. When a phase difference is created between the magnetomotive force vector and the field vector, torque is generated, the stepping motor 101 rotates, and the load moves.

Since this state is open loop control, it is necessary to select ω so that the stepping motor 101 does not step out. Now,
When the load moves to the reference position and the reference position detection means 104 detects this, the position data correction means 10 shown in FIG.
The output data of the electronic scale means 103 at the reference position is latched into the data launch 301 of No. 5. At the same time, the second position command generating means 110 stops increasing the output data and maintains the output data at that time. This causes the load to stop near the reference position. Since the subtracter 302 subtracts the data latched in the data latch 301 from the output data XO of the electronic scale means 103,
Current position data X which becomes zero at the reference position is obtained as the output of the position data correction means 105. Therefore, from now on, positioning operations can be performed using this current position data X.

Next, in order to perform closed-loop control, it is necessary to be able to determine the phase of the excitation current of the stepping motor 101 based on the current position data Take the correspondence of the phase relationship. This is achieved by adding correction data to the operating electrical angle data. The correction data can be obtained as follows. In the feeding operation to the reference position, the output of the second position command generation means 110 at the reference position is used as the initial value of the correction data,
A closed loop is formed and the positioning operation to the reference position is started.

After this positioning operation is stabilized, the human power applied to the function generating means 111 is again used as correction data.

Thereafter, closed loop control is performed using this correction data.

In order to explain in more detail, the description of the torque generation mechanism of the stepping motor will be repeated again.

The torque generated by the stepping motor is a torque T proportional to sinφ given by 204), where φ is the electrical phase difference between the field vector due to the field and the magnetomotive force vector due to the armature current.

T=Φ lm5in(φ, −φ, > −−−−,,(
14) Here, φ is the electrical phase angle of the magnetomotive force vector, and φ is the electrical phase angle of the field vector.

To control the generated torque T, set the value in parentheses on the right side to 1π
It must be set between /2 and π/2. In other words, it is necessary to be able to determine φ to a value corresponding to the generated torque between φf-π/2 and φ, 1π/2.
φ itself can be determined by current command data to the driving means 112. However, the size of φ, which is the basis for calculating φ, cannot be directly known.

Therefore, in the position control device of the present invention, the current position data X plus the correction data φ0 for the operating electrical angle data is used as the estimated amount φf of this φf. In other words, φf・−X + φC・ ・ ・・・・・ 0ω
It is. As described above, φ changes as the stepping motor rotates. The rotation of the stepping motor can be known from the current position data X. therefore,
By obtaining correction data φ, which corresponds to the phase difference between the encoder and the stepping motor, φ can be detected from the current position data X.

However, the estimated value φf obtained from the correction data φC
・If the error is not within ±π/2, the polarity of the generated torque will be reversed. The error of the estimated value φt is φ.

Then, the generated torque is T=Φ-1m5in(φ, -φf) =Φ-1m5in(φ--(φf'-φ,)---06
This is because it becomes 1. In this case, stable closed loop control cannot be performed.

Furthermore, even when φ is within ±π/2, the maximum value of the generated torque is reduced to Cotφ0 times compared to the case where φ,=0. In other words, φ to generate maximum torque.

Even if φ is adjusted so that −φzu・ becomes π/2, T−φ
・1m stn(g/2+φ,)-φ・Imcos(
φ, )...07].

In this case, since the maximum generated torque decreases, performance such as response speed deteriorates. As described above, unless correct correction data φC is obtained, the performance of the positioning device cannot be obtained.

Therefore, in the position control device of the present invention, as described above, -
The positioning operation is performed by closed-loop control based on the initial correction data, and the final correction data is obtained from the operating electrical angle data at the time of settling. The correction data φ obtained in this way.

can obtain sufficient accuracy.

Now, when obtaining correction data, closed loop control is performed assuming correction data, but as a condition for transitioning to closed loop control, at least a negative feedback loop must be constructed. Otherwise, positive feedback will occur, making it impossible to stabilize the positioning operation. In other words, the problem is how to select the initial value of the correction data assumed at this time.

