Vibration-type drive device

Abstract

The present invention provides a vibration-type drive device, which is a vibration-type actuator having an elastic body, a vibrating body provided with an electromechanical energy conversion element, and a contact body that is in contact with the elastic body, vibration of the vibrating body causing the vibrating body and the contact body to move relative to one another in a prescribed movement direction. The vibration includes: a first vibration component generated in the vibrating body by a voltage applied to the electromechanical energy conversion element; and a second vibration component generated in the vibrating body by the contact between the contact body and the elastic body. A signal corresponding to the second vibration component is detected, and the relative velocity between the vibrating body and the contact body is detected from this signal.

Description

Vibration type drive unit

[0001] The present invention relates to an apparatus for detecting and controlling the position, velocity and thrust of a vibratory drive.

[0002] The moving speed of the contact body driven by the vibration of the vibrating body of the vibration actuator is approximately proportional to the vibration amplitude of the vibrating body in an unloaded state, so in simple speed control applications, speed control is performed using a means for detecting the vibration amplitude instead of a speed sensor.

[0003] In Patent Document 1, the vibration amplitude of the vibrator is used instead of a speed sensor to control the speed, but when an external force acts on the moving object, the speed cannot be detected with high accuracy.

[0004] Furthermore, when detecting the speed using an encoder or the like, it is difficult to quickly detect the stopped state.

[0005] Patent No. 3191406

[0006] Therefore, the present invention provides a vibration type driving device and a control device for a vibration type driving device that can estimate speed with sufficient accuracy without relying on the generation of force (or torque) with a simple configuration.

[0007] The control device of the present invention is a control device for a vibration-type actuator having a vibrating body with an elastic body and an electromechanical energy conversion element, and a contact body in contact with the elastic body, wherein the vibrating body and the contact body move relatively in a predetermined movement direction due to vibration of the vibrating body, wherein the vibration includes a first vibration component generated in the vibrating body by a voltage applied to the electromechanical energy conversion element, and a second vibration component generated in the vibrating body by contact between the contact body and the elastic body, and the control device detects a signal corresponding to the second vibration component and detects the velocity between the vibrating body and the contact body based on the signal.

[0008] According to the present invention, it is possible to estimate the speed with sufficient accuracy using a simple configuration without relying on the generation of force (or torque). In addition, since it is possible to detect the speed including the direction, it is also possible to quickly detect the stopped state.

[0009]

[0010] A vibratory drive device for carrying out the present invention comprises:

[0011] First, the device is provided with a vibration type actuator having a vibrating body with an elastic body and an electromechanical energy conversion element, and a contact body that comes into contact with the elastic body, and a control device for the vibration type actuator.

[0012] The vibrating body and the contact body move relatively in a predetermined moving direction due to the vibration of the vibrating body.

[0013] The vibration includes a first vibration component generated in the vibrating body by a voltage applied to the electromechanical energy conversion element, and a second vibration component generated in the vibrating body by contact between the contact body and the elastic body.The control device detects a signal corresponding to the second vibration component and detects the relative velocity between the vibrating body and the contact body based on the signal.

[0014] A detailed description will be given below with reference to the drawings.

[0015] 1A to 1E are diagrams showing an example of a schematic configuration and vibration shape of a vibration actuator 100 according to a first embodiment of the present invention. The schematic configuration and operating principle of the vibration actuator 100 according to the first embodiment will be described using FIGS. 1A to 1E.

[0016] As shown in Fig. 1E, the vibration actuator 100 according to the first embodiment is configured to have a vibrating body 5 and a contact body 6. As shown in Fig. 1A and Fig. 1E, the vibrating body 5 is configured to have a piezoelectric element 2 and an elastic body 1 having two protrusions 80 that come into contact with the contact body 6. The piezoelectric element 2 forms a part of the vibrating body 5 and is a component that excites the vibrating body 5 to vibrate.

[0017] The piezoelectric element 2 is composed of a piezoelectric material and electrodes, and electrodes 3 and 4 are formed on the surface of the polarized piezoelectric material so that voltages can be applied independently, as shown in Fig. 1B. Piezoelectric ceramics can be used as the piezoelectric material.

[0018] These two electrodes are electrically insulated from each other, and two AC voltages whose phases can be changed independently are applied to them. The entire back surface of the piezoelectric element 2 is an electrode, and a ground potential can be connected from the surface of the piezoelectric element 2 through a via (not shown) provided in part of the piezoelectric element 2. This piezoelectric material is a single piece of piezoelectric material, but for the purpose of explaining the electrical circuit, the electrode 3, the electrode at ground potential, and the portion of the piezoelectric material sandwiched between them may be referred to as the piezoelectric body 3. The same is true for the piezoelectric body 4.

[0019] 1E is a slider that is brought into pressurized contact with the protrusion 80 of the vibrating body 5 with a constant pressure by a pressure mechanism (not shown). This contact body 6 (slider) is configured to move relatively in the direction indicated by the arrow on the paper due to vibrations excited in the vibrating body 5.

[0020] 1C and 1D are diagrams showing examples of vibration modes of the vibrating body 5. Fig. 1C shows the vibration shape of a vibration mode (thrust-up vibration mode) excited in the vibrating body 5 when AC voltages of the same amplitude and phase are applied to the piezoelectric bodies 3 and 4. The thrust-up vibration mode is one of the natural vibration modes of the vibrating body 5, and the direction of the natural vibration is approximately perpendicular to the contact surface of the vibrating body 5 in contact with the contact body 6. The degree of identity of the amplitude and phase may be determined by the user depending on the quality of the vibration wave desired.

[0021] On the other hand, FIG. 1D shows the vibration shape of a vibration mode (feedback vibration mode) excited in the vibrator 5 when AC voltages of the same amplitude and opposite phase are applied to the piezoelectric bodies 3 and 4.

[0022] The feed vibration mode is one of the natural vibration modes of the vibrating body 5, and the direction of the natural vibration is approximately horizontal to the contact surface of the vibrating body 5 with the contact body 6, and approximately coincides with the direction of the movement.

[0023] As an example, when the phase difference between the AC voltages applied to the piezoelectric bodies 3 and 4 is 0°, vibrations are excited in the vibration mode (thrust-up vibration mode) shown in Fig. 1C. When the phase difference between the AC voltages applied to the piezoelectric bodies 3 and 4 is 180°, vibrations are excited in the vibration mode (feed-up vibration mode) shown in Fig. 1D.

[0024] Furthermore, when the phase difference between the AC voltages applied to the piezoelectric bodies 3 and 4 is set to a value other than 0° and 180° (in practice, a value in the range of approximately 0° to ±120° is used), both vibration modes shown in Figures 1C and 1D are excited simultaneously. In this case, the contact body 6 (slider) that is in pressure contact with the protrusion 80 provided on the vibrating body 5 moves in the longitudinal direction of the rectangle of the vibrating body 5. As the phase difference moves away from 0°, the amplitude of the vibration mode (feed vibration mode) shown in Figure 1D increases, and the relative speed between the contact body 6 (slider) and the vibrating body 5 increases.

[0025] The forces that the vibrating body 5 receives include a piezoelectric excitation force that is generated by applying an AC voltage to the piezoelectric bodies 3 and 4 and that causes vibration in the vibrating body 5, a reaction force that the vibrating body 5 receives from a support member (not shown), and a reaction force that the vibrating body 5 receives from the contact body 6 (slider). Of these, the vibration corresponding to the force (piezoelectric excitation force) generated by applying an AC voltage to the piezoelectric bodies 3 and 4 that make up the vibrating body 5 is referred to as a first vibration component, and the vibration generated in the vibrating body 5 by the reaction force received from the contact body 6 (slider) is referred to as a second vibration component.

[0026] Furthermore, the vibration component due to the piezoelectric excitation force generated by the piezoelectric body 3 alone is classified as a third vibration component, and the vibration component due to the piezoelectric excitation force generated by the piezoelectric body 4 alone is classified as a fourth vibration component.

[0027] In the following, the sum or difference of the third vibration component generated by the first drive voltage and the fourth vibration component generated by the second drive voltage may be described. In this case, the drive vibration in the first direction generated based on one of the sum or difference, and the drive vibration in the second direction generated based on the other may be described. The direction of the drive vibration here means the direction in which the vibrator vibrates at the contact surface between the vibrator and the contact body when the drive vibration is generated, and the same applies to the direction of the natural vibration and the direction when the vibration component is expressed in the same direction.

[0028] Furthermore, the term "contact body" refers to a member that comes into contact with the vibrating body and moves relative to the vibrating body due to vibrations generated in the vibrating body. The contact between the contact body and the vibrating body is not limited to direct contact where no other member is interposed between them. The contact between the contact body and the vibrating body may also be indirect contact where another member is interposed between the contact body and the vibrating body, as long as the contact body moves relative to the vibrating body due to vibrations generated in the vibrating body. The "other member" is not limited to a member independent of the contact body and the vibrating body (for example, a high-friction material made of a sintered body). The "other member" may also be a surface-treated portion formed on the contact body or the vibrating body by plating, nitriding, or the like.

[0029] Furthermore, the term "vibrator" refers to a member that includes an elastic body and an electromechanical energy conversion element, and that vibrates when an AC voltage is applied to the electromechanical energy conversion element. The elastic body is mainly made of metal or ceramic, and the electromechanical energy conversion element may also serve as the elastic body.

[0030] FIG. 2 is a diagram showing a first configuration example of a driving device for a vibration actuator 100 according to a first embodiment of the present invention. FIG. 2 is composed of the vibration actuator 100, a unit for generating an AC voltage applied to the vibration actuator 100, a speed estimation unit for the vibration actuator 100, and a unit related to speed control. First, the AC voltage generation unit will be described. The AC signal generation unit 15 generates two-phase AC signals VA (first signal) and VB (second signal) based on frequency commands and ON-OFF commands from a command means (not shown) and a phase difference command output from a controlled variable calculation unit 20 (described later). The AC signals VA and VB are then connected to the primary windings of the transformers 7 and 8 via series resonant circuits formed by inductors 13 and 14 and capacitors 11 and 12, respectively. While this example shows an example in which the transformers 7 and 8 are connected via a series resonant circuit to shape the waveform and suppress changes in the voltage amplitude to the piezoelectric elements 3 and 4, it is also possible to connect only one of the inductors and capacitors, or to not connect the series resonant circuit. The voltages input to the primary windings of the transformers 7 and 8 are boosted and applied as a first drive voltage and a second drive voltage to the piezoelectric bodies 3 and 4 that constitute the vibrating body 5 of the vibration actuator 100 and are connected to the secondary windings. As mentioned above, although they are written in this manner for the purpose of explaining the electrical circuit, the piezoelectric bodies 3 and 4 are actually part of the integrated piezoelectric element 2.

[0031] Furthermore, the inductance values ​​of the secondary windings of the transformers 7 and 8 are frequency-matched to the damping capacitances of the piezoelectric elements 3 and 4. This allows a current that is roughly proportional to the vibration speed of the strain generated in the piezoelectric elements 3 and 4 to flow through the primary windings of the transformers 7 and 8.

[0032] Current detection resistors 9 and 10 are connected in series to the primary windings of transformers 7 and 8, and detect the current flowing through the primary windings of the transformers to generate a first detection signal, current signal IA, and a second detection signal, current signal IB. The relationship between current signal IA and current signal IB and the vibration of vibrating body 5 will be described separately.

[0033] Next, the configuration related to the speed estimation unit will be described. The second vibration component detection unit 16 and the thrust vibration amplitude detection unit 17 receive the current signal IA and the current signal IB, respectively, and detect the second vibration component and the component corresponding to the thrust vibration amplitude.

[0034] Here, if the waveforms of the current signal IA and the current signal IB contain many harmonics, the harmonic components may be sufficiently attenuated using a low-pass filter or a band-pass filter before being input to the second vibration component detection unit 16 and the thrust vibration amplitude detection unit 17.

[0035] As described above, the vibration component corresponding to the vibration caused by the force that the vibrating body 5 receives from the contact body 6 (slider) is the second vibration component.

[0036] The detected second vibration component and a component corresponding to the vibration amplitude in the direction in which the vibrator 5 pushes up the contactor 6 (slider) are input to a speed estimation unit 18, which estimates the speed according to the value of a phase difference command signal input at the same time. The speed estimation method and vibration detection will be described in detail later.

[0037] Next, the operation of the speed control section will be described. First, the estimated speed VS from the speed estimator 18 is compared with a speed command from a command means (not shown) by the comparator 19. Next, the comparison result from the comparator 19 is proportionally integrated by the control amount calculator 20 to generate a phase difference command signal. Then, the phase difference between the AC signals VA and VB is set, and the speed is controlled depending on the magnitude of the amplitude of the feed direction vibration excited in the vibrator 5.

[0038] Here, we will explain the relationship between the current signals IA and IB and the vibration of the vibrating body 5. As described above, the piezoelectric bodies 3 and 4 correspond to the electrodes 3 and 4 provided on the piezoelectric element 2 that constitutes the vibrating body 5. By applying AC signals to these electrodes, respectively, a piezoelectric excitation force is generated that vibrates the vibrating body 5. The vibration of the vibrating body generated by the piezoelectric excitation force generates strain in the piezoelectric body.

[0039] It is considered that the average strain distributed in the piezoelectric body is proportional to the vibration displacement of the section to which the piezoelectric body is attached. Since the piezoelectric effect generates electric charge proportional to the strain in the piezoelectric body, the current signal IA, which is the time derivative of the generated electric charge, is a signal corresponding to the average vibration velocity of the area of ​​the elastic body 1 where the section to which the electrode 3 is attached is projected (i.e., the piezoelectric body 3).

[0040] Similarly, the current signal IB is a signal corresponding to the vibration velocity of the portion of the elastic body 1 projected onto the section to which the electrode 4 is attached (i.e., the piezoelectric body 4).

[0041] Furthermore, current signal IA mainly contains a vibration component in the same direction as the third vibration component, and current signal IB mainly contains a vibration component in the same direction as the fourth vibration component. Note that the vibration component due to the piezoelectric excitation force generated by piezoelectric body 3 alone is the third vibration component, and the vibration component due to the piezoelectric excitation force generated by piezoelectric body 4 alone is the fourth vibration component.

[0042] The second vibration component detection unit 16 detects the second vibration component using the two detected signals, current signal IA and current signal IB.

[0043] Next, a description will be given of the detection of the thrust vibration amplitude performed by the thrust vibration amplitude detection unit 17. The thrust vibration corresponds to a component in the direction perpendicular to the plate of the plate-shaped vibrating body 5.

[0044] 1C, which is a vibration mode that occurs when the amplitudes of AC signals VA and VB applied to piezoelectric bodies 3 and 4 are equal and the phase difference is 0°. Therefore, the amplitude of the vibration velocity of the thrust vibration is approximately proportional to the amplitude of the sum signal of current signals IA and IB.

[0045] Furthermore, when the vibration displacement is equal, the amplitude of the vibration velocity increases or decreases in proportion to the vibration frequency, but since the frequencies of AC signals VA and VB do not change significantly, the amplitude of the vibration velocity can be considered to be roughly proportional to the vibration amplitude. Therefore, in the following explanation, current signal IA will be treated as a signal corresponding to the displacement of piezoelectric body 3, and current signal IB will be treated as a signal corresponding to the displacement of piezoelectric body 4, and the amplitude of the sum signal of current signals IA and IB will be explained as the thrust vibration amplitude.

[0046] The principle of velocity estimation will now be explained. FIG. 3 is a diagram schematically illustrating the relationship between the elliptical vibration locus of the tip of the protrusion 80 of the elastic body 1 and the relative force and relative velocity acting between the vibrating body 5 and the contact body 6 (slider) via the protrusion 80. All of the vibration loci in FIG. 3 are vibration loci of the tip of the protrusion 80 when the amplitudes of the AC signals VA and VB are equal and the phase difference is 45°. FIGS. 3(a) to 3(e) show vibration loci when the velocity between the vibrating body 5 and the contact body 6 (slider) is changed from -0.2 [rps] to 0.6 [rps] by an external force applied to the contact body 6 (slider). The direction of the arrow in FIG. 3 indicates the direction of the force acting on the contact body 6, and the length of the arrow indicates the magnitude of that force. 3(c), which has no arrows, is a state in which the external force acting on the contact body 6 is 0 [N], and the contact body 6 is moving at +0.2 [rps] relative to the vibrating body 5. The vibrating body 5 and the contact body 6 are in intermittent contact in the contact area at the tip of the protrusion 80, and the relative speed (speed difference) between the vibrating body 5 and the contact body 6 changes during this contact time. Depending on the difference in the relative speed (speed difference) and the contact pressure in the contact area, the frictional force generated between the vibrating body 5 and the contact body 6 also differs.

[0047] When the force applied to the contact body 6 is changed, the distribution of the speed difference between the vibrating body 5 and the contact body 6 in the contact area between the vibrating body 5 and the contact body 6 changes, and in conjunction with this, the distribution of the frictional force generated in the contact area also changes. Since the vibrating body 5 is vibrated by the frictional force generated during intermittent contact with the contact body 6, vibrations corresponding to the speed difference are superimposed on the vibrating body 5.

[0048] 3, the vibration locus of the tip of the protrusion 80 is elliptical, and this vibration ellipse is inclined in the opposite direction to the direction of the force acting on the tip of the protrusion 80 depending on the magnitude of the force acting from the contact body 6 to the protrusion 80. This phenomenon occurs when the vibration caused by the excitation received by the vibrating body 5 when the protrusion 80 comes into contact with the contact body 6 is superimposed on the vibrating body 5. This patent detects this superimposed vibration component (second vibration component) and estimates the relative velocity between the vibrating body 5 and the contact body 6.

[0049] 3 are characteristics when driven under conditions in which the frequency of the AC signals VA and VB is higher than the natural frequency of the vibration mode of the vibrating body 5. When the frequency of the AC signals VA and VB is lower than the natural frequency of the vibration mode of the vibrating body 5, the characteristics may differ from these, but the principle of detecting the second vibration component that changes with speed and estimating the speed remains the same.

[0050] The characteristics shown in FIG. 3 change depending on the relationship between the natural frequency of the vibration mode of the vibrating body 5 and the frequency of the AC signals VA and VB, the phase difference between the AC signals VA and VB, and other factors, so it is necessary to detect the second vibration component and estimate the speed according to the drive conditions.

[0051] The following description will be given of an example in which the vibrating body 5 is driven under the condition that the frequency of the AC signals VA and VB is higher than the natural frequency of the vibration mode of the vibrating body 5.

[0052] Next, the operation of the second vibration component detection unit 16 that detects the second vibration component, which is vibration generated in the vibrating body 5 due to vibration applied from the contact body 6 (slider), will be described in detail.

[0053] There are various methods for detecting the second vibration component, one of which is to detect the tilt of the vibration ellipse as shown in Figure 3. As mentioned above, the tilt of the vibration ellipse is highly correlated with the relative speed between the vibrating body 5 and the contact body 6 (slider), and detecting this value is considered to be the detection of a signal corresponding to the second vibration component.

[0054] Next, a first example of the second vibration component detection according to the first embodiment will be described.

[0055] 4A and 4B are diagrams showing a Lissajous waveform (vibration ellipse) illustrating a first example of detecting the second vibration component according to the first embodiment. FIG. 4A shows a Lissajous waveform (vibration ellipse) plotted with (current signal IA+current signal IB) on the vertical axis and (current signal IA-current signal IB) on the horizontal axis. (Current signal IA+current signal IB) shows a vibration waveform corresponding to the vibration mode of FIG. 1C (thrust-up vibration mode), and (current signal IA-current signal IB) shows a vibration waveform corresponding to the vibration mode of FIG. 1D (feed-back vibration mode). Here, assuming that current signal IA is expressed by Equation 1 and current signal IB is expressed by Equation 2,

[0056]

[0057]

[0058] The tilt angle φ1 of the vibration ellipse is given by Equation 3.

[0059]

[0060] The second vibration component detection unit 16 detects the amplitude ρ of the current signal IA, the amplitude σ of the current signal IB, and the phase difference (δ1-δ2) between the current signals IA and IB, and substitutes these into equation 3 to determine the second vibration component (the tilt angle of the vibration ellipse).

[0061] 5A and 5B show the relationship between the slope of the Lissajous waveform (vibration ellipse) and the speed, with Fig. 5A showing an example where the thrust vibration amplitude is small and Fig. 5B showing an example where the thrust vibration amplitude is relatively large. The line types in Fig. 5A and 5B indicate the difference in phase difference between AC signals VA and VB, and are represented by a solid line (90°), dotted line (45°), dashed line (0°), one-dot chain line (-45°), and two-dot chain line (-90°).

[0062] The relationship between the relative velocity between the contact body 6 and the protrusion 80 and the inclination angle of the vibration ellipse is approximately linear. Therefore, if the offset and inclination of each line on the graph are determined in advance for each thrust vibration amplitude and phase difference between the AC signals VA and VB, the velocity can be estimated by back-calculating from the inclination angle of the vibration ellipse. Furthermore, the greater the thrust vibration amplitude, the higher the sensitivity to the phase difference between the AC signals VA and VB, and the higher the accuracy of the velocity estimation.

[0063] In the above explanation, it has been explained that the change in the tilt angle φ1 of the Lissajous waveform (oscillating ellipse) is highly correlated with the velocity, but not only the tilt angle of the Lissajous waveform (oscillating ellipse) but also the width (minor axis) of the Lissajous waveform (oscillating ellipse) changes with the change in velocity. Therefore, the second vibration component may be a value obtained by adding, at a predetermined ratio, the tilt angle φ1 of the oscillating ellipse and the angle φ2 formed by the diagonal of the circumscribing rectangle of the oscillating ellipse and the center line of the oscillating ellipse shown in Figure 4A.

[0064] Furthermore, in Equation 3, only the part where the value changes may be extracted to obtain Equation 4, which may be used as the second vibration component S, or the result of substituting this into an arbitrary function may be used as the second vibration component S.

[0065]

[0066] In the above example, the vertical axis of the Lissajous waveform (vibration ellipse) is (current signal IA + current signal IB) and the horizontal axis is (current signal IA - current signal IB), but the slope of the vibration ellipse may also be found with the vertical axis as the current signal IA and the horizontal axis as the current signal IB. Figure 4B shows a Lissajous waveform (vibration ellipse) drawn with the vertical axis as the current signal IA and the horizontal axis as the current signal IB.

[0067] In this case, the tilt angle φ3 of the vibration ellipse is given by Equation 5, and the angle φ3 can be used as the second vibration component.

[0068]

[0069] Alternatively, the angle φ4 may be calculated in the same manner as in the above example, and the value obtained by adding the tilt angle φ3 and the angle φ4 at a predetermined ratio may be used as the second vibration component. Alternatively, the second vibration component S may be calculated by extracting only the part of the equation 5 where the value changes, as in equation 6, or by substituting this into an arbitrary function to obtain the second vibration component S.

[0070]

[0071] Next, a second example of the second vibration component detection according to the first embodiment will be described.

[0072] In the first example of detecting the second vibration component according to the first embodiment, the tilt angle of the vibration ellipse was calculated using Equation 3, but the tilt angle may also be calculated using other parameters of the vibration ellipse that change depending on the tilt angle of the vibration ellipse. Figures 4C and 4D are diagrams illustrating a second example of detecting the second vibration component according to the first embodiment, and Figure 4C is a diagram illustrating an example of detecting the second vibration component using an angle φ5 that changes depending on the tilt angle of the vibration ellipse.

[0073] In the first example of the second vibration component detection according to the first embodiment, the tilt of the axis of the vibration ellipse was used, but calculating this requires complex calculations such as those shown in Equation 3. The angle φ5 detected in this example can be directly detected from the sum signal and difference signal of the current signals IA and IB. The angle φ5 is the angle between the vertical axis and the line connecting the positive and negative peaks of (current signal IA + current signal IB). Figure 4D is a time-domain waveform diagram illustrating a method for detecting the angle φ5. The solid line in Figure 4D represents (current signal IA + current signal IB), the dotted line represents the differentiated waveform of the solid line, and the dashed line represents the waveform of (current signal IA - current signal IB). The angle φ5 is calculated by sampling the dashed signal at the peaks (maximum and minimum) of (current signal IA + current signal IB) to detect the values ​​of PT and PB, and then using Equation 7. Alternatively, the timing for detecting PT and PB may be the zero-crossing timing of the differentiated waveform of (current signal IA + current signal IB).

[0074]

[0075] The second vibration component detector 16 determines the second vibration component (angle φ5) as described above.

[0076] Furthermore, the second vibration component S may be expressed by Equation 8 or Equation 9.

[0077]

[0078]

[0079] As in the first example of the second vibration component detection according to the first embodiment, not only the tilt angle but also the width (minor axis) of the vibration ellipse changes with a change in speed. Therefore, the second vibration component S may be determined by adding, at a predetermined ratio, both the angle φ6 and the angle φ5 formed by the diagonal of the circumscribing rectangle of the vibration ellipse shown in FIG. 4C and the line indicating the angle φ5.

[0080] Furthermore, the parameters representing the Lissajous waveform (vibration ellipse) can be defined as various parameters such as major axis, height, width, etc. in addition to the tilt angle, minor axis, etc. used in the above explanation. Therefore, the second vibration component S may be detected using other parameters as long as they change depending on the tilt angle of the Lissajous waveform (vibration ellipse).

[0081] Next, a third example of the second vibration component detection according to the first embodiment will be described.

[0082] In the first and second examples of second vibration component detection according to the first embodiment, the second vibration component is extracted from the shape of the vibration ellipse, but in this example, it is found from the amplitude of the current. Second vibration component detection unit 16 in this example receives current signal IA and current signal IB, finds the amplitude of current signal IA and the amplitude of current signal IB, calculates (amplitude of current signal IA - amplitude of current signal IB), and outputs the result as second vibration component S.

[0083] Alternatively, the second vibration component S may be calculated by dividing (the amplitude of the current signal IA-the amplitude of the current signal IB) by (the amplitude of the current signal IA+the amplitude of the current signal IB).

[0084] 6A and 6B are diagrams showing the relationship with speed when the second vibration component S is (amplitude of current signal IA - amplitude of current signal IB). Fig. 6A shows an example when the thrust vibration amplitude is small, and Fig. 6B shows an example when the thrust vibration amplitude is relatively large. The line types in Figs. 6A and 6B indicate the difference in phase difference between AC signals VA and VB, and are represented as a solid line (90°), dotted line (45°), dashed line (0°), dot-dash line (-45°), and two-dot-dash line (-90°).

[0085] Comparing the characteristics of FIGS. 6A and 6B with those of FIGS. 5A and 5B, it can be seen that the slope of the vibration ellipse and (amplitude of current signal IA - amplitude of current signal IB) have very similar characteristics.

[0086] As with the first example of the second vibration component according to the first embodiment, the relationship between the relative velocity between the contact body 6 and the protrusion 80 and (amplitude of current signal IA - amplitude of current signal IB) is linear. Therefore, by determining in advance the offset and slope of each line for each thrust vibration amplitude and the phase difference between AC signals VA and VB, the velocity can be easily estimated from (amplitude of current signal IA - amplitude of current signal IB).

[0087] Next, a fourth example of the second vibration component detection according to the first embodiment will be described.

[0088] This example is an example of detection when the current signal is represented as a vector.

[0089] Specifically, in this example, a vector based on the amplitude and phase of the first detection signal is defined as the first signal vector, and a vector based on the amplitude and phase of the second detection signal is defined as the second signal vector. Furthermore, either the sum or difference of the first signal vector and the second signal vector may be defined as the first vibration vector, and the other may be defined as the second vibration vector. A vector component in the same direction as the first vibration vector may be defined as the same direction component, and a vector component in the normal direction of the first vibration vector may be defined as the normal direction component. A second vibration component may be calculated from the ratio based on the difference between the same direction components of the first signal vector and the second signal vector and the difference between the normal direction components of the first signal vector and the second signal vector.

[0090] 7A and 7B are vector diagrams of current signals, and Fig. 7A is a diagram showing current signal IA, current signal IB, and their sum and difference signals in vector form. The second vibration component S shown in the third example of the second vibration component according to the first embodiment can be expressed using vectors as in Equation 10 and Equation 11.

[0091]

[0092]

[0093] FIG. 7( b ) is a vector diagram showing the current signal IA and the current signal IB. The current signal IA is designated as a first signal vector, and the current signal IB is designated as a second signal vector. The diagram shows the two vectors, each divided into two orthogonal vibration components. The two orthogonal vibration components are a vibration component in the same direction as the upthrust vibration component (first vibration vector) (first signal vector + second signal vector) and a vibration component in the normal direction. The difference between the components in the same direction as the upthrust vibration component (first vibration vector) of the first signal vector and the second signal vector is highly correlated with the slope of the vibration ellipse. Therefore, as in Equation 12, the components in the same direction as the upthrust vibration component (first vibration vector) can be calculated for each of the first signal vector and the second signal vector, and the difference between these can be used as the second vibration component S. Alternatively, as in Equation 13, the value of Equation 12 can be divided by the magnitude of the upthrust vibration component (first vibration vector) to determine the second vibration component S.

[0094]

[0095]

[0096] Furthermore, there is also a case where a component in the normal direction with respect to the upward vibration component (first vibration vector) of the first signal vector (current signal IA) and the second signal vector (current signal IB) is used. As shown in Equation 14, for each of the first signal vector (current signal IA) and the second signal vector (current signal IB), the sum of a predetermined ratio (x:y) of the difference between the component in the same direction and the component in the normal direction with respect to the upward vibration component (first vibration vector) can be set as the second vibration component S.

[0097] Alternatively, as in Equation 15, the second vibration component S may be calculated by dividing the value of Equation 14 by the magnitude of the thrust vibration component (first vibration vector).

[0098]

[0099]

[0100] Here, a method for calculating the second vibration component S of Equation 12 to Equation 15 will be described. Equations 12 to 15 are calculations that include trigonometric functions, and also require detection of a phase difference. This makes the structure of the second vibration component detection unit 16 complex. Therefore, an example of detection using synchronous detection instead of this calculation will be described. A method for detecting the second vibration component S using synchronous detection is shown below.

[0101] Figure 8 is a diagram explaining a method for determining the magnitude of each directional component using synchronous detection. Figure 8(a) shows the reference waveform (solid line) of (current signal IA + current signal IB), the signal waveform (dashed line) into which the components are resolved, and the differentiated waveform (dotted line) of (current signal IA + current signal IB). Figure 8(b) shows the detection of the component in the same direction as the vector of (current signal IA + current signal IB), and Figure 8(c) shows the detection of the component in the normal direction of the vector of (current signal IA + current signal IB).

[0102] The solid line in Fig. 8(b) is a reference signal that is 1 when the sign of the solid line in Fig. 8(a) is positive and -1 when it is negative, and the dashed line in Fig. 8(b) is the multiplication result of this reference signal by the signal shown by the dashed line in Fig. 8(a). The dotted line in Fig. 8(b) shows the average value of this multiplication result, and indicates the magnitude of the vibration component in the same direction as the vector of (current signal IA + current signal IB).

[0103] Next, the solid line in Fig. 8(c) is a reference signal that is 1 when the sign of the dotted line in Fig. 8(a) is positive and -1 when it is negative, and the dashed line in Fig. 8(c) is the result of multiplying the signal of the dashed line in Fig. 8(a) by this reference signal. The dotted line in Fig. 8(c) shows the average value of the multiplication result, which indicates the magnitude of the vibration component in the normal direction to the vector of (current signal IA+current signal IB).

[0104] In this way, if synchronous detection is used and calculations including trigonometric functions are not required, it becomes easy to realize the second vibration component detection unit 16 using an FPGA or the like.

[0105] Next, a fifth example of the second vibration component detection according to the first embodiment will be described.

[0106] In the fourth example of the second vibration component in the first embodiment, the second vibration component was detected by obtaining the vectors of the current signal IA and the current signal IB, but in the fifth example, the second vibration component S is detected using the vector of (current signal IA - current signal IB).

[0107] 9 is a diagram showing the relationship between the first vibration vector, which is the sum of the first signal vector (current signal IA) and the second signal vector (current signal IB), and the second vibration vector, which is the difference between them. As with the fourth example of the second vibration component according to the first embodiment, the component of the second vibration vector in the same direction as the thrust vibration component (first vibration vector) is highly correlated with the slope of the vibration ellipse. The characteristics of the values ​​shown in Equations 16 and 17, which calculate the second vibration component S using the component of the second vibration vector in the same direction as the thrust vibration component (first vibration vector), are very similar to the characteristics shown in FIGS. 6A and 6B.

[0108]

[0109]

[0110] Furthermore, a component in the normal direction to the upward vibration component of the second vibration vector (first vibration vector) may also be used. As shown in Equation 18 and Equation 19, the second vibration component S may be calculated by adding the component in the same direction and the component in the normal direction to the upward vibration component of the second vibration vector (first vibration vector) at a predetermined ratio (x:y).

[0111]

[0112]

[0113] As in the fourth example of the second vibration component according to the first embodiment, the second vibration component S can also be obtained using synchronous detection in this example.

[0114] Next, a sixth example of the second vibration component detection according to the first embodiment will be described.

[0115] While the above example explained a method for detecting the second vibration component S corresponding to a Lissajous figure or vector display, this example explains an example in which the second vibration component S is detected by synchronous detection of a waveform on the time axis. In the above example, synchronous detection is used to find the vibration component in the same direction as the thrust direction, but in this example, the second vibration component S is found directly by synchronous detection.

[0116] The second vibration component is excited by contact between the vibrating body 5 and the contact body 6 (slider), and is generated in the vibrating body 5 as a response to the contact and is superimposed on the first vibration component. Therefore, the second vibration component is generated on the vibrating body 5 with a certain phase delay, starting from the timing of contact. This starting timing is the timing of the peak of vibration in the vibration mode (thrust-up vibration mode) shown in Fig. 1C, and the generated vibration is superimposed on the first vibration component with a phase delay that varies for each vibration mode depending on the excitation frequency. Vibration caused by the frictional force acting in the relative movement direction between the vibrating body 5 and the contact body 6 (slider) is generated mainly in the vibration mode (feed vibration mode) shown in Fig. 1D, and is superimposed on the vibration of the feed vibration mode of the first vibration component with a phase delay θs that corresponds to the response characteristics of the feed vibration mode.

[0117] 10(a) and 10(b) are diagrams illustrating a sixth example of the second vibration component detection according to the first embodiment, and are diagrams for explaining the operation of synchronous detection. FIG. 10(a) shows the waveform (solid line) of (current signal IA - current signal IB) when there is no load. Additionally, the same figure shows the superimposed vibration waveform (dotted line) superimposed on the waveform when there is no load, the waveform (dashed line) of (current signal IA - current signal IB) on which the superimposed vibration waveform (dotted line) is superimposed, and the waveform (chain line) of (current signal IA + current signal IB). Furthermore, FIG. 10(b) is a diagram illustrating the detection of the superimposed vibration waveform component by synchronous detection.

[0118] The solid line in Fig. 10(b) is a reference signal that is 1 when the sign of the superimposed vibration waveform (dotted line) in Fig. 10(a) is positive and -1 when it is negative, and the dashed line in Fig. 10(b) is the multiplication result of this reference signal by the signal shown by the dashed line in Fig. 10(a). The dotted line in Fig. 10(b) shows the average value of the multiplication result, and this value changes depending on the amplitude of the superimposed vibration waveform (dotted line) in Fig. 10(a).

[0119] Here, the superimposed vibration waveform (dotted line) in FIG. 10(a) represents a vibration component generated in the vibrating body 5 when the vibrating body 5 is excited by the contact body 6 (slider). This vibration component cannot be directly detected because it is superimposed on the vibration when no load is applied. Therefore, the second vibration component detection unit 16 uses synchronous detection to detect the vibration component containing a large amount of the superimposed vibration waveform. First, the phase of the superimposed vibration waveform is delayed by a phase θs from the peak phase of the waveform (dash-dotted line) of (current signal IA + current signal IB) in FIG. 10(a). Therefore, to extract this phase component, a reference signal (solid line) shown in FIG. 10(b) is generated. Note that the phase delay θs varies depending on the driving state and is therefore set according to the driving state. Next, the waveform (dashed line) of (current signal IA - current signal IB) on which the superimposed vibration waveform (dotted line) in FIG. 10(a) is superimposed is multiplied by the reference signal (solid line) in FIG. 10(b) and averaged to obtain the second vibration component S. Alternatively, the second vibration component S may be obtained by dividing the value obtained by synchronous detection by the amplitude of (current signal IA+current signal IB).

[0120] The value of θs can be determined in advance by measuring the amplitude of (current signal IA + current signal IB) and the phase difference between AC signals VA and VB, and can be prepared as a data table or function.

[0121] In this example, the reference signal is a pulse signal, but it may be a sine wave or other waveform.

[0122] Next, a seventh example of the second vibration component detection according to the first embodiment will be described.

[0123] 10(c) and (d) are diagrams illustrating a seventh example of the second vibration component detection according to the first embodiment. FIG. 10(c) shows the waveform (solid line) of (current signal IA-current signal IB) under no load, and the superimposed vibration waveform (dotted line) superimposed thereon. It also shows the waveform (dashed line) of (current signal IA-current signal IB) and the waveform (dash-dotted line) of (current signal IA+current signal IB) superimposed with the superimposed vibration waveform (dotted line).

[0124] Figure 10(d) shows the detection of the superimposed vibration waveform component by integrating the waveform (dashed line) of (current signal IA - current signal IB) on which the actually detected superimposed vibration waveform (dotted line) is superimposed over a predetermined phase interval.

[0125] The solid line in FIG. 10(d) is a gate signal in which the phase interval (0°±dθ) centered on phase 0° of the waveform (solid line) of (current signal IA-current signal IB) at no load in FIG. 10(c) is -1, the phase interval (180°±dθ) centered on phase 180° is 1, and the other phase intervals are 0. The dashed line in FIG. 10(d) is the multiplication result of this gate signal by the dashed line signal in FIG. 10(c). The dotted line in FIG. 10(d) shows the average value of the multiplication result, and this value changes depending on the amplitude of the superimposed vibration waveform (dotted line) in FIG. 10(c).

[0126] Here, the waveform (solid line) of (current signal IA-current signal IB) when there is no load in FIG. 10(c) can only be detected when there is no load. Therefore, the phase difference θX between the waveform (solid line) of (current signal IA-current signal IB) when there is no load and the waveform (dashed dotted line) of (current signal IA+current signal IB) in FIG. 10(c) is set in advance as a data table or function as a value that changes depending on various vibration states. For example, the phase difference θX can be set depending on the amplitude of (current signal IA+current signal IB) and the phase difference between AC signal VA and AC signal VB, etc.

[0127] 10(d) as the second vibration component S. Alternatively, the second vibration component S may be obtained by dividing the value indicated by the dotted line in FIG.

[0128] Next, an eighth example of the second vibration component detection according to the first embodiment will be described.

[0129] In this example, an equivalent circuit model of the vibrator 5 and drive circuit is used to generate (current signal IA - current signal IB) (second comparison signal) when there is no load for the AC signal VA (first signal) and AC signal VB (second signal). The superimposed vibration waveform is extracted by subtracting the second comparison signal from the difference between the actually measured current signal IA (first detection signal) and current signal IB (second detection signal). Figure 11A shows an example of the equivalent circuit model. Reference numeral 50 denotes a filter that simulates the operation of the equivalent circuit of the vibrator 5 and drive circuit when there is no load. The circuit diagram within the block includes a series resonant circuit consisting of inductors 13 and 14 and capacitors 11 and 12, transformers 7 and 8, an equivalent circuit of the vibrator 5 including the piezoelectric elements 3 and 4, and resistors 9 and 10 for current detection, and the operation of these components is simulated by calculation. When the waveforms of the AC signals VA and VB are input to the filter 50, the filter 50 outputs a current signal IAS that imitates the current signal IA and a current signal IBS that imitates the current signal IB in real time.

[0130] FIG. 11B is a diagram showing a second configuration example of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. FIG. 11B shows an example in which a second vibration component is detected using a filter 50. Components similar to those shown in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof will be omitted. The AC signals VA and VB output by the AC signal generator 15 are input to the filter 50, which outputs a current signal IAS simulating the current signal IA under no load and a current signal IBS simulating the current signal IB under no load. The second vibration component detector 16 receives the current signals IA, IB, and IAS, IBS as inputs. Based on this input, the second vibration component detector 16 subtracts (current signal IAS - current signal IBS) (second comparison signal) from the difference between the current signal IA (first detection signal) and the current signal IB (second detection signal) to detect the amplitude SF of the superimposed vibration waveform. As shown in Equation 20, the sign of the phase difference θSAB between the superimposed vibration waveform and (current signal IA+current signal IB) is used as the sign of the amplitude SF of the superimposed vibration waveform, and this is output as the second vibration component S.

[0131] In the above example, the second vibration component S was obtained from a signal obtained by subtracting the second comparison signal from the difference between the current signal IA (first detection signal) and the current signal IB (second detection signal) using (current signal IAS - current signal IBS) as the second comparison signal. However, depending on the configuration of the vibrating body 5 and the polarization directions of the piezoelectric bodies 3 and 4, (current signal IAS + current signal IBS) may be used as the first comparison signal. In that case, the second vibration component S may be obtained from a signal obtained by subtracting the first detection signal from the sum of the current signal IA (first detection signal) and the current signal IB (second detection signal).

[0132]

[0133] Moreover, the current signal IAS may be used as the first comparison signal, and the current signal IBS may be used as the second comparison signal.

[0134] The difference between the current signal IA (first detection signal) and the current signal IAS (first comparison signal) and the difference between the current signal IB (second detection signal) and the current signal IBS (second comparison signal) may be calculated, and the difference in their amplitudes may be used as the second vibration component S. This can be expressed as a vector as shown in Equation 21.

[0135]

[0136] 12A is a diagram illustrating the configuration of a current signal generating unit 51 in which an AC signal generating unit 15 is added to a filter 50. The current signal generating unit 51 outputs current signals IAS and IBS that simulate current signals IA and IB when there is no load, based on a frequency command from a command means (not shown) and a phase difference command from a controlled variable calculating unit 20.

[0137] Fig. 12B is a diagram showing a third configuration example of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. Fig. 12B shows an example in which the second vibration component is detected using a current signal generating unit 51. Components similar to those shown in Fig. 2 and Fig. 11B are given the same reference numerals, and detailed description thereof will be omitted.

[0138] The outputs of the filter 50 and the current signal generator 51 do not have to be analog signals, but may be, for example, digital waveform information or waveform information such as amplitude and phase.

[0139] Next, the operation of the speed estimation unit 18 will be described. As shown in Figures 6A and 6B, the sensitivity and offset value of the output of the second vibration component detection unit 16 to the speed differ depending on the phase difference between the AC signals VA and VB and the amplitude of the thrust vibration. Therefore, in order to estimate the speed from the second vibration component, it is necessary to correct the sensitivity and offset value of the output of the second vibration component detection unit 16 in accordance with the phase difference between the AC signals VA and VB and the amplitude of the thrust vibration.

[0140] 13A to 13D are diagrams showing the correction coefficients for determining velocity from the second vibration component S shown in FIGS. 6A and 6B and the results of estimating velocity. FIG. 13A shows the sensitivity correction coefficient γ, and FIG. 13B shows the offset correction coefficient ε, showing the correction coefficients for each thrust amplitude and the phase difference between AC signal VA and AC signal VB. The line types indicate the phase difference between AC signal VA and AC signal VB, and some representative lines are shown: solid line (90°), dotted line (45°), dashed line (0°), one-dot chain line (-45°), and two-dot chain line (-90°). Equation 22 is an equation for estimating velocity VS from the value of the second vibration component S.

[0141]

[0142] In the case of characteristics in which the value of the second vibration component S changes linearly with respect to the velocity, as in Figures 6A and 6B, the velocity can be estimated by using the offset and sensitivity correction coefficients for each thrust amplitude and phase difference between the AC signals VA and VB that have been calculated in advance. The characteristics in Figures 13A and 13B may be stored as a data table, but they may also be stored as functions T1 and T2 of the thrust vibration amplitude and the phase difference between the AC signals VA and VB. Equation 23 shows the function T1 of the offset correction coefficient ε, and Equation 24 shows the function T2 of the sensitivity correction coefficient γ.

[0143]

[0144]

[0145] 13A and 13B show the relationship between the phase difference between AC signals VA and VB, the amplitude of thrust vibration, and the correction coefficient, but the frequencies of AC signals VA and VB may be used instead of the amplitude of thrust vibration. In that case, the sensitivity correction coefficient γ and offset correction coefficient ε are determined from a data table or functions T3 and T4 based on the frequency and phase difference of AC signals VA and VB during driving. Equation 25 shows function T3 of offset correction coefficient ε, and Equation 26 shows function T4 of sensitivity correction coefficient γ.

[0146]

[0147]

[0148] Furthermore, the amplitudes of the AC signals VA and VB and other parameters may be added to the input arguments of the functions T3 and T4.

[0149] 13C and 13D are graphs showing the results of estimating the velocity using the correction coefficients of Fig. 13A and 13B for the second vibration component S shown in Fig. 6A and 6B, and show the relationship between the actually measured velocity and the estimated velocity. Fig. 13C shows the result of estimating the velocity from the characteristics of Fig. 6A, and Fig. 13D shows the result of estimating the velocity from the characteristics of Fig. 6B. The graph of Fig. 13D, which has a larger thrust amplitude, tends to have a smaller error in the estimated velocity relative to the actual velocity than the graph of Fig. 13C.

[0150] In the above explanation, an example was shown in which the velocity is defined as a linear expression of the second vibration component S and the velocity is estimated using the offset correction coefficient ε and the sensitivity correction coefficient γ, but the relationship with the velocity may be defined using polynomial approximation, trigonometric functions, etc. In that case, the coefficients corresponding to the number of terms in the approximation equation become a function with multiple arguments such as T1 to T4 above.

[0151] Next, we will explain the vibration detection means used to detect the second vibration component. The above explanation shows an example in which the vibration of the vibrating body 5 is detected by the current flowing through the primary winding of a transformer. This assumes a case in which a piezoelectric element is connected to the secondary winding of the transformer. Specifically, this utilizes the relationship in which the vibration velocity of the piezoelectric element and the fundamental component of the current in the primary winding of the transformer are approximately proportional when the damping capacitance of the piezoelectric element and the parallel resonant frequency of the inductor in the secondary winding of the transformer are set close to the driving frequency. Although not shown in Figures 2, 11B, and 12B, a capacitor or inductor that adjusts the relationship between the parallel resonant frequency and the driving frequency may be connected in parallel with the piezoelectric element. Another method for detecting vibration is known to use a mechanical arm current detection method. This method involves connecting a reference capacitor with the same capacitance as the damping capacitance of the piezoelectric element in parallel with the piezoelectric element, and detecting vibration from the difference between the current flowing through the piezoelectric element and the current flowing through the reference capacitor. The fundamental component of the current in the primary winding of the transformer can produce a current signal roughly equivalent to the known mechanical arm current.

[0152] Furthermore, when detecting the vibration waveform using current, particularly when the waveforms of the AC signals VA and VB are square waves, the current signal may contain many harmonic components. In such cases, the detected current signal may be subjected to waveform conversion using a low-pass filter, band-pass filter, or the like, and the waveform after extracting the fundamental wave component may be used as the vibration waveform.

[0153] Furthermore, a piezoelectric element for detecting vibration may be separately provided in addition to the piezoelectric element for driving the vibrator.

[0154] FIG. 14A is a diagram showing a fourth configuration example of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. FIG. 14A is a diagram showing an example in which a piezoelectric element for detecting vibrations is provided on the vibrating body 5 separately from the driving piezoelectric element. Components similar to those shown in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof will be omitted. Piezoelectric body 22 and piezoelectric body 23 are piezoelectric elements for vibration detection, with piezoelectric body 22 outputting a vibration detection signal SA and piezoelectric body 23 outputting a vibration detection signal SB. Furthermore, piezoelectric body 22 is provided overlapping piezoelectric body 3, and piezoelectric body 23 is provided overlapping piezoelectric body 4. By providing the piezoelectric body 22 overlapping piezoelectric body 3, the vibrations of the driving piezoelectric body 3 and the driving piezoelectric body 4 can be detected with high accuracy. The vibration detection piezoelectric body may be provided separately from the driving piezoelectric element as described above. Alternatively, a detection electrode region independent of the driving electrode may be provided on the driving piezoelectric element to form a vibration detection piezoelectric region and be used as the vibration detection piezoelectric body.

[0155] Figure 14B is a diagram showing a fifth example configuration of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. In the configuration of Figure 14B, the speed estimation unit and the speed control unit shown in Figure 2 are performed by a known CPU 34. Note that the same components as those shown in Figure 2 are given the same reference numerals, and detailed description thereof will be omitted.

[0156] The CPU 34 receives the second vibration component S output by the second vibration component detection unit 16 and the thrust-up vibration amplitude output by the thrust-up vibration amplitude detection unit 17 to estimate and control the speed and the thrust-up vibration amplitude. Figures 15, 16A, and 16B are flowcharts showing the operation of the CPU 34. Figure 15 shows the control steps for controlling the speed, and Figures 16A and 16B show the control steps for controlling the thrust-up vibration amplitude. First, we will explain Figure 15. In step S101, the CPU 34 sets a predetermined speed command Vcom, sets the phase difference command Ph to an initial phase difference of 0°, and sets the ON-OFF command to ON.

[0157] Subsequently, in step S102, the CPU 34 determines whether or not it is time to measure. If it is determined that it is not time to measure (S102 / No), the CPU 34 waits in step S102.

[0158] On the other hand, if it is determined in step S102 that it is time to measure (S102 / Yes), the process proceeds to step S103.

[0159] In step S103 , the CPU 34 acquires the second vibration component S output from the second vibration component detection unit 16 and the thrust vibration amplitude TS output from the thrust vibration amplitude detection unit 17 .

[0160] Next, in step S104, the CPU 34 performs calculations based on the values ​​of the thrust vibration amplitude TS and the phase difference command Ph acquired in step S103. That is, the CPU 34 calculates a sensitivity correction coefficient γ and an offset correction coefficient ε using these and functions T1 and T2 defined by a data table, calculation formulas, etc. Then, the CPU 34 calculates a speed VS using the second vibration component S acquired in step S103, the sensitivity correction coefficient γ, and the offset correction coefficient ε. In the subsequent steps, the CPU 34 compares the speed VS calculated in step S104 with the above-mentioned speed command Vcom to control the phase difference command Ph.

[0161] Next, the control of the phase difference command Ph will be described in steps S105 to S111.

[0162] In step S105, the CPU 34 compares the speed command Vcom set in step S101 with the speed VS calculated in step S104.

[0163] If the result of the comparison in step S105 is that the speed command Vcom is smaller (<) than the speed VS, the process proceeds to step S106.

[0164] In step S106, the CPU 34 subtracts a predetermined phase dPh from the phase difference command Ph.

[0165] Subsequently, in step S107, the CPU 34 determines whether the phase difference command Ph is smaller than −90°.

[0166] If it is determined in step S107 that the phase difference command Ph is smaller than -90° (S107 / Yes), the process proceeds to step S108.

[0167] In step S108, the CPU 34 sets the phase difference command Ph to -90°.

[0168] If the result of the comparison in step S105 is that the speed command Vcom is greater than (>) the speed VS, the process proceeds to step S109.

[0169] In step S109, the CPU 34 adds a predetermined phase dPh to the phase difference command Ph.

[0170] Subsequently, in step S110, the CPU 34 determines whether the phase difference command Ph is greater than +90°.

[0171] If it is determined in step S110 that the phase difference command Ph is greater than +90° (S110 / Yes), the process proceeds to step S111.

[0172] In step S111, the CPU 34 sets the phase difference command Ph to +90°.

[0173] When the process of step S108 is completed, when the process of step S111 is completed, or when the speed command Vcom and the speed VS are equal (=) in the comparison of step S105, the process proceeds to step S112. Note that by repeating the operations of steps S105 to S111, the phase difference command Ph is controlled so that the speed VS approaches the speed command Vcom.

[0174] Subsequently, in step S112, the CPU 34 determines whether or not a stop command has been input. If the result of this determination is that a stop command has not been input (S112 / No), the CPU 34 returns to step S102 and performs the processes from step S102 onward.

[0175] On the other hand, if it is determined in step S112 that a stop command has been input (S112 / Yes), the process proceeds to step S113.

[0176] In step S113, the CPU 34 sets the ON-OFF command to OFF, causing the outputs of the AC signals VA and VB output by the AC signal generator 15 to become 0 V, and the contact body 6 (slider) of the vibration actuator 100 to stop.

[0177] When the process of step S113 ends, the process of the flowchart shown in FIG. 15 ends.

[0178] 16A, first, in step S201, the CPU 34 sets a predetermined thrust vibration amplitude command TScom, and sets the frequency command Frq to the initial frequency F0.

[0179] Subsequently, in step S202, the CPU 34 determines whether or not it is time to measure. If it is determined that it is not time to measure (S202 / No), the CPU 34 waits in step S202.

[0180] On the other hand, if it is determined in step S202 that it is time to measure (S202 / Yes), the process proceeds to step S203.

[0181] In step S203, the CPU 34 acquires the thrust vibration amplitude TS output from the thrust vibration amplitude detection unit 17.

[0182] In the subsequent steps, the thrust vibration amplitude command TScom is compared with the thrust vibration amplitude TS detected in step S203, and the frequency command Frq is controlled.

[0183] Next, the control of the frequency command Frq will be described in steps S204 to S210.

[0184] In step S204, the CPU 34 compares the thrust-up vibration amplitude command TScom set in step S201 with the thrust-up vibration amplitude TS detected in step S203.

[0185] If the comparison result in step S204 indicates that the thrust-up vibration amplitude command TScom is smaller (<) than the thrust-up vibration amplitude TS, the process proceeds to step S205.

[0186] In step S205, the CPU 34 adds a predetermined frequency dFrq to the frequency command Frq.

[0187] Subsequently, in step S206, the CPU 34 determines whether the frequency command Frq is greater than Fmax.

[0188] If it is determined in step S206 that the frequency command Frq is greater than Fmax (S206 / Yes), the process proceeds to step S207.

[0189] In step S207, the CPU 34 sets the frequency command Frq to Fmax.

[0190] If the comparison result in step S204 indicates that the thrust vibration amplitude command TScom is greater than (>) the thrust vibration amplitude TS, the process proceeds to step S208.

[0191] In step S208, the CPU 34 subtracts the predetermined frequency dFrq from the frequency command Frq.

[0192] Subsequently, in step S209, the CPU 34 determines whether the frequency command Frq is smaller than Fmin.

[0193] If it is determined in step S209 that the frequency command Frq is smaller than Fmin (S209 / Yes), the process proceeds to step S210.

[0194] In step S210, the CPU 34 sets the frequency command Frq to Fmin.

[0195] When the processing of step S207 is completed, when the processing of step S210 is completed, or when the comparison of step S204 shows that the thrust-up vibration amplitude command TScom and the thrust-up vibration amplitude TS are the same (=), the process proceeds to step S211. Note that by repeating the operations of steps S204 to S210, the frequency command Frq is controlled so that the thrust-up vibration amplitude TS approaches the thrust-up vibration amplitude command TScom.

[0196] Subsequently, in step S211, the CPU 34 determines whether or not a stop command has been input. If the result of this determination is that a stop command has not been input (S211 / No), the CPU 34 returns to step S202 and performs the processes from step S202 onward.

[0197] On the other hand, if it is determined in step S211 that a stop command has been input (S211 / Yes), the process of the flowchart shown in FIG. 16A ends.

[0198] In the explanation of FIG. 15 , the values ​​of the thrust-up vibration amplitude TS and the phase difference command Ph are substituted into the functions T1 and T2 to calculate the sensitivity correction coefficient γ and the offset correction coefficient ε, but functions T3 and T4 using the frequency command Frq instead of the thrust-up vibration amplitude TS may also be used.

[0199] Furthermore, in the above example, the thrust-up vibration amplitude is controlled by the frequency command Frq to the AC signal generator 15, but the amplitudes of the AC signals VA and VB output by the AC signal generator 15 may also be controlled. Fig. 16B is a flowchart showing the control operation of the thrust-up vibration amplitude when the AC signal generator 15 controls the amplitudes of the AC signals VA and VB by a voltage amplitude command (not shown). The steps in Fig. 16B will be described below.

[0200] First, in step S301, the CPU 34 sets a predetermined thrust vibration amplitude command TScom, sets the frequency command Frq to the initial frequency F0, and sets the voltage amplitude command VS to the minimum voltage amplitude Vmin.

[0201] Subsequently, in step S302, the CPU 34 determines whether or not it is time to measure. If it is determined that it is not time to measure (S302 / No), the CPU 34 waits in step S302.

[0202] On the other hand, if it is determined in step S302 that it is time to measure (S302 / Yes), the process proceeds to step S303.

[0203] In step S303 , the CPU 34 acquires the thrust vibration amplitude TS output from the thrust vibration amplitude detection unit 17 .

[0204] In the subsequent steps, the above-mentioned thrust vibration amplitude command TScom is compared with the thrust vibration amplitude TS detected in step S303, and the voltage amplitude command VS is controlled.

[0205] Next, the control of the voltage amplitude command VS will be described in steps S304 to S310.

[0206] In step S304, the CPU 34 compares the thrust vibration amplitude command TScom set in step S301 with the thrust vibration amplitude TS detected in step S303.

[0207] If the comparison result in step S304 indicates that the thrust-up vibration amplitude command TScom is smaller (<) than the thrust-up vibration amplitude TS, the process proceeds to step S305.

[0208] In step S305, the CPU 34 subtracts a predetermined voltage dVS from the voltage amplitude command VS.

[0209] Subsequently, in step S306, the CPU 34 determines whether the voltage amplitude command VS is smaller than Vmin.

[0210] If it is determined in step S306 that the voltage amplitude command VS is smaller than Vmin (S306 / Yes), the process proceeds to step S307.

[0211] In step S307, the CPU 34 sets the voltage amplitude command VS to Vmin.

[0212] If the comparison result in step S304 indicates that the thrust vibration amplitude command TScom is greater than (>) the thrust vibration amplitude TS, the process proceeds to step S308.

[0213] In step S308, the CPU 34 adds a predetermined voltage dVS to the voltage amplitude command VS.

[0214] Subsequently, in step S309, the CPU 34 determines whether the voltage amplitude command VS is greater than Vmax.

[0215] If it is determined in step S309 that the voltage amplitude command Vs is greater than Vmax (S309 / Yes), the process proceeds to step S310.

[0216] In step S310, the CPU 34 sets the voltage amplitude command VS to Vmax.

[0217] When the processing of step S307 is completed, when the processing of step S310 is completed, or when the comparison of step S304 shows that the thrust-up vibration amplitude command TScom and the thrust-up vibration amplitude TS are the same (=), the process proceeds to step S311. Note that by repeating the operations of steps S304 to S310, the voltage amplitude command VS is controlled so that the thrust-up vibration amplitude TS approaches the thrust-up vibration amplitude command TScom.

[0218] Subsequently, in step S311, the CPU 34 determines whether or not a stop command has been input. If the result of this determination is that a stop command has not been input (S311 / No), the CPU 34 returns to step S302 and performs the processes from step S302 onward.

[0219] On the other hand, if it is determined in step S311 that a stop command has been input (S311 / Yes), the process of the flowchart shown in FIG. 16B ends.

[0220] Figure 17 is a diagram showing a sixth example configuration of the drive device for the vibration actuator 100 according to the first embodiment of the present invention. In Figure 17, the functions of the second vibration component detection unit 16 and the thrust-up vibration amplitude detection unit 17 are realized by an A / D converter 35 and an FPGA 36. The same components as those shown in Figure 2 are assigned the same reference numerals, and detailed descriptions thereof will be omitted. The waveform information of the current signal IA and the current signal IB is converted into digital data by the A / D converter 35 and input into the FPGA 36, where the second vibration component and thrust-up vibration amplitude are detected. Within the FPGA 36, various detection methods for the second vibration component described above can be selected depending on the situation, and the second vibration component S is detected by performing a composite calculation of the results detected by multiple detection methods.

[0221] The CPU 34 reads out the second vibration component S and the thrust vibration amplitude from the FPGA 36, and performs processing in accordance with the flowcharts of FIGS. 15 and 16A.

[0222] Next, another example of the vibration type actuator will be described.

[0223] In the above explanation, the velocity estimation technique was explained using as an example a vibration actuator using a plate-shaped vibrating body 5 having two different natural vibration modes as shown in Figures 1A to 1E, but there are also vibration actuators of other types that can be used to estimate velocity using a similar method.

[0224] 18A to 18D are diagrams showing an example of a schematic configuration and vibration shape of a vibration actuator 200. The schematic configuration and operating principle of the vibration actuator 200 according to the first embodiment will be described using these Figures 18A to 18D.

[0225] As shown in Fig. 18D, the vibration actuator 200 according to the first example is configured to have a vibrating body 205 and a contact body 206. The vibrating body 205 is a plate-shaped vibrating body made of a conductive material, and as shown in Fig. 18A and 18D, is configured to have a piezoelectric element 202 and an elastic body 201 having protrusions 280 on its plate-shaped surface that come into contact with the contact body 206. The piezoelectric element 202 forms a part of the vibrating body 205 and is a component for exciting the vibrating body 205.

[0226] 18A, two electrodes 203 and 204 are formed on the surface of the piezoelectric element 202. These two electrodes 203 and 204 are electrically insulated from each other, and two AC voltages with independently varying phases are applied to them. The entire back surface of the piezoelectric element 202 is an electrode, and a ground potential can be connected from the surface of the piezoelectric element 202 through a via (not shown) provided in part of the piezoelectric element 202. In the following description, the electrodes 203 and 204 will be referred to as the piezoelectric body 203 and the piezoelectric body 204, respectively.

[0227] 18D is a slider that is brought into pressurized contact with the protrusion 280 of the vibrating body 205 at a constant pressure by a pressure mechanism (not shown). This contacting body 206 (slider) is configured to move in the direction of the arrow on the paper surface by vibrations excited in the vibrating body 205.

[0228] 18B and 18C are diagrams showing examples of vibration modes of the vibrating body 205. FIG. 18B shows the vibration shape (stretching vibration) of a vibration mode (thrust-up vibration mode) excited in the vibrating body 205 when AC voltages of the same amplitude and phase are applied to the piezoelectric bodies 203 and 204. FIG. 18C shows the vibration shape (bending vibration) of a vibration mode (feed-up vibration mode) excited in the vibrating body 205 when AC voltages of the same amplitude and phase but opposite to each other are applied to the piezoelectric bodies 203 and 204. That is, when the phase difference between the AC voltages applied to the piezoelectric bodies 203 and 204 of the vibrating body 205 is set to 0°, the vibration mode (thrust-up vibration mode) shown in FIG. 18B is excited. When the phase difference between the AC voltages applied to the piezoelectric bodies 203 and 204 of the vibrating body 205 is set to 180°, the vibration mode (feed-up vibration mode) shown in FIG. 18C is excited. Furthermore, when the phase difference between the AC voltages applied to the piezoelectric bodies 203 and 204 of the vibrating body 205 is set to a phase other than 0° and 180° (in practice, a range of approximately 0° to ±120° is used), both of the vibration modes shown in Figures 18B and 18C are excited simultaneously. In this case, the contact body 206 (slider) that is in pressure contact with the protrusion 280 provided on the vibrating body 205 moves in the short direction of the rectangle of the vibrating body 205.

[0229] As the phase difference moves away from 0°, the amplitude of the vibration mode (feed vibration mode) shown in FIG. 18C increases, and the relative speed between the contact member 206 (slider) and the vibrating member 205 increases.

[0230] If the piezoelectric elements 203 and 204 are replaced with the piezoelectric elements 3 and 4, the driving device for the vibration type actuator 100 according to the first embodiment can be applied.

[0231] In the above example, the amplitude of the sum signal of current signal IA and current signal IB is taken as the thrust vibration amplitude, but depending on the structure of the vibration actuator, the amplitude of the difference signal between current signal IA and current signal IB may also be the thrust vibration amplitude.

[0232] 19A to 19D are diagrams showing the schematic configuration of a vibration actuator 300. The vibration actuator 300 uses the same vibration mode as the vibration actuator 200, but the position of the protrusion that comes into contact with the contact body is different, and the amplitude of (current signal IA - current signal IB) corresponds to the thrust vibration amplitude.

[0233] 19B and 19C are diagrams showing examples of vibration modes of the vibrating body 305. Fig. 19B shows the vibration shape (bending vibration) of a vibration mode (thrust-up vibration mode) excited in the vibrating body 305 when AC voltages of the same amplitude and opposite phase are applied to the piezoelectric bodies 303 and 304. Fig. 19C shows the vibration shape (stretching vibration) of a vibration mode (feed-back vibration mode) excited in the vibrating body 305 when AC voltages of the same amplitude and in phase are applied to the piezoelectric bodies 303 and 304.

[0234] Furthermore, in the above example, the second vibration component is detected using (current signal IA-current signal IB) and the thrust vibration amplitude is detected using (current signal IA+current signal IB), but the opposite is true in the case of the vibration actuator 300. That is, in the case of the vibration actuator 300, the second vibration component is detected using (current signal IA+current signal IB) and the thrust vibration amplitude is detected using (current signal IA-current signal IB).

[0235] Based on this, if the correspondence between the thrust vibration and the feed vibration is reversed and the piezoelectric elements 303 and 304 are replaced with the piezoelectric elements 3 and 4, the driving device for the vibration type actuator 100 according to the first embodiment can be applied.

[0236] In the above example, a phase difference command is input to the speed estimator 18, but the actual phase difference between the AC signals VA and VB or the drive voltages generated in response thereto may be measured and input instead.

[0237] Furthermore, in the above example, the thrust can be estimated from the velocity VS estimated from the second vibration component S. The method for this is explained below. The velocity when a predetermined thrust F0 is generated and the slope of the thrust change with respect to the velocity change are determined in advance for the phase difference between the AC signals VA and VB. Figure 20A shows the phase difference between the AC signals VA and VB and the velocity (reference velocity: V0) when the thrust is a predetermined value F0, and Figure 20B shows the ratio (β) of the thrust change with respect to the velocity change. Then, the thrust FS can be calculated using Equation 27.

[0238]

[0239] In the above example, the speed was controlled by manipulating the phase difference between the AC signals VA and VB, but the speed may also be controlled by controlling the voltage amplitude of the AC signal VB while keeping the phase difference fixed at a predetermined phase difference.

[0240] 21 is a diagram showing a seventh example of the configuration of the driving device for the vibration actuator according to the first embodiment, in which the phase difference command sent from the CPU 34 to the AC signal generating unit 15 in FIG. 17 is replaced with a VB voltage amplitude command. Since the VB voltage amplitude controls the speed including its sign, the VB voltage amplitude is treated as signed, and the output of the AC signal VB is manipulated by multiplying the AC signal VB by the sign.

[0241] 22A and 22B show examples of the waveforms of AC signal VA, AC signal VB, and the VB voltage amplitude command. Fig. 22A shows the signal waveform of AC signal VA, and Fig. 22B shows the signal waveform of AC signal VB (solid line) and the VB voltage amplitude command (dashed line). The AC signal VB is shifted in phase by 90° relative to AC signal VA, and the sign of the phase difference between AC signal VA and AC signal VB changes depending on the sign of the VB voltage amplitude (dashed line).

[0242] In the above example, the speed was controlled by manipulating the phase difference between AC signals VA and VB, so the speed was estimated using the offset correction coefficient ε and sensitivity correction coefficient γ with the phase difference as a parameter, as in Equations 23 to 26. Similarly, when controlling the speed using the VB voltage amplitude, it is necessary to estimate the speed using the offset correction coefficient ε and sensitivity correction coefficient γ with the VB voltage amplitude as a parameter instead of the phase difference.

[0243] Furthermore, equation 27 calculates the thrust using the reference speed V0 with the phase difference as a parameter and the ratio (β) of the thrust change to the speed change. Here too, the thrust can be calculated by using the reference speed V0 with the VB voltage amplitude as a parameter instead of the phase difference and the ratio (β) of the thrust change to the speed change.

[0244] In the above explanation, since the change in the amplitude of the thrust vibration is small relative to the change in the speed of the contact body 6 due to the force acting on the contact body 6, the speed was estimated using the thrust vibration amplitude detected by the thrust vibration amplitude detection unit 17, but the feed vibration amplitude may also be used for speed estimation. The feed vibration amplitude can be detected by measuring the amplitude of the difference signal between the current signal IA and the current signal IB.

[0245] 23A and 23B are diagrams showing an example of a schematic configuration of a vibration actuator 400 according to a second embodiment of the present invention. The schematic configuration and operating principle of the vibration actuator 400 according to the second embodiment will be described using these Figures 23A and 23B.

[0246] As shown in Fig. 23B, the vibration actuator 400 according to the second embodiment includes a vibrating body 405, a contact body 406, and a rotating shaft 407 connected to the contact body 406. As shown in Fig. 23A, the vibrating body 405 is a cylindrical vibrating body made of a conductive material, and is configured with piezoelectric bodies 403 and 404, and an elastic body 401 that sandwiches the piezoelectric bodies from above and below and has a protrusion 480 on the top of the cylinder. The piezoelectric body 403 excites vibrations that cause the vibrating body 405 to expand and contract in the height direction of the cylinder, and the piezoelectric body 404 is a component that excites torsional vibrations in the vibrating body 405 about the central axis of the cylinder, and is sandwiched and fixed between the elastic body 401 by a tightening member (not shown).

[0247] 23B is a rotor that is brought into pressurized contact with the protrusion 480 of the vibrating body 405 with a constant pressure by a pressure mechanism (not shown). The contacting body 406 (rotor) rotates the rotating shaft 407 and the contacting body 406 (rotor) by vibrations excited by the vibrating body 405.

