JP2602096B2 - Linear pulse motor drive controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a linear pulse motor drive control device.

(Problems to be Solved by the Invention of the Related Art) A linear pulse motor is a type of stepping motor, and is also called a linear stepping motor, and has features common to stepping motors.

The total moving amount of the linear pulse motor is proportional to the total number of input pulses, and the speed is proportional to the frequency of the input pulses.

By utilizing this property, a positioning control system can be constituted by digital signals.

 There is no loss of synchronism if used within the rated range.

However, in reality, it cannot be said that step-out due to external load fluctuation or the like never occurs.

FIG. 6 is a schematic diagram for explaining a linear pulse motor and its operating principle.

The slide section 30 includes a permanent magnet 31, an electromagnet (EMA) 32, and an electromagnet (EMB) 33.

The electromagnet (EMA) 32 and the electromagnet (E
MB) 33 is supplied with a drive current from a drive circuit (not shown).

The drive circuit supplies an exciting current generated corresponding to the supplied pulse train.

As shown in FIG. 6 (I), when a current in the illustrated direction is applied only to the electromagnet (EMB) 33, the magnetic force is doubled at the pole of the electromagnet (EMB) 33, the magnetic force is canceled at the pole, and the magnetic force is balanced. Then, the slide unit 30 stops at the position shown in (I).

As shown in (II), when a current in the illustrated direction is applied only to the electromagnet (EMA) 32, the magnetic force is doubled at the pole of the electromagnet (EMA) 32, the magnetic force is canceled at the pole, and the magnetic force is balanced (II). The slide unit 30 moves to the position shown in (1) 1/4 pitch and stops.

In the present invention, one pitch corresponds to one pitch of the stator scale.
Defined as pitch (peak + valley).

By applying a step-like cosine wave to the electromagnet (EMB) 33 and a step-like sine wave to the electromagnet (EMA) 32 in the above-described device, one cycle can be made smaller, for example, 1 / 16,1.
/ 32 ...

In such a case, in order to detect an accurate movement amount of the slide unit, a detection device having a resolution capable of measuring at least a small unit of the microstep drive is required.

7 and 8 are schematic diagrams each showing an example of a conventional closed-circuit drive linear pulse motor.

In the example shown in FIG. 7, a rack 41 having a finer pitch is provided separately from the stator scale 40. The slide portion has a pinion 38 that meshes with the rack 41, and this rotation is taken in by a rotary encoder 39.

In the example shown in FIG. 8, a linear encoder 50 is provided in parallel with the stator scale 40, and the position of the slide section 30 is detected by a sensor 37 which moves integrally with the slide section 30.

Control is performed again based on information obtained from these sensors. As an example, JP-A-63-287391
The invention of a step-out correction circuit for a linear pulse motor disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-26095 can be mentioned.

However, according to the invention of the step-out correction circuit, when the drive current of the slide portion coil is not constant, and the amount of movement of the slide portion is made smaller than one pitch by changing this, for example, 1/16 (or 1 / In the case of (32, 1/64), the resolution of the detector must be a high-performance one capable of measuring the minimum movement unit, or the accuracy must be sacrificed.

Therefore, the present inventors have conducted various studies on characteristics when the linear pulse motor loses synchronism.

As a result, they have found that the vehicle can only be stopped at a position that satisfies certain conditions with respect to the control target point (a position where the slide portion and the stator scale are magnetically balanced in the excited state).

In other words, the relative relationship between the teeth of the slide section and the teeth of the stator scale at the control target point is maintained even when the step-out occurs. When it should be, the teeth of the slide are exactly matched to the stator scale and other peaks, even in a step-out and balanced condition.

That is, it was confirmed that the step-out result occurred in units of one pitch. This is because the moving amount of the slide portion is 1
It was also confirmed that the same applies when the pitch is smaller than the pitch.

