JPH07170783A - Access controller for conveying linear motor - Google Patents

Abstract

PURPOSE:To provide an access controller for bringing motor speed substantially into agreement with an access command input by providing a means for damping the motor speed in a part of a servo system, and suppressing the unnecessary increase and rapid change of the speed. CONSTITUTION:If a frequency function f1 is inputted from a command input 1, motor speed (v) rises with a delay. In accordance with this, position deviation DELTAN increases also, and tries to increase the motor speed rapidly. But the motor control signal corresponding to DELTAN becomes suppressed one, since the increase of the motor speed is detected by a speed-voltage converter 12 and voltage proportional to the speed is fed back to a comparator 13. As a result, the motor speed is damped, and the speed (v) changes slowly and does not exceed the input command f1. A similar response approximately equal to f1 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control device for a transport linear motor, and more particularly to a control device suitable for shortening access time.

[0002]

2. Description of the Related Art Recently, a conveyance system using a linear motor has been widely used in various fields such as industrial equipment and consumer equipment.

FIG. 6 is a block diagram of a general servo system used for access control of a conventional linear motor. In the figure, 1 is an access command input, 2 is an access command input terminal of the linear motor control device, 3 is an integrator, 4 is an output of the integrator 3 and the position detector 10 (the number of pulses is counted by using an optical encoder or the like). To detect the position), 5 is a control amplifier, 6 is the thrust constant of the linear motor, 7 is the load mass of the linear motor, and 8 is
Reference numerals 9 and 9 denote integrators, respectively.

In the apparatus shown in FIG. 6, the command input 1 is f _t shown in FIG. 7A in order to accelerate the linear motor speed up to the midpoint of the access target position and decelerate after the midpoint.
The linear function is driven so that the comparison error ΔN between the integral value N and the encoder pulse number N ′ detected by the position detector 10 becomes zero, so-called position feedback control is performed. Showed operating waveforms of the main part in FIG. 7, as the frequency function comprising f _t equal to the numerical value N ₀ to the integrated value to the access target set time T ₀ (area) by converting the access command distance in number of encoder pulses Therefore, in principle, the traveling speed of the linear motor follows f _t, and the movement distance also converges to the target position x ₀ at the set time T _{0 as} indicated by x in (c). Is.

As related known examples of this type, there are JP-A 1-320647 and JP-A-2-179975.

[0006]

However, in the access control device of FIG. 6, since the moving position of the motor, that is, the speed is made to follow the frequency function of f _t only by the position feedback control, the speed goes too far. Occurs, and as a result, the required time is extended with respect to the access set time T ₀ .

This aspect is shown by the characteristic of the broken line in FIG. The motor speed v rises with a delay with respect to f _t due to the influence of inertia such as the load mass as shown in FIG.
A rapid acceleration occurs due to an increase in the position deviation ΔN in the diagram (b), and exceeds f _t at time t ₁ . Then, the time t _2, i.e. the time t ₁ once becomes zero are ΔN at the time the deviation ΔN which occurs by the previous at a rate of follow-up delay is absorbed by the excessive speed of the time t ₁ after and time t ₂ later, the ΔN Is reversed and the motor speed is rapidly reduced. Time t ₂ By analogy from the case (a) FIG.
Since the subsequent speed v is larger than f _t , the integrated value (area) of both before the access setting time T ₀ becomes larger at the actual movement distance than at the input command f _t . That is, as shown in FIG. 6C, the motor movement distance x ′ at T ₀ causes an overshoot with respect to the target value x ₀ , and thereafter, since the pull-in control of this overshoot works with vibration, the access convergence point is It will be extended to T ₀ ′.

The above-mentioned phenomenon and operation are based on the access command input f.
It is essentially unavoidable in a system in which _t is given as a frequency function as shown in Fig. (a) and the motor speed follows this only by position feedback control.
Access speed cannot be increased.