[0248] Next, the driving operation of the vibration actuator 400 will be described. The vibration actuator 400 is an actuator that rotates and drives a contact body 406 (rotor) by a composite vibration of stretching vibration (thrust-up vibration) and torsional vibration (feed-in vibration) excited in a vibrating body 405. When an AC voltage of a predetermined frequency is applied to the piezoelectric body 403, stretching vibration (thrust-up vibration) is excited in the vibrating body 405, and when the voltage is applied to the piezoelectric body 404, torsional vibration (feed-in vibration) is excited in the vibrating body 405. Therefore, when the stretching vibration (thrust-up vibration) and the torsional vibration (feed-in vibration) are excited with a temporal phase shift, the contact body 406 (rotor) rotates.

[0249] Here, we will explain the differences between the vibration actuator 400 and the vibration actuator 100. In addition to the difference in shape, these actuators also have a major difference in drive. This is because the vibration actuator 100 excites thrust-up vibration with the in-phase component of the applied two-phase AC voltage and feed vibration with the out-of-phase component, whereas each phase of the two-phase AC voltage individually corresponds to thrust-up vibration and feed vibration. Therefore, while the vibration actuator 100 controls the amplitude balance between the thrust-up vibration and feed vibration by the phase difference between the applied two-phase AC voltage, the vibration actuator 400 does not change the amplitude balance between the thrust-up vibration and feed vibration even if the phase difference is manipulated. Therefore, the vibration actuator 400 controls the balance between the thrust-up vibration and feed vibration by manipulating the amplitude balance of the two-phase AC voltage or the voltage amplitude of one of the phases.

[0250] Next, vibration excitation of the vibrating body 405 caused by an external force of the vibration actuator 400 will be described. An example will be described in which the vibrating body 405 is driven under conditions in which the frequency of the two-phase AC voltage is higher than the natural frequency of the thrust-up vibration mode of the vibrating body 405. In the vibration actuator 400, the locus of the vibration ellipse at the contact portion between the protrusion 480 and the contact body 406 (rotor) also tends to be similar to that shown in FIG.

[0251] 3, the vibration locus of the tip of the protrusion 480 when the vibration actuator 400 is driven is also elliptical, and this vibration ellipse tilts in the opposite direction to the direction of the force acting on the tip of the protrusion 480 depending on the magnitude of the force. This phenomenon occurs when the vibration caused by the excitation received by the vibrating body 405 when the protrusion 480 comes into contact with the contact body 406 (rotor) is superimposed on the vibrating body 405, and this superimposed vibration component (second vibration component) is detected to estimate the speed. Furthermore, since the second vibration component changes depending on the relationship between the natural frequency of the vibration mode of the vibrating body 405 and the frequency of the AC voltage applied to the piezoelectric body, it is necessary to detect the second vibration component and estimate the speed depending on the drive conditions.

[0252] The following description will be given of an example in which the vibrating body 5 is driven under the condition that the frequency of the two-phase AC voltage is higher than the natural frequency of the vibration mode of the vibrating body 5.

[0253] FIG. 24 is a diagram showing a first example of the configuration of a driving device for a vibration type actuator 400 according to a second embodiment of the present invention.

[0254] First, the AC voltage generation unit will be described. The AC signal generation unit 15 generates two-phase AC signals VA (first signal) and VB (second signal) that are 90° out of phase with each other, based on a frequency command from a command means (not shown) and a VB voltage amplitude command output from a controlled variable calculation unit 20. The AC signal VA has a predetermined amplitude, and the AC signal VB has an amplitude according to the VB voltage amplitude command. When the VB voltage amplitude command is a negative value, the AC signal VB is output with its polarity inverted.

[0255] The AC signals VA and VB are connected to the primary windings of the transformers 7 and 8 via series resonant circuits consisting of inductors 13 and 14 and capacitors 11 and 12, respectively. The voltages input to the primary windings of the transformers 7 and 8 are boosted and applied as a first drive voltage and a second drive voltage to the piezoelectric elements 403 and 404 of the vibration actuator 400, which are connected to the secondary windings. Here, the inductance values ​​of the secondary windings of the transformers 7 and 8 are frequency-matched to the damping capacitances of the piezoelectric elements 403 and 404. As a result, a current roughly proportional to the vibration speed of the piezoelectric elements 403 and 404 flows through the primary windings of the transformers 7 and 8.

[0256] Meanwhile, resistors 9 and 10 are connected in series to the primary windings of transformers 7 and 8. These resistors 9 and 10 convert the current flowing through the primary windings of the connected transformers into voltage to generate current signals IA and IB. Current signal IA (first detection signal) is a signal corresponding to the expansion / contraction vibration mode (thrust-up vibration mode) of vibrating body 405, and current signal IB (second detection signal) is a signal corresponding to the torsional vibration mode (feed-back vibration mode) of vibrating body 405.

[0257] Next, the configuration related to speed estimation and control will be described. The second vibration component detection unit 16 and the thrust-up vibration amplitude detection unit 17 receive the current signal IA and the current signal IB to detect the second vibration component and the thrust-up vibration amplitude. The speed estimation unit 18 detects the speed using the second vibration component detected here, the vibration amplitude of the stretching vibration mode (thrust-up vibration mode) of the vibrating body 405, and the VB voltage amplitude command value.

[0258] The detected speed is then compared with a speed command from a command means (not shown) by a comparison means 19, and a VB voltage amplitude command signal is generated in a control amount calculation unit 20 according to the comparison result. Then, the voltage amplitude of the AC signal VB is set, and the speed is controlled depending on the magnitude of the amplitude of the feed vibration mode excited in the vibrating body 405.

[0259] The speed estimation method and vibration detection method will be described in detail later.

[0260] A first example of the second vibration component detection according to the second embodiment will now be described.

[0261] 25A and 25B are diagrams for explaining a first example of second vibration component detection according to the second embodiment, showing an example of a Lissajous waveform (vibration ellipse) used for second vibration component detection. Fig. 25A shows a Lissajous waveform (vibration ellipse) plotted with current signal IA on the vertical axis and current signal IB on the horizontal axis. Current signal IA is a vibration waveform of the stretching vibration mode (thrust-up vibration mode) of vibrating body 405, and current signal IB is a vibration waveform of the torsional vibration mode (feed-forward vibration mode) of vibrating body 405, and φ7 indicates the tilt angle of the vibration ellipse.

[0262] Here, if the current signal IA is expressed by Equation 28 and the current signal IB is expressed by Equation 29,

[0263]

[0264]

[0265] The tilt angle φ7 of the vibration ellipse is given by Equation 30.

[0266]

[0267] The second vibration component detection unit 16 detects the amplitude ρ of the current signal IA, the amplitude σ of the current signal IB, and the phase difference (δ1-δ2) between the current signals IA and IB, and substitutes these into equation 30 to determine the second vibration component (the tilt angle of the vibration ellipse).

[0268] In the above explanation, it has been explained that the change in the inclination angle φ7 of the vibration ellipse is highly correlated with the speed, but not only the inclination angle of the vibration ellipse but also the width (minor axis) of the vibration ellipse changes with the change in speed. Therefore, taking this influence into consideration, the second vibration component S may be a value obtained by adding, at a predetermined ratio, the inclination angle φ7 of the vibration ellipse and the angle φ8 formed by the diagonal of the circumscribing rectangle of the vibration ellipse and the center line of the vibration ellipse.

[0269] Furthermore, the second vibration component S may be obtained by extracting only the changing portion of Equation 30, as Equation 31, or by substituting this into an arbitrary function.

[0270]

[0271] In the above example, the vertical axis of the Lissajous waveform (vibration ellipse) represents the current signal IA, and the horizontal axis represents the current signal IB, but the slope of the vibration ellipse may also be found by using the vertical axis as (current signal IA + current signal IB) and the horizontal axis as (current signal IA - current signal IB). Figure 25B shows a Lissajous waveform (vibration ellipse) drawn using signals obtained by multiplying current signal IA and current signal IB by coefficients αA and αB, respectively, with the vertical axis representing the sum signal and the horizontal axis representing the difference signal.

[0272] Here, when the coefficients αA and αB are set to 1, the inclination angle φ9 of the vibration ellipse is expressed by Equation 32, and the angle φ9 can be set as the second vibration component S.

[0273]

[0274] Alternatively, similarly to the above example, the angle φ10 may be calculated, and the value obtained by adding both the tilt angle φ9 and the angle φ10 at a predetermined ratio may be used as the second vibration component S. Alternatively, the second vibration component S may be calculated as Equation 33, which is obtained by extracting only the part of the equation that changes, or the result of substituting this into an arbitrary function may be used as the second vibration component S.

[0275]

[0276] Next, a second example of the second vibration component detection according to the second embodiment will be described.

[0277] In the first example of second vibration component detection according to the second embodiment, the tilt angle of the vibration ellipse was calculated using Equation 30. However, the tilt angle may also be calculated using other parameters of the vibration ellipse that change depending on the tilt angle of the vibration ellipse. Figures 25C and 25D are diagrams illustrating a second example of second vibration component detection according to the second embodiment, and Figure 25C is a diagram illustrating an example of detecting a second vibration component using angle φ11, which changes depending on the tilt angle of the vibration ellipse. In the first example of second vibration component detection according to the second embodiment, the tilt of the axis of the vibration ellipse was used, but calculating this requires complex calculations such as Equation 30. The angle φ11 detected in this example can be directly detected from current signals IA and IB. The angle φ11 is the angle between the line connecting the positive and negative peaks of current signal IA and the vertical axis. Figure 25D is a diagram illustrating a method for detecting angle φ11. In Figure 25D, the solid line represents current signal IA, the dotted line represents the differentiated waveform of the solid line, and the dashed line represents the waveform of current signal IB. The angle φ11 is calculated by detecting the values ​​of PT and PB by sampling the dashed signal at the timing of the peak of the current signal IB and using Equation 34. The timing for detecting PT and PB may also be the timing of the zero crossing of the differentiated waveform of the current signal IA.

[0278]

[0279] The second vibration component detector 16 obtains the second vibration component (angle φ11) as described above.

[0280] Furthermore, the second vibration component S may be expressed by Equation 35 or Equation 36.

[0281]

[0282]

[0283] As in the first example of the second vibration component detection according to the second embodiment, not only the tilt angle but also the width (minor axis) of the vibration ellipse changes with a change in speed. Therefore, the second vibration component S may be determined by adding, at a predetermined ratio, both the angle φ12 and the angle φ11 formed by the diagonal of the circumscribing rectangle of the vibration ellipse shown in FIG. 25C and the line indicating the angle φ11.

[0284] Next, a third example of the second vibration component detection according to the second embodiment will be described.

[0285] In the first and second examples of second vibration component detection according to the second embodiment, the second vibration component was extracted from the shape of the vibration ellipse, but it can also be determined directly from the amplitude of the current. The second vibration component detection unit 16 in this example inputs the current signals IA and IB and determines the amplitudes of (current signal IA + current signal IB) and (current signal IA - current signal IB). The second vibration component S is then calculated as (the amplitude of (current signal IA + current signal IB) - the amplitude of (current signal IA - current signal IB)). While the above calculations involve direct addition and subtraction of the current signals IA and IB, they may also be multiplied by different coefficients αA and αB before addition and subtraction. This is because stretching vibration, which is a thrust vibration, and torsional vibration, which is a feed vibration, are excitations that utilize completely different phenomena. In other words, stretching vibration utilizes the longitudinal effect or lateral effect of a piezoelectric material, while torsional vibration utilizes the thickness-shear effect of a piezoelectric material. Therefore, the sensitivity of the current to vibration is adjusted by multiplying the current signal IA and the current signal IB by coefficients αA and αB, respectively. The second vibration component S may be obtained by dividing the above calculation result by the amplitude of the current signal IA.

[0286] In the following description, other than in the figures and equations, the signal obtained by multiplying the current signal IA by the coefficient αA will be referred to as the current signal αIA, and the signal obtained by multiplying the current signal IB by the coefficient αB will be referred to as the current signal αIB.

[0287] Next, a fourth example of the second vibration component detection according to the second embodiment will be described.

[0288] This example is an example of detection when the current signal is represented as a vector. Figure 26 is a vector diagram of the current signal, and Figure 26(a) is a diagram showing the current signal αIA, the current signal αIB, and their sum and difference signals as vectors. The second vibration component S shown in the third example of the second vibration component according to the second embodiment can be expressed as in Equation 37 and Equation 38.

[0289]

[0290]

[0291] 26(b) is a diagram showing the vectors of (current signal αIA + current signal αIB) and (current signal αIA - current signal αIB) resolved into the same direction as the vector of current signal αIA, which is the thrust-up vibration component, and the normal direction. The difference between the components of the vectors of (current signal αIA + current signal αIB) and (current signal αIA - current signal αIB) that are in the same direction as the vector of current signal αIA is highly correlated with the slope of the vibration ellipse, and the values ​​shown in Equation 39 and Equation 40 can be taken as the second vibration component S.

[0292]

[0293]

[0294] Furthermore, the component in the normal direction of the vector of the current signal αIA may also be detected and added to Equation 39 or Equation 40 at a predetermined ratio (x:y) to obtain the second vibration component S. This can be expressed as Equation 41 and Equation 42.

[0295]

[0296]

[0297] Here, we will explain how to calculate the second vibration component S of Equation 39 to Equation 41. Equations 39 to 42 are calculations that include trigonometric functions, and also require detection of a phase difference. This makes the structure of the second vibration component detection unit 16 complex. Therefore, we will explain an example in which synchronous detection is used instead of these calculations and phase difference detection.

[0298] A method for detecting the second vibration component S using synchronous detection will be described below.

[0299] That is, one of the sum signal or difference signal of the first detection signal and the second detection signal is used as a reference signal, and the other is used as a measurement target signal, with the phase of the reference signal being used as a reference phase. A signal corresponding to the second vibration component is detected by integrating the measurement target signal over a phase interval set relative to the reference phase.

[0300] Figure 27 is a diagram explaining a method for determining the magnitude of each directional component using synchronous detection. Figure 27(a) shows the waveform of the reference current signal αIA (solid line), the signal waveform to be resolved into components (dashed line), and the differentiated waveform of the current signal αIA (dotted line). Figure 27(b) shows the detection of the component in the same direction as the vector of the current signal αIA, and Figure 27(c) shows the detection of the component in the normal direction to the vector of the current signal αIA.

[0301] The solid line in Fig. 27(b) is a reference signal that is 1 when the sign of the solid line in Fig. 27(a) is positive and -1 when it is negative, and the dashed line in Fig. 27(b) is the multiplication result of this reference signal by the signal shown by the dashed line in Fig. 27(a). The dotted line in Fig. 27(b) is the average value of this multiplication result, and indicates the magnitude of the vibration component in the same direction as the vector of the current signal αIA.

[0302] The solid line in Fig. 27(c) is a reference signal that is 1 when the sign of the dotted line in Fig. 27(a) is positive and -1 when it is negative, and the dashed line in Fig. 27(c) is the multiplication result of this reference signal by the signal shown by the dashed line in Fig. 27(a). The dotted line in Fig. 27(c) is the average value of this multiplication result, and indicates the magnitude of the vibration component in the normal direction of the vector of the current signal αIA.

[0303] Next, a fifth example of the second vibration component detection according to the second embodiment will be described.

[0304] In a fifth example of the second oscillatory component according to the second embodiment, the second oscillatory component is detected using the vector of the current signal αIB. Figure 28 is a diagram showing the relationship between the vector of the current signal αIA and the vector of the current signal αIB. As in the fourth example of the second oscillatory component according to the second embodiment, the second oscillatory component is largely contained in components in the same direction as the vector of the current signal αIA, and the characteristics of the values ​​shown in Equations 43 and 44 are very similar to the characteristics shown in Figures 6A and 6B shown in the first embodiment.

[0305]

[0306]

[0307] Furthermore, the normal component of the vector of the current signal αIA may also be detected and added to Equation 43 or Equation 44 at a predetermined ratio (x:y) to obtain the second vibration component S. This can be expressed as Equation 45 and Equation 46.

[0308]

[0309]

[0310] Here, we will explain how to find the second vibration component S of Equation 43 to Equation 46. As in the fourth example of the second vibration component according to the second embodiment, calculations may be performed using Equation 43 to Equation 46, but the second vibration component S may also be found using synchronous detection.

[0311] Next, a sixth example of the second vibration component detection according to the second embodiment will be described.

[0312] While the above example explained a method for detecting the second vibration component S corresponding to a Lissajous figure or vector display, this example explains a method for detecting the second vibration component S by synchronous detection of a waveform on the time axis. In the above example, synchronous detection is used to find the vibration component in the same direction as the thrust direction, but in this example, the output of the synchronous detection is directly output as the second vibration component S.

[0313] The second vibration component is excited by contact between the vibrating body 405 and the contact body 406 (rotor), and is generated in the vibrating body 405 as a response to the contact and superimposed on the first vibration component. Therefore, the second vibration component is generated on the vibrating body 405 with a certain phase delay, starting from the timing of contact. This starting point is the timing when the displacement reaches the peak of vibration in the stretching vibration mode (thrust-up vibration mode) of the vibrating body 405, and the generated vibration is superimposed on the first vibration component with a phase delay that varies for each vibration mode depending on the excitation frequency. Vibration caused by frictional force acting in the direction of relative movement between the vibrating body 405 and the contact body 406 (rotor) may occur mainly in the torsional vibration mode (feed vibration mode) of the vibrating body 405. In this case, the first vibration component is superimposed on the vibration of the torsional vibration mode (feed vibration mode) with a phase delay θs that corresponds to the response characteristics of the feed vibration mode.

[0314] 29(a) and (b) are diagrams illustrating a fifth example of detecting a second vibration component according to the second embodiment, and are diagrams for explaining the operation of synchronous detection. Fig. 29(a) shows the waveform of current signal IB under no load (solid line), the superimposed vibration waveform (dotted line) superimposed on the waveform under no load, the waveform of current signal IB on which the superimposed vibration waveform (dotted line) is superimposed (dashed line), and the waveform of current signal IA (dashed line). Fig. 29(b) is a diagram illustrating the detection of the superimposed vibration waveform component by synchronous detection.

[0315] The solid line in Fig. 29(b) is a reference signal that is 1 when the sign of the superimposed vibration waveform (dotted line) in Fig. 29(a) is positive and -1 when it is negative, and the dashed line in Fig. 29(b) is the multiplication result of this reference signal by the signal shown by the dashed line in Fig. 29(a). The dotted line in Fig. 29(b) shows the average value of the multiplication result, which changes depending on the amplitude of the superimposed vibration waveform (dotted line) in Fig. 29(a).

[0316] Here, the superimposed vibration waveform (dotted line) in Figure 29(a) represents a vibration component generated in the vibrating body 405 when the vibrating body 405 is excited by the contact body 406 (rotor). Because this vibration component is superimposed on the vibration during no-load operation, it is difficult to directly detect. However, since the phase of the superimposed vibration waveform is delayed by θs from the peak phase of the waveform (dashed dotted line) of the current signal IA in Figure 29(a), if θs is known, this relationship can be used to generate the reference signal (solid line) in Figure 29(b). The second vibration component detector 16 selects θs according to the drive state, performs synchronous detection, and outputs the obtained average value. Alternatively, the value obtained by synchronous detection divided by the amplitude of the current signal IA may be used as the second vibration component S.

[0317] The value of θs can be obtained in advance by measuring the amplitude of the current signal IA and the voltage amplitude of the AC signal VB, and can be prepared as a data table or function.

[0318] In this example, the reference signal is a pulse signal, but it may be a sine wave or other waveform.

[0319] Next, a seventh example of the second vibration component detection according to the second embodiment will be described.

[0320] 29(c) and (d) are diagrams illustrating a seventh example of the second vibration component detection according to the second embodiment. Fig. 29(c) shows the waveform of current signal IB under no load (solid line), the superimposed vibration waveform (dotted line) superimposed thereon, the waveform of current signal IB on which the superimposed vibration waveform (dotted line) is superimposed (dashed line), and the waveform of current signal IA (dashed-dotted line). Fig. 29(d) shows the detection of the superimposed vibration waveform component by integrating the waveform of current signal IB (dashed line) on which the superimposed vibration waveform (dotted line) is superimposed over a predetermined phase interval.

[0321] The solid line in Figure 29(d) is a gate signal that sets -1 in the phase section (0°±dθ) centered on phase 0° of the waveform (solid line) of the current signal IB in Figure 29(c) when there is no load, 1 in the phase section (180°±dθ) centered on phase 180°, and 0 in the other phase sections. The dashed line in Figure 29(d) is the multiplication result of this gate signal by the signal shown by the dashed line in Figure 29(c). The dotted line in Figure 29(d) shows the average value of the multiplication result, and this value changes depending on the amplitude of the superimposed vibration waveform (dotted line) in Figure 29(c).

[0322] Here, the waveform of the current signal IB (solid line) when there is no load in Figure 29(c) can only be detected when there is no load. Therefore, the phase difference θX between the waveform of the current signal IB (solid line) when there is no load and the waveform of the current signal IA (dashed dotted line) in Figure 29(c) is set in advance as a data table according to various vibration states. For example, the phase difference θX can be set according to the amplitude of the current signal IA, the voltage amplitude of the AC signal VB, etc.

[0323] The second vibration component detection unit 16 may output the value of the dotted line in Figure 29 (d) as the second vibration component S directly, or may divide the value by the amplitude of the current signal IA and use the result as the second vibration component S.

[0324] Next, an eighth example of the second vibration component detection according to the second embodiment will be described.

[0325] In this example, an equivalent circuit model of the vibrator 405 and drive circuit is used to generate a current signal IB signal when no load is applied to the AC signals VA and VB. This signal is then subtracted from the measured current signal IB to extract the superimposed vibration waveform. Figure 30A shows an example of the equivalent circuit model. Reference numeral 52 denotes a filter that simulates the operation of the equivalent circuit of the vibrator 405 and drive circuit when no load is applied. The circuit diagram within the block includes a series resonant circuit consisting of inductors 13 and 14 and capacitors 11 and 12, an equivalent circuit of the vibrator 405 including transformers 7 and 8, piezoelectric elements 403 and 404, and current detection resistors 9 and 10, the operation of which is simulated by calculation. When the waveforms of the AC signals VA and VB are input to the filter 52, it outputs a current signal IAS that simulates the current signal IA and a current signal IBS that simulates the current signal IB in real time.

[0326] FIG. 30B is a diagram showing a second configuration example of a driving device for a vibration actuator 400 according to a second embodiment of the present invention, illustrating an example in which a second vibration component is detected using a filter 52. Components similar to those shown in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof will be omitted. The AC signals VA and VB output by the AC signal generator 15 are input to the filter 52. In this case, the filter 52 outputs a current signal IAS (first comparison signal) simulating the current signal IA under no load and a current signal IBS (second comparison signal) simulating the current signal IB under no load. The second vibration component detector 16 then inputs the current signals IA, IB, and IAS, IBS, and detects the amplitude SF of the superimposed vibration waveform from the difference between the current signal IB (second detection signal) and the current signal IBS (second comparison signal).

[0327] As shown in Equation 47, the sign of the phase difference θSA between the superimposed vibration waveform and the current signal IA is used as the sign of the amplitude SF of the superimposed vibration waveform, and this is output as the second vibration component S.

[0328]

[0329] There are other methods for determining the second oscillatory component S. For example, the signals obtained by multiplying the current signals IA and IAS by a coefficient αA are defined as current signals αIA and αIAS, and the signals obtained by multiplying the current signals IB and IBS by a coefficient αB are defined as current signals αIB and αIBS. Then, the difference in amplitude between the difference signal between (current signal αIA + current signal αIB) and (current signal αIAS + current signal αIBS) and the difference signal between (current signal αIA - current signal αIB) and (current signal αIAS - current signal αIBS) can also be defined as the second oscillatory component S. This can be expressed as a vector in Equation 48.

[0330]

[0331] The output of the filter 52 does not have to be an analog signal, but may be, for example, digital waveform information or waveform information such as amplitude and phase.

[0332] Next, the operation of the speed estimating unit 18 will be described.

[0333] 31A and 31B are diagrams showing examples of correction coefficients for determining velocity from the second vibration component S, showing examples of correction coefficients for each thrust amplitude and voltage amplitude of the AC signal VB. FIG. 31A shows the sensitivity correction coefficient γ, and FIG. 31B shows the offset correction coefficient ε, showing their relationship with the thrust amplitude. The line types indicate the voltage amplitude of the AC signal VB, and representatively show a solid line (100 V), dotted line (50 V), dashed line (0 V), one-dot chain line (-50 V), and two-dot chain line (-100 V). Equation 49 is an equation for estimating velocity VS from the value of the second vibration component S when the value of the second vibration component S changes linearly.

[0334]

[0335] In this way, when the value of the second vibration component S changes linearly with respect to the speed, the speed can be estimated using a simple formula by using the offset and sensitivity correction coefficients for each thrust amplitude and voltage amplitude of the AC signal VB that have been calculated in advance. The characteristics of Figures 31A and 31B may be stored as a data table, but they may also be stored as functions T5 and T6 of the thrust vibration amplitude and the voltage amplitude of the AC signal VB. Equation 50 shows the function T5 of the offset correction coefficient ε, and Equation 51 shows the function T6 of the sensitivity correction coefficient γ.

[0336]

[0337]

[0338] 31A and 31B are diagrams showing examples of the relationship between the voltage amplitude of AC signal VB, the amplitude of thrust vibration, and the correction coefficient, but the frequencies of AC signals VA and VB may be used instead of the amplitude of thrust vibration. In that case, the sensitivity correction coefficient γ and the offset correction coefficient ε are determined from the frequencies of AC signals VA and VB during driving and the voltage amplitude of AC signal VB using a data table or functions T7 and T8. Equation 52 shows function T7 of offset correction coefficient ε, and Equation 53 shows function T8 of sensitivity correction coefficient γ.

[0339]

[0340]

[0341] In the above explanation, an example was shown in which the velocity is defined as a linear expression of the second vibration component S and the velocity is estimated using the offset correction coefficient ε and the sensitivity correction coefficient γ, but the relationship with the velocity may be defined using polynomial approximation, trigonometric functions, etc. In that case, the coefficients for each term become functions with multiple arguments such as T5 to T8 above.

[0342] Figure 32 is a diagram showing a third example of the configuration of the driving device for the vibration actuator 400 according to the second embodiment of the present invention. Figure 32 shows an example in which the speed estimation unit and the speed control unit of the driving device in Figure 24 are performed by a known CPU 34. Components similar to those shown in Figure 24 are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0343] 33 is a flow chart showing the operation of the CPU 34, showing the control steps for controlling the speed with the VB voltage amplitude. The control steps for the frequency command are the same as those explained in the first embodiment, so the explanation will be omitted.

[0344] First, in step S401, the CPU 34 sets a predetermined speed command Vcom, sets the VB voltage amplitude command VBcom to an initial voltage of 0, and sets the ON-OFF command to ON.

[0345] Subsequently, in step S402, the CPU 34 determines whether or not it is time to measure. If it is determined that it is not time to measure (S402 / No), the CPU 34 waits in step S402.

[0346] On the other hand, if it is determined in step S402 that it is time to measure (S402 / Yes), the process proceeds to step S403.

[0347] In step S403 , the CPU 34 acquires the second vibration component S output from the second vibration component detection unit 16 and the thrust vibration amplitude TS output from the thrust vibration amplitude detection unit 17 .

[0348] Next, in step S404, the CPU 34 calculates a sensitivity correction coefficient γ and an offset correction coefficient ε from the thrust vibration amplitude TS and the VB voltage amplitude command VBcom obtained in step S403. That is, the CPU 34 calculates a sensitivity correction coefficient γ and an offset correction coefficient ε using these and functions T5 and T6 defined by a data table, a calculation formula, etc. Then, the CPU 34 calculates a speed VS using the second vibration component S obtained in step S403, the sensitivity correction coefficient γ, and the offset correction coefficient ε. In the subsequent steps, the CPU 34 compares the above-mentioned speed command Vcom with the speed VS set in step S404 to control the VB voltage amplitude command VBcom.

[0349] Next, the control of the VB voltage amplitude command VBcom will be described in steps S405 to S411.

[0350] In step S405, the CPU 34 compares the speed command Vcom set in step S401 with the speed VS calculated in step S404.

[0351] If the result of the comparison in step S405 is that the speed command Vcom is smaller (<) than the speed VS, the process proceeds to step S406.

[0352] In step S406, the CPU 34 subtracts a predetermined voltage dVB from the VB voltage amplitude command VBcom.

[0353] Subsequently, in step S407, the CPU 34 determines whether the VB voltage amplitude command VBcom is smaller than VBmin.

[0354] If it is determined in step S407 that the VB voltage amplitude command VBcom is smaller than VBmin (S407 / Yes), the process proceeds to step S408.

[0355] In step S408, the CPU 34 sets the VB voltage amplitude command VBcom to VBmin.

[0356] If the result of the comparison in step S405 is that the speed command Vcom is greater than (>) the speed VS, the process proceeds to step S409.

[0357] In step S409, the CPU 34 adds a predetermined voltage dVB to the VB voltage amplitude command VBcom.

[0358] Subsequently, in step S410, the CPU 34 determines whether the VB voltage amplitude command VBcom is greater than VBmax.

[0359] If it is determined in step S410 that the VB voltage amplitude command VBcom is greater than VBmax (S410 / Yes), the process proceeds to step S411.

[0360] In step S411, the CPU 34 sets the VB voltage amplitude command VBcom to VBmax.

[0361] When the process of step S408 is completed, when the process of step S411 is completed, or when the speed command Vcom and the speed VS are equal (=) in the comparison of step S405, the process proceeds to step S412. Note that by repeating the operations of steps S405 to S411, the VB voltage amplitude command VBcom is controlled so that the speed VS approaches the speed command Vcom.

[0362] Subsequently, in step S412, the CPU 34 determines whether or not a stop command has been input. If the result of this determination is that a stop command has not been input (S412 / No), the CPU 34 returns to step S402 and performs the processes from step S402 onward.

[0363] On the other hand, if it is determined in step S412 that a stop command has been input (S412 / Yes), the process proceeds to step S413.

[0364] In step S413, the CPU 34 sets the ON-OFF command to OFF, causing the outputs of the AC signals VA and VB output by the AC signal generator 15 to become 0 V, and the contact body 406 (rotor) of the vibration actuator 400 stops.

[0365] When the process of step S413 ends, the process of the flowchart shown in FIG. 33 ends.

[0366] In the second embodiment, the value of the VB voltage amplitude command is used as an argument for setting the correction coefficient. However, the amplitude ratio between the AC signals VA and VB, the actually measured AC signal VB, or the amplitude of the drive voltage generated in response to the measured AC signal VB may also be used.

[0367] Furthermore, in the same manner as in the first embodiment, torque (or force) can be estimated from the velocity VS estimated from the second vibration component S. The method for estimating torque will be explained below as an example, but the method for detecting the force acting between the vibrating body and the contact body is similar.

[0368] The speed when a predetermined torque T0 is generated with respect to the voltage amplitude of the AC signal VB and the slope of the torque change with respect to the speed change are determined in advance. Figure 34A shows the voltage amplitude of the AC signal VB and the speed (reference speed: V0) when the torque is at the predetermined value T0, and Figure 34B shows the ratio (β) of the torque change with respect to the speed change. Then, the torque TR can be determined using Equation 54.

[0369] This reference speed: V0 is a reference value of the speed.

[0370]

[0371] In the above example, the speed was controlled by fixing the phase difference between AC signals VA and VB to 90° and manipulating the voltage amplitude of AC signal VB, but the speed may also be controlled by controlling the phase difference between AC signals VA and VB.

[0372] In the above example, the speed was controlled by manipulating the voltage amplitude of AC signal VB, so the speed was estimated using the offset correction coefficient ε and sensitivity correction coefficient γ with the VB voltage amplitude as a parameter, as in Equations 50 to 53. Similarly, when controlling the speed using the phase difference between AC signals VA and VB, it is necessary to estimate the speed using the offset correction coefficient ε and sensitivity correction coefficient γ with the phase difference as a parameter instead of the VB voltage amplitude.

[0373] Furthermore, equation 54 calculates the torque using a reference speed V0 with the VB voltage amplitude as a parameter and the ratio (β) of the torque change to the speed change. In this case too, the torque can be calculated by using a reference speed V0 with the phase difference as a parameter instead of the VB voltage amplitude and the ratio (β) of the torque change to the speed change.

[0374] In this embodiment, the piezoelectric body 403 excites vibrations that expand and contract the vibrating body 405, and the piezoelectric body 404 excites torsional vibrations on the vibrating body 405. On the other hand, in Fig. 23B, the same effect can be obtained by configuring the piezoelectric body 403 to excite bending in the left-right direction of the page, and the piezoelectric body 404 to excite bending in the depth direction of the page. In this case, the bending vibration caused by the vibration of the piezoelectric body 403 becomes a thrust vibration in the protrusion 480, and the bending vibration caused by the vibration of the piezoelectric body 404 becomes a feed vibration in the protrusion 480.

[0375] In the above description, the amplitude of the thrust vibration changes little relative to the change in the speed of the contact body 6 due to the force acting on the contact body 6, so the speed was estimated using the thrust vibration amplitude detected by the thrust vibration amplitude detection unit 17, but the feed vibration amplitude may also be used for speed estimation. The feed vibration amplitude can be detected by measuring the amplitude of the current signal IB.

[0376] Third Embodiment FIG. 35 is a diagram showing the general configuration of a vibration type actuator 500 according to a third embodiment.

[0377] 1A to 1E, and are in contact with the contact surfaces of the respective protrusions 580 along the circumference of the annular contact body 506. The thrusts of the three vibrating bodies 501, 502, and 503 are combined to increase the output torque.

[0378] FIG. 36 is a diagram showing a first configuration example of a driving device for a vibration actuator 500 according to a third embodiment of the present invention, in which the same components as those shown in FIG. 2 are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0379] Piezoelectric elements 504 and 505 are provided as excitation piezoelectric elements on vibrating body 501, piezoelectric elements 506 and 507 on vibrating body 502, and piezoelectric elements 508 and 509 on vibrating body 503. Each piezoelectric element can be divided into an A-phase side piezoelectric element connected to AC signal VA via inductor 13, capacitor 11, and three transformers, and a B-phase side piezoelectric element connected to AC signal VB via inductor 14, capacitor 12, and three transformers.

[0380] The A-phase piezoelectric elements are piezoelectric elements 504, 506, and 508, which are respectively connected to the secondary windings of transformers 60, 61, and 62. The primary windings of transformers 60, 61, and 62 are connected in series, with one end of the series connection connected to capacitor 11 and the other end connected to resistor 9 for current detection.

[0381] On the other hand, the B-phase piezoelectric elements are piezoelectric elements 505, 507, and 509, which are respectively connected to the secondary windings of transformers 63, 64, and 65. The primary windings of transformers 63, 64, and 65 are connected in series, with one end of the series connection connected to capacitor 12 and the other end connected to resistor 10 for current detection.

[0382] Resistor 9 detects a current signal IA corresponding to the vibration velocity of the A-phase piezoelectric element, and resistor 10 detects a current signal IB corresponding to the vibration velocity of the B-phase piezoelectric element.

[0383] Because the vibrating bodies 501, 502, and 503 are driven in a series connection, applying an AC voltage to the primary side of the transformer produces well-coordinated vibrations. Furthermore, the vibrations superimposed on each vibrating body change in a well-coordinated manner due to the frictional force acting between the protrusions 580 of the vibrating bodies 501, 502, and 503 and the contact body 506 (rotor). Because the vibrations of each vibrating body are well-coordinated, the vibrations of the vibrating bodies can be detected as a single vibration by detecting the current in the primary winding of the transformer, as in the first embodiment.

[0384] That is, in this embodiment in which a plurality of vibrators are connected in series and driven, the same method for detecting the second vibration component S as explained in the first embodiment can be used.

[0385] In the third embodiment, multiple vibrating bodies are connected in series to a transformer and a voltage is applied across both ends, but the piezoelectric bodies of multiple vibrating bodies may be connected directly in series without using a transformer. Furthermore, in the above embodiment, vibrations are detected using the current in the primary winding of the transformer, but a piezoelectric element for vibration detection may be separately provided in the vibrating body. In this case, since the vibrations of each vibrating body are synchronized by connecting them in series, the second vibration component S can be detected by detecting the vibration of one vibrating body, and speed and torque can be estimated and controlled in the same way as in the above embodiment.

[0386] Fourth Example FIG. 37A is a diagram showing a schematic configuration of a vibration type actuator 600 according to a fourth example.

[0387] A vibration actuator 600 according to the fourth embodiment is configured to include a vibrating body 605, a contact body 606 which is an annular rotor, and a rotating shaft 607 connected to the contact body 606 (rotor). The vibrating body 605 is an annular vibrating body made of a conductive material, and is configured to include a piezoelectric element 602 and an elastic body 601 which has a protrusion 680 on the upper surface of the annular vibrating body that comes into contact with the contact body 606 (rotor). The protrusion 680 has a friction member 681 made of resin at the contact point with the contact body 606 (rotor). The piezoelectric element 602 forms part of the vibrating body 605 and is a component for exciting vibrations to the vibrating body 605.

[0388] FIG. 37B is a diagram showing an example of a structure of a plurality of electrodes and electrical connection wiring configured in the piezoelectric element 602 shown in FIG. 37A.

[0389] 37B, the piezoelectric element 602 has 24 electrodes arranged at equal intervals on the circumference, and every fourth electrode of the piezoelectric element 602 is electrically connected by a connecting wire along the circumference. Here, the regions of the piezoelectric element 602 where the interconnected electrode groups are arranged will be referred to as piezoelectric body 611, piezoelectric body 612, piezoelectric body 613, and piezoelectric body 614, depending on the connection.

[0390] Furthermore, piezoelectric bodies 611 are arranged circumferentially at 60° intervals, and when AC voltage A is applied to piezoelectric bodies 611, six out-of-plane flexural vibrations are formed along the circumference of vibrating body 605. Furthermore, when AC voltages B, NA, and NB, which are shifted in phase by 90° from AC voltage A, are applied to piezoelectric bodies 612, 613, and 614, respectively, six out-of-plane traveling vibration waves are formed on vibrating body 605. These six traveling vibration waves then generate a relative force between protrusion 680 of vibrating body 605 and contact body 606 (rotor), causing contact body 606 (rotor) to rotate.

[0391] Piezoelectric element 602 is also provided with a plurality of electrodes for vibration detection, and the areas of piezoelectric element 602 where these electrodes are provided are referred to as piezoelectric body 615 and piezoelectric body 616. Piezoelectric body 615 detects vibrations excited by piezoelectric body 611 and piezoelectric body 613 and outputs vibration detection signal SA, while piezoelectric body 616 detects vibrations excited by piezoelectric body 612 and piezoelectric body 614 and outputs vibration detection signal SB.

[0392] 37C is a diagram showing a first example of the positional relationship between piezoelectric bodies 611 to 614 and protrusion 680. Protrusion 680 is provided at the center of the electrode compartment of piezoelectric bodies 611 and 613 to which AC voltages A and NA are connected. If the vibrations caused by piezoelectric bodies 611 and 613 are A-phase vibrations and the vibrations caused by piezoelectric bodies 612 and 614 are B-phase vibrations, the A-phase vibrations excite a thrust-up vibration that thrusts protrusion 680 up against contact body 606, and the B-phase vibrations excite a feed vibration that drives contact body 606 in the tangential direction of the contact surface of protrusion 680.

[0393] 38A is a diagram showing a first configuration example of a drive device for a vibration actuator 600 according to a fourth embodiment of the present invention. The same components as those shown in FIG. 24 are assigned the same reference numerals, and detailed description thereof will be omitted.

[0394] The vibration actuator 600 is an actuator driven by a four-phase AC voltage, where AC voltages A and NA, and AC voltages B and NB, are AC voltages with opposite phases. Pairs of piezoelectric elements 611, 613 and piezoelectric elements 612, 614 to which these opposite-phase AC voltages are applied are connected to center-tapped secondary windings of transformers 43 and 44. AC signals VA and VB, which are outputs from an AC signal generator, are applied to one end of the primary windings of transformers 43 and 44, and current detection resistors 45 and 46 are connected to the other end.

[0395] Current signal IA and current signal IB, which are signals detected by resistors 45 and 46, are input to second vibration component detection unit 16 and thrust-up vibration amplitude detection unit 17. Then, the second vibration component S and thrust-up vibration amplitude are detected by the operation described in the second embodiment above, and the rotational speed of contact body 606 (rotor) is detected by speed estimator 18. Then, comparison unit 19 compares the detected rotational speed with a speed command from command means (not shown), and control amount calculation unit 20 generates a VB voltage amplitude command signal in accordance with the comparison result, and controls the voltage amplitude of AC signal VB, thereby controlling the rotational speed.

[0396] In the fourth embodiment, in addition to speed control, thrust vibration amplitude control is also performed. The output of the thrust vibration amplitude detection unit 17 is compared with a thrust vibration amplitude command from a command means (not shown) by a comparison means 70. Next, the output of the comparison means 70 is input to a control amount calculation means 71, which generates a frequency command signal by proportional-plus-integral calculation. Then, the AC signal generation unit 15 sets the frequency of the AC signals VA and VB in accordance with the frequency command signal, thereby controlling the thrust vibration amplitude.

[0397] When the thrust vibration amplitude is controlled to a constant value, the contact state between the contact body 606 (rotor) and the vibrating body 605 becomes stable, thereby improving the stability of speed estimation.

[0398] 38B is a diagram showing a second configuration example of a drive device for a vibration actuator 600 according to a fourth embodiment of the present invention. The same components as those shown in FIG. 38A are assigned the same reference numerals, and detailed descriptions thereof will be omitted.

[0399] In the first configuration example of the driving device for the vibration actuator 600 according to the fourth embodiment, an example was shown in which vibration was detected using current signals IA and IB, but in the second configuration example, vibration is detected using piezoelectric elements 615 and 616. Piezoelectric element 615 outputs a vibration detection signal SA, and piezoelectric element 616 outputs a vibration detection signal SB. Since vibration is detected directly instead of using a current signal, the accuracy of velocity estimation can be improved.

[0400] Fig. 39A is a diagram showing a second example of the positional relationship between piezoelectric bodies 611 to 614 and protrusion 680. Protrusion 680 in Fig. 39A is provided between the electrode sections of piezoelectric bodies 611 and 612 to which AC voltages A and B are connected, and between the electrode sections of piezoelectric bodies 613 and 614 to which AC voltages NB and NA are connected. If the vibration caused by piezoelectric bodies 611 and 613 is defined as A-phase vibration, and the vibration caused by piezoelectric bodies 612 and 614 is defined as B-phase vibration, then a thrust vibration is excited by the sum component of the A-phase vibration and the B-phase vibration, and a feed vibration is excited by the difference component of the A-phase vibration and the B-phase vibration.

[0401] 40 is a diagram showing a third example of the configuration of a drive device for a vibration actuator 600 according to a fourth embodiment of the present invention. The same components as those shown in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, descriptions of cases in which the above-mentioned techniques such as vector calculation are used will be omitted.

[0402] The connections between the vibration actuator 600 and the transformers 43 and 44 and the connections between the resistors 45 and 46 are the same as those in the first configuration example of the drive device for the vibration actuator 600 according to the fourth embodiment. However, since the position of the protrusion 680 on the vibrating body 605 is different from that in the first configuration example of the drive device for the vibration actuator 600 according to the fourth embodiment, the connections of the current signals IA and IB to the second vibration component detection unit 16 and the thrust vibration amplitude detection unit 17 are different.

[0403] The current signal IA and the current signal IB are input to both a second vibration component detection unit 16 and a thrust-up vibration amplitude detection unit 17. (Current signal IA+current signal IB) indicates the thrust-up vibration component, and (current signal IA-current signal IB) indicates the feed vibration component, and the second vibration component S and the thrust-up vibration amplitude are detected by the operation described in the first embodiment above. Then, a speed estimation unit 18 detects the rotational speed of the contact body 606 (rotor).

[0404] FIG. 39B is a diagram showing a third example of the positional relationship between the piezoelectric bodies 611 to 614 and the protrusion 680.

[0405] Protrusion 680 is provided between the electrode sections of piezoelectric body 611 and piezoelectric body 614 to which AC voltage A and AC voltage N B are connected, and between the electrode sections of piezoelectric body 612 and piezoelectric body 613 to which AC voltage B and AC voltage N A are connected. If the vibration caused by piezoelectric bodies 611 and 613 is referred to as A-phase vibration and the vibration caused by piezoelectric bodies 612 and 614 is referred to as B-phase vibration, a thrust vibration is excited by the difference component between the A-phase vibration and the B-phase vibration, and a feed vibration is excited by the sum component of the A-phase vibration and the B-phase vibration.

[0406] Therefore, the following description will discuss the case where the position of the protrusion 680 of the vibration actuator 600 is as shown in Figure 39B. In other words, if this is driven by the drive device of Figure 40, then contrary to the above description, (current signal IA - current signal IB) will indicate the thrust-up vibration component, and (current signal IA + current signal IB) will indicate the feed vibration component. Accordingly, the second vibration component detector 16 and the thrust-up vibration amplitude detector 17 will also use reversed signals in their operations.

[0407] In this embodiment, too, torque can be estimated based on the estimated speed, as in the above embodiment. The speed when a predetermined torque T0 is generated with respect to the phase difference between AC signals VA and VB, and the slope of the torque change with respect to the speed change are determined in advance. Figure 41A shows the phase difference between AC signals VA and VB and the speed (reference speed: V0) when the torque is a predetermined value T0, and Figure 41B shows the ratio (β) of the torque change with respect to the speed change. Then, torque TR can be calculated using Equation 55.

[0408]

[0409] [Fifth Embodiment] In the above embodiments, a control device was described that estimates speed or torque and controls speed or torque in accordance with a speed or torque command value, but in this embodiment, an example will be described in which position control is performed using an estimated value of speed or speed and torque. Figure 42A is a diagram showing a first configuration example of a drive device for a vibration actuator 600 according to a fifth embodiment of the present invention. Figure 42A shows an example in which minor loop control of speed is applied to position control, and instead of detecting speed from differential information of the detected position, speed control is performed using an estimated value of speed according to the present invention.

[0410] The same components as those shown in Figure 40 are given the same reference numerals, and detailed description thereof will be omitted. Reference numeral 72 denotes a rotary encoder for detecting the rotational position of the vibration actuator 600. The position detected by the rotary encoder 72 is compared with a position command from a command means (not shown) by a comparison means 73. The position deviation is then input to a control amount calculation means 74, which generates a speed command signal.

[0411] Next, the speed command signal and the estimated speed from the speed estimator 18 are compared by a comparator 19. The comparison result is used by a control amount calculator 20 to generate a phase difference command signal through PI (proportional integral) calculation. In this way, the phase difference between the AC signals VA and VB output by the AC signal generator 15 is controlled, thereby controlling the speed and position.

[0412] The speed estimated by the speed estimation unit 18 is detected from the vibration amplitude of the vibrating body 605, and therefore can be detected quickly even in a stopped state. Therefore, the speed can be estimated in a short time after the AC signal generation unit 15 is commanded to turn ON by an ON-OFF signal from a command means (not shown). Here, to explain this effect, we will explain the operation when the vibration actuator 600 is started from a stopped state due to a holding torque caused by the frictional force between the vibrating body 605 and the contact body 606 while torque is applied to the rotation shaft 607 of the vibration actuator 600 in the OFF state.

[0413] First, assume that the position command and the current position are the same and the ON-OFF signal is switched from the OFF state to the ON state. Then, because the position deviation with respect to the position command is 0, the AC signal generator 15 generates a signal with a phase difference of 0° between the AC signals VA and VB. Next, in response to the thrust vibration amplitude command, the frequency of the AC signals VA and VB approaches the resonant frequency of the vibrating body 605, and the thrust vibration amplitude approaches a predetermined amplitude. When the vibration amplitude of the vibrating body 605 reaches a certain level, the reduced frictional force between the vibrating body 605 and the contact body 606 falls below the torque applied to the rotating shaft 607, and the rotating shaft 607 begins to rotate. Here, the position is controlled according to the position deviation and the estimated speed value, and the rotation returns to the position at startup.

[0414] If this operation were performed using PID control of the position, the amount of deviation from the initial position would be large because there would be a time delay before the position deviation is detected due to the influence of the rigidity between the rotary encoder 72 and the contact body 606 and the resolution of the rotary encoder 72. In contrast, if a speed estimate is used, the speed can be detected without being influenced by the rigidity between the rotary encoder 72 and the contact body 606 or the resolution of the rotary encoder 72, so it is possible to reduce the amount of deviation from the initial position.

[0415] 42A, the speed command is generated by the control amount calculation unit 74. On the other hand, a torque command may be generated and the torque may be calculated from information obtained by subtracting the reference speed from the estimated speed as described in the above embodiment and multiplying the result by the ratio (β) of the torque change to the speed change, thereby controlling the torque.

[0416] FIG. 42B is a diagram showing a second configuration example of a driving device for a vibration actuator 600 according to a fifth embodiment of the present invention. Components similar to those shown in FIG. 42A are assigned the same reference numerals, and detailed descriptions thereof will be omitted. Reference numeral 75 denotes a speed & torque estimator that receives input of the detected second vibration component superimposed on the vibrating body 605 and a component corresponding to the vibration amplitude in the direction in which the vibrating body 605 thrusts up against the contact body 606, and estimates the rotational speed of the contact body 606 and the torque between the vibrating body 605 and the contact body 606. Reference numeral 76 denotes a control variable calculator that receives input of a comparison result between the speed command signal, the estimated speed from the speed & torque estimator 75, and the speed command signal from the control variable calculator 74, performs PI (proportional integral) calculations, and generates a torque command signal. Reference numeral 77 denotes a comparator that compares the torque command signal with the estimated torque from the speed & torque estimator 75, and the comparison result is input to the control variable calculator 20, which performs PI (proportional integral) calculations to generate a phase difference command signal.

[0417] The configuration of Fig. 42B has an additional torque control loop compared to the configuration of Fig. 42A, and therefore allows for even faster control than the configuration of Fig. 42A. In other words, considering the state at startup described above, the magnitude of the torque applied to the outside can be detected when the speed changes slightly, allowing for faster control than with just a speed control loop.

[0418] 43A to 43C are diagrams showing an example of the schematic configuration of a vibration actuator 700. Also, Figures 44A to 44C are diagrams showing the vibration modes of the vibration actuator 700. The schematic configuration and operating principle of the vibration actuator 700 according to the sixth embodiment will be described below with reference to Figures 43A to 43C and 44A to 44C.

[0419] As shown in FIG. 43B , the vibration actuator 700 according to the sixth embodiment includes a vibrating body 705 and a contact body 706. As shown in FIG. 43A , the vibrating body 705 is a cylindrical vibrating body made of a conductive material, and is composed of piezoelectric bodies 703 and 704 and an elastic body 701 that sandwiches the piezoelectric bodies from above and below and has a protrusion 780 on the top of the cylinder. Furthermore, as shown in FIG. 44C , the piezoelectric body 704 generates vibrations (stretching vibration mode) that expand and contract the vibrating body 705 in the height direction of the cylinder. Furthermore, as shown in FIGS. 44A and 44B , the piezoelectric body 703 generates two bending vibrations that cause the vibrating body 705 to bend in two orthogonal directions. Furthermore, the piezoelectric bodies 703 and 704 are sandwiched and fixed between the elastic body 701 by a fastening member (not shown).

[0420] The contactor 706 shown in FIG. 43B is a plate-like movable body that is pressed into contact with the protrusion 780 of the vibrating body 705 with a constant pressure by a pressure mechanism (not shown) and is supported so as to be movable in the direction of the arrow (X direction) and the depth direction (Y direction) of the drawing. This contactor 706 can move in any direction in the XY plane by vibrations excited in the vibrating body 705. FIG. 43C shows the arrangement of electrodes provided on the piezoelectric body 703, which are insulated from each other. The electrodes are arranged in four parts of a circle, with electrodes 711 and 713 for exciting bending vibrations in the X direction in the vibrating body 705, and electrodes 712 and 714 for exciting bending vibrations in the Y direction. In the following explanation, electrodes 711, 712, 713, and 714 will be referred to as piezoelectric bodies 711, 712, 713, and 714.

[0421] FIG. 45A is a diagram showing a first configuration example of a drive device for a vibration-type actuator 700 according to the sixth embodiment, and shows the configuration of a control device that controls the position of a contact body 706 in the XY plane.

[0422] Reference numeral 78 denotes an AC voltage generator that outputs AC signals VA, VBX, and VBY based on a frequency command from control calculation unit 71, a VBX voltage amplitude command output from control amount calculation unit 20, and a VBY voltage amplitude command from control calculation unit 86. The AC signals VA and VBX, and the AC signals VA and VBY, are signals that are 90° out of phase with each other, with the AC signal VA set to a predetermined amplitude and the AC signals VBX and VBY set to amplitudes based on the VBX voltage amplitude command and the VBY voltage amplitude command, respectively. Furthermore, when the VBX voltage amplitude command and the VBY voltage amplitude command are negative values, the AC signals VBX and VBY are output with their polarities inverted.

[0423] The AC signal VA is connected to the primary winding of the transformer 7, with the other end connected to a current detection resistor 9, and the boosted AC voltage A is applied to the piezoelectric element 704 of the vibration actuator 700, which is connected to the secondary winding. The AC signals VBX and VBY are connected to the primary windings of the transformers 43 and 44, with the other ends connected to current detection resistors 45 and 46, respectively. An AC voltage VBX that is inverted in phase with the boosted AC voltage BX is applied to the piezoelectric elements 711 and 713, which are connected to the secondary winding of the transformer 43. Similarly, an AC voltage VBY that is inverted in phase with the boosted AC voltage BY is applied to the piezoelectric elements 712 and 714, which are connected to the secondary winding of the transformer 44.

[0424] Here, the inductance values ​​of the secondary windings of the transformers 7, 43, and 44 are frequency-matched to the damping capacitances of the piezoelectric elements 704 and 711 to 714. This allows currents to flow through the primary windings of the transformers 7, 43, and 44 that are roughly proportional to the vibration strain rates of the piezoelectric elements 704 and 711 to 714. Resistors 9, 45, and 46 convert the currents flowing through the primary windings of the connected transformers into voltages, thereby generating current signals IA, IBX, and IBY.

[0425] Each current signal indicates a different vibration state, with current signal IA (first detection signal) indicating the expansion / contraction vibration mode (thrust-up vibration mode) of vibrating body 704. Furthermore, current signal IBX (second detection signal (X)) indicates the bending vibration mode in the X direction (X-direction feed vibration mode) of vibrating bodies 711 and 713, and current signal IBY (second detection signal (Y)) indicates the bending vibration mode in the Y direction (Y-direction feed vibration mode) of vibrating bodies 712 and 714.

[0426] Next, the configuration related to velocity estimation and control will be described. The thrust-up vibration amplitude detection unit 17 receives the current signal IA to detect the thrust-up vibration amplitude. The second vibration component detection unit 16 and the second vibration component detection unit 79 receive the current signals IBX and IBY to detect the X- and Y-direction components of the second vibration component, respectively. The velocity estimation unit 80 receives the X- and Y-direction components of the detected second vibration component, the vibration amplitude of the stretching vibration mode (thrust-up vibration mode) of the vibrating body 704, and the VBX voltage amplitude command and VBY voltage amplitude command values. Based on these inputs, the velocity estimation unit 80 detects the velocity in the X direction (estimated X velocity) and the velocity in the Y direction (estimated Y velocity).

[0427] The detected estimated X and Y velocities are integrated by integrating means 81 and 82 and converted into X and Y positions, respectively. The X and Y positions indicate changes (displacements) from the initial values ​​of integrating means 82. The X and Y positions are then compared with X and Y position commands from command means (not shown) by comparing means 73 and 83, respectively, and X and Y velocity commands are generated by control amount calculating units 74 and 84 in accordance with the respective comparison results. Next, the X and Y velocity commands are compared with the estimated X and Y velocities by comparing means 19 and 85, respectively, and VBX and VBY voltage amplitude commands are generated by control amount calculating units 20 and 86 in accordance with the respective comparison results. The positions of contact body 706 in the X and Y directions are controlled by the control device operating in this manner.

[0428] Furthermore, the integrating means 81 and integrating means 82 can reset errors accumulated due to integration errors by externally inputting an X reset signal and a Y reset signal, respectively.

[0429] FIG. 45B is a diagram showing a second configuration example of the driving device for the vibration type actuator 700 according to the sixth embodiment, which is a configuration obtained by removing the minor speed loop control system from the configuration of FIG. 45A.

[0430] The control amount calculation unit 74 and the control amount calculation unit 84 perform PID control calculations to generate a VBX voltage amplitude command and a VBY voltage amplitude command.

[0431] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0432] This application claims priority based on Japanese Patent Application No. 2023-139406, filed on August 30, 2023, the entire contents of which are incorporated herein by reference.

[0433] 100, 200, 300, 400, 500, 600, 700 Vibration type actuator 5, 205, 305, 405, 501, 502, 503, 605, 705 Vibration body 6, 206, 306, 406, 506, 606, 706 Contact body 80, 280, 380, 480, 580, 680, 780 Protrusion 15, 78 AC signal generation unit 16, 79 Second vibration component detection unit 17 Push-up vibration amplitude detection unit 18, 80 Speed ​​estimation unit 75 Speed ​​& torque estimation unit 19, 70, 73, 77, 83, 85 Comparison means 20, 71, 74, 76, 84, 86 Control amount calculation means 3, 4, 203, 204, 303, 304, 403, 404, 504 to 509, 611 to 614, 703, 704, 711 to 714 Piezoelectric body 9, 10, 45, 46 Resistor 7, 8, 43, 44, 61 to 65 Transformer 34 CPU 50, 52 Filter

Claims

1. A control device for a vibration type actuator having a vibrating body equipped with an elastic body and an electro-mechanical energy conversion element, and a contact body in contact with the elastic body, wherein the vibrating body and the contact body move relatively in a predetermined movement direction due to vibration of the vibrating body, the vibration including a first vibration component generated in the vibrating body by a voltage applied to the electro-mechanical energy conversion element, and a second vibration component generated in the vibrating body by contact of the contact body with the elastic body, the control device detecting a signal corresponding to the second vibration component, and detecting the relative speed between the vibrating body and the contact body based on the signal.

2. The control device according to claim 1, characterized in that the electro-mechanical energy conversion element is configured to be applied with a first drive voltage based on a first signal and a second drive voltage based on a second signal, the first vibration component includes a drive vibration in a first direction generated based on one of the sum or difference of a third vibration component generated by the first drive voltage and a fourth vibration component generated by the second drive voltage, and a drive vibration in a second direction generated based on the other, the second vibration component includes at least one of the drive vibration in the first direction and the drive vibration in the second direction, and the signal corresponding to the second vibration component is detected based on a first detection signal that detects vibration in the same direction as the third vibration component and a second detection signal that detects vibration in the same direction as the fourth vibration component.

3. A control device according to claim 2, wherein a signal corresponding to said second vibration component is detected from the difference between the amplitude of said first detection signal and the amplitude of said second detection signal.

4. The control device according to claim 2, characterized in that the signal corresponding to the second vibration component is detected from at least one of the parameters that change depending on the tilt in a Lissajous figure drawn using the first detection signal and the second detection signal, namely, the tilt angle, the minor axis, the major axis, and the height.

5. A control device according to claim 4, wherein said Lissajous figure is drawn with a first axis corresponding to said first detection signal and a second axis corresponding to said second detection signal.

6. The control device according to claim 4, wherein said Lissajous figure is drawn with a first axis being the sum signal of said first detection signal and said second detection signal, and a second axis being the difference signal of said first detection signal and said second detection signal.

7. The control device according to claim 2, characterized in that a vector based on the amplitude and phase of the first detection signal is defined as a first signal vector, a vector based on the amplitude and phase of the second detection signal is defined as a second signal vector, either the sum or the difference of the first signal vector and the second signal vector is defined as a first vibration vector and the other is defined as a second vibration vector, a vector component in the same direction as the first vibration vector is defined as a same direction component, and a vector component in the normal direction of the first vibration vector is defined as a normal direction component, and a signal corresponding to the second vibration component is detected from a ratio set according to a difference between the same direction components of the first signal vector and the second signal vector and a difference between the normal direction components of the first signal vector and the second signal vector, and a magnitude of the first vibration vector.

8. The control device according to claim 2, characterized in that the first detection signal is a first signal vector, the second detection signal is a second signal vector, either the sum or the difference of the first signal vector and the second signal vector is a first vibration vector and the other is a second vibration vector, a vector component in the same direction as the first vibration vector is a same direction component, and a vector component in the normal direction of the first vibration vector is a normal direction component, and a signal corresponding to the second vibration component is detected from a ratio set according to the magnitude of the first vibration vector between the same direction component of the second vibration vector and the normal direction component of the second vibration vector.

9. A control device as described in claim 2, characterized in that one of the sum signal or difference signal of the first detection signal and the second detection signal is used as a reference signal and the other is used as a measurement target signal, the phase of the reference signal is used as a reference phase, and a signal corresponding to the second vibration component is detected by integrating the measurement target signal in a phase interval set relatively to the reference phase.

10. A control device as described in claim 2, characterized in that one of the sum signal or difference signal of the first detection signal and the second detection signal is used as a reference signal and the other is used as a measurement target signal, the phase of the reference signal is used as a reference phase, and the measurement target signal is synchronously detected with a reference signal generated with a phase difference set relatively to the reference phase, thereby detecting a signal corresponding to the second vibration component.

11. A control device as described in claim 2, characterized in that a first comparison signal corresponding to the first detection signal and a second comparison signal corresponding to the second detection signal are generated based on at least one of the amplitude, phase difference, and frequency of the voltages based on the first signal and the second signal, and a signal corresponding to the second vibration component is detected from the difference between the first detection signal and the first comparison signal and the difference between the second detection signal and the second comparison signal.

12. A control device as described in claim 2, characterized in that it generates either a first comparison signal corresponding to the sum of the first detection signal and the second detection signal, or a second comparison signal corresponding to the difference between the first detection signal and the second detection signal, based on at least one of the amplitude, phase difference, and frequency of the voltage based on the first signal and the second signal, and detects a signal corresponding to the second vibration component from the difference between the sum of the first detection signal and the second detection signal and the first comparison signal, or the difference between the difference between the first detection signal and the second detection signal and the second comparison signal.

13. A control device as described in any one of claims 2 to 12, characterized in that the relative velocity is detected based on a signal corresponding to the second vibration component, the amplitude of the sum or the amplitude of the difference between the first detection signal and the second detection signal, and the phase difference or amplitude between the first signal and the second signal or the first drive voltage and the second drive voltage.

14. A control device as described in any one of claims 2 to 12, characterized in that the vibrating body has a first natural vibration and a second natural vibration, and excites the first natural vibration in response to one of the sum or difference of the first driving voltage and the second driving voltage, and excites the second natural vibration in response to the other.

15. The control device according to claim 1, characterized in that the electro-mechanical energy conversion element is configured to receive a first drive voltage based on a first signal and a second drive voltage based on a second signal, the first vibration component includes a drive vibration in a first direction generated based on the first drive voltage and a drive vibration in a second direction generated based on the second drive voltage, and the second vibration component includes a vibration component in at least one of the first direction and the second direction, and a signal corresponding to the second vibration component is detected from a first detection signal that detects a vibration component in the same direction as the drive vibration in the first direction including the drive vibration in the first direction, and a second detection signal that detects a vibration component in the same direction as the drive vibration in the second direction including the drive vibration in the second direction.

16. A control device as claimed in claim 15, characterized in that a signal corresponding to the second vibration component is detected from the difference between the amplitude of the sum of the first detection signal and the second detection signal and the amplitude of the difference between the first detection signal and the second detection signal.

17. The control device according to claim 15, characterized in that the signal corresponding to the second vibration component is detected from at least one of the parameters that change depending on the tilt, the tilt angle, the minor axis, the major axis, the height, and the width, in a Lissajous figure drawn using the first detection signal and the second detection signal.

18. The control device according to claim 17, wherein said Lissajous figure is drawn with a first axis corresponding to said first detection signal and a second axis corresponding to said second detection signal.

19. The control device according to claim 17, wherein the Lissajous figure is drawn with a first axis being a sum signal of the first detection signal and the second detection signal, and a second axis being a difference signal of the first detection signal and the second detection signal.

20. The control device as described in claim 15, characterized in that a vector based on the amplitude and phase of the first detection signal is defined as a first vibration vector, a vector based on the amplitude and phase of the second detection signal is defined as a second vibration vector, a vector component in the same direction as the first vibration vector is defined as a same direction component, and a vector component in the normal direction of the first vibration vector is defined as a normal direction component, and a signal corresponding to the second vibration component is detected from a ratio set according to the magnitude of the first vibration vector between the same direction component of the second vibration vector and the normal direction component of the second vibration vector.

21. The control device as described in claim 15, characterized in that a vector based on the amplitude and phase of the first detection signal is defined as a first vibration vector, a vector based on the amplitude and phase of the second detection signal is defined as a second vibration vector, a vector component in the same direction as the first vibration vector is defined as a same direction component, and a vector component in the normal direction of the first vibration vector is defined as a normal direction component, and a signal corresponding to the second vibration component is detected from a ratio set according to the magnitude of the first vibration vector: the difference between the same direction component of the sum of the first vibration vector and the second vibration vector and the same direction component of the difference between the first vibration vector and the second vibration vector, the difference between the normal direction component of the sum of the first vibration vector and the second vibration vector and the normal direction component of the difference between the first vibration vector and the second vibration vector.

22. A control device as described in claim 15, characterized in that one of the first detection signal and the second detection signal is used as a reference signal and the other is used as a measurement target signal, the phase of the reference signal is used as a reference phase, and a signal corresponding to the second vibration component is detected by integrating the measurement target signal in a phase interval set relatively to the reference phase.

23. A control device as described in claim 15, characterized in that one of the first detection signal and the second detection signal is used as a reference signal and the other is used as a signal to be measured, the phase of the reference signal is used as a reference phase, and the signal to be measured is synchronously detected with a reference signal generated with a phase difference set relatively to the reference phase, thereby detecting a signal corresponding to the second vibration component.

24. A control device as described in claim 15, characterized in that it generates either a first comparison signal corresponding to the first detection signal or a second comparison signal corresponding to the second detection signal based on the amplitude, phase difference and frequency of the voltages based on the first signal and the second signal, and detects a signal corresponding to the second vibration component from the difference between the first detection signal and the first comparison signal or the difference between the second detection signal and the second comparison signal.

25. A control device as described in any one of claims 15 to 24, characterized in that the relative velocity is detected based on a signal corresponding to the second vibration component, the amplitude of the first detection signal, and the amplitude or phase difference between the first signal and the second signal or the first drive voltage and the second drive voltage.

26. A control device as described in any one of claims 2 to 12 and 15 to 24, characterized in that the relative velocity is detected based on a signal corresponding to the second vibration component and the frequency, amplitude and phase difference of the first signal and the second signal or the first drive voltage and the second drive voltage.

27. A control device as described in any one of claims 2 to 12 and 15 to 24, characterized in that the first vibration component consists of a driving vibration in the first direction in which the elastic body vibrates in a direction perpendicular to the contact surface at the contact surface between the elastic body and the contact body, and a driving vibration in the second direction in which the elastic body vibrates in the direction of relative movement between the elastic body and the contact body at the contact surface, and the second vibration component consists of a vibration component in the same direction as the driving vibration in the first direction and a vibration component in the same direction as the driving vibration in the second direction.

28. A control device as claimed in any one of claims 15 to 24, characterized in that the vibrating body has a first natural vibration and a second natural vibration, and the first driving voltage excites the first natural vibration and the second driving voltage excites the second natural vibration.

29. A control device as described in any one of claims 2 to 12 and 15 to 24, characterized in that the vibrating body is annular and has a first electrode segment and a second electrode segment provided at different positions of the electromechanical energy conversion element.

30. A control device as described in any one of claims 2 to 12 and 15 to 24, characterized in that the vibrating bodies are a plurality of independent vibrating bodies, the electro-mechanical energy conversion elements provided on each of the plurality of vibrating bodies are electrically connected in series, and the first drive voltage and the second drive voltage are applied to both ends of the electro-mechanical energy conversion elements connected in series.

31. A control device according to any one of claims 2 to 12 and 15 to 24, characterized in that the first and second detection signals are signals according to the output of an electro-mechanical energy conversion element.

32. A control device as described in any one of claims 2 to 12 and 15 to 24, characterized in that the first and second detection signals are signals corresponding to the currents flowing due to the first drive voltage and the second drive voltage.

33. The control device according to claim 32, wherein the signal corresponding to the current is a signal corresponding to a mechanical arm current proportional to the vibration velocity of the vibrating body.

34. A control device according to any one of claims 2 to 12 and 15 to 24, wherein the signal corresponding to the second vibration component varies with the relative velocity.

35. A control device as claimed in any one of claims 2 to 12 and 15 to 24, characterized in that the amplitude of the driving vibration in the first direction is controlled by setting the frequency or amplitude of a first signal and a second signal which are independent of each other.

36. The control device according to claim 1, further comprising a control circuit for detecting a force acting between said vibrating body and said contact body based on a predetermined reference value of the speed and said speed.

37. The control device according to claim 1, further comprising a step of detecting a displacement between the vibrating body and the contact body based on an integral value of the velocity.

38. The control device according to claim 1, further comprising a controller for controlling said vibration type actuator based on a speed command signal and said detected speed.

39. The control system of claim 36, further comprising: a force command signal and a controller for controlling said vibration actuator based on said detected force.

40. A control device according to claim 37, which controls said vibration type actuator based on a displacement command signal and said detected displacement.

41. The control device according to claim 38, further comprising a position detection means for detecting the position of the contact body, and generating the speed command signal based on a position command signal and the detected position.

42. A vibration actuator comprising an elastic body, a vibrating body having an electromechanical energy conversion element, and a contact body in contact with the elastic body, and a control device according to any one of claims 1 to 12 and 15 to 24, wherein the vibration of the vibrating body causes the vibrating body and the contact body to move relatively in a predetermined movement direction.

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