An object of the present invention is to pay attention to the step-out characteristics of the linear pulse motor and to obtain 1 / N of 1 pitch of the stator scale.
It is an object of the present invention to provide a linear pulse motor drive control device capable of accurately correcting a drive amount of a linear pulse motor that performs drive control in units of (N is an integer of 2 or more) with an extremely simple configuration.

(Means for Solving the Problems) In order to achieve the above object, a linear pulse motor drive control device according to the present invention is generated in a slide section having a permanent magnet and an electromagnet in accordance with a pulse train supplied to a drive circuit. A linear pulse motor drive control device that supplies a variable excitation current and performs drive control in units of 1 / N (N is an integer of 2 or more) of one pitch of a stator scale. A moving pitch number detecting sensor for detecting a moving amount of the slide portion; and a means for converting the number of driving pulses generated for a predetermined movement into a pitch number corresponding to the number of driving pulses. A comparing unit that compares the number of movement pitches of the slide unit driven by the pulse, and the number of pitches corresponding to the number of drive pulses and the slide. And a correction unit that supplies a drive pulse corresponding to a pitch number n (n is an integer) of a difference from the movement pitch number of the unit to the drive circuit as a correction pulse.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a block diagram showing an embodiment of a linear pulse motor drive control circuit according to the present invention.

FIG. 2 is a perspective view of a linear pulse motor equipped with a linear pulse motor drive control circuit according to the present invention, and FIG. 3 is a front view of the same.

Although the basic configuration of the slide portion 30 is as described above with reference to FIG. 6, in this embodiment, the driving circuit 1 drives the W1-2 phase, and 1/16 of one pulse is used. Excitation is performed so as to move the pitch.

The sensor 2 is moved integrally with the slide portion 30.

An output corresponding to the peaks and valleys of the stator scale is obtained by forming a bridge using a magnetoresistive element as the sensor 2, and an output pulse is generated every time the threshold value is exceeded.

The linear pulse motor drive control device includes a correction unit 20 that sends a correction pulse to the sensor 2, the comparison unit 10, and the drive circuit 1.
It is composed of

The comparison unit 10 is provided with a hexadecimal counter 11 to which a pulse train identical to the drive pulse (L) supplied to the drive circuit 1 from the central processing unit (CPU) 4 is supplied via the gate 5.

The gate 12 is connected to the output of the counter 11 and a signal indicating that the drive pulse (L) generated by the central processing unit (CPU) 4 is being generated.

The output of the gate is counted by the N counter 13.

Pulses from the sensor 2 described above is connected to the input terminal of the set terminal and N ₁ counter 15 of the flip-flop 17 of the comparison unit 10.

N output comparator 14 and the output of the N ₁ counter 15 of the counter 13
It is connected to the.

Here, the relationship between the flip-flop 17 and the counter 15 will be described in some detail.

Hex initial state counter 11, N counters 13, N ₁ counter 1
The values of 5 are all 0.

The count output of the hexadecimal counter 11 is output at the 16th drive pulse and input to the N counter 13.

Pulses from the sensor 2 is output to the 16-th drive pulse previously, it is input to the N ₁ counter 15. This is because when the pulse from the sensor 2 is output in the 17th drive pulse, it has already been output in the 1st drive pulse.

The foregoing, the pulse is input to the N ₁ counter 15 from the sensor 2, Until count output of 15-ary counter 11 is input to the N counter 13, N ₁ is than the value to be compared with the N One big.

The set terminal of the flip-flop 17, a pulse from the sensor 2 (= N ₁ counter input pulse) is input, the reset terminal count output of the hexadecimal counter 11 (= the input pulse of the N counter) is input Therefore, after the output of the driving pulse, if the flip-flop 17 is reset, the value to be compared with N is N ₁ , and if the flip-flop 17 is set, the value to be compared with N is N ₁
It is -1.

The output of the flip-flop, via a gate 16 controlled by the control circuit 21 is connected to the count-down input terminal of the N ₁ counter 15, if the flip-flop is set N-
Execute 1-.