An object of the present invention is to solve the above problems and to make the motor speed v substantially coincide with the access command input f _t , so that the maximum motor speed does not exceed the access command input and the access speed is increased. It is to provide an access control device of a linear motor capable of performing

[0010]

In order to achieve the above object, in the present invention, a speed damping means for damping the speed of the motor is interposed in a part of the servo system path to increase the speed unnecessarily and abruptly change. It has a control configuration for suppressing.

[0011]

The speed damping means functions to detect the motor speed and suppress the motor speed when the speed increases or when the speed tries to increase above a predetermined value, that is, to apply damping. Operates so as to substantially match the frequency function that is the access command input.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an access control device for a linear motor according to the present invention. In the figure, 11 is a speed damping means composed of a speed-voltage converter 12 and a comparator 13, and other parts denoted by the same reference numerals as those in FIG. 6 are the same or equivalent parts, and their operation is also It is the same.

In the embodiment shown in FIG. 1, the speed damping means 11 is used.
Thus, when the motor speed rises, or when the motor speed tries to rise above a predetermined value, damping is applied so as to suppress the motor speed so that the speed characteristic operates substantially in accordance with the frequency function f _t of the command input 1.

First, the structure and operation of the speed damping means 11, that is, the speed-voltage converter 12 and the comparator 13 different from the conventional access device shown in FIG. 6 will be described.

The speed-voltage converter 12 detects the motor traveling speed v and converts it into a voltage, for example, by D / A converting the count result of the encoder pulse number within a fixed time width. It is configured and operates to output a voltage proportional to speed.

The comparator 13 is composed of a differential amplifier or the like,
The detection output of the speed-voltage converter 12 and the output of the control amplifier 5 are comparatively amplified to output a motor control signal. As the motor speed increases, the speed-voltage converter 1
Since the voltage output from 2 increases, the motor control signal output from the comparator 13 is reduced, that is, the motor-generated thrust is weakened to reduce the speed.

The overall operation of this structure will be described below with reference to the operation waveforms shown in FIG.

When the frequency function f _t is input from the command input 1, the motor speed v is the same as in FIG. 7 as shown in FIG.
Stand up late. Accordingly, the position deviation ΔN is also (b)
As shown in the figure, the motor speed is increased, and the motor speed is rapidly increased. However, the increase in the motor speed is detected by the speed-voltage converter 12, and a voltage proportional to the speed is fed back to the comparator 13. The corresponding motor control signal is suppressed. As a result, since the motor speed is damped, the change of the speed v becomes gradual as shown in FIG. 7A, and the input command f _{t is changed} as in the conventional device shown in FIG.
, And a similar response is obtained that substantially matches f _t . Of course, the response characteristic of the speed v depends on the damping force, and depending on the desired speed characteristic, the damping coefficient, that is, the sensitivity (conversion gain) of the speed-voltage converter 12 or the comparison sensitivity (comparative sensitivity of the comparator 13 ( The feedback gain of the speed-voltage converter output) is appropriately changed.

Due to the speed damping, the response of the motor speed becomes slow, and then at time t ₂ , that is, at time t _2.
ΔN once becomes zero at the time point when the deviation of ΔN caused by the speed deviation from f _t is absorbed, and then at time t
After _2, ΔN reverses and the motor decelerates to converge to the target position. The point at time t ₂ operates so that the motor speed v becomes substantially equal to the command input f _{t due} to speed damping, and therefore approaches the point T ₀ side as compared with FIG. 7. This allows
There is no great difference between the speed v after time t ₂ and the integrated value (area) up to the set time T ₀ of access to the command input f _t ,
As shown in (c), the motor movement distance x ′ at the time point T ₀ does not cause a large overshoot as shown in FIG. 7 with respect to the target value x _0. Therefore, the retraction after T ₀ involves vibration. It is possible to shorten the access time.

