JPS63240386A - Controlling method for speed of motor power device - Google Patents

Abstract

PURPOSE:To obtain smoothly start, constant speed rotation and accurate stopping position accuracy by controlling a motor by a high speed rotation encoder at the time of starting and constant speed rotating and by a low speed rotation encoder at the time of braking and stopping. CONSTITUTION:The rotary shaft 12 of a small-sized DC motor 11 is connected through a high speed rotation encoder 13 to a reduction gear 14, and a low speed rotation encoder 16 is attached to the output shaft 15 of the gear 14. The output pulse number per one rotation of the encoder 13 is smaller than that of the encoder 16. The rotation control of the motor 11 at the time of starting and constant speed rotation is conducted by an output signal from the encoder 13. On the contrary, the stopping position is accurately calculated by utilizing an output signal from the encoder 15 having a fine detecting angle at the time of braking and stopping the motor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speed control method for a motor power device that extracts the rotational output of a motor via a speed reduction device.

(Prior art) For example, a motor power device that rotates an astronomical telescope needs to rotate extremely slowly, once a day, and when searching for a specific star, etc. You'll need twice the speed.

Furthermore, since an astronomical telescope has a high magnification of several tens to hundreds of times, its rotation must be extremely smooth and highly accurate.

Conventionally, as shown in FIG. 2, a gear reduction device 3 is provided on the rotating shaft 2 of the stepping motor 1 to reduce the speed, a worm is attached to the output shaft 4 of the stepping motor 1 to rotate the pan head at low speed, and a control unit 5 The number of rotations of the stepping motor 1 is controlled by changing the frequency of the stepping motor 1.

(Problem to be solved by the invention) However, in the case of the combination of the ° stepping motor and the 11NI\i reduction gear, the inertia of the stepping motor causes the telescope to vibrate when stopped, making it impossible to obtain an accurate stopping position. In order to do this, the reduction ratio of the gear reduction device was increased (this resulted in the problem that the gears would have more rattling and smooth startup and constant speed rotation could not be obtained).

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a speed control method for a motor power unit that provides smooth startup, constant speed rotation, and accurate stopping position accuracy.

(Means for Solving the Problems) A speed control method for a motor power device according to the present invention includes attaching a high-speed rotation encoder to a high-speed rotation part, and
A low-speed rotation encoder with a higher number of output pulses per revolution than the high-speed rotation encoder is attached to the low-speed rotation part, and the output of the high-speed rotation encoder is used during startup and constant speed rotation, and when braking and stopping. The invention is characterized in that the rotation speed of the motor is controlled by the output of a low-speed rotation encoder.

(Function) During startup and constant speed rotation, the motor is controlled by a high-speed rotation encoder that has a large number of rotations per single rotation time, and when stopped by braking, the motor is controlled by a low-speed rotation encoder that has a large number of output pulses per rotation. control.

(Example) FIG. 1 schematically shows an example of a motor power device according to the present invention. Rotating shaft 1 of small DC motor 10
1 is a gear reduction device 1 via a high-speed rotation encoder 13.
4, and an encoder 16 for low speed rotation is attached to the output shaft 15 of the gear reduction device 14. is controlled.

For example, when the motor 11 is rotating at a constant speed T,
If the number of output pulses of the encoder 13 is P, then the motor 1
When the rotation speed of the encoder 13 increases to T1 due to some influence, the output pulse of the encoder 13 also increases to Pl. Therefore, in response to the output signal from the encoder 13, the control unit 17 lowers the power supply voltage supplied to the motor 11 so that the number of output pulses of the encoder 13 becomes P, that is, the rotation speed of the motor 11 becomes constant. Feedback control.

If the rotation speed of the motor 11 decreases, the seventh motor 11
Increase the supply voltage to.

The number of output pulses per rotation of the encoder 13 for high-speed rotation is smaller than the number of output pulses per rotation of the encoder 16 for low-speed rotation. Therefore, encoder 1 for low speed rotation
6 has a finer detection angle.

