JPH0670563A - Drive controller for ultrasonic motor - Google Patents

Abstract

PURPOSE:To drive a rotor by adjusting the torque generated by each ultrasonic motor to be approximately constant without adjusting the torque generated by each ultrasonic motor at production in case of driving the rotor as with a plurality of ultrasonic motors as drive sources. CONSTITUTION:This is a drive controller which drives one rotated body 104, using a plurality of ultrasonic motors 111 and 121, and this is equipped with first and second ultrasonic motor driving means 112 and 122, which drive first and second ultrasonic motors, an output difference detecting means 102, which detects the difference of the output between the first and second ultrasonic motors, and an output difference control means 103, which controls both hand or one hand of the first and second ultrasonic motor driving means.

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 controller for driving and controlling a plurality of ultrasonic motors.

[0002]

2. Description of the Related Art Conventionally, a plurality of ultrasonic motors (hereinafter referred to as US
Generated torque (output) when driving a rotating body such as one rotating shaft or a rotating cylinder using M).
Since there is a case where the relationship between the rotation speed and the rotation speed differs from one ultrasonic motor to another, there may be a difference in the torque generated from each ultrasonic motor at a certain rotation speed. This will be described with reference to FIG. Figure 2
[Fig. 4] is a diagram showing a twisting moment generated in each part of the output shaft of the ultrasonic motor. 1st USM 201 and 2nd USM
202 is connected by a shaft 206, and further,
The load means 205 is attached to the shaft 206. If the shaft 206 is provided with the first and second twist amount detecting means 203 and 204 for detecting the twist amount, the twist moment of each part of the shaft 206 can be obtained, and the twist moments are generated from the first USM 201 and the second USM 202. The output (generated torque) can be obtained.

In the case shown in FIG. 2, the generated torque T
1, the rotation speed with respect to T2 is the ultrasonic motor 201,
02, each ultrasonic motor 20
The torque generated from 1,202 becomes equal. However, when the rotation speed with respect to the generated torques T1 and T2 differs depending on the ultrasonic motors 201 and 202, one shaft 206
Both ultrasonic motors 2 to be linked by
The rotational speeds of 01 and 202 are the same, and the generated torques T1 and T2 from the ultrasonic motors 201 and 202 are different as shown by the broken lines (the sum of the generated torques T1 and T2 is the load torque TL). . For this reason, there has been a problem that the capabilities of both ultrasonic motors 201 and 202 cannot be fully exhibited.

Further, there are large individual differences between the ultrasonic motors 201 and 202, and at a given frequency, the ultrasonic motor 2
When one of 01 and 202 hardly rotates, the stator and the mover are in pressure contact with each other, which may cause a load, which is an obstacle for improving the driving efficiency.

[0005]

On the other hand, adjustment such that independent drive circuits are installed in each ultrasonic motor to change the frequency of each drive signal (see FIG. 7 of JP-A-1-227669). ) Is considered, the generated torques T1, T from the ultrasonic motors 201, 202 are
There was a problem that adjusting 2 to be almost constant would increase the number of steps and hinder the improvement of mass productivity.

Further, when the rotation speed is changed according to the operating condition, each ultrasonic motor 2 at a certain adjusted rotation speed is used.
Although the generated torques T1 and T2 from 01 and 202 are constant, the rotational speed different from the adjusted rotational speed may cause a slight difference in the rotational speed due to individual differences.

A first object of the present invention is to drive a rotating body by using a plurality of ultrasonic motors as a driving source, without adjusting the torque generated by each ultrasonic motor during production. An object of the present invention is to provide a drive control device for an ultrasonic motor that can drive the generated torque by adjusting it to a substantially constant value. A second object of the present invention is to obtain a driving frequency for generating a substantially uniform driving force from each ultrasonic motor according to the rotation speed even if the rotation speed is changed in various cases. An object of the present invention is to provide a drive control device for an ultrasonic motor, which can be efficiently driven in almost the entire rotation range.

[0008]

In order to solve the above-mentioned problems, a drive control device for an ultrasonic motor according to the present invention uses a plurality of ultrasonic motors 111 and 121 to drive a single rotating body 104. In a drive control device for a sonic motor, first and second ultrasonic motor driving means 112, 122 for driving the first and second ultrasonic motors, and the first
And the output difference detection means 102 for detecting the difference between the outputs of the second ultrasonic motor and the measurement result of the output difference detection means,
An output difference control means 103 for controlling both or one of the first or second ultrasonic motor drive means is provided.