FIG. 3 shows a concrete application result for clarifying the effectiveness of the present invention according to the embodiment of FIG. Thrust force (K _f ) 6.4 N / V, position detector (K _p )
Using a motor with a resolution of 1 μm, a load mass of 2 kg and a distance of 1.34 mm (position detection encoder pulse count 1.34 x 1
0 ³ ) access command input pattern T ₀ = 12 ms, K
The actual motor speed v with respect to the command input f _t is actually measured under the setting conditions of v = 42 V / m / s and G _p = 0.06 V / pulse. 6A shows the case of the conventional apparatus of FIG. 6 and FIG. 6B shows the case of application of the embodiment of FIG. 1, both of which the vertical axis is the speed (mm / s) and the horizontal axis is the time (ms).
In the conventional device shown in FIG. 7A, too much speed overshoot occurs as shown in FIG. 7, and as a result, vibration is pulled back to pull back the excessive movement amount of the motor.
Although 8 ms is required, in the present invention shown in FIG. 8B, the motor speed becomes gentle due to the effect of speed damping as described above, which is substantially the same as the command input f _t , so that the access convergence is about 13 ms. The speed is getting faster.

FIG. 4 is a block diagram showing another embodiment of the linear motor access control apparatus according to the present invention. In the figure, reference numeral 14 is a motor speed detector, and 15 is a switching circuit. Other parts denoted by the same reference numerals as those in FIGS. 6 and 1 are the same or equivalent parts, and their operations are also the same. .

In the embodiment shown in FIG. 4, the speed damping operation is always turned on as in the embodiment shown in FIG. 1, but the speed damping is turned off when the motor speed is low to improve the followability of the motor speed. The control is performed only by the position servo system to speed up access.

The speed detector 14 is configured to detect the motor traveling speed by identifying the encoder pulse frequency, etc., and responds to the case where the motor speed is below a predetermined value or above a predetermined value. The control signal Es is output. Further, the switching circuit 15 is controlled by the control signal Es of the speed detector 14, and when Es is an identification signal of a predetermined speed or less, the contact is a broken line side in the drawing, and Es is an identification signal of a predetermined speed or more. In this case, the contact operates to switch to the solid line side in the figure.

With this configuration, when the speed at the time of starting the motor is below a predetermined value, the input of the switching circuit 15 is grounded so that the speed damping is disabled and the tracking of the motor speed is accelerated. Next, when the motor speed rises above a predetermined value, the contact of the switching circuit 15 is switched to the speed-voltage converter 12 side shown by the solid line in the figure, so the same speed damping control as in FIG. 1 works. Further, in the convergence region where the motor is decelerated and the speed is reduced to a predetermined value or less, the input of the switching circuit 15 is grounded again, so that the speed damping is inoperative.
As the followability of the motor speed is enhanced, pulling control to the access target position is performed only by the position servo system.

FIG. 5 is a block diagram showing another embodiment of the linear motor access control apparatus according to the present invention. In FIG. 6, reference numeral 16 is a position deviation detector that detects the position error output from the comparator 4, that is, the deviation of the actual motor movement position with respect to the integrated value of the access command input.
Further, the parts denoted by the same reference numerals as those in FIG. 4 indicate the same or equivalent parts, and their operations are also the same.

The embodiment of FIG. 5 is different from the embodiment of FIG. 4 in that the control of the speed damping ON / OFF operation is performed by detecting the motor speed, and is performed based on the deviation of the actual motor movement position. . The position deviation detector 16 discriminates the output ΔN of the comparator 4 and outputs a control signal Es corresponding to each when ΔN is a predetermined value or less or a predetermined value or more. Further, the switching circuit 15 is controlled by the control signal Es of the position deviation detector 16, and when Es is an identification signal of a predetermined deviation or less, the contact is on the side of the broken line in the figure and Es is a predetermined deviation or more as in FIG. If it is the identification signal of, the operation is performed so as to switch to the solid line side in the figure.

With this configuration, when the position deviation ΔN at the time of starting the motor is equal to or less than the predetermined value, the input of the switching circuit 15 is grounded, so that the speed damping is disabled and the tracking of the motor speed is accelerated. Next, when the position deviation ΔN rises above a predetermined value, the contact of the switching circuit 15 is switched to the speed-voltage converter 12 side indicated by the solid line in the figure, so the same speed damping control as in FIG. 1 works. Further, in the convergence region where the motor is decelerated and the position deviation ΔN is reduced to a predetermined value or less, the input of the switching circuit 15 is grounded again, so that the speed damping becomes non-operation, the followability of the motor speed is enhanced, and the position servo system is improved. The pull-in control to the access target position is carried out only by this.

Although the operation waveforms of the embodiments of FIGS. 4 and 5 are omitted, the essence of control is the same as that of the embodiment of FIG. 1, and the operation waveforms thereof are substantially the same as those of FIG.

The embodiments of the present invention have been described above.
In FIG. 1, the speed damping is performed by detecting the motor speed, but this is not particularly limited, and it is also possible to perform the speed damping by detecting the motor acceleration, for example. Further, in FIGS. 4 and 5, the speed detector 1 is exclusively used.
4, the position deviation detector 16 is provided, but this is not particularly limited. For example, the speed-voltage converter 12 functions as the speed detector 14, and the comparator 4 functions as the position deviation detector 16. It is also easy to provide the above, and various modifications are easy without departing from the scope of the present invention.

[0031]

As described above, according to the present invention, since the speed damping means for damping the speed of the motor is provided in a part of the servo system path, the motor speed becomes the frequency function which is the access command input. Operates so that they substantially match. As a result, the motor movement distance at the end of the input of the access command does not go too far with respect to the target value, and therefore, the access control can be speeded up without causing vibration in the pull-in control.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of a main part for explaining the operation of the embodiment of FIG.

FIG. 3 is a diagram showing actual measurement results of input commands and operating speeds in an application example of the embodiment of FIG.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional linear motor access control device.

7 is an operation waveform diagram of a main part for explaining the operation of the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Command input, 10 ... Position detector, 11 ... Speed damping means, 12 ... Speed-voltage converter, 13 ... Comparator, 14 ... Speed detector, 15 ... Switching circuit, 16 ... Position deviation detection.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Aoyama 5200 Mikkajiri, Kumagaya City, Saitama Hitachi Metals Co., Ltd.

Claims (4)

[Claims] 1. A linear motor device for transporting, comprising a position detector configured by an optical encoder or the like for detecting a moving position of the linear motor, accelerating to an intermediate point of an access target position and decelerating after the intermediate point. To detect the position error by comparing the integrated value of the access command input input as a frequency function with the output of the position detector by the first comparator,
An access control device for a linear motor for conveyance configured to obtain a control signal for the linear motor after appropriately passing the position error signal through a control amplifier, comprising speed damping means for damping the traveling speed of the linear motor. An access control device for a linear motor for conveyance, wherein the traveling speed of the linear motor is controlled to be substantially equal to the frequency function of the access command input. 2. A speed-voltage converter which detects the traveling speed of the linear motor and converts it into a voltage output, and a detection output of the speed-voltage converter and an output of the control amplifier. 2. The access control device for the linear motor for transport according to claim 1, wherein the access control device comprises a second comparator. 3. A speed-voltage converter for detecting the traveling speed of the linear motor and converting the speed damping means into a voltage output, a switching circuit connected to the speed-voltage converter, and an output of the switching circuit. And a second comparator for comparing the output of the control amplifier, and a speed detector for detecting the traveling speed of the linear motor and controlling the switching circuit. By the control of the switching circuit by the speed detector, 2. The transport linear motor according to claim 1, wherein when the traveling speed of the linear motor is a predetermined value or less, speed damping is turned off, and when the traveling speed is a predetermined value or more, the speed damping is turned on. Access control device. 4. A speed-voltage converter for detecting the traveling speed of the linear motor and converting the speed-damping means into a voltage output, a switching circuit connected to the speed-voltage converter, and an output of the switching circuit. And a second comparator that compares the output of the control amplifier with the second comparator, and a position error of the output of the first comparator is identified, and a deviation of the actual movement position of the linear motor with respect to the integrated value of the access command is detected to detect the deviation. If the position deviation of the linear motor is less than a predetermined value by the control of the switching circuit by the position deviation detector, speed damping is turned off, and the position deviation is more than a predetermined value. 2. The access control device for the linear motor for conveyance according to claim 1, wherein the speed damping is controlled to be turned on.