However, since the high-speed rotation encoder 13 rotates at high speed, the number of output pulses per minute is six places higher than that of the low-speed rotation encoder 16. Therefore, it is advisable to control the rotational speed of the motor 11 during startup and constant speed rotation using an output signal from the high-speed rotation encoder 13. In other words, it generally takes several pulses of time to stabilize after a signal is detected, so it would take too much time to use the output signal from the low-speed rotation encoder 16. . For this reason, the 8-speed rotary encoder 1 has a large number of output pulses per unit time.
Stable control is performed in a short time using the output signal from 3. On the other hand, when the motor 11 is stopped by braking, the stop position is accurately determined using the output signal from the low-speed rotation encoder 16 with a fine detection square.

When the motor speed control method according to the present invention is applied to the drive device of an astronomical telescope, the steady rotation speed of the motor 11 is 2.
The encoder 13 for high-speed rotation attached to the rotary shaft 12 has an output pulse rate of 40 pulses per revolution. Therefore, this encoder 13 outputs a signal of 100,000 pulses per minute.

The gear reduction gear 14 has a reduction ratio of 25000:1, and its output shaft 15 has a reduction ratio of 0. The speed is reduced by irpm.

The low-speed rotation encoder 16 attached to the output shaft 15 has an output pulse number of 200 pulses per rotation, and therefore outputs a signal of 20 pulses per minute. Since the rotation speed of the output shaft 15 is o, irpm,
It rotates 144 times per day, and a worm with a reduction ratio of 144:1 to the worm wheel is attached to it, and the astronomical telescope attached to the worm wheel rotates once a day.

In this way, the high-speed rotation encoder 13 rotates at a rate of 1 per minute.
While the encoder 16 for low-speed rotation only outputs a signal of 20 pulses per minute, if the encoder 13 for high-speed rotation is used to control startup, it can be controlled in less than 0.1 seconds. It's over. This is encoder 1 for low speed rotation.
If you use 6, it will take about 15 to 20 seconds.

Furthermore, if the encoder 13 for high-speed rotation is used for control during constant-speed rotation, stable control with high precision can be performed as the number of output pulses per minute is large.

Of course, the output pulses from the low speed rotation encoder 16 may also be used for control during constant speed rotation.

Also, 1IJa when braking and stopping is encoded by encoder 16 for low speed rotation.
By using this, since 200 pulse signals are output per rotation, the motor 11 can be stopped with an angular precision of 1.8 degrees. A braking signal to the motor 11 is output by a microcomputer that has previously stored data on the celestial objects (moon, stars, nebulae) that you want to see with the telescope, and calculates the relationship with the angle at which the telescope is currently facing. .

(Effects of the Invention) As described above, the method for controlling the speed 1111 of the initial force of the motor according to the present invention is to attach a high-speed rotation encoder to the ^-speed rotation part and to attach a high-speed rotation encoder to the low-speed rotation part. Attach a low-speed rotation encoder with a higher number of output pulses per rotation, and
The motor rotation speed is controlled by the output of the high-speed rotation encoder during vl and constant speed rotation, and by the output of the low-speed rotation encoder when braking and stopping, so quick control is achieved when starting spinning, and stable control is achieved during constant speed rotation. The control is
When braking to a stop, the accuracy of the stopping position is reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a speed control method for a motor power plant showing an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a speed control method for a motor power plant showing a conventional example. 2.12...Motor rotating shaft, 4.15...Gear reduction gear output shaft.

Claims (1)

[Claims] A speed control method for a motor power device in which a rotational output of a motor is extracted through a reduction gear, in which a high-speed rotation encoder is attached to a high-speed rotation section, and an output pulse per rotation of the high-speed rotation encoder is attached to a low-speed rotation section. A low-speed rotation encoder having a greater number of output pulses is attached, and the rotation speed of the motor is controlled by the output of the high-speed rotation encoder during startup and constant-speed rotation, and by the output of the low-speed rotation encoder during braking and stopping. 1. A speed control method for a motor power device, characterized in that: