JPH04308487A - Rotational positioning controller for rotary body and controller for ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide a rotational positioning controller for a rotary body which can drive a low rotation high torque rotary body and can position the rotary body with high accuracy. CONSTITUTION:The controller for ultrasonic motor comprises an ultrasonic motor 1, a control circuit 8 for rotary driving the ultrasonic motor 1, means 11 for detecting the rotational speed of the ultrasonic motor 1, a rotary body to be rotated through the ultrasonic motor 1, and means 7 for detecting the rotational position of the rotary body. The control circuit 8 controls the ultrasonic motor 1 so that the rotational speed thereof approaches a target rotational speed which is increased if the absolute value of the difference between the actual rotational position and a target rotational position of the rotary body is high otherwise decreased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body positioning control device and an ultrasonic motor control device suitable for use in potentiometers for adjusting sound volume and the like.

0002

2. Description of the Related Art A conventional rotational positioning control device for a rotating body will be described below with reference to FIG. 20 is a DC motor, and the rotating body 24 is rotated by this DC motor 20. A friction piece 25 is attached to a fixed portion of the rotating body (rotating plate) 24 so as to be in sliding contact with the peripheral edge thereof. Reference numeral 26 denotes a rotational position detecting means having a potentiometer configuration for detecting the rotational position of the rotary plate 24, which detects a rotational position from a ring-shaped resistor connected between the power supply +B and the ground, and a rotatable movable terminal that slides this resistor. The movable terminal rotates together with the rotary plate 24.

Reference numeral 21 denotes a variable DC voltage generating means for applying a driving voltage Vi to the motor 20, and the voltage is controlled and varied by a control device 22. The control device 22 includes a rotational position detection voltage Vout from the rotational position detection means 26,
Target rotational position voltage Vref of the rotational position detection means 26 corresponding to the target rotational position of the rotary plate 24 from the input terminal 23
are supplied and compared, and both voltages Vout and Vr
The drive voltage Vi applied to the motor 20 from the variable DC voltage generating means 21 is controlled so that the difference in ef becomes small. In this case, the smaller the voltage difference (absolute value) e, the smaller the voltage Vi, and the larger the voltage difference e, the larger the voltage Vi.

0004

[Problem to be Solved by the Invention] Generally, motors and their control systems have inertia, so even if the voltage applied to the motor reaches 0V, the motor does not stop immediately, and as a result, the rotating body This results in overshooting the target rotation position.

[0005] Furthermore, since many DC motors generally have high rotations and low torque, when driving a rotating body with low rotations and high torque, it is necessary to reduce the rotation of the DC motor using a gear etc. before driving the rotating body. This causes a dead zone due to backlash, making it impossible to perform highly accurate positioning.

In view of the above, the present invention provides a rotary positioning control device for a rotary body that can drive a low-rotation, high-torque rotary body and position the rotary body with high precision, and the rotary body. The present invention attempts to propose an ultrasonic motor control device that can control the rotational speed of an ultrasonic motor with high precision and is suitable for use in a rotational positioning control device.

[0007]

[Means for Solving the Problems] A rotational positioning control device for a rotating body according to the present invention includes an ultrasonic motor 1, a control circuit 8 for rotationally driving the ultrasonic motor 1, and a control circuit 8 for rotationally driving the ultrasonic motor 1.
, a rotating body rotated by the ultrasonic motor 1 , and a rotating position detecting unit 7 detecting the rotating position of the rotating body. , the ultrasonic motor 1 is controlled so that the rotational speed of the ultrasonic motor 1 approaches the target rotational speed, and when the absolute value of the difference between the rotational position of the rotating body and the target rotational position is large, the rotational speed of the ultrasonic motor 1 approaches the target rotational speed. When the rotational speed is high and the absolute value of the difference between the rotational position of the rotating body and the target rotational position is small, the target rotational speed is controlled so that the target rotational speed becomes small. be.

The ultrasonic motor control device according to the present invention includes:
It has an ultrasonic motor 1, a control circuit 8 for rotationally driving the ultrasonic motor 1, and a rotation detecting means 11 for detecting the rotation speed of the ultrasonic motor 1. The ultrasonic motor 1 is controlled so that the speed approaches the target rotational speed.

[0009]

[Operation] According to the rotational positioning control device for a rotating body according to the present invention, the control circuit 8 controls the ultrasonic motor 1 so that the rotational speed of the ultrasonic motor 1 approaches the target rotational speed.
control. When the absolute value of the difference between the rotational position of the rotating body and the target rotational position is large, the target rotational speed is large, and the absolute value of the difference between the rotational position of the rotating body and the target rotational position is large. When the target rotation speed is small, the target rotation speed is controlled so that the target rotation speed becomes small.