In this case, the output difference control means 103
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 detecting means. be able to.

Further, the output difference detecting means 103 can be characterized in that it detects an elastic deformation amount of a connecting member connecting the ultrasonic motors.

[0011]

According to the present invention, the output difference detecting means 102 detects the difference between the outputs of the first and second ultrasonic motors, and based on the detection result, the output difference control means 103 determines whether the output difference control means 103 is the first or the second. 2 Control the ultrasonic motor driving means. 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 detecting means. The generated torque from the ultrasonic motor can be adjusted to a substantially constant value before driving.

[0012]

Embodiments will be described in more detail below with reference to the drawings and the like. FIG. 1 is a block diagram showing a first embodiment of a drive control device for an ultrasonic motor according to the present invention. The first driving means 112 divides the driving signal into a first oscillating means 113 for emitting a driving signal and a first oscillating means 113.
It has a phase shifting means 114 and first amplifying means 115a and 115b for amplifying the two divided drive signals, respectively. The first USM 111 includes the first amplifying means 115a, 1
First excited by the input of the amplified drive signal from 15b
A first stator 111-1, which has a piezoelectric body and an elastic body that is joined to the piezoelectric body and generates a progressive vibration wave on the driving surface by its excitation, is pressed against the driving surface of the elastic body, First moving element 111-2 driven by an oscillating wave
It consists of and.

Similarly, the second driving means 122 outputs the driving signal to the second oscillating means 123 and the driving signal to the second oscillating means 123.
The second phase shifting means 124 which is divided into two, and the second amplifying means 125a and 12 which amplify the driving signals which are divided into two, respectively.
5b and. The second USM 121 has a second piezoelectric body that is excited by the input of the amplified drive signal from the second amplifying means 125a and 125b and an elastic body that is joined to the piezoelectric body and that generates a progressive vibration wave on the drive surface by the excitation. It is composed of a second stator 121-1 and a second mover 121-2 which is brought into pressure contact with the driving surface of the elastic body and is driven by the progressive vibration wave.

The first moving element 111-2 and the second moving element 121
-2 is connected by the output shaft 104. The output difference detection means 102 is provided on the output shaft 104, and is means for detecting a difference between output values from the first moving element 111-2 and the second moving element 121-2. Output difference control means 103
Is the first value according to the result of the measurement value of the output difference detecting means 102.
It is means for controlling the drive signal of the second oscillating means 123 so as to eliminate the difference in output value from the moving element 111-2 and the second moving element 121-2.

Next, the operation of the first embodiment will be described. The drive signal from the first oscillating means 113 is the first phase shifting means 11
4 through the first amplifying means 115, the first stator 111-1
Be transmitted to. As a result, a traveling wave is generated on the drive surface of the first stator 111-1, and the first mover 111-2 is driven. The drive signal from the second oscillating means 123 is also transmitted to the second stator 121-1 via the second phase shifting means 124 and the second amplifying means 125. As a result, the second stator 1
A traveling wave is generated on the driving surface of 21-1 and the second moving element 12
1-2 are driven.

At this time, the output difference detecting means 102 is
The difference in output between the mover 111-2 and the second mover 121-2 is detected by measuring the amount of elastic deformation such as twist of the output shaft 104. Then, the output difference control means 103
Output shaft 104 detected by output difference detection means 102
The elastic deformation amount acts to correct the frequency of the drive signal to eliminate the difference between the outputs from the ultrasonic motors 111 and 121.

FIG. 3 is a diagram showing the relationship between the torque generated by the ultrasonic motor according to the first embodiment and the rotation speed. The relationship between the generated torque and the rotation speed in the drive frequency range of the ultrasonic motors 111 and 121 changes depending on the frequency. Therefore, if the generated torque is desired to be increased, the drive frequency is lowered, and if the generated torque is desired to be reduced, the drive frequency is increased. By doing so, even if the adjustment process of the ultrasonic motors 111 and 121 is omitted, it is possible to automatically reduce the difference in output, and also to change the rotation speed when changing the rotation speed. The output difference can be automatically adjusted according to the speed. In the first embodiment, the first
The output difference between the moving element 111-2 and the second moving element 121-2 is detected by the output difference detecting means 102, and the output difference controlling means 103 controls the drive signal of the second oscillating means 123. Even when the drive signals of both the first oscillating means 113 and the second oscillating means 123 are controlled by the difference control means 103, the first moving element 111-2 and the second moving element 12
A similar effect occurs in that the output value difference from 1-2 is eliminated.

FIG. 4 is a block diagram showing the outline of a second embodiment of the drive control apparatus for the ultrasonic motor according to the present invention. The first driving means 12 outputs the driving signal to the first oscillating means 13 and the driving signal 2 having a phase difference of 1/4 wavelength.
A first phase shifting means 14 for dividing the driving signal into one driving signal, and a first amplifying means 15a for amplifying the divided driving signal,
15b and. The first USM 11 includes a first piezoelectric body 11-1a that is excited by the input of an amplification drive signal from the first amplifying means 15a and 15b, and the piezoelectric body 11-1a.
A first stator 11 having a first elastic body 11-1b joined to the first elastic body 11-1b that generates a progressive vibration wave on the driving surface by the excitation.
-1 and a first moving element 11-2 which is pressed against the driving surface of the elastic body 11-1b and driven by the progressive vibration wave. The first control means 16 detects the phase shift difference between the monitor voltage waveform of the voltage non-applied part 11-1a ₁ of the first piezoelectric body 11-1a and the input voltage waveform.
7 and output control means 18 for issuing a command to correct the frequency of the drive signal of the oscillation means 13 based on the output detection value of the output detection means 17.

The second driving means 22 includes a second oscillating means 23 which emits a driving signal, a second phase shifting means 24 which divides the driving signal into two driving signals having a phase difference of ¼ wavelength, and the above-mentioned division. It has the 2nd amplifier 25a, 25b which amplifies the drive signal respectively obtained. The second USM121 is
A second piezoelectric body 21-1a that is excited by the input of an amplification drive signal from the second amplifying means 25a and 25b, and a second piezoelectric body 21-1a that is joined to the piezoelectric body 21-1a and that generates a progressive vibration wave on the drive surface by the excitation. Second having two elastic bodies 21-1b
It is composed of a stator 21-1 and a second mover 21-2 which is brought into pressure contact with the driving surface of the elastic body 21-1b and is driven by the progressive vibration wave.

The first moving element 11-2 and the second moving element 21-2.
The load means (not shown) is connected by an output shaft 4. The first twist amount detecting means 2-1 includes the first moving element 1
It is a means for detecting the torque generated from the first USM 11 by measuring the amount of twist of the shaft 4 between the 1-2 and the second moving element 21-2. The second twist amount detecting means 2-2 is
It is a means for detecting the sum of the torque generated from the first and second USMs 11 and 12 by measuring the amount of twist of the shaft 4 between the second moving element 21-2 and the load means. In the second embodiment, the output difference measuring means 2 is constituted by the first twist amount detecting means 2-1 and the second twist amount detecting means 2-2.

The output difference control means 3 uses the result of the measurement value of the output difference measurement means 2 so as to eliminate the difference between the torques generated from the first and second USMs 11 and 21, and the second oscillation means 23.
Is a means for controlling the drive signal of. The output difference measuring means 2 and the output difference control means 3 constitute the second control means 1.

Next, the driving operation of the second embodiment will be described. The drive signal generated from the first oscillating means 13 is the first
The phase shifter 14 separates the two drive signals having a phase difference of 1/4 wavelength, and then the first amplifiers 15a and 15b amplify the respective drive signals. The piezoelectric body 11-1a of the first stator 11-1.
Applied to. As a result, a traveling wave is generated on the driving surface of the first stator 11-1 and the first wave is pressed against the driving surface.
The mover 11-2 rotates.

Since the driving of the moving element by the traveling wave is described in, for example, Japanese Patent Publication No. 1-17353,
The description is omitted here. The control of the rotation speed of the first moving element 11-2 is performed by, for example, as disclosed in Japanese Patent Laid-Open No. 61-251490, a monitor voltage waveform and an input voltage of a voltage non-applied portion of the first piezoelectric body 11-1a. The phase difference from the waveform is detected, and the output control means 18 corrects the frequency of the drive signal of the oscillating means 13 by the output detection value so as to control the rotation speed and the like. In addition, an encoder is provided on the output shaft 4 to measure the rotation speed, and the output control means 1 is measured according to the measured value.
A method of correcting the frequency of the drive signal of the oscillating means 13 in 8 may be used.

The driving signal generated from the second oscillating means 23 is also divided by the second phase shifting means 24 into two driving signals having a phase difference of 1/4 wavelength, and then the second amplifying means 25a,
They are amplified by 25b and applied to the piezoelectric body 21-1a of the second stator 21-1. As a result, the second stator 21
-1, which causes a traveling wave to be generated on the drive surface of the second stator 21-1 and causes the second mover 21-2 to rotate.

The first moving element 11-2 and the second moving element 21-2.
The output shaft 4 between and is twisted by the torque generated from the first USM 11 and is detected by the first twist amount detecting means 2-1. Further, the output shaft 4 between the second moving element 21-2 and the load means is twisted and twisted by the sum of the generated torques of the first and second USMs 11 and 21 (also called load torque of the load means). It is detected by the means 2-2. The output difference control means 3 acts so as to correct the frequency of the drive signal of the second USM 21 according to the detection amounts of the twist amount detection means 2-1, 2-2, and the generated torques from the first USM 11 and the second USM 21 are substantially equal. To do. The frequency correction method is
In the same way as shown in FIG. 3 in the first embodiment, the second US
When the generated torque applied to M21 is smaller than that of the first USM11, the drive frequency is lowered, and when it is large, the drive frequency is raised.

By doing so, each USM 11, 2
Even if the adjustment step 1 is omitted, the difference in the generated torque can be automatically reduced, and even when the rotation speed is changed according to the driving situation, it is automatically changed according to the rotation speed on the spot. The difference in generated torque can be adjusted.

As shown in FIG. 5, the amount of twist of the output shaft 4 can be detected electromagnetically or electrically by a strain gauge provided on the rotating shaft. The details of the electromagnetic detection method are published in the August 19, 1991 issue of Nikkei Mechanical Co., Ltd., so that the description here will be made briefly. First, as shown in FIG. 5, two gears 41 and 4 having the same number of teeth are provided between the first moving element 11-2 and the second moving element 21-2.
2 is attached so that there is no phase difference in the circumferential direction,
A sinusoidal voltage is output by the electromagnetic pickups 43 and 44, respectively. Thereby, the twist amount of the shaft 4 can be detected by measuring the shift of the peak of the sine wave.

Next, a method from electromagnetically detecting the twist of the output shaft 4 to controlling the oscillating means 13 will be described with reference to FIG.
Will be explained. First, the terminals are the first mover 1
1-2 is connected to the twist amount detecting means 2-1 provided between the second moving element 21-2 and the terminal is the first US
The electromagnetic pickup 43 of the gear 41 on the M11 side is connected to the electromagnetic pickup 44 of the gear 42 on the second USM 21 side.
Get more signal. The shaft 4 in this position has the first USM1
The torsional moment corresponding to the torque generated from 1 is received, and the shaft 4 is twisted by that amount. Then, the terminals,
A sine wave having a phase difference is input from the square wave converters 31a and 31b and converted by the square wave converters 31a and 31b. Phase difference detector 32
a outputs the difference from the rising edge of the square wave A at the terminal to the rising edge of the square wave B at the terminal as a square wave E.
It can be seen that this square wave E has a longer holding time as the twist of the shaft 4 increases.

On the other hand, the terminals are the second moving element 21-2.
Amount detecting means 2-2 provided between the load means and the load means
The terminal obtains a signal from the electromagnetic pickup of the gear on the second USM 21 side, and the terminal obtains a signal from the electromagnetic pickup of the gear on the load means side. The shaft 4 at this position receives a torsional moment by the sum of the torques generated from the first and second USMs 11 and 21, and the shaft 4 is twisted by that amount. Then, sine waves with a phase difference are input from the respective terminals, and are input to the square wave conversion units 31c and 31.
Convert with d. The phase difference detector 32b outputs the difference from the rising edge of the square wave C at the terminal to the rising edge of the square wave D at the terminal as a square wave F.

The square waves from the phase difference detectors 32a and 32b are converted into voltages Vc and Vcl corresponding to the holding time of the square waves by the voltage converters 33a and 33b composed of switching regulators and the like. This voltage Vc
The first computing unit 34 computes a relative correction amount by computing how much or less than the torque component (Vcl / 2) to be generated from both USMs 11 and 21. Here, a calculation such as -1 * {Vcl / 2- (Vcl-Vc)} = Vcl / 2-Vc is performed. The calculation result Vd is the first USM
When the generated torque of 11 is large, the voltage Vd becomes negative, and when the second USM 21 is large, it becomes positive. In order to boost this voltage Vd to the control voltage, the second arithmetic unit 35
Is multiplied by the coefficient a. The value Vrr is the current second U
This shows the relative correction amount with respect to the generated torque of the SM 21, and the larger the twist amount (generated torque amount), the larger the absolute value thereof. Next, by the third calculation unit 36,
The correction amount Vrr is added by the voltage Vf from the feedback unit 39 to determine the absolute correction amount Vr with respect to the reference voltage Vo. The fourth calculation unit 37 adds the correction amount Vr and the reference voltage Vo from the terminal, and the value Vi is V
It is output to the OC 38 and the feedback unit 39.

The VOC 38 generates a signal having a frequency corresponding to the value Vi at its terminal and outputs it to a waveform shaping section (not shown). As a result, the torque generated by the second USM 21 and the rotation speed characteristic change. And both USM1 at that time
The difference between the generated torques 1 and 21 is input again from the terminals ,, and Vrr is calculated.

On the other hand, the feedback section 39 inputs the value Vi from the fourth calculation section 37, obtains the difference from the reference voltage Vo, and returns the value Vf to the third calculation section 36. Then, in the third calculation unit 36 and the fourth calculation unit 37, Vf and the re-input Vrr are added, and the reference voltage Vo is further added to obtain Vi.
Is output. However, since the rotation speed may not change instantaneously due to the inertia of the rotor, the difference between the generated torque that should be generated from each USM 11 and 21 corresponding to the f value at a certain time and the actual USM 11 and 21. There may be a case where the difference in generated torque does not match, and a difference may occur between the correction amount calculated by the third calculation unit 36 and the fourth calculation unit 37 and the actually required amount. Therefore, in order to further enhance the effect, it is possible to consider a method in which the correction is performed by dividing the time into certain intervals. According to the method, a clock pulse is input to the feedback unit 39, the Vi feedback unit 39 is input only when the clock pulse is input, and the Vf value is held between the clock pulses and output to the second operation unit 35. To do so. This makes it possible to reduce the error in Vrr due to the response time of the rotation speed.

Electrical detection by the strain gauge is performed by V in FIG.
c and Vcl can be directly obtained,
The drive frequency can be corrected by using the same configuration for the feedback unit and VOC.

Next, based on the second embodiment, the first USM
Correct the difference in the generated torque between No. 11 and the second USM 21. First, assume that the generated torque of the second USM 21 is small. FIG. 2 shows the relationship between the generated torque and the rotation speed in the drive frequency range of the ultrasonic motor. In this case, the frequency of the input drive signal of the second USM 21 may be reduced and the generated torque for a certain rotation speed may be increased. Further, since Vc becomes larger than Vcl / 2, Vd becomes negative. Therefore, Vrr also becomes negative,
The frequency f is lowered by acting so that Vr and Vi are reduced. As a result, the rotation speed of the entire output shaft increases, but the rotation speed is corrected by the first control means as described above.

On the contrary, assume that the generated torque of the second USM 21 is large. In this case, the second USM21
The correction may be performed by increasing the frequency of the input drive signal and reducing the generated torque at a certain rotation speed. Also,
Since Vc becomes smaller than Vcl / 2, Vd becomes positive.
Therefore, Vrr also becomes positive, Vr and Vi are acted to increase, and the frequency f increases. As a result, the rotation speed of the entire output shaft decreases, but the rotation speed is corrected by the first control means as described above.

As in the second embodiment, the generated torque is detected by measuring the twist amount of the shaft 4, and each USM1
The method of uniformly correcting the torque generated from the USMs 11 and 21 can directly reflect the output from the USMs 11 and 21 in the correction of the driving frequency, and therefore, automatically adjusts even if there is individual difference in each USM 11 and 21. Even if the rotation speed is changed, it can be corrected to an appropriate drive frequency each time.
As described above, the method of detecting the phase difference of the gear or the output of the strain gauge and correcting the drive frequency is one method for achieving the object of the present invention, and is not limited to this. Absent.

FIG. 7 is a block diagram showing a third embodiment of the drive control apparatus for the ultrasonic motor according to the present invention. In the second embodiment, the case where two ultrasonic motors are connected by one rotating body has been described, but as shown in FIG.
It is also applicable when one or more ultrasonic motors are connected by one rotating body.

First, the first USM 311 is replaced with the first USM of FIG.
The first and second USMs 311 have the same configuration as M11.
321, between the second and third USMs 321, 331, and between the third USM 331 and the load means, first to third twist amount detecting means 301-1 and 301 similar to those of the second embodiment.
-2, 301-3, respectively. The load torque of the load means (first to third USMs 311, 321, 33)
1), the generated torque of the first USM 311 and the generated torque of the first and second USMs 311 and 321 are detected, and the output difference control means 304 is detected from the detected value.
Thus, the drive frequencies of the second and third USMs 321 and 331 are corrected.

An example of performing the correction is the same as the configuration and method shown in FIG. 6, but the calculation of the first calculation unit 34 needs to be changed as follows. The signals of the twist amounts input from the first to third twist amount detecting means 301-1 301-2, and 301-3 are sent to the square wave converter, the phase difference detector, and the voltage converter as in FIG. It outputs as a voltage via. First to third twist amount detecting means 301-1, 301-2, 3
The output corresponding to the input from 01-3 is Vc1, Vc2, V
If it is cL, when controlling the second USM 321, the first
The calculation in the calculation unit 34 is -1 * {VcL / 3- (Vc2-Vc1)}. As a result, it is possible to determine whether the torque generated by the second USM 321 is excessive or insufficient, and the second computing unit 34 and the subsequent components can correct the frequency with the same configuration and method as in FIG. 6. Also, the third USM3
When controlling 31, the calculation in the first calculation unit 34 is −1 × {VcL / 3− (VcL−Vc2)}. As a result, it is possible to determine whether the torque generated by the third USM 331 is excessive or insufficient, and the second computing unit 35 and the subsequent components can correct the frequency with the same configuration and method as in FIG. 6.

In each of the embodiments described above, the case where one rotary body is driven by a plurality of rotary ultrasonic motors has been described.
Even when moving one moving body with a plurality of linear ultrasonic motors, the elastic deformation amount such as bending of the moving body is detected,
If the elastic deformation amount is eliminated, the same effect can be obtained with the same configuration.

In each embodiment, the output difference control device is
Although an example in which the output torque of each ultrasonic motor is controlled to be substantially the same has been described, if the calculation of the calculation unit in FIG. 6 is changed, the output torque of each ultrasonic motor can be changed according to the purpose of use such as braking. It can be controlled differently.

[0042]

As described above in detail, according to the present invention, when one rotating body is driven by a plurality of ultrasonic motors, the torque generated from the first ultrasonic motor and the second ultrasonic motor is increased. Can be controlled independently by detecting the amount of twist of the shaft and the like based on the result. At this time, the generated torque can be made substantially the same by correcting the drive frequency. Therefore, even if the adjustment process is omitted,
You can get almost the same output from each ultrasonic motor,
Also, even when changing the rotation speed according to the driving situation,
Almost the same generated torque was obtained from each ultrasonic motor, enabling efficient driving.

[Brief description of 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 showing a twisting moment generated in each part of the output shaft.

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

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

FIG. 5 is an explanatory diagram when electromagnetically detecting a twist of a shaft.

FIG. 6 is a diagram showing an output control means of a second embodiment.

FIG. 7 is a block diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 11, 111, 311 1st USM 21, 121, 321 2nd USM 12, 112, 312 1st drive means 22, 122, 322 2nd drive means 2, 102, 301 Output difference detection means 2-1 and 302-1 1st Twist amount detecting means 2-2, 302-2 Second twist amount detecting means 302-3 Third twist amount detecting means 3, 103, 303 Output difference control means 4, 104, 304 Output shaft

Claims (3)

[Claims] 1. A drive control device for an ultrasonic motor that drives a single rotating body using a plurality of ultrasonic motors, comprising: first and second ultrasonic motors for driving the first and second ultrasonic motors.
Ultrasonic motor driving means, output difference detecting means for detecting a difference between the outputs of the first and second ultrasonic motors, and the first or second ultrasonic motor driving according to the measurement result of the output difference detecting means. A drive control device for an ultrasonic motor, comprising: an output difference control means for controlling both or one of the means. 2. The output difference control means drives the second ultrasonic motor 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 drive control device for the ultrasonic motor according to claim 1, wherein the drive control device controls the means. 3. The drive control of the ultrasonic motor according to claim 1, wherein the output difference detecting means detects an elastic deformation amount of a connecting member connecting the ultrasonic motors. apparatus.