JP3248545B2 - Ultrasonic motor drive controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor drive control device for driving and controlling a plurality of ultrasonic motors.

[0002]

2. Description of the Related Art Conventionally, a single ultrasonic motor has been used.
When driving a rotating body such as two rotating shafts or rotating cylinders,
Since the relationship between the rotational speed and the generated torque (output) may vary from one ultrasonic motor to another, there may be a difference in the torque generated from each ultrasonic motor at a certain rotational speed.

[0003] This will be described with reference to FIG. FIG. 5 is a diagram illustrating a torsional moment generated at each part of the output shaft of each ultrasonic motor (hereinafter, the ultrasonic motor is referred to as USM in the drawings). The first ultrasonic motor 101 and the second ultrasonic motor 102 are connected by a shaft 103, and a load means 104 is attached to the shaft 103.

[0005] In the case shown in FIG.
2, each ultrasonic motor 10
The torque generated from 1, 102 becomes equal. However, when the generated torques T1 and T2 with respect to the rotation speed are different for the respective ultrasonic motors 101 and 102, the generated torques T1 and T2 from the respective ultrasonic motors 101 and 102 are different as shown by the broken lines, and the load torque TL is different. (The sum of the generated torques T1 and T2 is the load torque TL
Is). For this purpose, both ultrasonic motors 101, 1
There was a problem that the ability of the No. 02 could not be fully exhibited.

[0005]

In order to cope with these problems, adjustment is performed by installing independent drive circuits for each of the ultrasonic motors 101 and 102 and changing the frequency of each drive signal (Japanese Patent Application Laid-Open No. 1-227669). However, adjusting the torques T1 and T2 generated from the ultrasonic motors 101 and 102 to be substantially constant increases the number of man-hours and hinders the improvement of mass productivity. .

Further, when the rotational speed is changed in accordance with the operating conditions, each ultrasonic motor 1 at an adjusted rotational speed is adjusted.
Although the torques T1 and T2 generated from the motors 01 and 102 are constant, a slight difference may occur in the rotation speed due to individual differences at a rotation speed different from the adjusted rotation speed.

A first object of the present invention is to reduce the torque generated from each ultrasonic motor without adjusting the torque generated by each ultrasonic motor during production when driving a plurality of ultrasonic motors as a drive source. An object of the present invention is to provide a drive control device for an ultrasonic motor that can be driven at a substantially constant level.

A second object of the present invention is to provide a driving signal voltage that generates a substantially uniform driving force from each ultrasonic motor according to the driving speed even if the driving speed is changed in such a case. Accordingly, it is an object of the present invention to provide a drive control device for an ultrasonic motor capable of performing efficient drive in almost all speed ranges.

[0009]

According to a first aspect of the present invention, there is provided an ultrasonic motor drive control device comprising the same relative motion member as a component.
First driving the first and second ultrasonic motor (1, 2) that
And second ultrasonic motor driving means (13-15, 23-2
5) and first and second detection of first and second output signals output from the first and second ultrasonic motors, respectively.
Output detection means (11ap, 21ap); output difference detection means (4) for detecting a difference between the first output signal and the second output signal based on detection results of the first and second output detection means; the detection result of the output difference detecting means, before both or one of the first or second ultrasonic motor driving means
The driving forces of the first and second ultrasonic motors are in a predetermined relationship.
And output difference control means (5) for controlling the output difference.

The second solution is the same relative movement.
First and second ultrasonic motor driving means (213 to 215, 2) for supplying first and second driving signals to first and second ultrasonic motors (201, 202) each having a member as a constituent member.
23 to 225) and first and second drive signal detecting means (216, 2) for detecting the first and second drive signals, respectively.
26) an output difference detection means (204) for detecting a difference between the first drive signal and the second drive signal based on detection results of the first and second drive signal detection means; and an output difference detection means According to the detection result, both or one of the first and second ultrasonic motor driving means is connected to the first and second ultrasonic motors.
Output difference control means (205) for controlling the driving force of the motor so as to have a predetermined relationship .

Further, a third solution is the same relative operation.
First and second ultrasonic motor driving means (313 to 315, which provide first and second driving signals to first and second ultrasonic motors (301, 302) having moving members as constituent members .
323 to 325) and first and second output detecting means (311ap, 321ap) for detecting first and second output signals output from the first and second ultrasonic motors, respectively.
And a first for detecting the first and second drive signals, respectively.
And second drive signal detection means, first phase difference detection means (316) for detecting a phase difference between the first drive signal and the first output signal, and the second drive signal and the second output signal. Second phase difference detection means (326) for detecting the phase difference of
An output difference detecting means (304) for detecting a difference between the two phase differences detected by the first and second phase difference detecting means; and the first or second ultrasonic motor according to a detection result of the output difference detecting means. Both or one of the driving means is connected to the first and second
Output difference control means (305) for controlling the driving force of the ultrasonic motor to have a predetermined relationship .

In these cases, the fourth solution means is characterized in that the output difference control means controls the frequency of a drive signal input to the first or second ultrasonic motor. In a fifth aspect, the output difference control means controls an input voltage of a drive signal input to the first or second ultrasonic motor. In a sixth aspect of the present invention, the output difference control means controls a frequency and an input voltage of a drive signal input to the first or second ultrasonic motor. According to a seventh aspect of the present invention, there is provided an offset correcting unit for detecting an offset value of the first and second ultrasonic motors and correcting a detection signal of the output difference detecting unit. In an eighth solution, the first and the second methods are used.
And a second output detecting means, wherein the first or second ultrasonic
It is characterized by detecting a current input to the data .

[0013]

According to the present invention, the first output difference detecting means can be used.
And the output difference of the second ultrasonic motor is detected, and the output difference control means controls the first or second ultrasonic motor driving means based on the detection result. At this time, the output difference control means controls the second ultrasonic motor driving means so as to eliminate the output difference of the second ultrasonic motor with respect to the first ultrasonic motor based on the measurement result of the output difference detection means. The output from the ultrasonic motor can be adjusted to be substantially constant and driven.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, an embodiment will be described in more detail with reference to the drawings and the like. FIG.
FIG. 3 is a diagram illustrating a first embodiment of a drive control device for an ultrasonic motor according to the present invention. The first driving unit includes a first oscillating unit 13 for generating a driving signal, a first phase shifting unit 14 for dividing the driving signal into two, and a first amplifying unit 15a for amplifying the two divided driving signals. , 15b. The first ultrasonic motor 1 includes first amplifying means 15a, 15
Piezoelectric body 1 excited by input of amplified drive signal from b
A first stator 11 having an elastic body 11b joined to the piezoelectric body 11a and generating a progressive vibration wave on the driving surface by excitation of the piezoelectric body 11a; First mover 12 driven by waves
It is composed of

Similarly, the second driving means includes a second oscillating means 23 for generating a driving signal, a second phase shifting means 24 for dividing the driving signal into two, and a second driving signal for dividing the driving signal into two. It has second amplifying means 25a and 25b for amplifying. The second ultrasonic motor 2 includes second amplifying means 25a,
A second stator 21 having a piezoelectric body 21a excited by the input of the amplified drive signal from the piezoelectric body 5b and an elastic body 21b joined to the piezoelectric body 21a and generating a progressive vibration wave on a driving surface by the excitation; The second moving member 2 which is brought into pressure contact with the driving surface of the driving member 21b and driven by the traveling vibration wave
And 2. The first ultrasonic motor 1 and the second ultrasonic motor 2 are connected via a connecting shaft 3.

The output difference detecting means 4 includes the first ultrasonic motor 1
-Electric conversion element 11ap provided on the piezoelectric body 11a of FIG.
Signal voltage output from the second ultrasonic motor 2
-Electric conversion element 21ap provided on the piezoelectric body 21a of FIG.
This is a means for detecting a difference between the vibration signal voltage value output from the controller and the vibration signal voltage value. The output difference control means 5 changes the drive signal of the second oscillating means 23 based on the result of the measurement value of the output difference detection means 4 so as to eliminate the output value difference between the first movable element 12 and the second movable element 22. It is a means to control.

Next, the operation of the first embodiment will be described. The drive signal from the first oscillator 13 is transmitted to the first stator 11 via the first phase shifter 14 and the first amplifier 15. As a result, a progressive vibration wave is generated on the drive surface of the first stator 11, and the first mover 12 is driven. The driving of the moving element by the traveling vibration wave is described in, for example,
No. 7354, etc., the explanation is omitted here. The drive signal from the second oscillating means 23 is also transmitted to the second stator 21 via the second phase shifting means 24 and the second amplifying means 25. As a result, a progressive vibration wave is generated on the driving surface of the second stator 21, and the second moving element 22 is driven.

At this time, the output difference detecting means 4 determines the vibration signal voltage value output from the electromechanical transducer 11ab provided on the piezoelectric body 11a of the first ultrasonic motor 1 and the vibration signal voltage value of the second ultrasonic motor 2. The difference between the vibration signal voltage value output from the electromechanical transducer 21ab provided on the piezoelectric body 21a is detected.

FIG. 2 is a diagram showing the relationship between the drive signal frequency, the vibration signal voltage from the electromechanical transducer provided on the piezoelectric body, and the number of revolutions. Piezoelectric body 1 of ultrasonic motors 1 and 2
1a, a mechanical-electrical conversion element 11ab provided on 21a,
The rotation speed of the ultrasonic motors 1 and 2 under a predetermined load can be obtained from the vibration signal voltage from the signal 21ab. FIG. 3 is a diagram showing the relationship between the generated torque of the ultrasonic motor and the rotation speed. The relationship between the generated torque at a certain frequency and the rotational speed is also schematically shown in FIG.
It can be obtained from the vibration signal voltage from 1ab. Therefore, the output difference between the two ultrasonic motors 1 and 2 can be detected by measuring the voltage difference between the two vibration signals. The output difference control means 5 acts so as to correct the frequency of the drive signal based on the result of the output difference detection means 4, and controls so as to eliminate the difference between the outputs from the ultrasonic motors 1, 2.

As shown in FIG. 3, the relationship between the generated torque and the rotational speed of the ultrasonic motors 1 and 2 at a certain driving frequency changes depending on the frequency of the driving signal. Therefore, if it is desired to increase the generated torque at the same rotation speed, the frequency of the drive signal should be reduced. If it is desired to reduce the generated torque at the same rotation speed, the frequency of the drive signal should be increased. By doing so, the difference in output can be automatically reduced even if the step of adjusting the ultrasonic motors 1 and 2 is omitted,
Further, even when the desired rotation speed is changed, the output difference can be automatically adjusted according to the rotation speed at that time.

In the first embodiment, the output difference between the first movable element 12 and the second movable element 22 is detected by the output difference detecting means 4, and the output difference controlling means 5 drives the second oscillating means 23. Although the signal is controlled, the drive signal of the first oscillation means 13 may be controlled by the output difference control means 5, or the first
Even if the drive signals of both the oscillating means 13 and the second oscillating means 23 are controlled, a similar effect is obtained in that the output value difference between the first movable element 12 and the second movable element 22 is eliminated.

First ultrasonic motor 1 and second ultrasonic motor 2
In the case where not only the generated torque of the first piezoelectric member 11a but also the rotational speed of the connecting shaft 3 is controlled, for example, as disclosed in Japanese Patent Application Laid-Open No. 61-251490, If the phase difference between the signal voltage waveform and the input voltage waveform is detected and the output control value (not shown) corrects the frequency of the drive signal of the oscillating means 13 based on the output detection value so as to control the rotation speed and the like. Good. In addition, an encoder is provided on the connection shaft 4 to measure the rotation speed,
A method of correcting the frequency of the drive signal of the oscillation unit 13 by an output control unit (not shown) based on the measured value may be used.
By doing so, both the rotation speed and the generated torque can be controlled.

Next, a method from the detection of the output difference to the control of the oscillation means will be described with reference to FIG. First, the terminal is connected to the piezoelectric body 11 a of the first ultrasonic motor 1.
It is connected to the mechanical-electrical conversion element 11ap provided above and the mechanical-electrical conversion element 21ap provided on the piezoelectric body 21a of the second ultrasonic motor 2, and the terminal is connected to the stator 12 of the first ultrasonic motor 1. The terminal obtains the vibration signal voltage of the stator 22 of the second ultrasonic motor 2 from the terminal.

The difference between these vibration signal voltages V1 and V2 is
As described with reference to FIG. 2, the difference can be regarded as a difference between the output (generated torque) of the first ultrasonic motor 1 and the second ultrasonic motor 2. Therefore, the output of the second ultrasonic motor 2 can be substantially matched with the output of the first ultrasonic motor 1 by the difference between the voltage V2 and the voltage V1.

The difference between the voltage V2 and the voltage V1 is calculated by the output difference detecting means 4 (Vd = V1-V2). The resulting voltage Vd (= V1−V2) becomes positive when the torque generated by the first ultrasonic motor 1 is large,
Becomes negative when the generated torque is large. This voltage Vd
Indicates the amount of correction relative to the current torque generated by the second ultrasonic motor 2, and the larger the difference between the oscillating voltages, the larger the absolute value. In order to increase this voltage Vd to the control voltage, the first arithmetic unit 51 multiplies the coefficient by (-1 × a). The value Vrr (= -1 × a × Vd
) Indicates the amount of correction relative to the current output of the second ultrasonic motor 2, and the greater the difference between the oscillating voltages (equivalent to the amount of generated torque), the greater the absolute value.

Next, the correction amount Vrr is added by the voltage Vf from the feedback unit 54 by the second calculation unit 52, and the absolute correction amount Vr (= Vrr + Vf) is determined with respect to the reference voltage Vo. Decide. Next, the voltage Vr and the reference voltage Vo from the terminal are added by the third arithmetic unit 53, and this value Vi (= Vo + Vr) is output to the voltage controlled oscillator 23a constituting the oscillating means 23.

The voltage controlled oscillator 23a generates a signal having a frequency corresponding to the value Vi, and outputs the signal from a terminal to a waveform shaping unit (not shown). As a result, the generated torque and the rotation speed characteristics of the second ultrasonic motor 2 change. Then, the difference between the vibration signal voltages of the two ultrasonic motors 1 and 2 at that time is input again from the terminal, and Vrr is calculated.

On the other hand, the feedback section 54 receives the voltage Vi from the third calculation section 53, calculates the difference from the reference voltage Vo, and returns the value Vf (= Vi−Vo) to the second calculation section 52. . Then, the second arithmetic unit 52 adds the voltage Vf and the re-input voltage Vrr, and further adds the reference voltage Vo by the third arithmetic unit 53 to output the voltage Vi.

Next, an operation for correcting the output difference between the first ultrasonic motor 1 and the second ultrasonic motor 2 will be described based on the first embodiment. First, it is assumed that the torque generated by the second ultrasonic motor 2 is small. In this case, correction may be performed to reduce the frequency of the drive signal of the second ultrasonic motor 2 and increase the generated torque for a certain rotation speed.
Here, since the voltage V1 becomes higher than the voltage V2, the voltage Vd becomes negative. Therefore, the voltage Vrr also becomes negative, and the voltage Vr and the voltage Vi are acted on so as to decrease, and the frequency of the drive signal from the voltage controlled oscillator 23a decreases.

Conversely, it is assumed that the torque generated by the second ultrasonic motor 2 is large. In this case, it is sufficient to increase the frequency of the drive signal of the second ultrasonic motor 2 and reduce the generated torque for a certain rotational speed. Here, since the voltage V1 becomes smaller than the voltage V2, the voltage Vd becomes positive. Therefore, the voltage Vrr also becomes positive, and the voltage Vrr
r and the voltage Vi are increased, and the frequency of the drive signal from the voltage controlled oscillator 23a is increased.

(Second Embodiment) In the first embodiment, the control of the oscillation means is performed by changing the frequency of the drive signal. However, a method of changing the voltage of the drive signal may be used. FIG. 6 is a diagram showing the relationship between the generated torque of the ultrasonic motor and the rotation speed. The relationship between the generated torque and the rotational speed of the ultrasonic motors 1 and 2 at a certain drive frequency changes depending on the voltage of the drive signal. Therefore, if you want to increase the generated torque,
If it is desired to increase the voltage of the drive signal and reduce the generated torque, the voltage of the drive signal may be reduced.

FIG. 7 is a diagram for explaining a voltage control method of the ultrasonic motor driving device according to the second embodiment. First, the terminals are a mechanical-electrical conversion element 11ap provided on the piezoelectric body 11a of the first ultrasonic motor 1 and a mechanical-electrical conversion element 21a provided on the piezoelectric body 21a of the second ultrasonic motor 2.
The terminal receives the vibration signal voltage of the stator 12 of the first ultrasonic motor 1 and the terminal obtains the vibration signal voltage of the stator 22 of the second ultrasonic motor 2.

The difference between these vibration signal voltages V1 and V2 is
As described with reference to FIGS. 2 and 3, the difference can be regarded as a difference between the outputs of the first ultrasonic motor 1 and the second ultrasonic motor 2. Therefore, the difference between the voltage V2 and the voltage V1 causes the second
The output of the ultrasonic motor 2 can be substantially matched with the output of the first ultrasonic motor 1.

The difference between the voltage V2 and the voltage V1 is calculated by the output difference detecting means 4. The resulting voltage Vd (= V1−
V2) is positive when the output of the first ultrasonic motor 1 is large, and negative when the output of the second ultrasonic motor 2 is large. This Vd value indicates a relative correction amount with respect to the current output of the second ultrasonic motor 2, and the larger the difference between the oscillating voltages, the larger the absolute value. This voltage V
In order to boost d to the control voltage, the first arithmetic unit 61 multiplies the coefficient a. The value Vrr (= a × Vd) indicates a current relative correction amount with respect to the output of the second ultrasonic motor 2, and the larger the difference between the vibration voltages (the amount of generated torque), the larger the correction amount. Absolute value increases.

Next, the correction amount V
rr is added by the voltage Vf from the feedback unit 64 to determine an absolute correction amount Vr (= Vrr + Vo) corresponding to the reference voltage Vo. Next, the voltage Vr and the reference voltage Vo from the terminal are added by the third calculation unit 63, and this value Vi (= Vr + Vo) is output to the A / D conversion unit 65 and the feedback unit 64.

The A / D converter 65 transmits the digital signal Sd corresponding to the Vi value to the amplification controller 66. The amplification control section 66 sends a control signal Ss corresponding to the Sd value to the amplification section 23b of the second oscillation means 23.

The second oscillating means 23 comprises an oscillating section 23a and an amplifying section 23b, amplifies the drive signal from the oscillating section 23a to an amount of amplification selected by the amplifying section 23b, and then amplifies the phase shift means. To communicate. The amplifying unit 23b amplifies the drive signal from the oscillating unit 23a in the second oscillating unit 23 by the amount of amplification corresponding to the control signal Ss. When the Va value is large, the amplification is controlled to increase the amount of amplification in the amplifying unit 23b. When the Va value is small, the amplification unit 2b is controlled.
Control is performed so that the amount of amplification in 3b is reduced.

On the other hand, the feedback section 64 receives the voltage Vi from the third calculation section 63, obtains a difference from the reference voltage Vo, and obtains the voltage value Vf (= Vi−Vo) from the second calculation section 62. To return. Then, the second arithmetic unit 62 adds the voltage Vf and the re-input voltage Vrr, and further adds the third arithmetic unit 6
3, the reference voltage Vo is added to output a voltage Vi.

FIG. 8 is a diagram for explaining a method of selecting the amount of amplification of the drive signal. The amplification amount control unit 66 includes a control signal generation unit that can select a signal like a multiplexer and can generate a control signal, and switching elements Q1 to Q8 such as MOS field effect transistors that can be turned on and off by the control signal. Have been. The control signal generator of the amplification amount controller 66 receives the digital signal Sd from the A / D converter 65, and switches the switching elements Q1 to Q1 according to the signal Sd.
Q8 is selected, and the selected switching elements Q1 to Q8 are selected.
To transmit an ON signal. Switching element Q turned ON
1 to Q8 open the feedback section of the operational amplifier A1 to which the resistors Rf1 to Rf8 are connected.

Resistors Rf1 to Rf8 having different resistance values are connected in parallel to the feedback section of the operational amplifier A1. , The amount of amplification of the operational amplifier A1 can be determined.

In the second embodiment, in order to make the description easy to understand, the digital signal from the A / D converter 65 is set to 8 bits, and the switching element Q and the resistor Rf are set to 8 bits each.
However, the digital signal from the A / D converter 65 is
It is also possible to use four switching elements Q and four resistors Rf. Further, the digital signal from the A / D converter 65 may be 16 bits, and the number of the switching elements Q and the resistances Rf may be 16 or more. The greater the number of bits, the number of switching elements, and the number of resistors, the more precise control is possible.

Next, an operation for correcting a difference in generated torque between the first ultrasonic motor 1 and the second ultrasonic motor based on the second embodiment will be described. First, it is assumed that the torque generated by the second ultrasonic motor 2 is small. In this case, it is sufficient to increase the input voltage of the drive signal of the second ultrasonic motor 2 so as to increase the generated torque for a certain rotation speed. Here, since the voltage V1 is higher than the voltage V2, the voltage Vd is positive. Accordingly, the voltage Vrr also becomes positive, the voltage Vr and the voltage Vi are increased, and a signal for increasing the amplification amount by the A / D converter 65 is transmitted to the amplification amount controller 66. The amplification amount control unit 66 turns on the switching elements Q1 to Q8 to which the resistors Rf1 to Rf8 of the amplifier for increasing the amplification amount are connected.
As a result, the voltage of the drive signal from the oscillator 23a increases.

Conversely, it is assumed that the torque generated by the second ultrasonic motor 2 is large. In this case, correction may be made to reduce the input voltage of the drive signal of the second ultrasonic motor 2 and reduce the torque generated for a certain rotational speed.
Here, since the voltage V1 becomes smaller than the voltage V2, the voltage Vd becomes negative. Accordingly, the voltage Vrr also becomes negative, and the voltage Vr and the voltage Vi are operated so as to be reduced.
The signal for reducing the amplification amount is transmitted to the amplification amount control unit 66 by the D conversion unit 65, and the amplification amount control unit 66 turns on the switching elements Q1 to Q8 to which the resistors Rf to Rf8 of the amplifier for reducing the amplification amount are connected. To As a result, the voltage of the drive signal from the oscillating unit 23a decreases.

(Third Embodiment) In the first and second embodiments, an example has been described in which the frequency and the voltage of the drive signal from the oscillating unit 23 are controlled, but in the third embodiment, the oscillating unit 2 is controlled.
Two of the voltage and frequency of the drive signal from the control unit 3 are controlled. This control method will be described with reference to FIG.

The control method of the third embodiment is the same as the method shown in FIG. 4, except that the part prior to the third arithmetic unit 53 is changed as follows. The output value Vi from the third calculation unit 53 is input to both the oscillation unit 23 and the A / D conversion unit 75. The oscillating unit 23 is provided with the voltage-controlled oscillator 7 in the same manner as described above.
7 to control the frequency of the drive signal. On the other hand, A
The / D conversion section 75 is transmitted to the amplification amount control section 76 and controls the voltage of the drive signal in the same manner as described above.

When increasing the output of the ultrasonic motor to be controlled, the frequency f1 is decreased and the voltage is increased.
When decreasing the output of the ultrasonic motor to be controlled, the frequency f1 is increased and the voltage is decreased. Thus, the control of frequency and voltage is respectively opposite to the value of Vi. Therefore, in the third embodiment, the Vi value is = Vo +
Since it is Vr, the Vi value input to the A / D converter is calculated as b × (−1 × Vi + 2Vo) = b × (Vo−Vr) (b: coefficient), and the calculated value is A / D conversion was performed.

The method of controlling the driving frequency of the oscillating means with reference to FIG. 4, the method of controlling the driving signal voltage of the oscillating means with reference to FIGS. Although the method of controlling the frequency and the drive signal voltage has been described,
The control of the drive frequency and the drive signal voltage is not limited to the method of these embodiments, and it is within the scope of the present invention if the drive frequency and the drive signal voltage can be controlled by other methods.

(Fourth Embodiment) In the first, second and third embodiments,
Although the difference between the vibration signal voltages of the electromechanical transducers provided on the piezoelectric bodies of the two ultrasonic motors was detected, the output of the two ultrasonic motors could also be detected by detecting the current input to the two ultrasonic motors. It is possible to control the difference.

FIG. 10 is a view for explaining a fourth embodiment of the drive control apparatus for an ultrasonic motor according to the present invention. The first driving unit includes a first oscillating unit 213 that emits a driving signal, a first phase shifting unit 214 that divides the driving signal into two, and a first amplifying unit 2 that amplifies the two divided driving signals.
15a and 215b. First ultrasonic motor 2
Reference numeral 01 includes a piezoelectric body 211a which is excited by input of an amplified drive signal from the first amplifying means 215a and 215b, and an elastic body 211b which is joined to the piezoelectric body 211a and generates a progressive vibration wave on a driving surface by the excitation. The first stator 211 is brought into pressure contact with the driving surface of the elastic body 211b,
And the first movable element 212 driven by the traveling vibration wave.

Similarly, the second driving means includes a second oscillating means 223 for generating a driving signal, a second phase shifting means 224 for dividing the driving signal into two, and a driving signal divided into two. And second amplification means 225a and 225b for amplification. The second ultrasonic motor 202 is joined to the piezoelectric body 221a and the piezoelectric body 221a which are excited by the input of the amplified drive signal from the second amplifying means 225a and 225b, and generates the progressive vibration wave on the drive surface by the excitation. A second stator 221 having an elastic body 221b is provided, and a second movable element 222 which is brought into pressure contact with the driving surface of the elastic body 221b and is driven by the progressive vibration wave.

First and second input current detecting means 216, 2
Reference numeral 26 denotes a unit for detecting the amount of current input to the first and second ultrasonic motors 201 and 202, respectively. The output difference detection means 204 is a means for detecting a current difference between the first input current detection means 216 and the second input current detection means 226. The output difference control unit 205 determines whether the first mover 212 and the second mover 2
22 so that the output value difference from the second oscillating means 22 is eliminated.
23 is a means for controlling the drive signal.

Next, the operation of the fourth embodiment will be described. The drive signal from the first oscillation means 213 is transmitted to the first phase shift means 21
4 and to the first stator 211 via the first amplifying means 215. As a result, a progressive vibration wave is generated on the driving surface of the first stator 211, and the first moving element 212 is driven. In addition, the drive signal from the second oscillation unit 223 is also transmitted to the second stator 221 via the second phase shift unit 224 and the second amplification unit 225. As a result, a progressive vibration wave is generated on the driving surface of the second stator 221 and the second moving element 222 is driven. At this time, the output difference detection means 204
The output difference between the moving element 212 and the second moving element 222 is detected by calculating the difference between the amount of current input to the first ultrasonic motor 201 and the amount of current input to the second ultrasonic motor 202.

FIG. 11 is a diagram showing the relationship between the drive signal frequency, the input current, and the rotation speed. In the driving frequency range, the rotation speed of a predetermined load can be obtained from the input current.
The relationship between the rotation speed and the generated torque is as shown in FIG. 3 and FIG. 6, and by measuring the difference between the input current amounts of the two ultrasonic motors 201 and 202, the two ultrasonic motors 201 and 202 are measured. An output difference can be detected. The output difference control means 205 acts to correct the frequency and voltage of the drive signal from the result of the output difference detection means 204,
The difference between the outputs from the ultrasonic motors 201 and 202 is eliminated.

(Fifth Embodiment) FIG. 12 is a view for explaining a fifth embodiment of the drive control apparatus for an ultrasonic motor according to the present invention. The phase difference between the drive signal input to the first ultrasonic motor 301 and the vibration signal from the mechanical-electrical conversion means 311ap installed on the piezoelectric body 311a of the first ultrasonic motor 301, and the second ultrasonic motor 302 Is detected by detecting a phase difference between a drive signal input to the second ultrasonic motor 302 and a vibration signal from a mechanical-electrical conversion unit 321 ap installed on the piezoelectric body 321 a of the second ultrasonic motor 302. It is possible to control the output difference between the sonic motors 301 and 302.

The first driving means includes a first oscillating means 313 for generating a driving signal, a first phase shifting means 314 for dividing the driving signal into two, and a first amplifying the driving signal divided into two. Amplifying means 315a and 315b. The first ultrasonic motor 301 includes a first amplifying unit 315
a, a piezoelectric body 311a excited by the input of the amplified drive signal from the 315b and the piezoelectric body 311a,
A first stator 311 having an elastic body 311b that generates a progressive vibration wave on the driving surface by the excitation;
and a first moving element 312 which is brought into pressure contact with the driving surface b and driven by the progressive vibration wave.

Similarly, the second driving means includes a second oscillating means 323 for generating a driving signal, a second phase shifting means 324 for dividing the driving signal into two, and a driving signal divided into two. It has second amplifying means 325a and 325b for amplifying. The second ultrasonic motor 302 is joined to the piezoelectric body 321a and the piezoelectric body 321a that are excited by the input of the amplified drive signal from the second amplifying means 325a and 325b, and generates a progressive vibration wave on the drive surface by the excitation. A second stator 321 having an elastic body 321b is formed, and a second movable element 322 that is brought into pressure contact with the driving surface of the elastic body 321b and is driven by the progressive vibration wave.

The first phase difference detection means 316 includes a drive signal input to the first ultrasonic motor 301 and a mechanical-electrical conversion element of a non-voltage applying portion provided on the piezoelectric body 311a of the first ultrasonic motor 301. The phase difference between the vibration signal output from the 311ap and the vibration signal is detected. The second phase difference detecting means 3
Reference numeral 26 denotes a drive signal input to the second ultrasonic motor 302, a vibration signal output from the electromechanical conversion element 321ap of the voltage non-applying unit provided on the piezoelectric body 321a of the second ultrasonic motor 302, Is detected. The output difference detecting means 304 includes first and second phase difference detecting means 316,
This is a means for detecting the difference between the 26 phase differences. The output difference control means 305 changes the drive signal of the second oscillation means 323 based on the result of the measurement value of the output difference detection means 304 so as to eliminate the output value difference between the first mover 312 and the second mover 322. It is a means to control.

Next, the operation of the fifth embodiment will be described. The drive signal from the first oscillation means 313 is supplied to the first phase shift means 31
4 and to the first stator 311 via the first amplifying means 315. As a result, a progressive vibration wave is generated on the drive surface of the first stator 311 and the first mover 312 is driven. In addition, the drive signal from the second oscillation unit 323 is also transmitted to the second stator 321 via the second phase shift unit 324 and the second amplification unit 325. As a result, a progressive vibration wave is generated on the driving surface of the second stator 321, and the second movable element 322 is driven.

At this time, the first phase difference detecting means 316
The drive signal input to the first ultrasonic motor 301 and the first
The phase difference between the vibration signal output from the electromechanical transducer 311ap of the voltage non-applying part provided on the piezoelectric body 311a of the ultrasonic motor 301 is detected. Further, the second phase difference detecting unit 326 is configured to detect a driving signal input to the second ultrasonic motor 302 and the piezoelectric body 321 a of the second ultrasonic motor 302.
The electromechanical conversion element 321a of the voltage non-applying part provided above
A phase difference between the vibration signal output from p and the vibration signal is detected. The output difference detecting means 304 includes a first and a second phase difference detecting means 3.
Detect phase difference between 16, 326

FIG. 13 is a diagram showing the relationship between the drive signal frequency, the phase difference, and the rotation speed. In the driving frequency range, the rotation speed of a predetermined load can be obtained from the phase difference. The relationship between the rotational speed and the generated torque is as shown in FIGS. 3 and 6, and by measuring the phase difference between the two ultrasonic motors 301 and 302, the two ultrasonic motors 301 and 3 are measured.
02 can be detected. The output difference control means 305 acts to correct the frequency and voltage of the drive signal based on the result of the output difference detection means 304 so as to eliminate the difference between the outputs from the ultrasonic motors 301 and 302.

Sixth Embodiment In the first to fifth embodiments, the drive control device of the ultrasonic motor for driving the rotating body has been described. However, the method of detecting and controlling the output difference according to the present invention is not described. Also applicable to linear type. FIG. 14 is a view for explaining a sixth embodiment (linear type) of the drive control apparatus for an ultrasonic motor according to the present invention. The first drive unit has a first oscillation unit 413 that emits a drive signal. The first linear ultrasonic motor 401 includes a first vibrating unit 411a for generating a progressive vibration wave in the first elastic body 411c based on the drive signal, and a first vibrating means sandwiching the first elastic body 411c. The first elastic body 411c is located on the side opposite to the means 411a.
A first stator 411 having a first vibration absorbing unit 411b for absorbing the traveling vibration wave of the first direction, and a first elastic body 411c excited by the first vibration unit 411a to generate the traveling vibration wave on the driving surface. , The first moving element 41 that is brought into pressure contact with the driving surface of the elastic body 411c and is driven by the progressive vibration wave.
And 2.

Similarly, the second driving means has a second oscillation means 423 for generating a driving signal. The linear second ultrasonic motor 402 includes a second vibrating means 421a for generating a progressive vibration wave in the second elastic body 421c based on the drive signal, and a second vibrating means sandwiching the second elastic body 421c. The second elastic body 421c is located on the side opposite to the means 421a.
A second stator 421 having a second vibration absorber 421b that absorbs the traveling vibration wave of the second direction, an elastic body 421c that is excited by the second vibration unit 421a and generates a traveling vibration wave on the driving surface, The second moving element 42 is brought into pressure contact with the driving surface of the two elastic bodies 421c and is driven by the traveling vibration wave.
And 2.

The first mover 412 and the second mover 422 are
They are connected by connecting means 403. The output difference detection unit 404 includes a vibration signal voltage output from the electromechanical conversion unit 411cp provided on the first elastic body 411c,
The electromechanical conversion means 4 provided on the second elastic body 421c
This is a means for detecting the difference between the vibration signal voltage output from 21 cp and the vibration signal voltage. The output difference control unit 405 controls the drive signal of the second oscillation unit 423 based on the result of the output difference detection unit 404 so as to eliminate the output value difference between the first mover 412 and the second mover 422. It is.

Next, the operation of the sixth embodiment will be described. The driving signal from the first oscillating means 413 is
1a, and the first vibrating means 411a
A traveling vibration wave is generated at 11c, and the first movable element 412 is driven. The progressive vibration wave from the first vibrating means 411a is propagated along the first elastic body 411c, but when reaching the end of the first elastic body 411c, it returns as a reflected wave and returns to the first vibrating means. In order to disturb the waveform of the traveling vibration wave from 411a, the traveling vibration wave is absorbed by the first vibration absorber 411b.

The drive signal from the second oscillating means 423 is transmitted to the second oscillating means 421a,
21a generates a progressive vibration wave in the second elastic body 421c, and the second movable element 422 is driven. Second vibration means 4
The progressive vibration wave from 22 propagates along the second elastic body 421c, but when it reaches the end of the second elastic body 421c,
In order to return as a reflected wave and disturb the waveform of the progressive vibration wave from the second vibrating means 421a, the second vibration absorbing means 421
The progressive vibration wave is absorbed by b.

At this time, the output difference detection means 404
The difference between the outputs of the mover 412 and the second mover 422 is determined by the first
Electromechanical conversion means 411 provided on elastic body 411c
The vibration signal voltage output from the cp and the second elastic body 421
It is determined by detecting the difference between the vibration signal voltage output from the mechanical-electrical conversion means 421cp provided in c.
Next, the output difference control means 405
4 works to correct the frequency and voltage of the drive signal, and the ultrasonic motors 401, 4
02 so as to eliminate the difference in output.

(Seventh Embodiment) In each of the above-described embodiments, the vibration signal voltage, the input current, and the phase difference are detected, and the magnitude of the output of the ultrasonic motor is obtained according to the amount. The output may be different due to the individual difference of the ultrasonic motor even if the vibration signal voltage, the input current and the phase difference. Therefore, an offset may occur in a plurality of ultrasonic motors to be controlled. Therefore, in the seventh embodiment, in order to further reduce the output difference of the ultrasonic motor, an offset correction unit for correcting the offset is provided, and the information is transmitted to the output difference detection unit.

FIG. 15 is a view for explaining a seventh embodiment of the driving apparatus for an ultrasonic motor according to the present invention. The configuration and operation of the seventh embodiment are substantially the same as those of the first embodiment. However, in this embodiment, an offset correction unit 85 is newly provided, and the information is transmitted to the output difference detection unit 4. It has become. In the output difference detecting section 4, the vibration signal voltages V1, V2
, And an operation of correcting the correction value ΔV from the offset correction unit 85 is performed.
2 (Vd = V1-V2 + .DELTA.V). The subsequent steps from the first arithmetic operation shown in FIG. 81 are the same as those shown in FIG. In the present embodiment, the method of performing the offset correction on the output difference detection value has been described. However, the method of performing the offset correction on the input difference detection value shown in the fourth embodiment may be used.
The method of performing the offset correction on the phase difference between the input and output shown in the fifth embodiment may be used.

(Modification) In this embodiment, a piezoelectric element is connected to an electro-mechanical conversion element which changes electric energy into mechanical energy and is joined to a driving surface of an elastic body to generate a progressive vibration wave. Was used, but an electrostrictive element may be used.

[0070]

As described above, according to the present invention,
When one driving body is driven by a plurality of ultrasonic motors, the torque generated from the first ultrasonic motor and the second ultrasonic motor is used as an output signal or an input signal or an input signal and an output signal of each ultrasonic motor. And the like, and the drive can be independently controlled based on the result. At this time, the generated torque can be made substantially the same by correcting the frequency and / or the frequency of the drive signal. Therefore, even if the adjustment step is omitted, almost the same output can be obtained from each ultrasonic motor, and efficient driving can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a drive control device for an ultrasonic motor according to the present invention.

FIG. 2 is a diagram illustrating a relationship between a drive signal frequency, a vibration signal voltage from a mechanical-electric element, and a rotation speed.

FIG. 3 is a diagram showing a relationship between a generated torque and a rotation speed of an ultrasonic motor.

FIG. 4 is a diagram illustrating output control of a second ultrasonic motor according to the first embodiment.

FIG. 5 is a diagram showing a torsional moment generated by each part of the output shaft.

FIG. 6 is a diagram showing a relationship between a generated torque and a rotation speed of an ultrasonic motor.

FIG. 7 is a diagram showing a second embodiment of the drive control device for an ultrasonic motor according to the present invention.

FIG. 8 is a diagram illustrating a method of selecting an amplification amount of a drive signal.

FIG. 9 is a diagram showing a third embodiment of the drive control apparatus for an ultrasonic motor according to the present invention.

FIG. 10 is a view showing a fourth embodiment of the drive control device for an ultrasonic motor according to the present invention.

FIG. 11 is a diagram illustrating a relationship between a drive signal frequency, an input current, and a rotation speed.

FIG. 12 is a diagram showing a fifth embodiment of the drive control apparatus for an ultrasonic motor according to the present invention.

FIG. 13 is a diagram illustrating a relationship between a drive signal frequency, a phase difference, and a rotation speed.

FIG. 14 is a view showing a sixth embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 15 is a view showing a seventh embodiment of the drive control device for the ultrasonic motor according to the present invention.

[Description of sign]

1, 101, 201, 301, 401 First ultrasonic motor 2, 102, 202, 302, 402 Second ultrasonic motor 3, 103, 203, 303 Connecting shaft 4, 204, 304, 404 Output difference detecting means 5, 205, 305, 404 Output difference control means 11ap, 21ap Mechanical-electrical conversion element 216, 226 Input current detection means 316, 326 Phase difference detection means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (8)

(57) [Claims] (1) An identical relative movement member is provided as a constituent member.
First and second driving the first and second ultrasonic motor to
Ultrasonic motor driving means; first and second output detecting means for respectively detecting first and second output signals output from the first and second ultrasonic motors; first and second output detecting means An output difference detecting means for detecting a difference between the first output signal and the second output signal according to the detection result of the first or second ultrasonic motor driving means according to a detection result of the output difference detecting means. Both or one of the first and the second
And an output difference control means for controlling the driving force of the second ultrasonic motor to have a predetermined relationship . 2. An apparatus having the same relative motion member as a constituent member.
First and second driving signals for detecting the first and second drive signals, respectively; the first and second and the first and second ultrasonic motor driving means providing a first and a second drive signal to the ultrasonic motor to Detecting means; based on the detection results of the first and second drive signal detecting means,
Output difference detecting means and for detecting a difference between the first driving signal and the second driving signal; a detection result of the output difference detecting means, said one or both of the first or second ultrasonic motor driving means First and
And an output difference control means for controlling the driving force of the second ultrasonic motor to have a predetermined relationship . 3. An apparatus having the same relative motion member as a constituent member.
The first and second and the first and second ultrasonic motor driving means providing a first and a second drive signal to the ultrasonic motor to; first and second output is outputted from the first and second ultrasonic motor First and second output detection means for detecting signals, respectively; first and second drive signal detection means for detecting the first and second drive signals, respectively; the first drive signal and the first output signal; A first phase difference detecting means for detecting a phase difference between the first and second output signals; a second phase difference detecting means for detecting a phase difference between the second drive signal and the second output signal; An output difference detecting means for detecting a difference between the two detected phase differences; and, based on a detection result of the output difference detecting means, one or both of the first and second ultrasonic motor driving means,
And an output difference control means for controlling the driving force of the second ultrasonic motor to have a predetermined relationship . 4. The apparatus according to claim 1, wherein the output difference control means controls a frequency of a drive signal input to the first or second ultrasonic motor. Drive control device for ultrasonic motor. 5. The apparatus according to claim 1, wherein the output difference control means controls an input voltage of a drive signal input to the first or second ultrasonic motor. A drive control device for the ultrasonic motor according to the above. 6. The apparatus according to claim 1, wherein the output difference control means controls a frequency and an input voltage of a drive signal input to the first or second ultrasonic motor. 2. A drive control device for an ultrasonic motor according to claim 1. 7. An offset correcting means for detecting an offset value of said first and second ultrasonic motors and correcting a detection signal of said output difference detecting means. A drive control device for an ultrasonic motor according to any one of the above. 8. The apparatus according to claim 1, wherein said first and second output detecting means include:
Detects current input to first or second ultrasonic motor
The ultrasonic motor according to claim 1, wherein
Drive control device.