JP2002233179A - Dc-motor control method and dc-motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a time required for deceleration without deteriorating positioning accuracy. SOLUTION: In an apparatus, whose mechanism is driven by a DC motor which is a power source, a speed command value for the DC motor is generated in accordance with a speed profile (b) expressed by a 6th order function which has a large deceleration rate, immediately after the start of deceleration and the time, while being driven at a low speed immediately before a stop is long in comparison with a speed profile (a) expressed by a generally used cubic function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a DC motor, and more particularly to a control for shortening a time required for deceleration when driving a mechanism using a DC motor as a power source. .

[0002]

2. Description of the Related Art At present, motors are used as power sources for various devices. In particular, DC motors have a simple structure, do not require maintenance, have little rotation unevenness and vibration, and can perform high-speed and high-precision control. For many reasons, they are widely used in OA equipment and household appliances.

The control of a general DC motor will be described with an example. FIG. 5A is a block diagram showing a speed control procedure of a general DC motor. Such DC motor control is based on PID (proportional integral and dif
ferential) control or classical control. The procedure will be described.

First, a target speed to be given to a controlled object is given in the form of a speed command 501. FIG. 5B shows a speed command 50.
1 shows two commonly used forms,
(A) is a form that gives a target speed at a constant value from the beginning.
Is a form in which the speed is increased at a constant rate and is led to the target speed.

[0005] Such a speed command 501 is sent to a motor 505 via a motor driver circuit 504, and the rotation of the motor causes the mechanical mechanism 506 to move. When the movement starts, the current scanning speed 507 of the mechanical mechanism 506 (for example, a carriage in a printer) is calculated by a speed conversion circuit 509 from a signal of an encoder sensor 508 attached to the mechanical mechanism 506 and a timer built in the printer. Is done.

[0006] Then, from the speed command value 501, the scanning speed 5
07 is passed to the PID calculation circuit 503 as a speed error 502 that is insufficient with respect to the target speed.
The energy to be given to the DC motor at that time is PI
It is calculated by a method called D operation. The motor driver circuit 504 having received the pulse width modulation (hereinafter referred to as “PWM (Pulse Width Modul)” for changing the pulse width of the applied voltage while keeping the motor applied voltage constant, for example.
)), the current value is adjusted by changing the duty of the applied voltage, and the DC motor 50 is controlled.
The energy given to 5 is adjusted to control the speed.

In a system for performing such control, in order to realize high-precision position control, it is necessary to suppress the speed immediately before stopping to the lowest possible speed. In other words, if the speed immediately before the stop is high, a large overrun occurs after reaching the stop target position, making it difficult to ensure high accuracy.

Further, in order to stably hold down the speed immediately before the stop to a low speed, it is necessary to further suppress the speed immediately before the stop to a low speed. That is, as the profile at the time of deceleration of the speed command described above, it is generally desirable to use a curve in which the deceleration becomes gentler in proportion to approaching the stop position.
No. 894 discloses a method using a cubic curve and a quintic curve.

[0009]

However, in the method using the cubic curve and the quintic curve described in the above publication, if the deceleration immediately before the stop is gentle, the deceleration immediately after the start of the deceleration is also gentle. As a result, the time required for deceleration becomes unnecessarily long, and the time required to stop increases.

This is because the curve drawn by the above function is symmetric with respect to its center point, and the sum of the deceleration in the first half (immediately after the start of deceleration) of the curve indicating the speed command profile and the curve This is because the sum of the decelerations in the latter half (immediately before stopping) is equal to the total.

However, in actual motor control,
As long as the controlled object satisfies the condition that can be followed, deceleration with a steeper gradient is possible immediately after the start of deceleration than immediately before the stop, and the tertiary and quintic curves are not sufficiently controlled. Means that.

For this reason, it is difficult to achieve both a reduction in the speed immediately before stopping and a reduction in the time required for deceleration in order to improve the positioning accuracy.
This has been a problem to be solved when designing equipment using a C motor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method and apparatus for controlling a DC motor which can reduce the time required for deceleration without lowering the positioning accuracy. The purpose is to do.

[0014]

In order to achieve the above object, a DC motor control method according to the present invention is a method for controlling a DC motor in a device that drives a mechanism using the DC motor as a power source. The speed command value for the motor is generated according to a profile in which the deceleration in the first half of the deceleration area is set to be larger than the deceleration in the second half of the area.

