JPH0580856A - Motor controller - Google Patents

Abstract

PURPOSE:To suppress a speed error within a specific range even if there is load variation during operation and to eliminate the need for a process for adjustments even if there is the individual difference in load. CONSTITUTION:A speed detecting circuit 6 detects the operation speed of a controlled system 5 and the whole or part of data on the detected speed are held in a data holding circuit 7. A proportional control constant calculating circuit 8 calculates the proportional control constant as a PID control parameter from the held data and sets the proportional control constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for a motor used in, for example, a printer or a facsimile.

[0002]

2. Description of the Related Art Conventionally, in a serial printer, a DC motor and its control device have been used as a drive source for scanning a carriage equipped with a printing means (for example, a dot impact method, an ink jet method, a thermal transfer method, etc.). .. When a general serial printer receives print data from an external computer or the like, the motor rotation is started to drive the carriage, and printing is started when a certain speed is reached. When the data for one line is printed, the motor is stopped and the paper for one line is fed.
Further, if there is print data, the above operation is repeated to continue printing.

Next, a carriage drive motor (hereinafter, CR
The operation of the motor) will be described in detail.

First, when a print start command is sent from the computer, the CR motor is started by the controller of the printer via the motor control device. For example, in FIG.
Immediately after the start, the vehicle is gradually accelerated so that noise or vibration does not occur or overcurrent does not flow to the motor, as shown in FIG. Then, printing is performed by performing constant speed control at a predetermined speed. After printing is completed, the machine decelerates and stops immediately. That is, during acceleration and deceleration, control is performed so that noise or the like does not occur due to rapid speed changes, and at constant speed, control is performed so as not to disturb printing accuracy.

The speed control of such a CR motor is generally performed by a servo system having a PID control loop shown in FIG. 6, and finally by changing the voltage applied to the motor or the duty of PWM. Done.

Here, description will be made assuming that the duty of PWM is controlled to control the motor speed. First, the moving speed of the controlled object (here, the carriage) or the rotating speed of the motor detected by a speed detecting mechanism such as an encoder is subtracted from the externally instructed speed to obtain a speed error Ve.
To calculate. Next, for example, the operation amount (here, the duty of PWM) is calculated according to the following equation (1).

[0007]

[Equation 1]

Here, Kp is a proportional control constant, Ki is an integral control constant, and Kd is a differential control constant.

The duty of PWM applied to the motor driver is changed according to the calculated value to control the speed of the carriage. In recent years, microprocessors (hereinafter MP
(U) is remarkably improved in performance, and the above-described control is digitally controlled by using the MPU. In this case, the parameters of Kp, Ki, Kd are stored in the RAM or ROM.

[0010]

However, in such speed control of the carriage, the speed error cannot be suppressed within a desired range in the following cases.

(1) Due to secular change of the carriage mechanism,
The load has changed significantly.

(2) When an ink tank is mounted on the carriage, the weight of the carriage varies depending on the amount of ink consumed.

(3) The load changes greatly due to a large environmental change.

Further, if there is a large variation in carriage load among individuals during mass production, a process of adjusting three parameters for each individual may be required.

The object of the present invention is to solve the above-mentioned problems, to suppress the speed error within a predetermined range even if the load fluctuates during operation, and to adjust even if there are individual differences in the load. It is to provide a motor control device that does not require a process for

[0016]

In order to achieve such an object, the present invention provides a detecting means for detecting an operating speed of a controlled object and all or part of speed data of the speed detected by the detecting means. Holding means for holding, a calculating means for calculating the PID control parameter from the data held by the holding means, and a setting means for setting the control parameter calculated by the calculating means.

[0017]

In the present invention, the operating speed of the controlled object is detected by the detecting means, all or part of the speed data of the speed detected by the detecting means is held by the holding means, and calculation is performed from the data held by the holding means. The PID control parameter is calculated by the means, and the PI calculated by the calculation means
The D parameter is set by the setting means.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.

In the figure, 5 is a control target. A motor 4 drives a controlled object. A motor driver 3 drives the motor 4. 2 is PWM
The control circuit PWM-controls the motor driver 3.

A speed detecting circuit 6 detects the speed of the controlled object 5. A data holding circuit 7 holds a necessary amount of data among the speed data detected by the speed detection circuit 6 at an appropriate timing. Reference numeral 8 is a proportional control constant calculation circuit for calculating a proportional control constant Kp which is one of the parameters of PID control based on the data held in the data holding circuit 7.