What is required here is at least the ability to construct a negative feedback loop. In other words, the error in the estimated value of φ is ±
It is necessary to be able to assume correction data that can fall within π/2 as an initial value. Therefore, the position control device of the present invention uses the output of the second position command generation means 110 at the time when the reference position is reached in the feeding operation to the reference position as the initial value of this correction data. In other words, the fact that torque can be generated to move the load to the reference position without step-out through closed-loop control means that φ
, -φ, is within ±π/2. Therefore, even if the output of the second position command generating means 110 at this time, that is, φ, is assumed to be φ, the error is ±π
It is guaranteed that it is within /2. Further, since the current position data is zero at the reference position, φ at the reference position is the correction data itself for keeping the error in the estimated value of φ within ±π/2.

In order to perform the operation to obtain the correction data as described above,
Following the operation of feeding the load to the reference position, the output of the second position command generation means 110 at the reference position is latched in the data latch 501 of the operation electrical angle data correction means 109 shown in FIG. This becomes the initial value of the correction data. In order to enter the 9 positioning operation to the reference position,
The first position command generation means generates a reference position, that is, zero position command data. Thereafter, the switch 602 of the function generating means 111 is switched, and the output of the adder 601 is input to the address data generating means 603. This causes a transition from open-loop control to closed-loop control.

The above correction data contains errors because in most cases, φ1 does not equal φ due to the influence of friction and the like. Therefore, closed loop control is performed to detect this error and obtain more accurate correction data. The first position command generation means 106 outputs zero to position to the reference position. The existing position data when the data generated by the second position command generation means 110 stops is generally not zero;
One of the causes is the effect of load inertia. In other words, this is because even after the correction data is latched at the reference position, it continues to move and may stop at a position past the reference position.

Furthermore, if the increase in data generated by the second position command generating means 110 is greater than the resolution that can be detected by the electronic scale means, the motor will almost always stop at a position beyond the reference position.

Therefore, the current position data X, which is the output of the position data correction means 105 which corrected the output of the electronic scale means 103, has some value, which becomes the deviation data E in the comparison means 107. Furthermore, the deviation data E is calculated by PID calculation by the operation electrical angle data calculation means 108.
It is converted into generated torque data to make the deviation zero.

If the correction data in the operation electrical angle data correction means 109 is of real value, this generated torque data will be zero.

However, as described above, since the correction data includes errors, some value is output as the generated torque data. The operating electrical angle data correction/correction means 109 adds correction data to this torque data, and the function generation means 111 adds current position data and converts it into two-phase current command data. As a result, torque is generated in the stepping motor 101, and positioning to the reference position is performed. Finally, when the stepping motor 101 moves the load to the reference position and its movement stabilizes, the settling detection means 503 of the operation electrical angle data correction means 109 shown in FIG. A signal is output to latch the output data of the electrical angle data correction means. The data latched here is the sum of the output data of the operating electrical angle data calculating means 108 and the correction data of the operating electrical angle data correcting means 109.

After settling, the output data of the operation electrical angle data calculation means 10B is originally zero. Therefore, the output data of the operation electrical angle data calculation means at this point is considered to be an error in the correction data. In this way, true correction data can be obtained by latching the correction data plus the error.

The above operation will be explained using diagrams. FIG. 8 is a diagram showing the relationship between the input to the operation electrical angle correction means 109 and the torque actually generated. In FIG. 8, A is the generated torque characteristic when the correction data is correct. For this characteristic,
If an input is given within the range (■), a torque within the range (■) will be generated. However, if the initially assumed correction data contains an error, the generated torque characteristic will become as shown in B in FIG. 8.

In this case, as in the case where the generated torque characteristic is A, when input data is given in the range ``■'', the range of generated torque decreases to the range ``■''. Further, when zero point data is given as input data to make the generated torque zero, a residual torque of an amount indicated by TO is generated. These causes deterioration of control performance as described above. In this state, if a positioning operation to one reference point is performed without performing closed-loop control, it will eventually settle to point a in the generated torque characteristic diagram of FIG. At this time, the operating electrical angle calculation means 108 outputs φ, as shown in FIG.
The data corresponding to is entered. This is, in other words, an amount corresponding to the error in the initially assumed correction data. Therefore, the sum of the error in this correction data and the initially assumed correction data is used as new correction data. This φ.

By adding this to the correction data, it is possible to shift the input range given by the range (■) to the range (2). As a result, the data at the 0 point is shifted to the 0'' point, the residual torque becomes zero, and the range of generated torque is also expanded to the range (■).

Through the series of initialization operations described above, the correction data can be determined, and from this point onward, the positioning operation can be started using these correction data. In the positioning operation, the stepping motor 101 and the load can be moved to the target position according to the position command data output by the first position command generation means 106.

In addition, in the above embodiment, the case where the position command generated by the first position command generation means when transitioning to closed loop control is used as the reference position has been explained, but in other cases, the correction data can be changed by simple calculation operations. Since the initial value can be calculated, the value of the position command data can be arbitrarily determined.

In the first embodiment described above, the position data correction means, the comparison means, the operation electrical angle data calculation means, the operation electrical angle data correction means, the second position command generation means, and the function generation means are realized by hardware. Although described above, it is also possible to realize these operations in software by a computer whose operations are controlled by a program recorded in a memory.

FIG. 9 shows a block diagram of a position control device according to a second embodiment of the present invention. The stepping motor 1011 encoder 102, electronic scale means 103, reference position detecting means 104, first position command generating means 106, and driving means 112 are the same as those in the first embodiment shown in FIG.

The remaining components are replaced in the second embodiment of the invention by a microcomputer 901 that includes a central processing unit, a program storage memory, a working memory, and an interface input/output board. The microcomputer 901 inputs the output of the electronic scale means 103 and the output of the first position command generating means 106, and inputs the output of the driving means 11.
Generates a current command to 2. microcomputer 901
The program to be executed can be programmed using the same procedure as in the first embodiment, and its flowchart is as shown in Fig. 1θ.

The processing procedure of the program to be executed by the microcomputer in the second embodiment of the present invention will be explained using FIG.

When the power is turned on, processing 801 is performed.

Next, in process 802, the load is moved to the reference position in process 801. Here, an operation is performed to move the load to the reference position. Next, in process 802, it is determined whether the load has reached the reference position in process 801. If the reference position has been reached, the process moves to the next process 803, and if not, the process 801 is performed again. In process 803, a process for correcting position data is performed. That is, the electronic scale means 10 at the reference position
3 is stored, and from now on, that data is subtracted from the output of the electronic scale means 103. Continuing,
In process 805, a process for correcting the operation electrical angle data is performed. Closed loop control is performed using the position command data finally used in process 801 and correction data for the position data obtained in process 803, and data corresponding to the input of the function generation means after settling is stored, and subsequent operations are performed. This is correction data for electrical angle data.

This completes the initialization operation, and in step 805 a positioning operation is performed based on the position command data output from the first position command generation means 106.

Effects of the Invention As described above, the position control device of the present invention constantly detects the current position of the stepping motor with high resolution using the encoder and electronic scale means, and controls the closed loop control system by feeding back the current position. Since this configuration controls the position of the stepping motor, the performance of the stepping motor can be brought out to its limit without fear of step-out, and a high-speed, high-reliability position control device can be realized.

Further, the position control device of the present invention can electrically damp the stepping motor by the differential compensation function of the operation electrical angle data calculation means, so that vibrations generated during positioning can be suppressed as much as possible. This makes it possible to quickly settle the position, providing the quick response required by a position control device.

Furthermore, the steady-state deviation that occurs between the command position and the current position can be reduced to zero by the integral compensation function of the operation electrical angle data calculation means, so it is possible to realize a position control device with high positioning accuracy. .

Furthermore, the position control device of the present invention configures a closed loop using the excitation state of the stepping motor at the reference position as temporary operating electrical angle data correction data, performs positioning to the reference position, and performs stepping after the positioning is settled. Since we have adopted a method that obtains correction data from the motor's excitation state and then uses that data to automatically correct the electrical phase of the current command, the stepping motor is always operated efficiently within the most desirable torque angle range. It can be driven well and the speed of the device can be increased. Furthermore, since the step of adjusting the mechanical phase of the stepping motor at the reference position can be eliminated from the manufacturing process, this greatly contributes to improved productivity.

Therefore, if the position control device of the present invention is used, for example, as a drive source for a magnetic disk device or a printer, high-speed, high-precision, and high-resolution positioning performance can be easily achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a position control device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a specific configuration of the electronic scale means of FIG. 1, and FIG. FIG. 4 is a block diagram showing the structure of the position data correction means, FIG. 4 is a block diagram showing the structure of the comparison means and the operating electrical angle data calculating means of FIG. 1, and FIG. 5 is a block diagram showing the arrangement of the operating electrical angle data correcting means of FIG. 1. FIG. 6 is a block diagram showing the configuration of the function generating means in FIG. 1, FIG. 7 is a diagram explaining the principle of torque generation in a stepping motor, FIG. 8 is a diagram of generated torque characteristics, and FIG. 9 is a block diagram showing the configuration of the function generating means in FIG. 1 is a block diagram of a position control device according to a second embodiment of the present invention, and FIG. 1O is a basic flowchart of a built-in program of a microcomputer used in the second embodiment of the present invention. 101...Stepping motor, 102...
...Encoder, 103...Electronic scale means, 104...Reference position detection means, 105.
...position data correction means, 106 ...first position command generation means, 107 ...comparison means,
10th... Operation electrical angle data calculation means, 10
9... Operation electrical angle data correction means, 110.
...Second position command generating means, 111...
- Function generation means, 112...driving means.

Claims (12)

[Claims] (1) A stepping motor, an encoder that outputs signals of multiple phases different from each other according to the movement of the stepping motor, and a signal that processes the output signal of the encoder and outputs a signal that corresponds to the operating position of the stepping motor. electronic scale means; reference position detection means for detecting that the load driven by the stepping motor is at a reference position; a position data correction means for correcting the output of the stepping motor and outputting current position data; a first position command generation means for commanding the positioning position of the stepping motor; and a position command output by the first position command generation means. a comparison means for outputting deviation data according to a deviation between the data and the current position data outputted by the position data correction means; and operation electrical angle data as an operation amount for the stepping motor that receives the deviation data from the output of the comparison means. an operating electrical angle data computation means for calculating the operating electrical angle data; an operating electrical angle data correcting means for outputting data obtained by correcting the operating electrical angle data outputted by the operating electrical angle data computing means; a second position command generation means that outputs position command data to reach the position; in an initial state, the position command data outputted by the second position command generation means is output from the position data correction means after the position correction is completed; function generating means for outputting current command data of multiple phases for the stepping motor; and a drive means for supplying a drive current to the stepping motor. (2) The electronic scale means includes a carrier signal generating means, a modulating means for modulating the carrier signal outputted from the carrier signal generating means by the output signal of the encoder, and a demodulating means for demodulating the phase information of the output signal of the modulating means. 2. The position control device according to claim 1, wherein the position control device includes: (3) Claim (1) characterized in that the operation electrical angle data calculation means includes differential compensation filter means.
The position control device described. (4) Claim (3) characterized in that the operation electrical angle data calculation means includes integral compensation filter means.
The position control device described. (5) The function generation means includes a memory means that tabulates function data according to a certain function, an addition means that adds the outputs of the operation electrical angle data correction means and the position data correction means, and an output of the addition means or and address data generation means for generating address data for the memory means from the output of the second position command generation means, and reads function data from the memory means in accordance with the address data and outputs a plurality of phases having different phases from each other. The position control device according to claim 1, wherein the position control device is configured to output a signal. (6) The position control device according to claim 5, wherein the address data generation means includes a limit means for discarding the higher-order data output from the addition means. (7) The position control device according to claim (5), wherein the function of the function generating means is a multi-phase substantially sine wave. (8) The position data correction means, the comparison means, the operation electrical angle data calculation means, the operation electrical angle data correction means, the second position command generation means, and the function generation means include a program memory in which the processing contents are recorded; 2. The position control device according to claim 1, further comprising computer means comprising a central processing unit, a working memory, an input/output port, etc., which executes processing according to the program. (9) The position data correction means includes a data latch means for storing the output of the electronic scale means at the reference position detected by the reference position detection means, and data stored by the data latch means from the output of the electronic scale means. 2. The position control device according to claim 1, further comprising a subtraction means for subtracting the current position data. (10) The operation electric angle data correction means includes a data latch means for storing the input to the function generation means after a certain period of time after setting the position command data output from the first position command generation means to a predetermined value, and the operation electric The position control according to claim 1, further comprising correction data addition means for adding the correction data stored by the data latch means to the output of the angle data calculation means and inputting the result to the function generation means. Device. (11) After the operation electrical angle data correction means sets the position command data output from the first position command generation means to a predetermined value, when the deviation data output from the comparison means falls within a preset threshold value. data latch means for storing the input to the function generation means; and correction data addition means for adding the correction data stored by the data latch means to the output of the operation electrical angle data calculation means and inputting the result to the function generation means. The position control device according to claim 1, characterized in that it comprises: (12) The operation electric angle data correction means includes data latch means that uses the position command data of the second position command generation means as the initial value of the correction data. 11) The position control device according to any one of the above.