According to another aspect of the present invention, there is provided a DC motor control apparatus for driving a mechanism using a DC motor as a power source. Is provided in accordance with a profile in which the deceleration in the first half of the deceleration area is set to be larger than the deceleration in the second half of the area.

That is, according to the present invention, in a device for driving a mechanism by using a DC motor as a power source, the deceleration in the first half of the deceleration region is controlled according to a profile set larger than the deceleration in the second half of the region. Generate a speed command value.

In this manner, the time required for deceleration can be reduced while securing the time for driving at a low speed immediately before the stop, and the time required for stopping without lowering the positioning accuracy can be shortened. Alternatively, the positioning accuracy can be improved without changing the time required for stopping.

Therefore, the mechanism driven by the DC motor is quickly and accurately moved to improve the throughput of the device using the DC motor, or without decreasing the throughput of the device using the DC motor. DC
The positioning accuracy of the mechanism driven by the motor can be improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. Here, a serial type ink jet printer equipped with a recording head having a detachable ink tank will be described as an example.

FIG. 1 is an overall perspective view showing a schematic configuration of a serial type ink jet printer according to this embodiment. In the figure, 101 is a recording head having an ink tank,
Reference numeral 102 denotes a carriage on which the recording head 101 is mounted.

A guide shaft 103 is inserted into a bearing portion of the carriage 102 in a slidable manner in the main scanning direction, and both ends of the shaft are fixed to a chassis 114. The drive motor 10 is driven via a belt 104 which is a carriage drive transmission means engaged with the carriage 102.
5 is transmitted, and the carriage 102 moves in the main scanning direction.

During recording standby, the recording paper 115 is stacked on the paper supply base 106, and at the start of recording, the recording paper is supplied by a paper supply roller (not shown). In order to convey the fed recording paper, the conveyance roller 110 is rotated via a gear train (motor gear 108, conveyance roller gear 109) as a transmission means by a driving force of a paper conveyance motor 107 which is a DC motor, and a pinch roller The recording paper 115 is conveyed by an appropriate feed amount by the pinch roller 111 which is pressed by the conveying roller 110 by a spring (not shown) and is driven to rotate, and the conveying roller 110.

Here, the slit amount of the code wheel (rotary encoder film 116) pressed into the conveying roller 109 is detected by the encoder sensor 117, and the conveying amount is detected.
It is managed by counting, and enables highly accurate control of the feed amount.

FIG. 2 is a block diagram illustrating a control configuration of the printer shown in FIG. In the figure, reference numeral 401 denotes a CPU for controlling the printer of the printer,
The recording process is controlled using the printer control program, printer emulation, and recording font stored in the storage device 02.

Reference numeral 403 denotes a RAM which stores expanded data for recording and data received from the host. Reference numeral 404 denotes a recording head, and 405, a motor driver for driving a motor for conveying the recording paper and for moving the carriage. 406, a printer controller;
3 for controlling access, exchanging data with the host device, and transmitting control signals to the motor driver. A temperature sensor 407 including a thermistor detects the temperature of the printer.

The CPU 401 performs mechanical / electrical control of the main body according to a control program in the ROM 402 and transmits information such as emulation commands sent from the host device to the printer device from an I / O data register in the printer controller 406. The control corresponding to the reading and the command is written to the I / O register and the I / O port in the printer controller 406 to perform the reading.

FIG. 3 is a block diagram for explaining the detailed configuration of the printer controller 406 shown in FIG.
The same reference numerals are given to the same components.

In the figure, reference numeral 501 denotes an I / O register which exchanges data with a host at a command level. Reference numeral 502 denotes a reception buffer controller which directly writes data received from a register into the RAM 403.

Reference numeral 503 denotes a print buffer controller which reads print data from a print data buffer of a RAM at the time of printing and sends the data to the printer head 404. 504, a memory controller;
It controls memory access in three directions for the AM 403. 505, a print sequence controller;
Control the print sequence. A host interface 231 controls communication with the host.

Hereinafter, the deceleration profile according to the present embodiment will be described with an example in which the transport motor 107 is controlled.

The configuration for performing the speed control in this embodiment is almost the same as the general configuration described with reference to FIG. 5A, but differs in the configuration for generating the speed command 501. FIG. 4 shows a comparison between a curve profile b of a speed command value according to a sixth-order function of the present embodiment and a curve profile a of a speed command value according to a conventionally proposed cubic function.

In the present embodiment, a formula for calculating a speed command value having a profile indicated by b is:
The following equation: Vy = (V1−V2) (2 · Tx ³ −3 · T · Tx ² + T
³ ) Use ² / T ⁶ + V2.

Here, the variables used in the equations represent V1: initial speed V2: final speed T: required time for deceleration Tx: elapsed time after starting deceleration Vy: speed command value at time Tx.

As shown in FIG. 4, when the same time is required from the start of deceleration to the end of deceleration to obtain the same deceleration, a deceleration profile a by a cubic function is compared with a deceleration profile b by a sixth-order function. Then, it can be seen that the deceleration after the start of deceleration is larger and the deceleration immediately before the stop is smaller in the profile of the sixth order function than in the profile of the third order function.

In view of the actual motor control, such a profile based on the sixth order function can perform a sharper deceleration immediately after the start of deceleration than immediately before the stop, as long as the condition that the controlled object can follow is satisfied. It can be said that this method is suitable when deceleration is performed at a higher speed than a profile using a cubic function.

Further, in the profile by the sixth order function,
Compared to the profile based on the third order, the time for driving at a low speed immediately before stopping can be set longer, so that the deceleration time can be reduced without lowering the stopping accuracy. Is expected to improve.

In a specific example, when the above-described deceleration profile by the sixth-order function is applied to the recording paper transport motor of the ink jet printer, the deceleration time can be reduced without lowering the accuracy of the stop position. .

In this embodiment, the deceleration profile is obtained by a sixth-order function. However, the deceleration immediately after the start of deceleration is greater than that of a cubic function, and the motor is driven at a low speed immediately before the stop. If the profile is a deceleration profile having a long time, a profile obtained by a function other than the above-described sixth-order function may be applied.

In the above-described embodiment, the present invention is applied to the deceleration control of the DC motor of the serial type ink jet printer. However, the present invention is not limited to the ink jet printer but is applied to various devices using the DC motor. It is possible.

An object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU or MP) of the system or the apparatus.
It goes without saying that U) can also be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0045]

As described above, according to the present invention, it is possible to shorten the time required for deceleration while securing the time for driving at a low speed immediately before stopping, and to stop without lowering the positioning accuracy. Reduce the time it takes to
Alternatively, the positioning accuracy can be improved without changing the time required for stopping.

Therefore, the mechanism driven by the DC motor is quickly and accurately moved to improve the throughput of the device using the DC motor, or without decreasing the throughput of the device using the DC motor. DC
The positioning accuracy of the mechanism driven by the motor can be improved.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing a schematic configuration of a serial ink jet printer as an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a control configuration of the printer of FIG.

FIG. 3 is a block diagram illustrating a detailed configuration of the printer controller of FIG. 2;

FIG. 4 is a graph showing a speed command profile generated by the embodiment of the present invention and a conventionally known speed command profile.

FIG. 5A is a block diagram showing a speed control procedure of a general DC motor.

FIG. 5B is a graph showing two forms generally used as speed commands.

Continued on the front page (72) Inventor Toyo Koji 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) in Canon Inc. 5H571 BB06 GG01 GG02 JJ20 JJ22 JJ23 JJ24 LL50

Claims (10)

[Claims] 1. A method for controlling a DC motor in a device for driving a mechanism using a DC motor as a power source, wherein a speed command value for the motor is set such that a deceleration in a first half of a deceleration region is in a second half of the region. A method for controlling a DC motor, wherein the DC motor is generated according to a profile set larger than deceleration. 2. The DC motor control method according to claim 1, wherein the profile sets a long time for driving at a low speed in the latter half of the deceleration region. 3. The DC motor control method according to claim 1, wherein the profile is represented by a continuous curve. 4. The method according to claim 1, wherein the profile is represented by a sixth-order function. 5. A storage medium storing a program code for implementing the DC motor control method according to claim 1. Description: 6. A control device for a DC motor in a device for driving a mechanism using a DC motor as a power source, wherein a speed command value for the motor is set such that a deceleration in a first half of a deceleration region is in a second half of the region. A control device for a DC motor, comprising: a speed command value generation unit that generates a speed command value according to a profile set larger than a deceleration. 7. The DC motor control device according to claim 6, wherein the profile sets a long time for driving at a low speed in the latter half of the deceleration region. 8. The control device according to claim 6, wherein the profile is represented by a continuous curve. 9. The control device for a DC motor according to claim 6, wherein the profile is represented by a sixth-order function. 10. An electronic apparatus comprising the DC motor control device according to claim 6. Description: