JP2012235656A - Drive controller of vibration-type actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive controller of a vibration-type actuator, which suppresses occurrence of unnecessary vibration in a low speed drive region where behavior becomes unstable, stabilizes driving and can suppress power consumption.SOLUTION: The drive controller of the vibration-type actuator includes: a vibrator including an elastic body in which an electromechanical energy conversion element is arranged; and a mobile body which is directly or indirectly brought into contact with the vibrator. The mobile body is relatively moved to the vibrator with friction force generated by a vibration wave excited by the vibrator with an applied voltage to the electromechanical energy conversion element. The drive controller also includes control means for variably controlling a frequency and an amplitude of the applied voltage depending on a speed command from command means. The control means increases the amplitude of the applied voltage in a previously determined drive region.

Description

  The present invention relates to a drive control device for a vibration type actuator, and more particularly to a drive control device for a vibration type actuator that can be stably rotated at a low speed.

Ultrasonic motors, which are a type of vibration actuator, are mounted on copiers, interchangeable lenses for cameras, and the like.
In recent years, higher rotational accuracy, higher efficiency, and the like have been demanded as devices have higher performance and lower power consumption.
Such a vibration type actuator has a feature that it can be driven at a low speed and a high torque as compared with an electromagnetic motor typified by a DC brushless motor. However, there is a problem to meet the above demand.
For example, depending on the contact state between a stator composed of an elastic body and a piezoelectric element and a rotor that is a moving body, behavior may not be stable in an extremely low speed rotation region, and unnecessary vibration may be generated. It was the cause.

In order to cope with the abnormal noise and speed unevenness depending on the contact state as described above, Patent Document 1 proposes a method for avoiding the contact state between the stator and the rotor being a boundary region between the full contact and the partial contact. ing.
Here, as the method, a method is adopted in which the amplitude of the AC voltage applied to the vibration type actuator is temporarily changed.

JP 2005-192276 A

However, the vibration type actuator according to the conventional example has the following problems.
First, in the above conventional example, the voltage is changed when the target speed reaches the boundary region. Therefore, when the initial target speed at the start corresponds to the boundary region, the voltage is set higher than usual from the beginning. In such a case, the starting current increases, that is, power consumption increases.
On the other hand, if the voltage is set lower than usual, there may be a case where a voltage sufficient for activation cannot be ensured depending on conditions such as after endurance or at a low temperature and the apparatus does not start.
Furthermore, the reason why the behavior is not stable in the extremely low speed rotation region is not only that the contact state between the stator and the rotor becomes the boundary region between the full contact and the partial contact, but also the surface pressure unevenness that varies depending on the location, the stator and the rotor There are also cases where the flatness variation is triggered.
Due to a plurality of factors as described above, the resonance frequency of the vibrating body may temporarily approach the frequency of the driving voltage, and as a result, fluctuations may become severe.
For this reason, it is not always sufficient to stabilize the behavior only by avoiding that the contact state becomes the boundary region between the full contact and the partial contact as in the conventional example.

  In view of the above problems, the present invention provides a vibration type actuator that can suppress the generation of unnecessary vibration in a low-speed drive region where the behavior is unstable, stabilize the drive, and reduce power consumption. The object is to provide a drive control device.

A drive control apparatus for a vibration type actuator of the present invention includes a vibration body having an elastic body provided with an electro-mechanical energy conversion element, and a moving body that directly or indirectly contacts the vibration body,
A drive control device for a vibration type actuator that moves the moving body relative to the vibrating body by a frictional force generated by a vibration wave excited by the vibrating body by a voltage applied to the electro-mechanical energy conversion element. And
Control means for variably controlling at least the frequency and amplitude of the applied voltage based on a speed command from the command means;
The control means increases the amplitude of the applied voltage in a predetermined drive region.

ADVANTAGE OF THE INVENTION According to this invention, the drive control apparatus of the vibration type actuator which can suppress the generation | occurrence | production of the unnecessary vibration in the low-speed drive area | region where behavior is unstable, can stabilize drive, and can aim at suppression of power consumption. Can be realized.

The block diagram explaining the structural example of the drive control apparatus of the vibration type actuator in Example 1 of this invention. Schematic which shows the structural example of the vibration type actuator in Example 1 of this invention. Schematic which shows the mode of a vibration of the vibration type actuator in Example 1 of this invention. Schematic which shows the electrode of the vibration type actuator in Example 1 of this invention. Schematic which shows the example of the vibration amplitude-frequency characteristic of the vibration type actuator in Example 1 of this invention. Schematic which shows the example of the frequency difference of the drive frequency and the resonance frequency at the time of the frequency sweep of the vibration type actuator of Example 1 of this invention. Schematic which shows the difference in the behavior by a drive voltage at the time of the frequency sweep of the vibration type actuator of Example 1 of this invention. The block diagram which shows the structure of the calculator in Example 1 of this invention, and the schematic which shows an input-output characteristic. The block diagram explaining the structural example of the drive control apparatus of the vibration type actuator in Example 2 of this invention. Schematic which shows the example of the phase difference-frequency characteristic of the drive voltage and vibration amplitude of a vibration type actuator in Example 2 of this invention. Schematic which shows the example of the phase difference of a drive voltage and a vibration amplitude at the time of the frequency sweep of the vibration type actuator of Example 2 of this invention. The block diagram which shows the structure of the calculator in Example 2 of this invention, and the schematic which shows an input-output characteristic.

A drive control apparatus for a vibration type actuator according to the present invention includes a vibrating body having an elastic body provided with an electro-mechanical energy conversion element, and a moving body that directly or indirectly contacts the vibrating body, A drive control device for a vibration type actuator that moves the moving body relative to the vibrating body by a frictional force generated by a vibration wave excited by the vibrating body by a voltage applied to a mechanical energy conversion element, Control means for variably controlling at least the frequency and amplitude of the applied voltage based on a speed command from the command means is provided, and the control means increases the amplitude of the applied voltage in a predetermined drive region.
In the present invention, the “moving body that is in direct or indirect contact with the vibrating body” is not only provided with a moving body so as to be in direct contact (physical contact) with the vibrating body but also a sliding member therebetween. It also means that a configuration including a friction member or a vibration transmitting member for transmitting vibration is included. That is, it means that the vibration energy of the vibrating body is configured to be transmitted to the moving body.
The “predetermined drive region” typically means “a drive region in which the behavior of the vibration type actuator may be unstable”. For example, the low speed region of the rated speed region of the vibration type actuator (For example, a speed region of 10% or less of the maximum speed). Further, when the drive region is defined from the viewpoint of frequency, it can also be referred to as a predetermined frequency band (frequency region). Further, “behavior is unstable” means a state in which stable driving cannot be performed at a speed according to a set value (control value). For example, when the steady drive is performed at the speed (region), the change in the speed is larger than when the steady drive is performed in another speed region, or when the vehicle stops, it can be said that the behavior is unstable.
Although the form for implementing this invention is demonstrated by the following examples, this invention is not limited at all by description of these Examples.

[Example 1]
The vibration type actuator according to the first embodiment of the present invention is in contact with or indirectly connected to a vibration body having a metal or ceramic elastic body provided with a piezoelectric element by an electro-mechanical energy conversion element. A moving body is provided.
Then, the moving body is moved relative to the vibrating body by a frictional force generated by a vibration wave using a resonance phenomenon of a natural vibration mode excited by the vibrating body by an applied voltage to the electro-mechanical energy conversion element. .
At that time, the vibration type actuator can generate an excitation force by inputting an AC voltage having the same frequency as the excitation frequency.

First, a vibration type actuator using a piezoelectric element and its rotation principle will be described below.
FIG. 2 is a schematic configuration diagram illustrating an example of a vibration type actuator, and FIG. 3 is a schematic diagram illustrating a state of vibration of the vibration type actuator.
Elastic bodies 2 a and 2 b sandwich the piezoelectric element 1, and these constitute a vibrating body 2 together. The vibrating body 2 is assembled with a rotor 4 that is rotated by a frictional force generated between the flexible substrate 3 for supplying power to the piezoelectric element 1 and the elliptical vibration formed on the upper surface of the vibrating body 2.
In order to rotate the rotor, a natural vibration mode of bending vibration in two orthogonal directions which the vibrating body 2 has is used. When these two vibrations are generated in a state where the temporal phase is shifted by 90 °, the upper structure of the vibrating body 2 vibrates so as to swing around the constricted portion.
This is shown in FIG. This vibration force is transmitted via a frictional force to the rotor 4 pressed against the upper portion of the vibrating body 2 by a pressing means (not shown), and is taken out as a rotational output.
FIG. 4 shows an electrode pattern for power feeding formed on the piezoelectric element 1.
The electrode is divided into four sections, and an AC voltage of A phase and B phase is supplied to each electrode via the flexible substrate 3. The signs of the electrodes 1a (+), 1a (−), 1b (+), and 1b (−) of the piezoelectric element 1 indicate the polarization direction, and the opposing electrodes are polarized to have opposite polarities, respectively. .
By applying the same drive voltage to the opposing electrodes, an excitation force in the reverse direction is generated, and vibrations in one natural vibration mode are excited corresponding to the A phase and the B phase, respectively.

Next, the basic control principle of the vibration type actuator will be described.
FIG. 5 is a diagram showing the relationship between the frequency of vibration excited by the vibrating body 2 of the vibration type actuator and the vibration amplitude of the vibrating body 2.
Here, description will be made using a thin solid line showing typical characteristics (the thick dotted line will be described later). Fr indicates the resonance frequency of the vibrating body 2, and when the drive frequency approaches the resonance frequency Fr from a region where the driving frequency is higher than the resonance frequency Fr, the vibration amplitude of the vibrating body 2 gradually increases, and the maximum amplitude, that is, the maximum at the resonance frequency Fr. The speed becomes Vmax.
And when it becomes a frequency lower than the resonance frequency Fr, it has an asymmetric characteristic in which the vibration amplitude suddenly decreases.
The rotational speed (drive speed) of the vibration type actuator is proportional to the vibration amplitude, and the speed control of the vibration type actuator is usually performed in a region higher than the resonance frequency Fr in consideration of controllability.

Hereinafter, drive control of the vibration type actuator based on the above principle will be described.
FIG. 1 is a block diagram showing a configuration example of a drive control device for a vibration type actuator in this embodiment, and shows a system for controlling the rotational speed of the rotor 4 in accordance with a speed command from a command means (not shown). .
An AC voltage generator 11 that generates a two-phase AC voltage according to a frequency command and an amplitude command applies AC voltages φA and φB having a phase difference of 90 ° to the piezoelectric elements 1a and 1b.
The rotational speed of the rotor 4 (not shown) is detected by a speed detector 12 such as a rotary encoder.
A subtractor 13 calculates the difference between the speed detection signal and a speed command from a command means (not shown).
Based on this difference signal, the controller 14 feedback-controls the frequency of the AC voltage (hereinafter referred to as drive frequency) by known PID control or the like.
For acceleration / deceleration accompanying the start and stop of the vibration type actuator, a speed command having a predetermined acceleration is given from a command means (not shown), and a frequency insertion command is issued from the controller 14 to control the rotational speed of the rotor 4. Is done.

Here, the region where the behavior becomes unstable at an extremely low speed after the rotor 4 starts rotating will be described with reference to FIGS. 5 and 6.
In the unstable region as described above, it has been clarified that the vibration state is not stable due to the following factors.
That is, when the contact state between the vibrating body 2 and the rotor 4 is a boundary region between full contact and partial contact, the contact pressure between the vibrating body 2 and the rotor 4 varies depending on the location, The vibration state may not be stable due to variations in flatness.
FIG. 6 is a graph plotting the transition of the difference between the drive frequency and the resonance frequency in the process of starting the vibration actuator at the frequency Fs and sweeping the frequency to the target frequency Ft corresponding to the target rotational speed Vt. A curve indicated by a thin solid line α represents a global transition.
After the start of sweeping from Fs, in the vicinity of the frequency Fr ′, the resonance frequency temporarily approaches the drive frequency, so that the frequency difference between the two becomes small, and the above-described vibration state becomes an unstable region.
In this region, the resonance frequency is also oscillating due to the above-described factors, and the difference between the resonance frequency and the driving frequency is also oscillating as shown by the thick solid line β in FIG. In this state, if the difference between the two has taken a negative value, it will stall (stop).

In FIG. 5, when the rotational speed during acceleration passes near the speed Vmax ′ in FIG. 5, the vibration amplitude (speed) -frequency characteristics temporarily move as indicated by the thick dotted line and become vibrational. In the state (corresponding to β in FIG. 6),
This corresponds to stalling (stopping) when drive frequency <resonance frequency Fr ′.
When the vibration state is stabilized after passing through the unstable region, the resonance frequency is far and returns to Fr, so that the frequency sweep can be completed up to Ft.
In the curve α in FIG. 6, the interval from the minimum value near the frequency Fr ′ to Ft corresponds to this.
In the vibration type actuator of the type shown in FIG. 2 used by the present inventors, it has been experimentally confirmed that the rotational speed Vmax ′ is centered around 2 [rps].

To suppress this phenomenon,
It is desirable to set the amplitude of the drive voltage to a larger value.
This is because the greater the amplitude of the drive voltage, the stronger the excitation force and the more stable the vibration.
FIG. 7 shows an example of the difference in behavior at the time of frequency sweep by the drive voltage.
FIG. 7A shows the behavior at the start of the vibration type actuator when the drive voltage has a normal amplitude and FIG. 7B shows a drive voltage having a larger amplitude than usual.
In the figure, indicated by “R”, in a low speed range of about 2 ± 1 slightly [rps], the speed fluctuation is large and the vibration state is unstable at normal amplitude, whereas the vibration speed is unstable at higher amplitude than normal. It can be seen that it is accelerating stably without fluctuation.
However, if the drive voltage having a higher amplitude than usual is applied to the vibration actuator at all times or during acceleration / deceleration, power consumption increases unnecessarily. Therefore, it is desirable to apply a driving voltage necessary and sufficient for stable driving to suppress an unnecessary increase in power consumption.

Therefore, in this embodiment, the central rotational speed at which the vibration state becomes unstable is measured in advance, and control is performed to increase the amplitude of the drive voltage in accordance with the difference from the speed command from the command means (not shown). Do.
Specifically, the subtracter 15 of FIG. 1 obtains a difference between the above-described central rotational speed at which the vibration state measured in advance becomes unstable and a speed command from a command means (not shown). After performing a predetermined calculation at 16, amplitude control for outputting a drive voltage amplitude command to the AC voltage generator 11 is performed.
FIG. 8A shows an example of the configuration of the arithmetic unit 16, and FIG. 8B shows a graph showing the input / output characteristics, that is, the relationship between the difference and the amplitude command.
The difference is divided by the difference limit setting value in the divider 100 and then squared in the multiplier 101.
Further, only a value equal to or lower than the upper limit value 1 passing through the saturator (limiter) 102 is subtracted from the value 1 by the subtractor 103.
After that, the gain multiplied by the multiplier 104 is added to the amplitude value of the drive voltage at the normal time by the adder 105 and output as an amplitude command.

Note that Gain in the multiplier 104 is a set value of the maximum increase amplitude. When the computing unit 16 is configured in this way, the amplitude command is as shown in FIG.
That is, the amplitude command takes the maximum value “normal voltage amplitude value + maximum increase amplitude (Gain)” at the central rotational speed (difference 0) at which the vibration state becomes unstable, and the rotational speed is separated by the difference limit set value. It has a square characteristic that gives a normal voltage amplitude.
For example, in correspondence with the speed region “R” in FIG. 7 described above, the central rotational speed is 2 [rps], the difference limit setting value is 1.2 [rps], the gain is 0.2, and the normal voltage Let the amplitude be 0.5.
As a result, the amplitude command from startup to 0.8 [rps] is 0.5, from which the amplitude command increases as a square function, and the maximum amplitude becomes 0.7 at 2 [rps].
When the rotational speed exceeds 2 [rps], the amplitude command decreases in a square function, and when it exceeds 3.2 [rps], it returns to 0.5, which is the normal amplitude. Note that the amplitude of the drive voltage is standardized, and 1 is the maximum value.

As described above, by configuring the computing unit 16, the amplitude of the drive voltage can be increased as necessary in a region where the vibration state becomes unstable.
Although the present embodiment is configured to obtain a square function characteristic, of course, the scope of the present invention is not limited to this.
In order to reduce the amount of calculation, it may be a linear characteristic, or a zero-order characteristic that increases a discontinuous constant value.
Alternatively, higher-order characteristics may be given, or asymmetric characteristics such as changing the characteristics depending on the sign of the speed difference may be given.
In addition, the method for determining the central rotational speed at which the vibration state becomes unstable may be a fixed value obtained experimentally, or it may be measured on the production line of the factory to optimize for each actuator. Good.
Furthermore, instead of the central rotational speed, control may be performed based on the difference from the frequency command using a frequency value corresponding to that speed. Needless to say, the same control as that during acceleration described above can be performed during deceleration.

As described above, by performing variable control to increase the amplitude of the voltage applied to the vibration type actuator according to the difference between the central rotational speed at which the vibration state measured in advance becomes unstable and the speed command. It becomes possible to suppress the phenomenon that the vibration state becomes unstable.
As a result, it is possible to stabilize the drive by suppressing the generation of unnecessary vibrations in the low-speed drive region where the behavior is unstable, and to suppress the power consumption.

[Example 2]
As the second embodiment, a configuration example different from the first embodiment will be described.
In the present embodiment, since the basic configuration is the same as that of the first embodiment except that the difference in phase difference, not the rotational speed difference, is feedback-controlled, the overlapping description is omitted.
FIG. 9 is a block diagram illustrating a configuration example of the drive control device for the vibration type actuator in the present embodiment.
FIG. 1 in the first embodiment is different from FIG. 1 in that a vibration detection sensor 1c using a piezoelectric element is provided in a vibration body 2 (not shown), and a phase difference between an AC signal φA and a vibration detection signal φS is set to a preset center phase difference. The difference is that the amplitude of the AC voltage is controlled based on the difference.
The phase difference between the AC voltage φA and the vibration detection signal φS is detected by the phase difference detector 17, and the difference between this and the above-mentioned center phase difference is obtained by the subtractor 15. Get the amplitude command.

FIG. 10 is a diagram showing the relationship between the driving frequency and the phase difference.
Here, description will be made using a thin solid line showing typical characteristics (the thick dotted line will be described later).
As is well known, the phase difference between the voltage signal φA applied to the vibration type actuator and the signal φS that detects the vibration of the vibration type actuator gradually increases as the frequency decreases from a region higher than the resonance frequency Fr, and the resonance frequency Fr. Pass through a point of -90 degrees.
Such characteristics correspond to the vibration amplitude characteristics of FIG. 5 and FIG. 6 described in the first embodiment, and the change of the resonance frequency can be detected by using the phase difference as a parameter.

Here, the region where the behavior becomes unstable at an extremely low speed after the rotor 4 starts rotating will be described with reference to FIGS. 10 and 11.
FIG. 11 is a graph plotting the transition of the phase difference in the frequency sweep process. A curve indicated by a thin solid line α represents a global transition.
After the start of sweeping from Fs, in the vicinity of the frequency Fr ′, the resonance frequency temporarily approaches the drive frequency, so that the phase difference becomes close to −90 degrees, and the vibration state described in the first embodiment is an unstable region. Become.
In this region, the resonance frequency is also oscillating due to the above-described factors, and the phase difference is also oscillating as shown by the thick solid line β in FIG. In this state, when the phase difference exceeds -90 degrees, it stalls (stops).
In FIG. 10, the phase difference in the state (corresponding to β in FIG. 11) in which the phase difference-frequency characteristic temporarily moves to the vicinity shown by the thick dotted line and becomes oscillating during frequency sweep. Corresponds to stalling when the angle exceeds −90 degrees.
When the vibration state is stabilized after passing through the unstable region, the resonance frequency is far and the phase difference characteristic returns to the state indicated by a thin solid line, so that the frequency sweep can be completed up to Ft.
In the curve α in FIG. 11, the interval from the frequency Fr ′ to Ft corresponds to this.
As described above, the curve indicating the difference between the driving frequency and the resonance frequency described in FIG. 6 of Example 1 and the phase difference curve in FIG. 11 have a one-to-one correspondence, and the minimum value near Fr ′ in FIG. Corresponds to the maximum value in the vicinity of Fr ′ in FIG.

In order to suppress the above phenomenon, it is desirable to set the amplitude of the drive voltage to a larger value.
However, in order to minimize the increase in power consumption, it is desirable to appropriately apply a driving voltage necessary and sufficient for stable driving.
Therefore, in this embodiment, the central phase difference at which the vibration state becomes unstable, that is, the central phase difference which is the maximum value is measured in advance, and the difference between this and the phase difference during driving of the vibration type actuator is measured. In response to this, control is performed to increase the amplitude of the drive voltage.
Specifically, in the subtractor 15 of FIG. 9, the difference between the above-described center phase difference at which the previously measured vibration state becomes unstable and the phase difference detection signal from the phase difference detector 17 is obtained. After performing a predetermined calculation by the calculator 16, amplitude control for outputting a drive voltage amplitude command to the AC voltage generator 11 is performed.
FIG. 12A shows a configuration example of the arithmetic unit 16, and FIG. 12B shows a graph showing the input / output characteristics, that is, the relationship between the difference and the amplitude command.
The difference is first input to a saturator (limiter) 106, and only values below the upper limit 0 pass. Since the configuration of the arithmetic unit 16 thereafter is the same as that of the first embodiment (the arithmetic unit 16 shown in FIG. 8), the details are omitted.

When the computing unit 16 is configured in this way, the amplitude command is as shown in FIG. That is, the amplitude command takes the maximum value “normal voltage amplitude value + maximum increase amplitude (Gain)” at the center phase difference at which the vibration state becomes unstable, and the normal voltage at the rotational speed separated by the difference limit set value on the negative side. Has a square characteristic that gives amplitude.
By maintaining the maximum value on the positive side, the difference in the phase difference is unstable and oscillating, and the excitation force is increased even when the center phase difference is closer to resonance. There is an effect to keep.
In this embodiment, the phase difference between the AC voltage and the vibration of the vibrating body 2 is used as the method for detecting the change in the resonance frequency. However, the scope of the present invention is not limited to this.
For example, a random number signal is superimposed on the frequency command, the frequency response characteristic of the speed fluctuation of the rotor 4 with respect to this frequency fluctuation is measured, and the difference between the resonance frequency and the driving frequency of the vibrating body 2 is directly estimated from the gain characteristic and the phase characteristic. Also good.
Further, the processing described in the present embodiment may be performed only in the unstable region, and may not be performed in a velocity region close to resonance that exceeds the target velocity Vt.

As explained above, according to the difference between the central AC voltage and the vibration phase difference of the vibrating body 2 where the vibration state measured in advance becomes unstable, and the phase difference during driving of the vibration type actuator, Variable control is performed to increase the amplitude of the voltage applied to the vibration type actuator.
Thereby, it becomes possible to suppress the phenomenon that the vibration state becomes unstable.
In addition, an increase in power consumption accompanying an increase in voltage amplitude can be suppressed to a necessary minimum, and both driving stabilization and power consumption suppression in a low rotation speed region can be realized.

1: Piezoelectric element 2: Vibrating body 2a, 2b: Elastic body 3: Flexible substrate 4: Rotor 11: AC voltage generator 12: Speed detector 13: Subtractor 14: Controller 15: Subtractor 16: Calculator

Claims (5)

A vibrating body having an elastic body provided with an electro-mechanical energy conversion element; and a moving body that directly or indirectly contacts the vibrating body,
A drive control device for a vibration type actuator that moves the moving body relative to the vibrating body by a frictional force generated by a vibration wave excited by the vibrating body by a voltage applied to the electro-mechanical energy conversion element. And
Control means for variably controlling at least the frequency and amplitude of the applied voltage based on a speed command from the command means;
A drive control apparatus for a vibration type actuator, wherein the control means increases the amplitude of the applied voltage in a predetermined drive region. The predetermined drive region is such that the frequency of the applied voltage is higher than the resonant frequency of the vibrating body, and the difference obtained by subtracting the resonant frequency of the vibrating body from the frequency of the applied voltage during the frequency sweep of the applied voltage is minimal. It is a region centered on the frequency where the value is taken,
The driving speed of the moving body corresponding to the region is measured in advance, and the amplitude of the applied voltage is increased according to the difference between the driving speed of the moving body measured in advance and the speed command from the command means. The drive control apparatus for a vibration type actuator according to claim 1.   The driving speed of the moving body measured in advance is a driving speed in a region where the driving speed of the moving body fluctuates most at a frequency sweep of the applied voltage with the applied voltage being constant. Item 3. A drive control device for a vibration type actuator according to Item 2. Preliminarily measuring the applied voltage corresponding to the low-speed drive region where the behavior is unstable and the phase difference in the vibrator,
The applied voltage measured in advance and the phase difference in the vibrator;
2. The drive control apparatus for a vibration type actuator according to claim 1, wherein the amplitude of the applied voltage is increased in accordance with a difference between the applied voltage during driving of the vibration type actuator and a phase difference in the vibrating body. .   The calculation means for calculating a difference between a resonance frequency of the vibrating body and a resonance frequency of the applied voltage is provided, and the amplitude of the applied voltage is increased according to an output of the calculation means. Drive controller for vibration type actuators.

Images