Vibration type drive device

Abstract

To solve the problem in the case where vibration amplitude detection means of a vibrator is used in place of a speed sensor in speed control of a vibration type actuator, the speed detection accuracy when a direction of movement is inverted or while being loaded is low in conventional methods.SOLUTION: A vibration type drive device is a vibration type actuator comprising a vibrator including an elastic body and an electrical-mechanical energy conversion element and a contact body in contact with the elastic body and in which the vibrator and the contact body are moved relatively in predetermined movement directions by the vibration of the vibrator. The vibration includes: a first vibration component which is generated in the vibrator by a voltage applied to the electrical-mechanical energy conversion element; and a second vibration component which is generated in the vibrator by the contact of the contact body and the elastic body. A signal corresponding to the second vibration component is detected, and relative speeds of the vibrator and the contact body are detected from the signal.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] The moving speed of a contact body driven by the vibration of a vibrating body of a vibration actuator is approximately proportional to the vibration amplitude of the vibrating body under no load. Therefore, 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. However, when an external force acts on the moving object, the speed cannot be detected with high accuracy.

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

[0005] [Patent Document 1] Patent No. 3191406 Summary of the Invention [Problem to be solved by the invention]

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

[0007] The control device of the present invention is a control device for a vibration type actuator having a vibrator having an elastic body and an electromechanical energy conversion element, and a contact body in contact with the elastic body, in which the vibrator and the contact body move relatively in a predetermined moving direction due to vibration of the vibrator, The vibration is a first vibration component generated in the vibrating body by a voltage applied to the electromechanical energy conversion element; 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 velocity between the vibrating body and the contact body based on the signal. Effect of the Invention

[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. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a vibration actuator according to a first embodiment and a first example of a vibration shape; [Diagram 2] FIG. 1 is a diagram showing a first example of the configuration of a drive device for a vibration actuator according to a first embodiment; [Diagram 3] Schematic diagram showing the relationship between the relative speed between the vibrating body and the contact body and the vibration locus of the vibrating body [Figure 4] FIG. 1 is a diagram illustrating a first and a second example of detecting a second vibration component according to a first embodiment; [Diagram 5] FIG. 11 is a diagram showing the relationship between the speed and the inclination of the vibration ellipse according to the first embodiment. [Figure 6] FIG. 13 is a diagram showing the relationship between speed and (amplitude of current signal IA-amplitude of current signal IB) in the first embodiment; [Figure 7] FIG. 11 is a diagram for explaining a fourth example of detecting a second vibration component according to the first embodiment; [Figure 8]FIG. 1 is a diagram for explaining a method for determining the magnitude of a vector of a component in the same direction as the thrust vibration direction and a component in the normal direction from a vibration waveform according to the first embodiment. [Figure 9] FIG. 11 is a diagram for explaining a fifth example of detecting a second vibration component according to the first embodiment; [Figure 10] FIG. 13 is a diagram for explaining sixth and seventh examples of detecting a second vibration component according to the first embodiment; [Figure 11] FIG. 1 is a diagram showing a second example of the configuration of an equivalent circuit model of a drive circuit and a vibrator according to a first embodiment, and a drive device for a vibration type actuator using the same; [Figure 12] FIG. 11 is a diagram for explaining a third example of the configuration of the driving device for the vibration actuator according to the first embodiment and the function of a current signal generating unit 51 used therein. [Figure 13] FIG. 11 is a diagram showing a correction coefficient for calculating a velocity from a second vibration component S according to the first embodiment and a result of estimating the velocity. [Figure 14] 13A and 13B are diagrams showing fourth and fifth examples of the configuration of the driving device of the vibration actuator according to the first embodiment; [Figure 15] FIG. 1 is a flow chart showing the speed control operation executed by the CPU 34 according to the first embodiment. [Figure 16] FIG. 11 is a flowchart showing the operation of controlling the thrust vibration amplitude executed by the CPU 34 according to the first embodiment. [Figure 17] FIG. 13 is a diagram showing a sixth example of the configuration of the driving device of the vibration actuator according to the first embodiment; [Figure 18] FIG. 1 is a diagram showing a second example of a schematic configuration and a vibration shape of a vibration actuator according to a first embodiment; [Figure 19] FIG. 11 is a diagram showing a third example of a schematic configuration and a vibration shape of a vibration actuator according to a first embodiment; [Figure 20] FIG. 1 is a diagram showing a ratio (β) of a thrust change to a reference speed and a speed change according to a first embodiment; [Figure 21] FIG. 13 is a diagram showing a seventh example of the configuration of the driving device of the vibration actuator according to the first embodiment; [Figure 22]FIG. 10 is a diagram showing an example of an AC signal waveform and a VB voltage amplitude command waveform according to the first embodiment; [Figure 23] FIG. 1 is a diagram showing a first example of a schematic configuration of a vibration actuator according to a second embodiment; [Figure 24] FIG. 13 is a diagram showing a first example of the configuration of a driving device for a vibration actuator according to a second embodiment; [Diagram 25] FIG. 13 is a diagram for explaining a first and a second example of detecting a second vibration component according to the second embodiment; [Figure 26] FIG. 13 is a diagram for explaining a third example of detecting a second vibration component according to the second embodiment; [Figure 27] FIG. 11 is a diagram for explaining a method for determining the magnitude of a vector of a component in the same direction as the thrust vibration direction and a component in the normal direction from a vibration waveform according to the second embodiment. [Figure 28] FIG. 13 is a diagram for explaining a fourth example of detecting a second vibration component according to the second embodiment; [Figure 29] FIG. 13 is a diagram for explaining fifth and sixth examples of detecting a second vibration component according to the second embodiment. [Diagram 30] FIG. 13 is a diagram showing a second example of the configuration of an equivalent circuit model of a drive circuit and a vibrator according to a second embodiment, and a drive device for a vibration actuator using the same; [Diagram 31] FIG. 11 is a diagram showing a correction coefficient for calculating a velocity from a second vibration component S according to the second embodiment. [Diagram 32] FIG. 13 is a diagram showing a third example of the configuration of a driving device for a vibration actuator according to a second embodiment; [Diagram 33] FIG. 11 is a flow chart showing the speed control operation executed by the CPU 34 according to the second embodiment. [Diagram 34] FIG. 13 is a diagram showing a ratio (β) of a torque change to a reference speed and a speed change according to a second embodiment. [Diagram 35] FIG. 13 is a diagram showing an example of a schematic configuration of a vibration actuator according to a third embodiment; [Diagram 36] FIG. 13 is a diagram showing a configuration example of a driving device for a vibration actuator according to a third embodiment; [Figure 37]FIG. 13 is a diagram showing a schematic configuration of a vibration actuator according to a fourth embodiment, a first example of electrical connections of piezoelectric electrodes, and a positional relationship between a protruding structure of a vibrating body and a piezoelectric body; [Figure 38] 13A and 13B are diagrams showing first and second examples of the configuration of a driving device for a vibration actuator according to a fourth embodiment; [Figure 39] 13A and 13B are diagrams showing second and third examples of the positional relationship between the protrusion structure provided on the vibrating body of the vibration actuator according to the fourth embodiment and the piezoelectric body; [Diagram 40] FIG. 13 is a diagram showing a third example of the configuration of a driving device for a vibration actuator according to a fourth embodiment; [Diagram 41] FIG. 13 is a diagram showing a ratio (β) of a torque change to a reference speed and a speed change according to a fourth embodiment. [Diagram 42] 13A and 13B are diagrams showing first and second examples of the configuration of a driving device for a vibration actuator according to a fifth embodiment; [Diagram 43] FIG. 13 is a diagram showing an example of a schematic configuration of a vibration actuator according to a sixth embodiment; [Diagram 44] FIG. 13 is a diagram showing vibration modes of a vibration actuator according to a sixth embodiment. [Diagram 45] 13A and 13B are diagrams showing first and second examples of the configuration of a driving device for a vibration actuator according to a sixth embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A vibratory drive device for implementing the present invention includes the following:

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

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

[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] The following will explain this in detail with reference to the drawings.

[0015] [First Example] 1 is a diagram 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 operation principle of the vibration actuator 100 according to the first embodiment will be described with reference to FIG.

[0016] As shown in Fig. 1(e), 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. 1(a) and Fig. 1(e), the vibrating body 5 is configured to have a piezoelectric element 2 and an elastic body 1 having two protrusions 80 that contact the contact body 6. The piezoelectric element 2 forms a part of the vibrating body 5 and is a component for exciting the vibrating body 5.

[0017] In addition, 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 a voltage can be applied independently, as shown in Fig. 1(b). Piezoelectric ceramics can be used as the piezoelectric material.

[0018] These two electrodes are electrically insulated from each other, and two AC voltages that can change phases 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 front 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 are sometimes referred to as the piezoelectric body 3. The same is true for the piezoelectric body 4.

[0019] 1(e) 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 by vibration excited in the vibrating body 5.

[0020] 1(c) and 1(d) are diagrams showing examples of vibration modes of the vibrating body 5. FIG. 1(c) 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 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] 1(d) shows the vibration shape of a vibration mode (feeding vibration mode) excited in the vibrating body 5 when AC voltages of the same amplitude and opposite phase are applied to the piezoelectric bodies 3 and 4. 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 and approximately coincides with the direction of the movement at the contact surface between the vibrating body 5 and the contact body 6.

[0022] As an example, when the phase difference between the AC voltages applied to the piezoelectric bodies 3 and 4 is 0°, vibration is excited in the vibration mode (thrust-up vibration mode) shown in Fig. 1(c). When the phase difference between the AC voltages applied to the piezoelectric bodies 3 and 4 is 180°, vibration is excited in the vibration mode (feed vibration mode) shown in Fig. 1(d).

[0023] Furthermore, when the phase difference of 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 about 0° to ±120° is used), both vibration modes shown in Fig. 1(c) and Fig. 1(d) 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 Fig. 1(d) becomes larger, and the relative speed between the contact body 6 (slider) and the vibrating body 5 increases.

[0024] 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 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 application of an AC voltage to the piezoelectric bodies 3 and 4 that constitute the vibrating body 5 is defined 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 defined as a second vibration component.

[0025] 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.

[0026] In the following, the sum or difference of the third vibration component generated by the first driving voltage and the fourth vibration component generated by the second driving voltage may be described. In this case, the driving vibration in the first direction generated based on one of the sum or difference, and the driving vibration in the second direction generated based on the other may be described. The direction of the driving vibration here means the direction in which the vibrator vibrates at the contact surface between the vibrator and the contact body when the driving vibration is generated, and the same applies to the direction of the natural vibration and the direction when the vibration component in the same direction is expressed.

[0027] Moreover, 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 with no other member interposed between the contact body and the vibrating body. The contact between the contact body and the vibrating body may be indirect contact with another member 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 be a surface-treated portion formed on the contact body or the vibrating body by plating, nitriding, or the like.

[0028] In addition, the term "oscillating body" 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.

[0029] 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 generator of an AC voltage applied to the vibration actuator 100, a speed estimation unit of the vibration actuator 100, and a part related to speed control. First, the generator of the AC voltage will be described. The AC signal generator 15 generates two-phase AC signals VA (first signal) and VB (second signal) based on a frequency command and an ON-OFF command from a command means (not shown) and a phase difference command output from a control amount calculation unit 20 (described later). 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. Here, in this example, an example is shown in which the transformers 7 and 8 are connected via a series resonant circuit in order to shape the waveform and suppress changes in the voltage amplitude to the piezoelectric bodies 3 and 4, but it is also possible to connect only one of the inductors and the capacitor, or to not connect the series resonant circuit. The voltage input to the primary windings of the transformers 7 and 8 is 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, which are connected to the secondary windings. Note that, as described above, although this notation is used for the purpose of explaining the electric circuit, the piezoelectric bodies 3 and 4 are actually part of the integrated piezoelectric element 2.

[0030] Moreover, the inductor value of the secondary windings of the transformers 7 and 8 is frequency-matched to the damping capacitance of the piezoelectric bodies 3 and 4. This allows a current that is roughly proportional to the vibration speed of the strain generated in the piezoelectric bodies 3 and 4 to flow through the primary windings of the transformers 7 and 8.

[0031] Current detection resistors 9 and 10 are connected in series to the primary windings of the transformers 7 and 8, and detect the current flowing through the primary windings of the transformers to generate a first detection signal, a current signal IA, and a second detection signal, a current signal IB. The relationship between the current signals IA and IB and the vibration of the vibrating body 5 will be described separately.

[0032] Next, a 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 and detect the second vibration component and the component corresponding to the thrust vibration amplitude.

[0033] Here, when the waveforms of the current signals IA and IB contain many harmonics, the harmonic components may be sufficiently attenuated by 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.

[0034] 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.

[0035] The detected second vibration component and a component corresponding to the vibration amplitude in the direction in which the vibrator 5 pushes up the contact body 6 (slider) are input to a speed estimation unit 18, and the speed is estimated 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 separately.

[0036] Next, the operation of the speed control section will be described. First, the estimated speed VS from the speed estimation section 18 is compared with a speed command from a command means (not shown) by the comparison means 19. Next, the comparison result of the comparison means 19 is proportional-integral calculated by the control amount calculation section 20 to generate a phase difference command signal. Then, the phase difference between the AC signal VA and the AC signal VB is set, and the speed is controlled depending on the magnitude of the amplitude of the feed direction vibration excited in the vibrating body 5.

[0037] Here, the relationship between the current signals IA and IB and the vibration of the vibrating body 5 will be described. As described above, the piezoelectric bodies 3 and 4 correspond to the electrodes 3 and 4 provided on the piezoelectric element 2 constituting 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.

[0038] 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 an 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).

[0039] Similarly, the current signal IB is a signal corresponding to the vibration velocity of the part of the elastic body 1 where the section to which the electrode 4 is attached is projected (that is, the piezoelectric body 4).

[0040] In addition, the current signal IA mainly contains a vibration component in the same direction as the third vibration component, and the 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 the piezoelectric body 3 alone is the third vibration component, and the vibration component due to the piezoelectric excitation force generated by the piezoelectric body 4 alone is the fourth vibration component.

[0041] The second vibration component detection section 16 detects the second vibration component using the two detected signals, the current signal IA and the current signal IB.

[0042] Next, there will be described detection of the thrust-up vibration amplitude performed by the thrust-up vibration amplitude detection unit 17. The thrust-up vibration corresponds to a component in a direction perpendicular to the plate of the plate-shaped vibrating body 5.

[0043] 1(c), 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.

[0044] 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 is treated as a signal corresponding to the displacement of piezoelectric body 3, and current signal IB is 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 is described as the thrust vibration amplitude.

[0045] Now, the principle of speed estimation will be explained. Figure 3 is a diagram showing 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 speed acting between the vibration body 5 and the contact body 6 (slider) through the protrusion 80. All vibration loci in Figure 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°. Figures 3(a) to 3(e) show vibration loci when the speed between the vibration body 5 and the contact body 6 (slider) is changed from -0.2 [rps] to 0.6 [rps] by a force applied from the outside to the contact body 6 (slider). The direction of the arrow in Figure 3 indicates the direction of the force acting on the contact body 6, and the length of the arrow indicates the magnitude of the 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 that 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.

[0046] 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 subjected to vibration due to the above-mentioned frictional force generated during intermittent contact with the contact body 6, vibration according to the above-mentioned speed difference is superimposed on the vibrating body 5.

[0047] 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 that the vibrating body 5 receives 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 speed between the vibrating body 5 and the contact body 6.

[0048] 3 are characteristics when driven under conditions where 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 those shown, but the principle of estimating the speed by detecting the second vibration component that changes with the speed remains the same.

[0049] Since the characteristics 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, etc., it is necessary to detect the second vibration component and estimate the speed according to the driving conditions.

[0050] In the following description, an example will be described in which the vibrator 5 is 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 vibrator 5.

[0051] Next, a detailed description will be given of the operation of the second vibration component detection unit 16 that detects the second vibration component, which is the vibration generated in the vibrating body 5 due to the vibration applied from the contact body 6 (slider).

[0052] There are various methods for detecting the second vibration component, one of which is to detect the inclination of the vibration ellipse as shown in Figure 3. As described above, the inclination of the vibration ellipse is highly correlated with the relative speed between the vibrating body 5 and the contact body 6 (slider), and detecting such a value is regarded as detecting a signal corresponding to the second vibration component.

[0053] Now, a first example of the second vibration component detection according to the first embodiment will be described.

[0054] 4(a) and (b) are diagrams showing a Lissajous waveform (vibration ellipse) explaining a first example of detecting the second vibration component according to the first embodiment. FIG. 4(a) 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 (thrust-up vibration mode) of FIG. 1(c), and (current signal IA-current signal IB) shows a vibration waveform corresponding to the vibration mode (feed-forward vibration mode) of FIG. 1(d). Here, assuming that the current signal IA is expressed by equation 1 and the current signal IB is expressed by equation 2,

[0055]

number

[0056]

number

[0057] The inclination angle φ1 of the vibration ellipse is given by Equation 3.

[0058]

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[0059] 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 obtain the second vibration component (the inclination angle of the vibration ellipse).

[0060] Figure 5 shows the relationship between the slope of the Lissajous waveform (vibration ellipse) and the speed, with Figure 5(a) showing an example when the thrust vibration amplitude is small, and Figure 5(b) showing an example when the thrust vibration amplitude is relatively large. The line types in Figure 5 indicate the difference in phase difference between AC signal VA and AC signal VB, and are solid line (90°), dotted line (45°), dashed line (0°), one-dot chain line (-45°), and two-dot chain line (-90°).

[0061] The relationship between the relative speed 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 obtained in advance for each thrust vibration amplitude and the phase difference between the AC signals VA and VB, the speed can be estimated by back-calculating from the inclination angle of the vibration ellipse. In addition, the larger the thrust vibration amplitude, the higher the sensitivity to the phase difference between the AC signals VA and VB, and therefore the higher the accuracy of the speed estimation.

[0062] In the above explanation, it has been explained that the change in the inclination angle φ1 of the Lissajous waveform (oscillating ellipse) is highly correlated with the speed, but the Lissajous waveform (oscillating ellipse) changes not only the inclination angle but also the width (minor axis) of the Lissajous waveform (oscillating ellipse) with respect to the change in the speed. Therefore, the value obtained by adding both the inclination angle φ1 of the oscillating ellipse and the angle φ2 between the diagonal of the circumscribing rectangle of the oscillating ellipse and the center line of the oscillating ellipse shown in Figure 4(a) at a predetermined ratio may be used as the second vibration component.

[0063] In addition, in formula 3, only the part where the value changes may be extracted to obtain formula 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.

[0064]

number

[0065] In the above example, the vertical axis of the Lissajous waveform (oscillating ellipse) is (current signal IA + current signal IB) and the horizontal axis is (current signal IA - current signal IB), but the slope of the ellipse may be found by setting the vertical axis to the current signal IA and the horizontal axis to the current signal IB. Figure 4(b) shows a Lissajous waveform (oscillating ellipse) drawn with the vertical axis being the current signal IA and the horizontal axis being the current signal IB.

[0066] In this case, the inclination angle φ3 of the vibration ellipse is expressed by Equation 5, and the angle φ3 can be used as the second vibration component.

[0067]

number

[0068] Also, the angle φ4 may be calculated as in the above example, and the value obtained by adding both the inclination angle φ3 and the angle φ4 at a predetermined ratio may be used as the second vibration component. Also, 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 the result of substituting this into an arbitrary function may be used as the second vibration component S.

[0069]

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[0070] Next, a second example of the second vibration component detection according to the first embodiment will be described.

[0071] In the first example of detecting the second vibration component according to the first embodiment, the inclination angle of the vibration ellipse is calculated using Equation 3, but the inclination angle may be calculated using other parameters of the vibration ellipse that change depending on the inclination angle of the vibration ellipse. Figures 4(c) and (d) are diagrams explaining a second example of detecting the second vibration component according to the first embodiment, and Figure 4(c) is a diagram explaining an example of detecting the second vibration component using an angle φ5 that changes depending on the inclination angle of the vibration ellipse.

[0072] In the first example of the second vibration component detection according to the first embodiment, the inclination of the axis of the vibration ellipse is used, but to obtain this, a complex calculation such as that shown in Equation 3 is required. The angle φ5 detected in this example can be directly detected from the sum signal and difference signal of the current signal IA and the current signal IB. The angle φ5 is the angle between the line connecting the positive and negative peaks of (current signal IA+current signal IB) and the vertical axis, and FIG. 4(d) is a diagram of a time-axis waveform for explaining a method of detecting the angle φ5. The solid line in FIG. 4(d) is (current signal IA+current signal IB), the dotted line is the differentiated waveform of the solid line waveform, and the dashed line is the waveform of (current signal IA-current signal IB). The angle φ5 is obtained by detecting the values ​​of PT and PB by sampling the dashed line signal at the timing of the peaks (maximum and minimum) of (current signal IA+current signal IB) and using Equation 7. The timing for detecting PT and PB may also be the timing of the zero crossing of the differentiated waveform of (current signal IA+current signal IB).

[0073]

number

[0074] The second vibration component detection unit 16 obtains the second vibration component (angle φ5) as described above.

[0075] Moreover, the second vibration component S may be expressed by the formula 8 or 9.

[0076]

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[0077]

number

[0078] As in the first example of the second vibration component detection according to the first embodiment, 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, the second vibration component S may be determined by adding the angle φ6 and the angle φ5 formed by the diagonal of the circumscribing rectangle of the vibration ellipse shown in FIG. 4(c) and the straight line indicating the angle φ5 at a predetermined ratio.

[0079] Furthermore, the parameters representing the Lissajous waveform (oscillating ellipse) can be defined as various parameters such as major axis, height, width, etc., in addition to the inclination 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 according to the inclination angle of the Lissajous waveform (oscillating ellipse).

[0080] Next, a third example of the second vibration component detection according to the first embodiment will be described.

[0081] In the first and second examples of the 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 obtained from the amplitude of the current. The second vibration component detection unit 16 in this example receives the current signals IA and IB, obtains the amplitudes of the current signals IA and IB, calculates (the amplitude of the current signal IA - the amplitude of the current signal IB), and outputs it as the second vibration component S.

[0082] Also, the second vibration component S may be determined 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).

[0083] Fig. 6 is a diagram showing the relationship with speed when (amplitude of current signal IA - amplitude of current signal IB) is the second vibration component S. Fig. 6(a) shows an example when the thrust vibration amplitude is small, and Fig. 6(b) shows an example when the thrust vibration amplitude is relatively large. The line types in Fig. 6 indicate the difference in phase difference between AC signals VA and VB, and show a solid line (90°), dotted line (45°), dashed line (0°), one-dot chain line (-45°), and two-dot chain line (-90°).

[0084] Comparing the characteristics of FIG. 6 with those of FIG. 5, 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.

[0085] As in the first example of the second vibration component according to the first embodiment, the relationship between the relative speed between the contact body 6 and the protrusion 80 and (the amplitude of the current signal IA-the amplitude of the current signal IB) is linear. Therefore, by determining in advance the offset and inclination of each line for each thrust vibration amplitude and the phase difference between the AC signals VA and VB, the speed can be easily estimated from (the amplitude of the current signal IA-the amplitude of the current signal IB).

[0086] Next, a fourth example of the second vibration component detection according to the first embodiment will be described.

[0087] This is an example of detection when a current signal is represented as a vector.

[0088] 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 the difference between 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 a 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.

[0089] Fig. 7 is a vector diagram of a current signal, and Fig. 7(a) is a diagram showing the current signal IA, the 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 as in Equation 10 and Equation 11 using vectors.

[0090]

number

[0091]

number

[0092] FIG. 7(b) is a vector diagram showing the current signal IA and the current signal IB. The current signal IA is the first signal vector, and the current signal IB is the second signal vector, and the two vectors are divided into two orthogonal vibration components. The two orthogonal vibration components are a vibration component in the same direction and a vibration component in the normal direction with respect to the (first signal vector + second signal vector) which is the thrust vibration component (first vibration vector). The difference between the thrust vibration component (first vibration vector) and the component in the same direction of the first signal vector and the second signal vector is highly correlated with the inclination of the vibration ellipse. Therefore, as shown in Equation 12, the components in the same direction with respect to the thrust vibration component (first vibration vector) for each of the first signal vector and the second signal vector can be obtained, and the difference between them can be used as the second vibration component S. Also, as shown in Equation 13, the value of Equation 12 divided by the magnitude of the thrust vibration component (first vibration vector) can be used as the second vibration component S.

[0093]

number

[0094]

number

[0095] There are also cases where a component in the normal direction is used for the upward thrust vibration component (first vibration vector) of the first signal vector (current signal IA) and the second signal vector (current signal IB). 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 for the upward thrust vibration component (first vibration vector) can be set as the second vibration component S. Also, as shown in Equation 15, the value obtained by dividing the value of Equation 14 by the magnitude of the upward thrust vibration component (first vibration vector) may be set as the second vibration component S.

[0096]

number

[0097]

number

[0098] Here, a method for calculating the second vibration component S from Equation 12 to Equation 15 will be described. Equations 12 to 15 are calculations including trigonometric functions, and also require detection of the phase difference. This makes the structure of the second vibration component detection unit 16 complicated. 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.

[0099] Figure 8 is a diagram explaining how to find the magnitude of each directional component using synchronous detection. Figure 8(a) shows the reference waveform (current signal IA + current signal IB) (solid line), 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).

[0100] 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 with the signal of the dashed line in Fig. 8(a).The dotted line in Fig. 8(b) shows the average value of the multiplication result, and indicates the magnitude of the vibration component in the same direction as the vector of (current signal IA + current signal IB).

[0101] 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 multiplication result of the signal of the dashed line in Fig. 8(a) and 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).

[0102] In this way, if synchronous detection is used to eliminate the need for calculations including trigonometric functions, it becomes easy to realize the second vibration component detection unit 16 using an FPGA or the like.

[0103] Next, a fifth example of the second vibration component detection according to the first embodiment will be described.

[0104] In the fourth example of the second vibration component in the first embodiment, the second vibration component was detected by obtaining the vectors of current signal IA and 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).

[0105] 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 in 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 inclination of the vibration ellipse. The characteristics of the values ​​shown in Equation 16 and Equation 17, which calculate the second vibration component S using the component of the second vibration vector in the same direction relative to the thrust vibration component (first vibration vector), are very similar to those of FIG. 6.

[0106]

number

[0107]

number

[0108] In addition, a component in the normal direction to the thrust vibration component (first vibration vector) of the second vibration vector may be used. As shown in Equation 18 and Equation 19, the second vibration component S may be obtained by adding the same direction component and the normal direction component to the thrust vibration component (first vibration vector) of the second vibration vector at a predetermined ratio (x:y).

[0109]

number

[0110]

number

[0111] Incidentally, like the fourth example of the second vibration component according to the first embodiment, the second vibration component S can also be obtained by using synchronous detection in this example.

[0112] Next, a sixth example of the second vibration component detection according to the first embodiment will be described.

[0113] The above example explained a method for detecting the second vibration component S corresponding to a Lissajous figure or vector display, but this example explains an example of detecting the second vibration component S by synchronous detection of the waveform on the time axis. In the above example, synchronous detection was 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.

[0114] The second vibration component is excited by the 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, so it 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 the vibration in the vibration mode (thrust-up vibration mode) shown in Figure 1(c), and the generated vibration is superimposed on the first vibration component with a phase delay that differs for each vibration mode depending on the excitation frequency. The vibration caused by the frictional force acting in the relative movement direction between the vibrating body 5 and the contact body 6 (slider) is mainly generated in the vibration mode (feed vibration mode) shown in Figure 1(d), and is superimposed on the vibration of the feed vibration mode of the first vibration component with a phase delay θs according to the response characteristics of the feed vibration mode.

[0115] 10(a) and (b) are diagrams for explaining 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. In addition, 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 (current signal IA+current signal IB) (dashed line). FIG. 10(b) is a diagram showing the detection of the component of the superimposed vibration waveform by synchronous detection.

[0116] 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 the dashed signal in Fig. 10(a) and this reference signal. 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).

[0117] Here, the superimposed vibration waveform (dotted line) in FIG. 10(a) is a vibration component generated in the vibrator 5 when the vibrator 5 is excited by the contact body 6 (slider), and cannot be detected directly because it is superimposed on the vibration when no load is applied. Therefore, the second vibration component detection unit 16 detects the vibration component containing many vibration components of this superimposed vibration waveform using synchronous detection. First, since the phase of the superimposed vibration waveform is delayed by a phase of θs from the phase of the apex of the waveform (dash-dotted line) of (current signal IA+current signal IB) in FIG. 10(a), a reference signal (solid line) shown in FIG. 10(b) is generated to extract this phase component. Note that the phase delay amount θs differs depending on the driving state, so it is 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 by synchronous detection, and the second vibration component S is obtained by multiplying it by the reference signal (solid line) in FIG. 10(b). 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).

[0118] The value of θs can be obtained 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.

[0119] In this example, the reference signal is a pulse signal, but it may be a sine wave or other waveform.

[0120] Next, a seventh example of the second vibration component detection according to the first embodiment will be described.

[0121] 10(c) and (d) are diagrams for explaining 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) at 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) on which the superimposed vibration waveform (dotted line) is superimposed.

[0122] Figure 10(d) shows the detection of the superimposed vibration waveform component by integrating the waveform (dashed line) of the superimposed (current signal IA-current signal IB) that is actually detected as a superimposed vibration waveform (dotted line) over a specified phase interval.

[0123] The solid line in Fig. 10(d) is a gate signal in which the phase section (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 section (180°±dθ) centered on phase 180° is 1, and the other phase sections are 0. The dashed line in Fig. 10(d) is the multiplication result of this gate signal by the dashed 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).

[0124] Here, the waveform (solid line) of (current signal IA-current signal IB) at no load in Fig. 10(c) can only be detected at no load. Therefore, the phase difference θX between the waveform (solid line) of (current signal IA-current signal IB) at no load and the waveform (dash 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 according to various vibration states. For example, the phase difference θX can be set according to the amplitude of (current signal IA+current signal IB) and the phase difference between AC signal VA and AC signal VB.

[0125] 10(d) as the second vibration component S. Alternatively, the second vibration component S may be a value obtained by dividing the value by the amplitude of (current signal IA+current signal IB).

[0126] Next, an eighth example of the second vibration component detection according to the first embodiment will be described.

[0127] In this example, an equivalent circuit model of the vibrator 5 and the drive circuit is used to generate (current signal IA-current signal IB) (second comparison signal) when no load is applied for the AC signal VA (first signal) and the AC signal VB (second signal). The superimposed vibration waveform is extracted by subtracting the second comparison signal from the difference between the measured current signal IA (first detection signal) and the current signal IB (second detection signal). FIG. 11(a) shows an example of a circuit of the equivalent circuit model. 50 is a filter that simulates the operation of the equivalent circuit of the vibrator 5 and the drive circuit when no load is applied. The circuit diagram in 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 body 3 and the piezoelectric body 4, and resistors 9 and 10 for current detection, and the operation of these is simulated by calculation. When the waveforms of the AC signal VA and the AC signal VB are input to the filter 50, it outputs a current signal IAS that simulates the current signal IA in real time and a current signal IBS that simulates the current signal IB.

[0128] FIG. 11(b) is a diagram showing a second configuration example of the driving device of the vibration actuator 100 according to the first embodiment of the present invention. FIG. 11(b) shows an example of detecting the second vibration component using a filter 50. The same components as those shown in FIG. 2 are given the same reference numerals, and detailed description thereof will be omitted. The AC signals VA and VB output from the AC signal generating unit 15 are input to the filter 50, which outputs a current signal IAS simulating the current signal IA when no load is present, and a current signal IBS simulating the current signal IB when no load is present. The second vibration component detecting unit 16 receives the inputs of the current signals IA, IB, and the current signals IAS, IBS. With this input, the second vibration component detecting unit 16 detects the amplitude SF of the superimposed vibration waveform by subtracting (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). 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 set to the sign of the amplitude SF of the superimposed vibration waveform, and this is output as the second vibration component S.

[0129] In the above example, the second vibration component S is 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).

[0130]

number

[0131] 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.

[0132] 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 taken as the second vibration component S. This can be expressed as a vector in Equation 21.

[0133]

number

[0134] 12(a) is a diagram for explaining 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 simulating current signals IA and IB in the no-load state, based on a frequency command from a command means (not shown) and a phase difference command from a controlled variable calculation unit 20.

[0135] Fig. 12(b) 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. 12(b) shows an example in which the second vibration component is detected using a current signal generating unit 51. The same components as those shown in Fig. 2 and Fig. 11(b) are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0136] The outputs of the filter 50 and the current signal generating unit 51 do not have to be analog signals, but may be, for example, digital waveform information or waveform information such as amplitude and phase.

[0137] Next, the operation of the speed estimation unit 18 will be described. As shown in Fig. 6, 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 thrust vibration amplitude. 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 depending on the phase difference between the AC signals VA and VB and the thrust vibration amplitude.

[0138] Fig. 13 is a diagram showing the correction coefficient for determining the speed from the second vibration component S shown in Fig. 6 and the result of estimating the speed. Fig. 13(a) is the sensitivity correction coefficient γ, and Fig. 13(b) is the offset correction coefficient ε, showing the correction coefficient for each thrust amplitude and the phase difference between the AC signal VA and the AC signal VB. The line types indicate the phase difference between the AC signal VA and the AC signal VB, and a solid line (90°), dotted line (45°), dashed line (0°), dashed line (-45°), and dashed line (-90°) are shown as representative lines. Equation 22 is an equation for estimating the speed VS from the value of the second vibration component S.

[0139]

number

[0140] In the case of the characteristic in which the value of the second vibration component S changes linearly with respect to the speed as in Figure 6, the speed 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 obtained in advance. The characteristics in Figures 13(a) and (b) may be held as a data table, but they may also be held 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.

[0141]

number

[0142]

number

[0143] 13(a) and (b) show the relationship between the phase difference between the AC signals VA and VB, the thrust vibration amplitude, and the correction coefficient, but the frequency of the AC signals VA and VB may be used instead of the thrust vibration amplitude. In that case, the sensitivity correction coefficient γ and the offset correction coefficient ε are obtained from the frequency and phase difference of the AC signals VA and VB during driving using a data table or functions T3 and T4. Equation 25 shows the function T3 of the offset correction coefficient ε, and Equation 26 shows the function T4 of the sensitivity correction coefficient γ.

[0144]

number

[0145]

number

[0146] 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.

[0147] Figures 13(c) and (d) show the results of estimating the speed using the correction coefficients in Figures 13(a) and (b) for the second vibration component S shown in Figure 6, and show the relationship between the actually measured speed and the estimated speed. Figure 13(c) shows the results of estimating the speed from the characteristics in Figure 6(a), and Figure 13(d) shows the results of estimating the speed from the characteristics in Figure 6(b). Figure 13(d), which has a larger thrust amplitude, tends to have less error in the estimated speed from the actual speed than the characteristics in Figure 13(c).

[0148] 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 a polynomial approximation, a trigonometric function, etc. In that case, the coefficients, the number of which corresponds to the number of terms in the approximation equation, become functions with multiple arguments such as T1 to T4 above.

[0149] Next, a vibration detection means used to detect the second vibration component will be described. In the above description, an example was shown in which the vibration of the vibrating body 5 is detected by the current flowing through the primary winding of the transformer. This assumes the case in which a piezoelectric body is connected to the secondary winding of the transformer. That is, when the damping capacity of the piezoelectric body and the parallel resonance frequency and driving frequency of the inductor of the secondary winding of the transformer are set close to each other, the relationship in which the vibration speed of the piezoelectric body and the fundamental wave component of the current of the primary winding of the transformer are almost proportional is utilized. Although not shown in Figs. 2, 11(b), and 12(b), a capacitor or inductor that adjusts the relationship between the parallel resonance frequency and the driving frequency may be connected in parallel to the piezoelectric body. There is also a method of detecting vibration by a known method of detecting mechanical arm current. This is a method in which a reference capacitor with the same capacitance as the damping capacity of the piezoelectric body is connected in parallel to the piezoelectric body, and vibration is detected from the difference between the current flowing through the piezoelectric body and the current flowing through the reference capacitor. The fundamental wave component of the current of the primary winding of the transformer can obtain a current signal that is approximately equivalent to the known mechanical arm current.

[0150] In addition, when detecting the vibration waveform from the current, the current signal may contain many harmonic components, particularly when the waveforms of the AC signals VA and VB are square waves. In such a case, the current signal may be converted using a low-pass filter or band-pass filter after detection, and the waveform after extracting the fundamental wave component may be used as the vibration waveform.

[0151] Furthermore, a piezoelectric element for vibration detection may be provided separately in addition to the piezoelectric element for driving the vibrator.

[0152] FIG. 14(a) is a diagram showing a fourth configuration example of the driving device of the vibration type actuator 100 according to the first embodiment of the present invention. FIG. 14(a) is a diagram showing an example in which a piezoelectric element for detecting vibration is provided separately from the driving piezoelectric element in the vibrating body 5. The same components as those shown in FIG. 2 are given the same reference numerals, and detailed description thereof will be omitted. The piezoelectric body 22 and the piezoelectric body 23 are piezoelectric elements for vibration detection, the piezoelectric body 22 outputs a vibration detection signal SA, and the piezoelectric body 23 outputs a vibration detection signal SB. In addition, the piezoelectric body 22 is provided overlapping the piezoelectric body 3, and the piezoelectric body 23 is provided overlapping the piezoelectric body 4. By providing the piezoelectric body 22 overlapping, it is subjected to a strain similar to that of the overlapping piezoelectric body, and the vibration of the driving piezoelectric body 3 and the piezoelectric body 4 can be detected with high accuracy. The piezoelectric body for vibration detection may be provided separately from the driving piezoelectric element as described above, or a detection electrode region independent of the driving electrode may be provided on the driving piezoelectric element to form a piezoelectric body region for vibration detection and used as the piezoelectric body for vibration detection.

[0153] Fig. 14(b) is a diagram showing a fifth configuration example of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. In the configuration of Fig. 14(b), the speed estimation unit and the part that performs speed control in Fig. 2 are performed by a known CPU 34. Note that the same components as those shown in Fig. 2 are given the same reference numerals, and detailed explanations thereof will be omitted.

[0154] The CPU 34 receives the second vibration component S output from the second vibration component detection unit 16 and the thrust-up vibration amplitude output from the thrust-up vibration amplitude detection unit 17 to estimate and control the speed and to control the thrust-up vibration amplitude. Figs. 15 and 16 are flow charts showing the operation of the CPU 34. Fig. 15 shows the control steps for controlling the speed, and Fig. 16 shows the control steps for controlling the thrust-up vibration amplitude. First, Fig. 15 will be explained. 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.

[0155] Next, in step S102, the CPU 34 judges whether or not it is time to measure. If it is judged that it is not time to measure (S102 / No), the CPU 34 waits in step S102.

[0156] 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.

[0157] In step S103 , the CPU 34 acquires the second vibration component S output from the second vibration component detection unit 16 and the thrust-up vibration amplitude TS output from the thrust-up vibration amplitude detection unit 17 .

[0158] Next, in step S104, the CPU 34 performs calculations from 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, a calculation formula, 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 above-mentioned speed command Vcom with the speed VS calculated in step S104 to control the phase difference command Ph.

[0159] Next, the control of the phase difference command Ph will be described in steps S105 to S111.

[0160] In step S105, the CPU 34 compares the speed command Vcom set in step S101 with the speed VS calculated in step S104.

[0161] If the comparison result in step S105 indicates that the speed command Vcom is smaller (<) than the speed VS, the process proceeds to step S106.

[0162] In step S106, the CPU 34 subtracts a predetermined phase dPh from the phase difference command Ph.

[0163] Subsequently, in step S107, the CPU 34 determines whether the phase difference command Ph is smaller than −90°.

[0164] 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.

[0165] In step S108, the CPU 34 sets the phase difference command Ph to -90°.

[0166] If the comparison result in step S105 indicates that the speed command Vcom is greater (>) than the speed VS, the process proceeds to step S109.

[0167] In step S109, the CPU 34 adds a predetermined phase dPh to the phase difference command Ph.

[0168] Subsequently, in step S110, the CPU 34 determines whether the phase difference command Ph is greater than +90°.

[0169] 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.

[0170] In step S111, the CPU 34 sets the phase difference command Ph to +90°.

[0171] 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.

[0172] Subsequently, in step S112, the CPU 34 judges whether or not a stop command has been input. If the result of this judgment 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.

[0173] 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.

[0174] In step S113, the CPU 34 sets the ON-OFF command to OFF, which causes the outputs of the AC signals VA and VB output by the AC signal generating unit 15 to become 0 V, and the contact body 6 (slider) of the vibration actuator 100 stops.

[0175] When the process of step S113 ends, the process of the flowchart shown in FIG. 15 ends.

[0176] 16(a) will now be described. First, in step S201, the CPU 34 sets a predetermined thrust-up vibration amplitude command TScom, and sets a frequency command Frq to an initial frequency F0.

[0177] Next, in step S202, the CPU 34 judges whether or not it is time to measure. If it is judged that it is not time to measure (S202 / No), the CPU 34 waits in step S202.

[0178] 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.

[0179] In step S 203 , the CPU 34 acquires the thrust-up vibration amplitude TS output from the thrust-up vibration amplitude detection unit 17 .

[0180] In the subsequent steps, the thrust-up vibration amplitude command TScom is compared with the thrust-up vibration amplitude TS detected in step S203 to control the frequency command Frq.

[0181] Next, the control of the frequency command Frq will be described in steps S204 to S210.

[0182] 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.

[0183] 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.

[0184] In step S205, the CPU 34 adds a predetermined frequency dFrq to the frequency command Frq.

[0185] Subsequently, in step S206, the CPU 34 determines whether or not the frequency command Frq is greater than Fmax.

[0186] If it is determined in step S206 that the frequency command Frq is greater than Fmax (S206 / Yes), the process proceeds to step S207.

[0187] In step S207, the CPU 34 sets the frequency command Frq to Fmax.

[0188] Also, if the comparison result in step S204 shows that the thrust-up vibration amplitude command TScom is greater (>) than the thrust-up vibration amplitude TS, the process proceeds to step S208.

[0189] In step S208, the CPU 34 subtracts a predetermined frequency dFrq from the frequency command Frq.

[0190] Subsequently, in step S209, the CPU 34 determines whether the frequency command Frq is smaller than Fmin.

[0191] If it is determined in step S209 that the frequency command Frq is smaller than Fmin (S209 / Yes), the process proceeds to step S210.

[0192] In step S210, the CPU 34 sets the frequency command Frq to Fmin.

[0193] When the process of step S207 is completed, when the process 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.

[0194] Next, in step S211, the CPU 34 judges whether or not a stop command has been input. If the result of this judgment is that a stop command has not been input (S211 / No), the CPU 34 returns to step S202 and performs the processes in and after step S202.

[0195] 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. 16(a) ends.

[0196] 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. However, functions T3 and T4 using the frequency command Frq instead of the thrust-up vibration amplitude TS may also be used.

[0197] In the above example, the thrust-up vibration amplitude is controlled by the frequency command Frq to the AC signal generating unit 15, but the amplitudes of the AC signals VA and VB output by the AC signal generating unit 15 may be controlled. Fig. 16(b) is a flow chart showing the control operation of the thrust-up vibration amplitude when the AC signal generating unit 15 controls the amplitudes of the AC signals VA and VB by a voltage amplitude command (not shown). The steps in Fig. 16(b) will be described below.

[0198] 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.

[0199] Next, in step S302, the CPU 34 judges whether or not it is time to measure. If it is judged that it is not time to measure (S302 / No), the CPU 34 waits in step S302.

[0200] 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.

[0201] In step S303, the CPU 34 acquires the thrust-up vibration amplitude TS output from the thrust-up vibration amplitude detection unit 17.

[0202] In the subsequent steps, the above-mentioned thrust-up vibration amplitude command TScom is compared with the thrust-up vibration amplitude TS detected in step S303 to control the voltage amplitude command VS.

[0203] Next, the control of the voltage amplitude command VS will be described in steps S304 to S310.

[0204] In step S304, the CPU 34 compares the thrust-up vibration amplitude command TScom set in step S301 with the thrust-up vibration amplitude TS detected in step S303.

[0205] 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.

[0206] In step S305, the CPU 34 subtracts a predetermined voltage dVS from the voltage amplitude command VS.

[0207] Subsequently, in step S306, the CPU 34 determines whether the voltage amplitude command VS is smaller than Vmin.

[0208] 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.

[0209] In step S307, the CPU 34 sets the voltage amplitude command VS to Vmin.

[0210] Also, if the comparison result in step S304 shows that the thrust-up vibration amplitude command TScom is greater (>) than the thrust-up vibration amplitude TS, the process proceeds to step S308.

[0211] In step S308, the CPU 34 adds a predetermined voltage dVS to the voltage amplitude command VS.

[0212] Subsequently, in step S309, the CPU 34 determines whether the voltage amplitude command VS is greater than Vmax.

[0213] 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.

[0214] In step S310, the CPU 34 sets the voltage amplitude command VS to Vmax.

[0215] When the process of step S307 is completed, when the process 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. 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.

[0216] Next, in step S311, the CPU 34 judges whether or not a stop command has been input. If the result of this judgment 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.

[0217] 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. 16(b) ends.

[0218] Fig. 17 is a diagram showing a sixth example of the configuration of the driving device for the vibration actuator 100 according to the first embodiment of the present invention. In Fig. 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 Fig. 2 are given 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, and the second vibration component and the thrust-up vibration amplitude are detected within the FPGA 36. Various detection methods for the second vibration component described above can be selected within the FPGA 36 depending on the situation, and the second vibration component S is detected by a composite calculation of the results detected by the multiple detection methods.

[0219] 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 flow charts of FIG. 15 and FIG. 16(a).

[0220] Next, another example of the vibration type actuator will be described.

[0221] In the above explanation, the velocity estimation technology has been described using as an example a vibration actuator using a plate-shaped vibrating body 5 having two different natural vibration modes as shown in Figure 1, but there are other types of vibration actuators for which the velocity can be estimated in a similar manner.

[0222] Fig. 18 is a diagram showing an example of a schematic configuration and vibration shape of a vibration actuator 200. The schematic configuration and operation principle of the vibration actuator 200 according to the first embodiment will be described with reference to Fig. 18.

[0223] The vibration actuator 200 according to the first embodiment includes a vibrating body 205 and a contact body 206, as shown in Fig. 18(d). The vibrating body 205 is a plate-shaped vibrating body made of a conductive material, and includes a piezoelectric element 202 and an elastic body 201 having a protrusion 280 on its plate-shaped surface that contacts the contact body 206, as shown in Fig. 18(a) and Fig. 18(d). The piezoelectric element 202 forms a part of the vibrating body 205 and is a component for exciting the vibrating body 205.

[0224] 18(a), two electrodes 203 and 204 are formed on the surface of the piezoelectric element 202. The two electrodes 203 and 204 are electrically insulated from each other, and two AC voltages whose phases change independently are applied to them. The entire back surface of the piezoelectric element 202 is an electrode, and the piezoelectric element 202 is configured so that a ground potential can be connected from the surface of the piezoelectric element 202 through a via (not shown) provided in a 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.

[0225] 18(d) is a slider that is brought into pressurized contact with the protrusion 280 of the vibrating body 205 with a constant pressure by a pressure mechanism (not shown). This contact body 206 (slider) is configured to move in the direction of the arrow on the paper by vibration excited in the vibrating body 205.

[0226] 18(b) and 18(c) are diagrams showing an example of the vibration mode of the vibrator 205. FIG. 18(b) shows the vibration shape (stretching vibration) of the vibration mode (thrust-up vibration mode) excited in the vibrator 205 when AC voltages of the same amplitude and in phase are applied to the piezoelectric body 203 and the piezoelectric body 204. FIG. 18(c) shows the vibration shape (bending vibration) of the vibration mode (feed-up vibration mode) excited in the vibrator 205 when AC voltages of the same amplitude and inverse phase are applied to the piezoelectric body 203 and the piezoelectric body 204. That is, when the phase difference of the AC voltages applied to the piezoelectric body 203 and the piezoelectric body 204 of the vibrator 205 is set to 0°, the vibration mode (thrust-up vibration mode) shown in FIG. 18(b) is excited. When the phase difference of the AC voltages applied to the piezoelectric body 203 and the piezoelectric body 204 of the vibrator 205 is set to 180°, the vibration mode (feed-up vibration mode) shown in FIG. 18(c) is excited. Furthermore, when the phase difference of the AC voltage applied to the piezoelectric body 203 and the piezoelectric body 204 of the vibrating body 205 is set to a phase other than 0° and 180° (actually, a range of about 0° to ±120° is used), both vibration modes in Fig. 18(b) and Fig. 18(c) 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 side direction of the rectangle of the vibrating body 205. Then, as the phase difference moves away from 0°, the amplitude of the vibration mode (feed vibration mode) shown in Fig. 18(c) becomes larger, and the relative speed between the contact body 206 (slider) and the vibrating body 205 increases.

[0227] If the piezoelectric elements 203 and 204 are replaced with the piezoelectric elements 3 and 4, the driving device for the vibration actuator 100 according to the first embodiment can be applied.

[0228] In the above example, the amplitude of the sum signal of current signals IA and IB is taken as the thrust vibration amplitude. However, depending on the structure of the vibration actuator, the amplitude of the difference signal between current signals IA and IB may be the thrust vibration amplitude.

[0229] 19 is a diagram showing a 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.

[0230] 19(b) and 19(c) are diagrams showing examples of vibration modes of the vibrating body 305. Fig. 19(b) 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. 19(c) shows the vibration shape (stretching vibration) of a vibration mode (feed 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.

[0231] 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).

[0232] Based on this, if the correspondence between the thrust vibration and the feed vibration is exchanged and the piezoelectric elements 303 and 304 are replaced with the piezoelectric elements 3 and 4, the driving device for the vibration actuator 100 according to the first embodiment can be applied.

[0233] 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 and the drive voltages generated in response thereto may be measured and input instead.

[0234] Furthermore, in the above example, the thrust can be estimated from the speed VS estimated from the second vibration component S. The method is explained below. The speed when a predetermined thrust F0 occurs with respect to the phase difference between the AC signals VA and VB and the slope of the thrust change with respect to the speed change are obtained in advance. Fig. 20(a) is a diagram showing the phase difference between the AC signals VA and VB and the speed when the thrust is a predetermined value F0 (reference speed: V0), and Fig. 20(b) is a diagram showing the ratio (β) of the thrust change with respect to the speed change. Then, the thrust FS can be obtained by Equation 27.

[0235]

number

[0236] In the above example, the speed was controlled by manipulating the phase difference between AC signals VA and VB. However, the speed may be controlled by controlling the voltage amplitude of AC signal VB while keeping the phase difference fixed at a predetermined phase difference.

[0237] 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 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.

[0238] Figure 22 shows examples of the waveforms of AC signal VA, AC signal VB, and the VB voltage amplitude command. Figure 22(a) shows the signal waveform of AC signal VA, and Figure 22(b) shows the signal waveform of AC signal VB (solid line) and the VB voltage amplitude command (dashed line). AC signal VB is shifted in phase by 90° with respect to AC signal VA, and the sign of the phase difference between AC signal VA and AC signal VB switches depending on the sign of the VB voltage amplitude (dashed line).

[0239] 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 shown 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.

[0240] Furthermore, equation 27 calculates the thrust using the reference speed V0 with the phase difference as a parameter and the ratio of the thrust change to the speed change (β).The thrust can also be calculated by using the reference speed V0 with the VB voltage amplitude as a parameter instead of the phase difference and the ratio of the thrust change to the speed change (β).

[0241] In the above explanation, since the amplitude of the thrust vibration changes little with respect 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 signals IA and IB.

[0242] [Second Example] 23 is a diagram 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 operation principle of the vibration actuator 400 according to the second embodiment will be described with reference to this Figure.

[0243] As shown in Fig. 23(b), 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. 23(a), the vibrating body 405 is a cylindrical vibrating body made of a conductive material, and is composed of a piezoelectric body 403 and a piezoelectric body 404, and an elastic body 401 that sandwiches the piezoelectric bodies from above and below and has a protrusion 480 on the upper part of the cylinder. The piezoelectric body 403 excites the vibrating body 405 with a vibration that expands and contracts in the height direction of the cylinder, and the piezoelectric body 404 is a component for excitating the vibrating body 405 with a torsional vibration about the central axis of the cylinder, and is sandwiched and fixed between the elastic body 401 by a tightening member (not shown).

[0244] 23(b) is a rotor that is brought into pressurized contact with a protrusion 480 of a vibrating body 405 with a constant pressure by a pressurizing mechanism (not shown). The contacting body 406 (rotor) rotates a rotating shaft 407 and the contacting body 406 (rotor) by vibration excited by the vibrating body 405.

[0245] The driving operation of the vibration actuator 400 will now 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 vibration) excited in a vibrator 405. When an AC voltage of a predetermined frequency is applied to the piezoelectric body 403, a stretching vibration (thrust-up vibration) is excited in the vibrator 405, and when it is applied to the piezoelectric body 404, a torsional vibration (feed vibration) is excited in the vibrator 405. Therefore, when the stretching vibration (thrust-up vibration) and the torsional vibration (feed vibration) are excited with a time phase shift, the contact body 406 (rotor) rotates.

[0246] Here, the difference between the vibration actuator 400 and the vibration actuator 100 will be explained. In addition to the difference in shape, there is a major difference in the drive between these actuators. The difference is that the vibration actuator 100 excites thrust-up vibration with the in-phase component of the applied two-phase AC voltage and excites feed vibration with the opposite phase component, whereas each phase of the two-phase AC voltage corresponds to thrust-up vibration and feed vibration individually. Therefore, the vibration actuator 100 controls the amplitude balance of the thrust-up vibration and the feed vibration by the phase difference between the applied two-phase AC voltage, but the vibration actuator 400 does not change the amplitude balance of the thrust-up vibration and the feed vibration even if the phase difference is manipulated. Therefore, the vibration actuator 400 controls the balance of the thrust-up vibration and the feed vibration by manipulating the amplitude balance of the two-phase AC voltage or the voltage amplitude of one of the phases.

[0247] Next, a description will be given of vibration excitation of the vibrating body 405 caused by an external force of the vibration actuator 400. 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.

[0248] 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 inclines 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 that the vibrating body 405 receives 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. In addition, since it 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 driving conditions.

[0249] The following description will be given of an example in which the vibrator 5 is driven under conditions in which the frequency of the two-phase AC voltage is higher than the natural frequency of the vibration mode of the vibrator 5.

[0250] FIG. 24 is a diagram showing a first configuration example of a driving device for a vibration actuator 400 according to a second embodiment of the present invention.

[0251] First, the AC voltage generating section will be described. The AC signal generating section 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 control amount calculating section 20. The AC signal VA has a predetermined amplitude, and the AC signal VB has an amplitude according to the VB voltage amplitude command, and when the VB voltage amplitude command is a negative value, the AC signal VB is output after being inverted in polarity.

[0252] 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 connected to the secondary windings. Here, the inductor values ​​of the secondary windings of the transformers 7 and 8 are frequency-matched with 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.

[0253] 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 a voltage to generate current signals IA and IB. Current signal IA (first detection signal) is a signal corresponding to the vibration in the stretching vibration mode (thrust-up vibration mode) of vibrating body 405, and current signal IB (second detection signal) is a signal corresponding to the vibration in the torsional vibration mode (feed-forward vibration mode) of vibrating body 405.

[0254] Next, the configuration related to the estimation and control of the speed will be described. The second vibration component detection unit 16 and the thrust-up vibration amplitude detection unit 17 input the current signals IA and 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 value of the VB voltage amplitude command.

[0255] The detected speed is 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.

[0256] The method of estimating speed and vibration detection will be described in detail later.

[0257] A first example of the second vibration component detection according to the second embodiment will now be described.

[0258] 25(a) and (b) are diagrams for explaining a first example of the second vibration component detection according to the second embodiment, and are diagrams showing an example of a Lissajous waveform (vibration ellipse) used for the second vibration component detection. Fig. 25(a) is a Lissajous waveform (vibration ellipse) drawn with the vertical axis representing the current signal IA and the horizontal axis representing the current signal IB. The current signal IA is a vibration waveform of the stretching vibration mode (thrust-up vibration mode) of the vibrating body 405, and the current signal IB is a vibration waveform of the torsional vibration mode (feed vibration mode) of the vibrating body 405, and φ7 indicates the inclination angle of the vibration ellipse.

[0259] Here, if the current signal IA is expressed by Equation 28 and the current signal IB is expressed by Equation 29,

[0260]

number

[0261]

number

[0262] The inclination angle φ7 of the vibration ellipse is given by Equation 30.

[0263]

number

[0264] 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 obtain the second vibration component (the inclination angle of the vibration ellipse).

[0265] 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 the speed. Therefore, taking this influence into consideration, the second vibration component S may be a value obtained by adding 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 at a predetermined ratio.

[0266] Moreover, the second vibration component S may be obtained by extracting only the changing portion of the formula 30, as formula 31, or the result of substituting this for an arbitrary function may be used as the second vibration component.

[0267]

number

[0268] In the above example, the vertical axis of the Lissajous waveform (vibration ellipse) is the current signal IA and the horizontal axis is the current signal IB, but the slope of the vibration ellipse may 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 25(b) shows a Lissajous waveform (vibration ellipse) plotted with the vertical axis as the sum signal and the horizontal axis as the difference signal of current signal IA and current signal IB multiplied by coefficients αA and αB, respectively.

[0269] Here, when the coefficients αA and αB are set to 1, the inclination angle φ9 of the vibration ellipse becomes Equation 32, and the angle φ9 can be set as the second vibration component S.

[0270]

number

[0271] Also, similarly to the above example, the angle φ10 may be calculated, and the inclination angle φ9 and the angle φ10 may be added at a predetermined ratio to obtain the second vibration component S. Also, the second vibration component S may be obtained by extracting only the part of the equation that changes, ie, equation 33, or the result of substituting this into an arbitrary function may be obtained as the second vibration component S.

[0272]

number

[0273] Next, a second example of the second vibration component detection according to the second embodiment will be described.

[0274] In the first example of the second vibration component detection according to the second embodiment, the inclination angle of the vibration ellipse is calculated by Equation 30, but the inclination angle may be calculated using other parameters of the vibration ellipse that change depending on the inclination angle of the vibration ellipse. Figures 25(c) and 25(d) are diagrams for explaining a second example of the second vibration component detection according to the second embodiment, and Figure 25(c) is a diagram for explaining an example of detecting the second vibration component using the angle φ11 that changes depending on the inclination angle of the vibration ellipse. In the first example of the second vibration component detection according to the second embodiment, the inclination of the axis of the vibration ellipse is used, but to calculate this, a complex calculation such as Equation 30 is required. The angle φ11 detected in this example can be directly detected from the current signal IA and the current signal IB. The angle φ11 is the angle between the line connecting the positive and negative vertices of the current signal IA and the vertical axis, and Figure 25(d) is a diagram for explaining a method of detecting the angle φ11. In Figure 25(d), the solid line is the current signal IA, the dotted line is the differentiated waveform of the solid line waveform, and the dashed line is the waveform of the current signal IB. The angle φ11 is obtained 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.

[0275]

number

[0276] The second vibration component detection unit 16 obtains the second vibration component (angle φ11) as described above.

[0277] Moreover, the second vibration component S may be expressed by Equation 35 or Equation 36.

[0278]

number

[0279]

number

[0280] As in the first example of the second vibration component detection according to the second embodiment, 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, the second vibration component S may be determined by adding the angle φ12 and the angle φ11 formed by the diagonal of the circumscribing rectangle of the vibration ellipse shown in FIG. 25(c) and the straight line indicating the angle φ11 at a predetermined ratio.

[0281] Next, a third example of the second vibration component detection according to the second embodiment will be described.

[0282] In the first and second examples of the second vibration component detection according to the second embodiment, the second vibration component is extracted from the shape of the vibration ellipse, but it can also be obtained directly from the amplitude of the current. The second vibration component detection unit 16 of this embodiment inputs the current signals IA and IB to obtain the amplitudes of (current signal IA+current signal IB) and (current signal IA-current signal IB). Then, (amplitude of (current signal IA+current signal IB)-amplitude of (current signal IA-current signal IB)) is calculated to obtain the second vibration component S. Here, in the above calculation, addition and subtraction are performed directly on the current signals IA and IB, but addition and subtraction may be performed after multiplying them by different coefficients αA and αB. This is because the stretching vibration, which is a thrust vibration, and the torsional vibration, which is a feed vibration, are excitations that utilize completely different phenomena. In other words, the stretching vibration is a vibration that utilizes the longitudinal effect or lateral effect of the piezoelectric body, while the torsional vibration utilizes the thickness slip effect of the piezoelectric body. Therefore, the current sensitivity to the vibration is adjusted by multiplying the current signals IA and IB by coefficients αA and αB, respectively. Moreover, the second vibration component S may be obtained by dividing the above calculation result by the amplitude of the current signal IA.

[0283] In the following description, except for 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.

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

[0285] This example is an example of detection when the current signal is represented as a vector. Fig. 26 is a vector diagram of the current signal, and Fig. 26(a) is a diagram showing the current signal αIA, the current signal αIB, and the signals of their sum and difference 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.

[0286]

number

[0287]

number

[0288] 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) in the same direction as the vector of current signal αIA is highly correlated with the inclination of the vibration ellipse, and the values ​​shown in Equation 39 and Equation 40 can be taken as the second vibration component S.

[0289]

number

[0290]

number

[0291] Moreover, 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 is expressed as Equation 41 and Equation 42.

[0292]

number

[0293]

number

[0294] Here, a method for calculating the second vibration component S of Equation 39 to Equation 41 will be described. Equations 39 to 42 are calculations including trigonometric functions, and also require detection of the phase difference. This makes the structure of the second vibration component detection unit 16 complicated. Therefore, an example in which synchronous detection is used instead of these calculations and detection of the phase difference will be described.

[0295] The method for detecting the second vibration component S using synchronous detection is shown below.

[0296] 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, the other is used as a measurement target signal, and the phase of the reference signal is used as a reference phase. 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.

[0297] 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 differential waveform of the current signal αIA (dotted line). Figure 27(b) shows the detection of a component in the same direction as the vector of the current signal αIA, and Figure 27(c) shows the detection of a component in the normal direction to the vector of the current signal αIA.

[0298] 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 of 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.

[0299] 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 of 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.

[0300] Next, a fifth example of the second vibration component detection according to the second embodiment will be described.

[0301] In the fifth example of the second vibration component according to the second embodiment, the second vibration 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 vibration component according to the second embodiment, the second vibration component is contained in many components in the same direction as the vector of the current signal αIA, and the characteristics of the values ​​shown in Equation 43 and Equation 44 are very similar to the characteristics shown in Figure 6 in the first embodiment.

[0302]

number

[0303]

number

[0304] Moreover, the component in the normal direction 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 is expressed as Equation 45 and Equation 46.

[0305]

number

[0306]

number

[0307] Here, we will explain how to calculate the second vibration component S from Equation 43 to Equation 46. As in the fourth example of the second vibration component according to the second embodiment, calculation may be performed using Equation 43 to Equation 46, but the second vibration component S can also be calculated using synchronous detection.

[0308] Next, a sixth example of the second vibration component detection according to the second embodiment will be described.

[0309] The above example explained a method for detecting the second vibration component S corresponding to the Lissajous figure and vector display, but this example explains a method for detecting the second vibration component S by synchronous detection of the waveform on the time axis. The above example also uses synchronous detection 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.

[0310] The second vibration component is excited by the 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 second vibration component, and is 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. The timing of this starting point is the timing when the displacement reaches the peak of the 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 differs for each vibration mode according to the excitation frequency. The vibration caused by the frictional force acting in the relative movement direction between the vibrating body 405 and the contact body 406 (rotor) may mainly occur in the torsional vibration mode (feed vibration mode) of the vibrating body 405. In that case, the first vibration component is superimposed on the vibration of the torsional vibration mode (feed vibration mode) with a phase delay θs according to the response characteristic of the feed vibration mode.

[0311] Figures 29(a) and (b) are diagrams for explaining a fifth example of detecting the second vibration component according to the second embodiment, and are diagrams for explaining the operation of synchronous detection. Figure 29(a) shows the waveform of the current signal IB when no load is applied (solid line), the superimposed vibration waveform (dotted line) superimposed on the waveform when no load is applied, the waveform of the current signal IB on which the superimposed vibration waveform (dotted line) is superimposed (dashed line), and the waveform of the current signal IA (dash-dotted line). Figure 29(b) is a diagram showing the detection of the superimposed vibration waveform component by synchronous detection.

[0312] 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 the signal of the dashed line in Fig. 29(a) and this reference signal. The dotted line in Fig. 29(b) shows the average value of the multiplication result, which changes according to the amplitude of the superimposed vibration waveform (dotted line) in Fig. 29(a).

[0313] Here, the superimposed vibration waveform (dotted line) in FIG. 29(a) is a vibration component generated in the vibrator 405 when the vibrator 405 is excited by the contact body 406 (rotor), and is difficult to detect directly because it is superimposed on the vibration when no load is applied. However, since the phase of the superimposed vibration waveform is delayed by the phase of θs from the phase of the peak of the waveform of the current signal IA in FIG. 29(a) (dashed line), if θs is known, this relationship can be used to generate the reference signal (solid line) in FIG. 29(b). The second vibration component detection unit 16 selects θs according to the driving state, performs synchronous detection, and outputs the obtained average value. In addition, the value obtained by synchronous detection divided by the amplitude of the current signal IA may be used as the second vibration component S.

[0314] The value of θs can be obtained in advance by measuring the amplitude of the current signal IA, the voltage amplitude of the AC signal VB, and the like, and prepared as a data table or a function.

[0315] In this example, the reference signal is a pulse signal, but it may be a sine wave or other waveform.

[0316] Next, a seventh example of the second vibration component detection according to the second embodiment will be described.

[0317] Figures 29(c) and (d) are diagrams for explaining a seventh example of the second vibration component detection according to the second embodiment. Figure 29(c) shows the waveform of the current signal IB (solid line) when no load is applied, the superimposed vibration waveform (dotted line) superimposed thereon, the waveform of the current signal IB (dashed line) on which the superimposed vibration waveform (dotted line) is superimposed, and the waveform of the current signal IA (dash-dotted line). Figure 29(d) is a diagram showing how the superimposed vibration waveform component is detected by integrating the waveform of the current signal IB (dashed line) on which the superimposed vibration waveform (dotted line) is superimposed in a predetermined phase section.

[0318] The solid line in Fig. 29(d) is a gate signal that sets the phase section (0°±dθ) centered on phase 0° of the waveform (solid line) of the current signal IB in Fig. 29(c) when there is no load to -1, the phase section (180°±dθ) centered on phase 180° to 1, and the other phase sections to 0. The dashed line in Fig. 29(d) is the multiplication result of this gate signal by the dashed signal in Fig. 29(c). The dotted line in Fig. 29(d) shows the average value of the multiplication result, and this value changes according to the amplitude of the superimposed vibration waveform (dotted line) in Fig. 29(c).

[0319] Here, the waveform of the current signal IB (solid line) at no load in Fig. 29(c) can only be detected at no load. Therefore, the phase difference θX between the waveform of the current signal IB (solid line) at no load and the waveform of the current signal IA (dashed line) in Fig. 29(c) (dotted line) 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 state of the amplitude of the current signal IA, the voltage amplitude of the AC signal VB, etc.

[0320] The second vibration component detection unit 16 may output the value of the dotted line in FIG. 29(d) as the second vibration component S as is, but may also divide the value by the amplitude of the current signal IA to obtain the second vibration component S.

[0321] Next, an eighth example of the second vibration component detection according to the second embodiment will be described.

[0322] In this example, a current signal IB signal at no load for the AC signal VA and the AC signal VB is generated using an equivalent circuit model of the vibrator 405 and the drive circuit, and the superimposed vibration waveform is extracted by subtracting this from the measured current signal IB. Figure 30(a) shows an example of the equivalent circuit model. 52 is a filter that simulates the operation of the equivalent circuit of the vibrator 405 and the drive circuit at no load. The circuit diagram in 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 bodies 403 and 404, and resistors 9 and 10 for current detection, and the operation of these is simulated by calculation. When the waveforms of the AC signal VA and the AC signal VB are input to the filter 52, it outputs a current signal IAS that simulates the current signal IA in real time and a current signal IBS that simulates the current signal IB.

[0323] FIG. 30(b) is a diagram showing a second configuration example of the driving device of the vibration actuator 400 according to the second embodiment of the present invention, and shows an example of detecting the second vibration component using a filter 52. The same components as those shown in FIG. 2 are given the same reference numerals, and detailed description thereof will be omitted. The AC signals VA and VB output from the AC signal generating unit 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 when no load is applied, and a current signal IBS (second comparison signal) simulating the current signal IB when no load is applied. The second vibration component detecting unit 16 receives 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).

[0324] As shown in Equation 47, the sign of the phase difference θSA between the superimposed vibration waveform and the current signal IA is set to the sign of the amplitude SF of the superimposed vibration waveform, and this is output as the second vibration component S.

[0325]

number

[0326] 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 the coefficient αA are defined as the current signals αIA and αIAS, and the signals obtained by multiplying the current signals IB and IBS by the coefficient αB are defined as the 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.

[0327]

number

[0328] 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.

[0329] Next, the operation of the speed estimation unit 18 will be described.

[0330] FIG. 31 shows an example of a correction coefficient for determining the speed from the second vibration component S, and shows an example of the correction coefficient for each thrust amplitude and voltage amplitude of the AC signal VB. FIG. 31(a) shows the sensitivity correction coefficient γ, and FIG. 31(b) shows the offset correction coefficient ε, showing the relationship with the thrust amplitude. The line type indicates the voltage amplitude of the AC signal VB, and a solid line (100V), dotted line (50V), dashed line (0V), one-dot chain line (-50V), and two-dot chain line (-100V) are shown as representative lines. Equation 49 is an equation for estimating the speed VS from the value of the second vibration component S when the value of the second vibration component S changes linearly.

[0331]

number

[0332] In this way, when the value of the second vibration component S changes linearly with respect to the speed, the speed can be estimated with 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 in Figure 31 may be held as a data table, but they may also be held 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.

[0333]

number

[0334]

number

[0335] 31 is a diagram showing an example of the relationship between the voltage amplitude of the AC signal VB, the thrust vibration amplitude, and the correction coefficient, but the frequencies of the AC signals VA and VB may be used instead of the thrust vibration amplitude. In that case, the sensitivity correction coefficient γ and the offset correction coefficient ε are determined from the frequencies of the AC signals VA and VB during driving and the voltage amplitude of the AC signal VB using a data table or functions T7 and T8. Equation 52 shows function T7 of the offset correction coefficient ε, and Equation 53 shows function T8 of the sensitivity correction coefficient γ.

[0336]

number

[0337]

number

[0338] In the above explanation, the velocity is defined as a linear expression of the second vibration component S, and an example is shown in which 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.

[0339] Fig. 32 is a diagram showing a third configuration example of a driving device for a vibration actuator 400 according to a second embodiment of the present invention. Fig. 32 shows an example in which the speed estimation unit and the speed control unit of the driving device in Fig. 24 are performed by a known CPU 34. The same components as those shown in Fig. 24 are given the same reference numerals, and detailed description thereof will be omitted.

[0340] 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.

[0341] 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.

[0342] Next, in step S402, the CPU 34 judges whether or not it is time to measure. If it is judged that it is not time to measure (S402 / No), the CPU 34 waits in step S402.

[0343] 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.

[0344] In step S 403 , the CPU 34 acquires the second vibration component S output from the second vibration component detection unit 16 and the thrust-up vibration amplitude TS output from the thrust-up vibration amplitude detection unit 17 .

[0345] Next, in step S404, the CPU 34 calculates from the thrust vibration amplitude TS and the VB voltage amplitude command VBcom acquired in step S403. That is, the CPU 34 calculates the sensitivity correction coefficient γ and the 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 the speed VS using the second vibration component S acquired 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.

[0346] Next, the control of the VB voltage amplitude command VBcom will be described in steps S405 to S411.

[0347] In step S405, the CPU 34 compares the speed command Vcom set in step S401 with the speed VS calculated in step S404.

[0348] If the comparison result in step S405 indicates that the speed command Vcom is smaller (<) than the speed VS, the process proceeds to step S406.

[0349] In step S406, the CPU 34 subtracts a predetermined voltage dVB from the VB voltage amplitude command VBcom.

[0350] Subsequently, in step S407, the CPU 34 determines whether the VB voltage amplitude command VBcom is smaller than VBmin.

[0351] 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.

[0352] In step S408, the CPU 34 sets the VB voltage amplitude command VBcom to VBmin.

[0353] If the comparison result in step S405 indicates that the speed command Vcom is greater (>) than the speed VS, the process proceeds to step S409.

[0354] In step S409, the CPU 34 adds a predetermined voltage dVB to the VB voltage amplitude command VBcom.

[0355] Subsequently, in step S410, the CPU 34 determines whether or not the VB voltage amplitude command VBcom is greater than VBmax.

[0356] 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.

[0357] In step S411, the CPU 34 sets the VB voltage amplitude command VBcom to VBmax.

[0358] 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.

[0359] Subsequently, in step S412, the CPU 34 judges whether or not a stop command has been input. If the result of this judgment 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.

[0360] 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.

[0361] In step S413, the CPU 34 sets the ON-OFF command to OFF, which causes the outputs of the AC signals VA and VB output by the AC signal generating unit 15 to become 0 V, and the contact body 406 (rotor) of the vibration actuator 400 stops.

[0362] When the process of step S413 ends, the process of the flowchart shown in FIG. 33 ends.

[0363] In the above second embodiment, an example has been shown in which the value of the VB voltage amplitude command is used as an argument for setting the correction coefficient, but it is also possible to use the amplitude ratio between the AC signal VA and the AC signal VB, or the amplitude of the actually measured AC signal VB or the amplitude of the drive voltage generated in response to the actually measured AC signal VB.

[0364] Also, in the same manner as in the first embodiment, the torque (or force) can be estimated from the velocity VS estimated from the second vibration component S. Below, a method for estimating the torque will be explained as an example, but the method for detecting the force acting between the vibrating body and the contact body is similar.

[0365] The speed when a certain torque T0 occurs 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 obtained in advance. Figure 34(a) shows the voltage amplitude of the AC signal VB and the speed (reference speed: V0) when the torque is at a certain value T0, and Figure 34(b) shows the ratio (β) of the torque change with respect to the speed change. Then, the torque TR can be obtained by Equation 54. This reference speed: V0 is the reference value of the speed.

[0366]

number

[0367] In the above example, the speed was controlled by fixing the phase difference between AC signals VA and VB at 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.

[0368] In the above example, the speed was controlled by manipulating the voltage amplitude of AC signal VB, so the speed was estimated using offset correction coefficient ε and sensitivity correction coefficient γ with the VB voltage amplitude as a parameter, as shown 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 offset correction coefficient ε and sensitivity correction coefficient γ with the phase difference as a parameter instead of the VB voltage amplitude.

[0369] Furthermore, equation 54 finds the torque using the reference speed: V0 with the VB voltage amplitude as a parameter and the ratio of torque change to speed change (β). Again, the torque can be found by using the reference speed V0 with the phase difference as a parameter instead of the VB voltage amplitude and the ratio of torque change to speed change (β).

[0370] 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 to the vibrating body 405. On the other hand, the same effect can be obtained by configuring the piezoelectric body 403 to bend in the left-right direction of the paper and the piezoelectric body 404 to bend in the depth direction of the paper in FIG. 23(b). 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.

[0371] In the above description, since the amplitude of the thrust vibration changes little with respect 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 current signal IB.

[0372] [Third Example] FIG. 35 is a diagram showing a schematic configuration of a vibration actuator 500 according to the third embodiment.

[0373] 1, and are in contact with each other at the contact surfaces of the respective protrusions 580 along the circumference of the annular contact body 506. The thrusts of the three oscillators 501, 502, 503 are combined to increase the output torque.

[0374] 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 are omitted.

[0375] Piezoelectric elements 504 and 505 are provided on vibrating body 501, piezoelectric elements 506 and 507 on vibrating body 502, and piezoelectric elements 508 and 509 on vibrating body 503 as excitation piezoelectric elements. 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.

[0376] 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 being connected to capacitor 11 and the other end being connected to resistor 9 for current detection.

[0377] 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.

[0378] Resistor 9 detects a current signal IA corresponding to the vibration velocity of the A-phase piezoelectric body, and resistor 10 detects a current signal IB corresponding to the vibration velocity of the B-phase piezoelectric body.

[0379] Since the vibrating bodies 501, 502, and 503 are driven in series connection, applying an AC voltage to the primary side of the transformer produces well-aligned vibrations. Furthermore, the vibrations superimposed on each vibrating body due to the frictional force acting between the protrusions 580 of the vibrating bodies 501, 502, and 503 and the contact body 506 (rotor) also change in a well-aligned manner. Since the vibrations of each vibrating body are well-aligned, it is possible to detect the vibrations of the vibrating bodies as a single vibration by detecting the current in the primary winding of the transformer, as in the first embodiment.

[0380] 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 described in the first embodiment can be used.

[0381] In the third embodiment, multiple vibrating bodies are connected in series to a transformer and a voltage is applied to both ends, but the piezoelectric bodies of multiple vibrating bodies may be directly connected in series without using a transformer. In the above embodiment, the vibration is detected by the current of the primary winding of the transformer, but a piezoelectric element for vibration detection may be provided separately on the vibrating body. In that case, the vibration of each vibrating body is synchronized by connecting them in series, so the second vibration component S can be detected by detecting the vibration of one vibrating body, and the speed and torque can be estimated and controlled in the same way as in the above embodiment.

[0382] [Fourth Example] FIG. 37(a) is a diagram showing a schematic configuration of a vibration actuator 600 according to the fourth embodiment.

[0383] The vibration type actuator 600 according to the fourth embodiment includes a vibrating body 605, a contact body 606 which is a circular rotor, and a rotating shaft 607 connected to the contact body 606 (rotor). The vibrating body 605 is a circular vibrating body made of a conductive material, and includes a piezoelectric element 602 and an elastic body 601 having a protrusion 680 on the upper surface of the ring that contacts the contact body 606 (rotor). The protrusion 680 has a friction member 681 made of resin at the contact portion with the contact body 606 (rotor). The piezoelectric element 602 forms a part of the vibrating body 605 and is a component for exciting the vibrating body 605.

[0384] FIG. 37(b) is a diagram showing an example of a structure of multiple electrodes and electrical connection wiring configured in the piezoelectric element 602 shown in FIG. 37(a).

[0385] 37(b), the piezoelectric element 602 has 24 electrodes arranged at equal intervals on the circumference, and the electrodes of the piezoelectric element 602 are electrically connected by connection wiring every four electrodes along the circumference. Here, the regions of the piezoelectric element 602 where the electrodes connected to each other are arranged will be called piezoelectric body 611, piezoelectric body 612, piezoelectric body 613, and piezoelectric body 614 for each connection.

[0386] Furthermore, the piezoelectric bodies 611 are arranged at 60° intervals on the circumference, and when AC voltage A is applied to the piezoelectric bodies 611, six out-of-plane flexural vibrations are formed along the circumference of the 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 the piezoelectric bodies 612, 613, and 614, respectively, six out-of-plane progressive vibration waves are formed on the vibrating body 605. These six progressive vibration waves generate a relative force between the protrusion 680 of the vibrating body 605 and the contact body 606 (rotor), causing the contact body 606 (rotor) to rotate.

[0387] Furthermore, the piezoelectric element 602 is provided with a plurality of electrodes for vibration detection, and the regions of the piezoelectric element 602 where these electrodes are provided are referred to as piezoelectric body 615 and piezoelectric body 616. The piezoelectric body 615 detects the vibration excited by the piezoelectric bodies 611 and 613 and outputs a vibration detection signal SA, and the piezoelectric body 616 detects the vibration excited by the piezoelectric bodies 612 and 614 and outputs a vibration detection signal SB.

[0388] 37(c) is a diagram showing a first example of the positional relationship between the piezoelectric bodies 611-614 and the protrusion 680. The protrusion 680 is provided at the center of the electrode sections of the piezoelectric bodies 611 and 613 to which AC voltages A and NA are connected. If the vibration caused by the piezoelectric bodies 611 and 613 is A-phase vibration and the vibration caused by the piezoelectric bodies 612 and 614 is B-phase vibration, the A-phase vibration excites a push-up vibration that pushes the protrusion 680 up against the contact body 606, and the B-phase vibration excites a feed vibration that drives the contact body 606 in the tangential direction of the contact surface of the protrusion 680.

[0389] Fig. 38(a) is a diagram showing a first configuration example of a driving 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 given the same reference numerals, and detailed descriptions thereof will be omitted.

[0390] The vibration actuator 600 is an actuator driven by a four-phase AC voltage, in which AC voltage A and AC voltage NA, and AC voltage B and AC voltage NB are AC voltages of opposite phases. Piezoelectric elements 611, 613 and piezoelectric elements 612, 614, which are paired to receive the opposite phase AC voltages, are connected to secondary windings with center taps of transformers 43 and 44. AC signals VA and VB, which are outputs from an AC signal generating unit, are applied to one end of the primary windings of the transformers 43 and 44, and resistors 45 and 46 for current detection are connected to the other end.

[0391] The current signals IA and IB detected by the resistors 45 and 46 are input to the second vibration component detection unit 16 and the thrust-up vibration amplitude detection unit 17. Then, the second vibration component S and the thrust-up vibration amplitude are detected by the operation described in the second embodiment, and the rotation speed of the contact body 606 (rotor) is detected by the speed estimation unit 18. Then, the detected rotation speed is compared with a speed command from a command means (not shown) by the comparison means 19, and a VB voltage amplitude command signal is generated by the control amount calculation unit 20 according to the comparison result, and the voltage amplitude of the AC signal VB is controlled, thereby controlling the rotation speed.

[0392] In the fourth embodiment, in addition to the speed control, the thrust-up vibration amplitude is also controlled. The output of the thrust-up vibration amplitude detection unit 17 is compared with a thrust-up 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 and 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, and the thrust-up vibration amplitude is controlled.

[0393] When the thrust vibration amplitude is controlled to be constant, the contact state between the contact body 606 (rotor) and the vibrating body 605 becomes stable, so that the stability of the speed estimation can be improved.

[0394] Fig. 38(b) is a diagram showing a second configuration example of a driving device for a vibration actuator 600 according to a fourth embodiment of the present invention. The same components as those shown in Fig. 38(a) are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0395] 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 by piezoelectric bodies 615 and 616. The piezoelectric body 615 outputs a vibration detection signal SA, and the piezoelectric body 616 outputs a vibration detection signal SB. Since vibration is detected directly instead of using a current signal, the accuracy of speed estimation can be improved.

[0396] Fig. 39(a) is a diagram showing a second example of the positional relationship between the piezoelectric bodies 611 to 614 and the protrusion 680. The protrusion 680 in Fig. 39(a) is provided between the electrode sections of the piezoelectric bodies 611 and 612 to which AC voltages A and B are connected, and between the electrode sections of the piezoelectric bodies 613 and 614 to which AC voltages NB and NA are connected. If the vibration caused by the piezoelectric bodies 611 and 613 is A-phase vibration and the vibration caused by the piezoelectric bodies 612 and 614 is 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.

[0397] Fig. 40 is a diagram showing a third configuration example of a driving 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 given the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, descriptions of the case where the above-mentioned techniques such as vector calculation are used will be omitted.

[0398] The connections of the vibration actuator 600 to the transformers 43 and 44 and the connections of 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-up vibration amplitude detection unit 17 are different.

[0399] The current signals IA and IB are input to both the second vibration component detection unit 16 and the 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, the speed estimation unit 18 detects the rotation speed of the contact body 606 (rotor).

[0400] FIG. 39(b) is a diagram showing a third example of the positional relationship between the piezoelectric bodies 611 to 614 and the protrusion 680. In FIG.

[0401] Protrusion 680 is provided between the electrode sections of piezoelectric body 611 and piezoelectric body 614 to which AC voltage A and AC voltage NB are connected, and between the electrode sections of piezoelectric body 612 and piezoelectric body 613 to which AC voltage B and AC voltage NA are connected. If the vibration caused by piezoelectric bodies 611 and 613 is A-phase vibration and the vibration caused by piezoelectric bodies 612 and 614 is B-phase vibration, then 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.

[0402] Therefore, the case where the position of the protrusion 680 of the vibration actuator 600 is as shown in Fig. 39(b) will be described below. That is, if this is driven by the drive device of Fig. 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 detection unit 16 and the thrust-up vibration amplitude detection unit 17 will also use reversed signals in their operations.

[0403] In this embodiment, the torque can be estimated based on the estimated speed as in the above embodiment. The speed when a certain torque T0 occurs with respect to the phase difference between the AC signals VA and VB and the slope of the torque change with respect to the speed change are obtained in advance. Fig. 41(a) shows the phase difference between the AC signals VA and VB and the speed (reference speed: V0) when the torque is a certain value T0, and Fig. 41(b) shows the ratio (β) of the torque change with respect to the speed change. Then, the torque TR can be obtained by Equation 55.

[0404]

number

[0405] [Fifth Example] In the above embodiments, a control device was described that estimates the speed or torque and controls the speed or torque according to a command value of the speed or torque, but in this embodiment, an example is described in which position control is performed using an estimated value of the speed or the speed and the torque. Fig. 42(a) 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. Fig. 42(a) shows an example in which minor loop control of the speed is applied to position control, and instead of detecting the speed from differential information of the detected position, speed control is performed using an estimated value of the speed according to the present invention.

[0406] The same components as those shown in Fig. 40 are denoted by 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.

[0407] Next, the speed command signal and the estimated speed from the speed estimator 18 are compared by the comparator 19. The comparison result is used to generate a phase difference command signal by PI (proportional integral) calculation in the controlled variable calculator 20. In this manner, the phase difference between the AC signals VA and VB output by the AC signal generator 15 is controlled, and the speed and position are controlled.

[0408] The speed estimated by the speed estimation unit 18 is detected from the vibration amplitude of the vibrating body 605, so it 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 be ON by an ON-OFF signal from a command means (not shown). Here, to explain this effect, an operation will be described in which 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 a torque is applied to the rotating shaft 607 of the vibration actuator 600 with the ON-OFF signal in the OFF state.

[0409] 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, since the position deviation is 0 with respect to the position command, the AC signal generating unit 15 generates a signal with the phase difference between the AC signals VA and VB being 0°. Next, the frequency of the AC signals VA and VB approaches the resonance frequency of the oscillator 605 in response to the thrust vibration amplitude command, and the thrust vibration amplitude approaches a predetermined amplitude. When the vibration amplitude of the oscillator 605 reaches a certain level, the frictional force between the oscillator 605 and the contact body 606, which has been reduced, falls below the torque applied to the rotating shaft 607, and the rotating shaft 607 starts to rotate. Here, the position is controlled in response to the position deviation and the speed estimate value, and the position returns to the position at the time of start.

[0410] 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, making it possible to reduce the amount of deviation from the initial position.

[0411] 42(a), a 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 estimated speed from the reference speed as described in the above embodiment and multiplying the result by the ratio (β) of the torque change to the speed change, to control the torque.

[0412] FIG. 42(b) is a diagram showing a second configuration example of a driving device for a vibration type actuator 600 according to a fifth embodiment of the present invention. The same components as those shown in FIG. 42(a) are given the same reference numerals, and detailed description thereof will be omitted. Reference numeral 75 denotes a speed & torque estimation unit which receives the second vibration component superimposed on the detected vibrating body 605 and a component corresponding to the vibration amplitude in the direction in which the vibrating body 605 pushes up the contact body 606, and estimates the rotation 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 amount calculation unit which receives a comparison result between the speed command signal, the estimated speed from the speed & torque estimation unit 75, and the speed command signal from the control amount calculation unit 74, performs a PI (proportional integral) calculation, and generates a torque command signal. Reference numeral 77 denotes a comparison means which compares the torque command signal with the estimated torque from the speed & torque estimation unit 75, and this comparison result is input to the control amount calculation unit 20, which performs a PI (proportional integral) calculation to generate a phase difference command signal.

[0413] The configuration in Fig. 42(b) has an additional torque control loop compared to the configuration in Fig. 42(a), so even faster control is possible than the configuration in Fig. 42(a). In other words, considering the above-mentioned start-up state, the magnitude of the torque applied to the outside can be detected when the speed changes slightly, so faster control is possible than with only a speed control loop.

[0414] [Sixth Example] Fig. 43 is a diagram showing an example of a schematic configuration of a vibration actuator 700. Fig. 44 is a diagram showing vibration modes of the vibration actuator 700. The schematic configuration and operating principle of a vibration actuator 700 according to a sixth embodiment will be described below with reference to Figs. 43 and 44.

[0415] The vibration actuator 700 according to the sixth embodiment includes a vibrating body 705 and a contact body 706, as shown in FIG. 43(b). As shown in FIG. 43(a), the vibrating body 705 is a cylindrical vibrating body made of a conductive material, and includes a piezoelectric body 703 and a piezoelectric body 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. The piezoelectric body 704 excites a vibration (stretching vibration mode) that expands and contracts the vibrating body 705 in the height direction of the cylinder, as shown in FIG. 44(c). The piezoelectric body 703 is configured to excite two bending vibrations in which the vibrating body 705 bends in two orthogonal directions, as shown in FIG. 44(a) and FIG. 44(b). The piezoelectric body 703 and the piezoelectric body 704 are sandwiched and fixed between the elastic body 701 by a fastening member (not shown).

[0416] The contact body 706 shown in FIG. 43(b) is a plate-shaped movable body that is pressed and contacted 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) on the paper. This contact body 706 can move in any direction on the XY plane by the vibration excited in the vibrating body 705. FIG. 43(c) shows the arrangement of electrodes provided on the piezoelectric body 703, and the electrodes are insulated from each other. The electrodes are formed by dividing a circle into four parts, and the electrodes 711 and 713 are electrodes for exciting bending vibration in the X direction in the vibrating body 705, and the electrodes 712 and 714 are electrodes for exciting bending vibration in the Y direction. In the following explanation, the electrodes 711, 712, 713, and 714 are piezoelectric bodies 711, 712, 713, and 714.

[0417] FIG. 45(a) is a diagram showing a first configuration example of a drive device for a vibration actuator 700 according to a sixth embodiment, and shows the configuration of a control device that controls the position of a contact body 706 in the XY plane.

[0418] Reference numeral 78 denotes an AC voltage generating unit, which outputs AC signals VA, VBX, and VBY based on the frequency command from control calculation unit 71, the VBX voltage amplitude command output by control amount calculation unit 20, and the VBY voltage amplitude command from control calculation unit 86. The AC signals VA and VBX, and the AC signals VA and VBY are signals with a phase difference of 90°, with the AC signal VA being set to a predetermined amplitude, and the AC signals VBX and VBY being 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 positive and negative inverted.

[0419] The AC signal VA is connected to the primary winding of the transformer 7, and a resistor 9 for current detection is connected to the other end, and the boosted AC voltage A is applied to the piezoelectric body 704 of the vibration actuator 700 connected to the secondary winding. The AC signals VBX and VBY are connected to the primary windings of the transformers 43 and 44, and a resistor 45 and a resistor 46 for current detection are connected to the other end, respectively. An AC voltage VBX having a phase inverted from the boosted AC voltage BX is applied to the piezoelectric body 711 and the piezoelectric body 713 connected to the secondary winding of the transformer 43. Similarly, an AC voltage VBY having a phase inverted from the boosted AC voltage BY is applied to the piezoelectric body 712 and the piezoelectric body 714 connected to the secondary winding of the transformer 44.

[0420] Here, the inductor values ​​of the secondary windings of the transformer 7, transformer 43, and transformer 44 are frequency-matched with the damping capacitances of the piezoelectric body 704 and the piezoelectric bodies 711 to 714. This allows a current to flow through the primary windings of the transformer 7, transformer 43, and transformer 44 that is roughly proportional to the vibration strain speed of the piezoelectric body 704 and the piezoelectric bodies 711 to 714. Resistor 9, resistor 45, and resistor 46 convert the current flowing through the primary windings of the connected transformers into a voltage to generate current signal IA, current signal IBX, and current signal IBY.

[0421] Each current signal indicates a different vibration state, and current signal IA (first detection signal) indicates the stretching vibration mode (thrust-up vibration mode) of vibrating body 704. Current signal IBX (second detection signal (X)) indicates the X-direction bending vibration mode (X-direction feed vibration mode) of vibrating bodies 711 and 713, and current signal IBY (second detection signal (Y)) indicates the Y-direction bending vibration mode (Y-direction feed vibration mode) of vibrating bodies 712 and 714.

[0422] Next, a configuration related to speed 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 signal IBX and the current signal IBY to detect the X-direction component and the Y-direction component of the second vibration component, respectively. The speed estimation unit 80 receives the X-direction component and the Y-direction component of the second vibration component detected here, the vibration amplitude of the stretching vibration mode (thrust-up vibration mode) of the vibrator 704, and the values ​​of the VBX voltage amplitude command and the VBY voltage amplitude command. Based on these inputs, the speed estimation unit 80 detects the speed in the X direction (estimated X speed) and the speed in the Y direction (estimated Y speed).

[0423] The detected estimated X speed and estimated Y speed are integrated by integration means 81 and 82, and converted into an X position and a Y position, respectively. The X position and the Y position indicate the change (displacement) from the initial value of integration means 82. The X position and the Y position are compared with an X position command and a Y position command from a command means (not shown) by comparison means 73 and comparison means 83, respectively, and an X speed command and a Y speed command are generated by control amount calculation unit 74 and control amount calculation unit 84 according to each comparison result. Next, the X speed command and the Y speed command are compared with an estimated X speed and an estimated Y speed by comparison means 19 and comparison means 85, respectively, and a VBX voltage amplitude command and a VBY voltage amplitude command are generated by control amount calculation unit 20 and control amount calculation unit 86 according to each comparison result. The position in the X direction and the position in the Y direction of contact body 706 are controlled by the control device operating in this manner.

[0424] Furthermore, the integrating means 81 and integrating means 82 can reset errors accumulated due to integration errors by means of an X reset signal and a Y reset signal, respectively, from the outside.

[0425] FIG. 45(b) is a diagram showing a second configuration example of a drive device for a vibration actuator 700 according to the sixth embodiment, which is a configuration obtained by removing the minor speed loop control system from the configuration in FIG. 45(a).

[0426] 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. [Explanation of symbols]

[0427] 100, 200, 300, 400, 500, 600, 700 Vibration 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 section 16, 79 Second vibration component detector 17 Thrust vibration amplitude detection unit 18, 80 Speed ​​estimation part 75 Speed ​​& Torque Estimation Unit 19, 70, 73, 77, 83, 85 means of comparison 20, 71, 74, 76, 84, 86 Control amount calculation means 3, 4, 203, 204, 303, 304, 403, 404, 504~509, 611~614, 703, 704, 711~714 Piezoelectric 9, 10, 45, 46 Resistance 7, 8, 43, 44, 61-65 Trans 34 CPU 50, 52 Filter

Claims

1. A control device for a vibration type actuator, comprising: a vibrator having an elastic body and an electromechanical energy conversion element; and a contact body in contact with the elastic body, wherein the vibrator and the contact body move relatively in a predetermined moving direction due to vibration of the vibrator, The vibration is a first vibration component generated in the vibrating body by a voltage applied to the electromechanical energy conversion element; 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 a relative velocity between the vibrating body and the contact body based on the signal.

2. the electromechanical 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 is a driving vibration in a first direction generated based on one of a sum or a difference between a third vibration component generated by the first driving voltage and a fourth vibration component generated by the second driving voltage, and a driving vibration in a second direction generated based on the other of the sum or the difference between the third vibration component generated by the first driving voltage and the fourth vibration component generated by the second driving voltage, the second vibration component includes at least one vibration component of a driving vibration in the first direction and a driving vibration in the second direction, The control device according to claim 1, characterized in that 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. 3. The control device according to claim 2, wherein a signal corresponding to the second vibration component is detected from a difference between an amplitude of the first detection signal and an amplitude of the second detection signal.

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

5. 5. The control device according to claim 4, wherein the Lissajous figure is drawn with a first axis representing the first detection signal and a second axis representing the second detection signal.

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

7. A vector based on the amplitude and phase of the first detection signal is called 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 between 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 a normal direction of the first vibration vector is defined as a normal direction component, a difference between the same direction components of the first signal vector and the second signal vector; and a difference between the normal components of the first signal vector and the second signal vector; and From the ratio set according to the magnitude of the first vibration vector, 3. The control device according to claim 2, further comprising a signal corresponding to said second vibration component being detected.

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

9. one of the sum signal and the difference signal of the first detection signal and the second detection signal is a reference signal, and the other is a measurement target signal; The phase of the reference signal is set as a reference phase, 3. The control device according to claim 2, wherein the 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. one of the sum signal and the difference signal of the first detection signal and the second detection signal is a reference signal, and the other is a measurement target signal; The phase of the reference signal is set as a reference phase, 3. The control device according to claim 2, wherein the signal corresponding to the second vibration component is detected by synchronously detecting the signal to be measured with a reference signal generated with a phase difference set relatively to the reference phase.

11. 3. The control device according to claim 2, further comprising: a first comparison signal corresponding to the first detection signal and a second comparison signal corresponding to the second detection signal, based on at least one of an amplitude, a phase difference, and a frequency of a voltage based on the first signal and the second signal; and a signal corresponding to the second vibration component is detected from a difference between the first detection signal and the first comparison signal and a difference between the second detection signal and the second comparison signal.

12. 3. The control device according to claim 2, further comprising: a first comparison signal corresponding to a sum of the first detection signal and the second detection signal; or a second comparison signal corresponding to a difference between the first detection signal and the second detection signal; based on at least one of an amplitude, a phase difference, and a frequency of a voltage based on the first signal and the second signal; and detecting 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. The control device according to 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 electromechanical 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 is a driving vibration in a first direction generated based on the first driving voltage and a driving vibration in a second direction generated based on the second driving voltage; the second vibration component includes a vibration component in at least one of the first direction and the second direction, The control device according to claim 1, characterized in that 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. 16. The control device according to claim 15, wherein a signal corresponding to the second vibration component is detected from a difference between an amplitude of a sum of the first detection signal and the second detection signal and an amplitude of a 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 parameters that change depending on tilt, including tilt angle, minor axis, major axis, height, and width, in a Lissajous figure drawn using the first detection signal and the second detection signal.

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

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

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

21. 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 a normal direction of the first vibration vector is defined as a normal direction component; A 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; a 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; 16. The control device according to claim 15, wherein a signal corresponding to the second vibration component is detected from a ratio set in accordance with the magnitude of the first vibration vector.

22. one of the first detection signal and the second detection signal is a reference signal and the other is a measurement target signal; The phase of the reference signal is set as a reference phase, 16. The control device according to claim 15, wherein the 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. The control device according to 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. 16. The control device according to claim 15, further comprising: a control circuit for detecting a signal corresponding to the second vibration component from a difference between the first detection signal and the first comparison signal, or a difference between the second detection signal and the second comparison signal, the control circuit generating a signal corresponding to the second vibration component from a difference between the first detection signal and the first comparison signal, or a difference between the second detection signal and the second comparison signal, based on an amplitude, a phase difference, and a frequency of a voltage based on the first signal and the second 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. 25. 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, the first driving voltage excites the first natural vibration and the second driving voltage excites the second natural vibration.

29. A control device 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 electro-mechanical 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 body is 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. 25. The control device according to claim 2, wherein the first and second detection signals are signals corresponding to outputs of an electro-mechanical energy conversion element.

32. A control device as claimed 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 currents flowing due to the first drive voltage and the second drive voltage.

33. 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 a vibration velocity of the vibrator.

34. 25. The control device according to claim 2, wherein the signal corresponding to the second vibration component varies with respect to 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 drive 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. 2. The control device according to claim 1, further comprising: a control unit for detecting a force acting between said vibrator and said contact body based on a predetermined reference value of the speed and said speed.

37. 2. The control device according to claim 1, wherein the displacement between the vibrating body and the contact body is detected based on the integral of the velocity.

38. 2. The control device according to claim 1, wherein the vibration type actuator is controlled based on a speed command signal and the detected speed.

39. 37. The control device of claim 36, wherein the control device controls the vibration actuator based on a force command signal and the detected force.

40. 38. The control device according to claim 37, wherein the vibration type actuator is controlled based on a displacement command signal and the detected displacement.

41. 39. The control device according to claim 38, further comprising a position detection means for detecting a 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 having a vibrator including an elastic body and an electromechanical energy conversion element, and a contact body in contact with the elastic body; A control device according to any one of claims 1 to 12 and 15 to 24, A vibration type driving device in which the vibrating body and the contact body move relatively in a predetermined moving direction due to vibration of the vibrating body.

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