According to the ultrasonic motor rotation control device according to the present invention, the control circuit 8 controls the ultrasonic motor 1 so that the rotation speed of the ultrasonic motor 1 approaches the target rotation speed.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 1(A).

The following equation 1 shows the correspondence between some of the symbols and symbol numbers used to explain the embodiments.

[0013]

[Math 1]

In FIG. 1(A), reference numeral 1 denotes an ultrasonic motor, and a pulley 3 is attached to a rotating shaft 2 of the ultrasonic motor. A pulley 5 is connected to a pulley 3 of the motor 1 via a belt 4. Although not shown in the drawings, for example, a rotary movable terminal of a potentiometer for volume adjustment is attached to this pulley 5 via a rotating shaft 6. Reference numeral 7 denotes a rotation position detection means having a potentiometer configuration for detecting the rotation position of the rotation movable terminal of this volume adjustment potentiometer, which includes a ring-shaped resistor connected between the power supply +B and the ground, and its resistance. It consists of a rotating movable terminal that slides on the body. The rotary movable terminal is attached to the pulley 5 via the rotating shaft 6. A movable terminal of the potentiometer 7 is attached to the pulley 5 via the rotating shaft 6. Then, the rotational force of the motor 1 is transmitted via the pulley 3, the belt 4, and the pulley 5 to the rotary movable terminal of the above-mentioned volume adjustment potentiometer.

If the reduction ratio of pulley 5 to pulley 3 is n, and the rotational speed (angular velocity) of pulley 3 is represented by symbol 1, then the rotational speed (angular velocity) of pulley 5 is represented by symbol 3.
Therefore, the rotational position (rotational angular position) of the pulley 5 is expressed as θ/n.

Reference numeral 10 denotes a voltage controlled oscillator, which generates oscillation signals f and f' with both frequencies f and a phase difference of 90°.These oscillation signals f and f' are supplied to the ultrasonic motor 1, and the The rotation speed (symbol 1) and rotation direction are controlled.

11 is a rotation detecting means, for example, the motor 1
It consists of a frequency generator consisting of a large number of magnet pieces arranged in a ring shape that rotate integrally with the motor 1, and a magnetic head installed on a fixed part near the magnet pieces, and the rotation speed of the motor 1 (symbol 1)
Detection voltage proportional to the rotation speed (symbol 5)
occurs.

8 is a microcomputer that controls the ultrasonic motor 1 via a D/A converter 9 and a voltage controlled oscillator 10.
control the rotation of The rotational speed (angular velocity) detection voltage (symbol 5) proportional to the rotational speed (symbol 1) of the motor 1 from the rotation detection means 11 [see FIG. 1(C)] is applied to the A/D converter 1.
3, it is converted into a digital voltage value (symbol 2) and supplied to the microcomputer 8, where it is compared with an internal target rotation speed (angular velocity) digital voltage value (symbol 4). The rotational speed detection voltage (symbol 5) changes, for example, in a range of 10V to 60V, as shown in FIG. 1(C). and,
The microcomputer 8 is

[0019]

[Math 2]

[0020] Then, in order to increase the frequency f of the oscillation signals f and f' supplied from the oscillator 10 to the motor 1,

[0021]

[Math 3]

[0022] If so, control numerical data Vfd that lowers the frequency f is outputted, and after this is supplied to the D/A converter 9 and converted into an analog voltage Vf, the oscillator 10 outputs an oscillation frequency control voltage. Supplied as. Here, the rotational speed (symbol 1) of the motor 1 and pulley 3,
The relationship with the oscillation frequency f of the oscillator 10 is as follows. That is, as shown in FIG. 1(B), the higher the frequency f, the lower the rotational speed (symbol 1) of the motor 1 becomes, and the lower the frequency f, the higher the rotational speed (symbol 1). In this case, Figure 1
As shown in (B), when the frequency f is 42kHz, the rotation speed (symbol 1) is 1500°/s, and the frequency f is 42kHz.
At 7kHz, the rotational speed (symbol 1) is 30°/s.

Further, the rotational position detection voltage Vout from the rotational position detection means 7 is supplied to the A/D converter 14, where it is converted into a digital voltage value θd and sent to the microcomputer 8.
is supplied to In the microcomputer 8, the rotational position detection digital voltage value θd is compared with the target rotational position digital voltage value θdref from the input terminal 8a, and the above-mentioned target rotational speed digital voltage value (symbol 4) is set according to the difference. It is determined. That is, the target rotational speed digital voltage value (symbol 4) becomes a function of the target rotational position digital voltage value θdref. The target rotational speed digital voltage value (symbol 4) increases as the absolute value of the difference between the rotational position detection digital voltage value θd and the target rotational position digital voltage value θdref increases. The smaller the absolute value of the difference between the dynamic position digital voltage values θdref is, the smaller the difference becomes. In addition, when there is margin in controlling the rotational speed (symbol 1) of motor 1, the target rotational speed digital voltage value (
Symbol 4) may be constant. Therefore, the rotational position detection digital voltage value θd becomes the target rotational position digital voltage value θdre.
f, the microcomputer 8 controls the motor 1.
In this case, the frequency f of the oscillation signals f and f' supplied to the motor 1 is 47kHz [Fig.
(B)] or 0Hz, the microcomputer 8 outputs the control numerical data Vfd, supplies it to the D/A converter 9, converts it to an analog voltage Vf, and causes the oscillator 10 to oscillate. It may be supplied as an output control voltage. In the case of an ultrasonic motor, the stator and rotor are brought into strong pressurized contact, so when the microcomputer 8 issues the above-mentioned stop command to the motor 1, the motor 1 immediately stops.

[0024] If the motor 1 is expected to rotate excessively due to wasted time in the deceleration mechanism or control cycle, the motor 1 may be stopped early or rotated in the reverse direction after stopping. However, the degree of excessive rotation of the motor 1 is extremely small in the case of an ultrasonic motor.

Incidentally, in the case of a DC motor, the angle of difference between the rotational position of the rotational position detection means 7 and the target rotational position is 1°.
It is impossible to achieve a rotation within this range unless a correction method such as integration of errors is used, and furthermore, the control time takes more than 1 second (in the case of a rotation of about 5 degrees).

However, when using the ultrasonic motor 1, it is possible to control the angle of difference between the rotational position of the rotational position detection means 7 and the target rotational position to 0.5° or less without correction. Moreover, the control time is less than 0.5 seconds.

[0027]

Effects of the Invention According to the rotational positioning control device for a rotating body of the present invention described above, there is provided an ultrasonic motor, a control circuit for rotationally driving the ultrasonic motor, and a rotation detecting means for detecting the rotational speed of the ultrasonic motor. and a rotating body rotated by an ultrasonic motor, and rotation position detection means for detecting the rotational position of the rotating body, and a control circuit that causes the rotational speed of the ultrasonic motor to approach a target rotational speed. In addition, when the absolute value of the difference between the rotational position of the rotating body and the target rotational position is large, the target rotational speed becomes large, and the rotational position of the rotating body and the target rotational position are controlled. The target rotational speed is controlled so that when the absolute value of the difference between rotational positions is small, the target rotational speed is small, so it is possible to drive a rotating body with low rotation and high torque, and in a short time. The rotating body can be positioned with high precision.

According to the above-described ultrasonic motor control device of the present invention, the ultrasonic motor has an ultrasonic motor, a control circuit for rotationally driving the ultrasonic motor, and a rotation detecting means for detecting the rotational speed of the ultrasonic motor. Since the control circuit controls the ultrasonic motor so that the rotational speed of the ultrasonic motor approaches the target rotational speed, the rotational speed of the ultrasonic motor can be controlled with high precision.

[Brief explanation of drawings]

[Figure 1] Block diagram and characteristic diagram of the embodiment

[Figure 2] Block diagram of conventional example

[Explanation of symbols]

1 Ultrasonic motor 3 Pulley 4 Belt 5 Pulley 7 Rotation position detection means 8. Microcomputer 10 Voltage controlled oscillator 11 Rotation detection means

Claims (2)

[Claims] 1. An ultrasonic motor, a control circuit for rotationally driving the ultrasonic motor, rotation detection means for detecting a rotational speed of the ultrasonic motor, and a rotating body rotated by the ultrasonic motor. and rotational position detection means for detecting the rotational position of the rotating body, and the control circuit includes:
The ultrasonic motor is controlled so that the rotational speed of the ultrasonic motor approaches the target rotational speed, and when the absolute value of the difference between the rotational position of the rotating body and the target rotational position is large, the When the target rotational speed is large and the absolute value of the difference between the rotational position of the rotating body and the target rotational position is small, the target rotational speed is controlled so that the target rotational speed becomes small. A rotational positioning control device for a rotating body, characterized in that: 2. An ultrasonic motor, a control circuit for rotationally driving the ultrasonic motor, and rotation detection means for detecting the rotational speed of the ultrasonic motor, wherein the control circuit controls the rotation of the ultrasonic motor. A control device for an ultrasonic motor, characterized in that the ultrasonic motor is controlled so that its rotational speed approaches a target rotational speed.