Reference numeral 9 denotes a subtractor, which subtracts speed data detected by the speed detection circuit 6 from speed instruction data input from the outside to calculate a speed error Ve.
Reference numeral 1 denotes a PID control circuit, which is a speed error Ve from the subtractor 9.
And the proportional control constant Kp set by the proportional control constant calculation circuit 8 are substituted into the equation (1) to obtain P of the PWM control circuit 2.
The duty of the WM is calculated.

The present embodiment is an example of obtaining an appropriate proportional control constant Kp among the constants of the equation (1). The operation speed of the controlled object 5 is detected by the speed detection circuit 6, and the detected speed data is data. After being held by the holding circuit 7, the proportional control constant calculation circuit 8 calculates the proportional control constant Vp.

On the other hand, the speed error Ve is obtained by subtracting the speed data detected by the speed detection circuit 6 from the speed instruction data input from the outside.

Then, the subtractor 9 is operated by the PID control circuit.
Substituting the speed error Ve from V and the proportional control constant Kp set by the proportional control constant calculation circuit 8 into the equation (1), P
The WM duty is calculated. Then, the calculated P
The PWM control circuit 2 performs PWM control of the motor driver 3 according to the duty of the WM, and the motor driver 3 drives the motor 4 to operate the control target.

When an encoder is used instead of the speed detection circuit 6, the interval between consecutive encoder pulses is counted based on a clock from a clock generating means (not shown) as shown in FIG. Speed data can be obtained based on the clock frequency.

FIG. 3 shows a second embodiment of the present invention.

Compared with the first embodiment, this embodiment is different in the control parameters obtained from the data held by the data holding circuit 7. That is, in the first embodiment, the proportional control constant calculation circuit 8 determines the proper proportional control constant Kp, but in the present embodiment, the integral control constant calculation circuit 10 determines the integral control constant Ki.

Therefore, the PID control circuit 1 substitutes the speed error Ve from the subtractor 9 and the integral control constant Ki set by the integral control constant calculation circuit 10 into the equation (1) to calculate the PWM duty. To be done.

In this embodiment, since the integral control constant Vi is optimized, there is an effect that a large speed fluctuation can be suppressed.

FIG. 4 shows a third embodiment of the present invention.

Compared with the first embodiment, this embodiment is different in the control parameters obtained from the data held by the data holding circuit 7. That is, in the first embodiment, the proper proportional control constant Kp is obtained by the proportional control constant calculation circuit 8, but in the present embodiment, the differential control constant Kd is obtained by the differential control constant calculation circuit 11.

Therefore, the PID control circuit 1 substitutes the speed error Ve from the subtractor 9 and the differential control constant Kd set by the differential control constant calculation circuit 11 into the equation (1) to calculate the PWM duty. To be done.

In this embodiment, since the differential control constant Vd is optimized, there is an effect that it is possible to suppress high-speed speed fluctuations.

[0035]

As described above, according to the present invention,
By holding all or part of the operating speed of the controlled object and setting the optimum control parameters calculated from this data, even if there is a large load change due to variations in individual differences or changes over time, speed errors can be eliminated. There is an effect that the process is suppressed within a desired range and a process for adjusting the variation is not required.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of obtaining velocity data by an encoder.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a conventional speed control method for a carriage drive motor.

FIG. 6 is a block diagram showing a drive control circuit of a conventional carriage drive motor.

[Explanation of symbols]

 1 PID control circuit 2 PWM control circuit 3 Motor driver 4 Motor 5 Control target 6 Speed detection circuit 7 Data holding circuit 8 Proportional control constant calculation circuit 9 Speed subtraction circuit 10 Integral control constant calculation circuit 11 Differential control constant calculation circuit 12 PWM control circuit

Claims (4)

[Claims] 1. A detection means for detecting an operation speed of a controlled object, a holding means for holding all or a part of speed data of a speed detected by the detection means, and a PID based on the data held by the holding means. A motor control device comprising: a calculation unit that calculates a control parameter; and a setting unit that sets the control parameter calculated by the calculation unit. 2. The motor control device according to claim 1, wherein the PID control parameter is a proportional control constant. 3. The motor control device according to claim 1, wherein the PID control parameter is an integral control constant. 4. The motor control device according to claim 1, wherein the PID control parameter is a differential control constant.