The correction unit 20 includes a sequence control circuit 21 for controlling the operation sequence of the device after the output of the driving pulse L is completed,
An oscillator 22 for generating the same pulse train as the drive pulse (L) and a gate 23 are included.

FIG. 4 is a schematic diagram showing a relationship between a driving pulse and an actual movement amount in the device according to the present invention.

First, referring to FIG. 4, the case where a step-out occurs and the principle of its correction will be described.

Now, it is assumed that the central processing unit (CPU) 4 has generated L drive pulses.

As a result, it is assumed that the excitation current pattern of the drive circuit 1 changes L times, the slide portion does not lose synchronism, and has correctly moved by l.

1 = (1/16) p × L (1) L = (16N + M) (2) l: Moving distance (when there is no step-out) p: Stator scale pitch L: Number of driving pulses N: Moving The number of teeth (when there is no step-out) M: an integer of 15 or less Note that M is any number (0 to 15) determined by the exciting current pattern corresponding to the final drive pulse, and 16 of the exciting current pattern Corresponding to the above, it is an integer value corresponding to any point obtained by dividing one pitch into 16.

It is assumed that a load that limits the movement of the slider is applied during the driving of the slider by the series of drive pulses, and the movement is limited, and then the load is removed.

It is assumed that the drive current pattern of the drive circuit 1 has changed L times, but the slide portion has moved by l ₁ (≦ l).

l ₁ = (1/16) p × L ₁ … (3) L ₁ = (16N ₁ + M) …… (4) l ₁ : Actual travel distance p: Stator scale pitch L ₁ : Corresponds to actual travel distance The number of driving pulses N ₁ : the number of teeth actually moved M: an integer of 15 or less Note that M is any one of (0 to 15) determined by the excitation current pattern corresponding to the final driving pulse determined by L described above. Even if the step-out occurs, if the load is finally removed, the above value is not affected by the presence or absence of the step-out.

 The number of pulses ΔL to be corrected is given by the following equation.

ΔL = L−L ₁ = 16 (N−N ₁ ) (5) In the present invention, N ₁ in the above formula (5) is moved together with the slide portion 30 to move the slide portion from the stator scale 40. Is detected by the moving pitch number detecting sensor 2 for detecting the number of moving pitches.

 N is obtained from the driving pulse L.

(N−N ₁ ) is calculated by the comparison unit 10 and is calculated by the correction units 20 to 16
(N−N ₁ ) is sent to the drive unit 1.

FIG. 5 is a flow chart for explaining the operation of the embodiment.

(Step 100) Start (Step 101) A drive pulse L (= 16 l / p) necessary for the distance l to be moved is transmitted from the central processing unit 4, monitoring whether the pulse is being transmitted, and comparing the pulse output signal with a comparison unit 10 gates
Send to 12.

When the transmission of a predetermined amount of pulses is completed, the pulse output signal is stopped.

(Step 102) by driving a timer control circuit 21 to end the delivery wait for elapse of the time T _1.

(Step 103) by the comparator 14 to compare the the N and N ₁ above.

N is obtained by counting the driving pulses applied to the comparing section 10 via the gate 5 during the pulse output by the hexadecimal counter 11 and inputting the count output to the N counter 13.

N ₁ is input to the N ₁ counter for one pulse each time one tooth actually moves from the sensor 2.

The N and N ₁ are compared by the comparator 14 of the comparison unit 10.

The timing of the comparison is performed by a signal from the sequence control circuit 21.

Since N = N ₁ a long if properly driven it (it step-out was not) will be confirmed, and it outputs a positioning completion signal indicating that was N = N ₁ in (step 108) (Step 109).

If (step 104) N ≠ N _1, the correction unit 20 the gate 23
And outputs the same output pulse of the oscillator 22 as the drive pulse via the gate 5 to the drive circuit 1 through the gate 5.

(Step 105) the slide unit 30 is moved by the drive pulse, repetition when the output of the sensor appears, the occurrence of the comparison → 1 tooth of the drive pulses until N = N ₁ (Step 10
It becomes the N = N ₁ 3) (step 108) → (Step 10
9) End the control.

(Step 106) If the output of the sensor does not appear, it means that the slide unit 30 cannot be moved even if a pulse is applied, so that an error signal is generated.

(Step 107) The operation ends because the slide unit 30 cannot be moved.

Various modifications can be made to the embodiment described in detail above within the scope of the present invention.

The drive system is not limited to the W1-2 phase, and is similarly applicable to a drive system having two or more stop positions within one pitch.

 The sensor may be a photoelectric sensor.

Although step-out with insufficient feed has been described as an example, correction can be made in the same manner when overrun is caused by an external force.

(Effects of the Invention) As described in detail above, the linear pulse motor drive circuit control device according to the present invention detects the number of movement pitches that move integrally with the slide portion and detect the amount of movement of the slide portion from the stator scale. No additional scales or racks are required, as it allows for control of the system.

The comparison unit compares the number of drive pulses generated for a predetermined movement with the number of movement pitches of the slide unit driven by the pulse detected by the sensor, so that step-out and step-out can be easily performed. The amount can be known, and abnormalities such as step-out can be easily detected.

Currently, linear pulse motors are mostly used in oven loop control systems.

Therefore, the user is dissatisfied with the fact that the user does not know even if an abnormal state such as step-out due to disturbance or the like occurs. The device according to the present invention can be easily applied to a conventional drive control device capable of controlling the minimum displacement of the slide portion to be smaller than one pitch by directly obtaining information from the stator scale.
Thus, the range of use of the linear pulse motor can be further expanded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a linear pulse motor drive control circuit according to the present invention. FIG. 2 is a perspective view of a linear pulse motor equipped with a linear pulse motor drive control circuit according to the present invention, and FIG.
1 is a front view of a linear pulse motor equipped with a linear pulse motor drive control circuit according to the present invention. FIG. 4 is a schematic diagram showing a relationship between a driving pulse and an actual moving amount in the device according to the present invention. FIG. 5 is a flowchart for explaining the operation of the linear pulse motor drive control circuit according to the present invention. FIG. 6 is a schematic view showing the principle of a linear pulse motor. FIG. 7 and FIG. 8 are schematic diagrams each showing an example of a conventional closed-circuit drive linear pulse motor. 1 ...... driving circuit 2 ...... sensor 4 ...... central processing unit (CPU) 10 ...... comparator unit 11 ...... hexadecimal counter 12 ...... gate 13 ...... N counter 14 ...... comparator circuit 15 ...... N ₁ counter 16 Gate 17 Flip-flop 20 Correction unit 21 Control circuit 22 Oscillator 23 Gate 30 Slide unit 31 Permanent magnet 32 Electromagnet (EMA) 33 Electromagnet (EMB) 37 …… Sensor 38 …… Pinion 39 …… Rotary encoder 40 …… Stator scale 41 …… Rack 50 …… Linear scale

Claims (1)

(57) [Claims] A variable excitation current generated corresponding to a pulse train supplied to a drive circuit is supplied to a slide portion having a permanent magnet and an electromagnet, and 1 / N of one pitch of a stator scale is provided.
A linear pitch motor drive control device that performs drive control in units of (N is an integer of 2 or more); a movement pitch number detection sensor that moves integrally with the slide portion and detects a movement amount of the slide portion from the stator scale; Means for converting to a number of pitches corresponding to the number of drive pulses generated for the predetermined movement, and comparing the number of pitches with the number of movement pitches of the slide section driven by the pulses detected by the sensor; And a correction unit that supplies a drive pulse corresponding to a pitch number n (n is an integer) of a difference between a pitch number corresponding to the drive pulse number and a movement pitch number of the slide unit to the drive circuit as a correction pulse. And a linear pulse motor drive control device comprising: