JP2013059143A - Multi-degree of freedom actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-degree of freedom actuator which can be made compact.SOLUTION: In order to match the direction of translation thrust with the direction of a drive vector generated by receiving the translation thrust, the multi-degree of freedom actuator Da comprises a plurality of more than two translation thrust elements 2 generating the translation thrust, a rotating body 1 engaging with the plurality of translation thrust elements 2 with a predetermined friction force, and a drive control unit which controls driving of the plurality of translation thrust elements 2. In order to achieve a degree of freedom that cannot be achieved directly by the plurality of translation thrust elements 2, the drive control unit controls the plurality of translation thrust elements 2 so that at least two of a plurality of remaining translation thrust elements 2 are driven in a period when one of the plurality of translation thrust elements 2 is stopped.

Description

  The present invention relates to a multi-degree-of-freedom actuator that can move around a plurality of rotation axes.

  Actuators that convert input energy into physical motion are incorporated into various devices that perform motion. For example, in an apparatus that handles light, an actuator is used, for example, for driving a focus lens or a zoom lens of an imaging optical system, and for example, an optical axis when a laser beam is incident on an optical modulator or an optical fiber. It is used for alignment, for example, for changing the monitoring direction of a monitoring camera or the like. It is desirable that an actuator used for driving along the optical axis direction of the lens, aligning the optical axis, changing the monitoring direction, and the like can generate movement in a plurality of directions depending on the application. An actuator capable of generating such movements in a plurality of directions is disclosed in Patent Document 1, for example.

  The device disclosed in Patent Document 1 is formed of a material attracted by magnetic force, or a rotationally driven sphere having a portion made of a material attracted by magnetic force, and a base for supporting the sphere. And a drive unit configured by a first, second, and third actuator unit, wherein each of the first, second, and third actuator units is expanded by application of a drive signal. The first, second, and third piezoelectric elements are disposed so that the first, second, and third piezoelectric elements extend substantially orthogonal to each other. One end of each is fixed to each other at one intersection to constitute a driving chip, and the other ends of the first, second and third are fixed to the base to support the driving chip so as to be movable in a three-dimensional direction. The first, second and third actuators The sphere unit is rotatably supported by the drive chip, and the base is interposed between the sphere and a drive unit that rotationally drives the sphere by friction between the intersection and the sphere. And a magnetic field generator configured to generate a variable magnetic field for adjusting a frictional force between the sphere and the piezoelectric unit. In the apparatus having such a configuration, drive torque is generated along the drive axis of the drive circle drawn by the drive chips of the first, second, and third actuator units, and the vector sum of these drive torques is actually a sphere. Is a driving torque for rotationally driving (see paragraph [0028]). In paragraph [0015] of Patent Document 1, the sphere is rotationally driven in an arbitrary direction by adjusting the extension amount by adjusting the drive signals applied to the first, second and third actuator units. It is described that it can be made.

JP 2010-045895 A

  By the way, in the apparatus disclosed in Patent Document 1, as described above, each of the first, second, and third actuator units is expanded by application of a drive signal. The piezoelectric element is combined in a triangular pyramid shape and has a drive chip at its apex, and the sphere is rotationally driven by a drive torque along a drive shaft generated by causing the drive chip to perform a circular motion. is there. For this reason, the actuator unit needs a predetermined size with a triangular pyramid shape. Further, since the circuit for generating the driving signal for the piezoelectric element is required for each of 3 × 3 = 9 piezoelectric elements, nine sets are required. For this reason, it is difficult to reduce the size of the apparatus disclosed in Patent Document 1 in terms of structure and circuit scale.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a multi-degree-of-freedom actuator that can be reduced in size.

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, the multi-degree-of-freedom actuator according to one aspect of the present invention includes three or more generating the translation thrust so that the direction of the translation thrust and the direction of the drive vector generated by receiving the translation thrust coincide with each other. A plurality of translational thrust elements; a rotating body that engages the plurality of translational thrust elements with a predetermined frictional force; and a drive control unit that controls driving of the plurality of translational thrust elements; In order to realize a degree of freedom that cannot be directly realized by the plurality of translation thrust elements, a plurality of remaining translation thrusts are stopped during a period in which one of the plurality of translation thrust elements is stopped. The plurality of translation thrust elements are controlled so as to drive at least two of the elements.

  Since the multi-degree-of-freedom actuator having such a configuration uses a plurality of translational thrust elements that can be reduced in size, it is possible to reduce the size.

  In the multi-degree-of-freedom actuator having such a configuration, the one translational thrust element rotates the rotating body around an axis orthogonal to the direction of the translational thrust, and thus the plurality of translational thrust elements are: The rotating body is rotated about an axis orthogonal to the direction of the resultant vector of translational thrusts. Therefore, in the multi-degree-of-freedom actuator having such a configuration, there is a degree of freedom that cannot be directly realized by the plurality of translation thrust elements due to the arrangement positions of the plurality of translation thrust elements with respect to the rotating body. May end up. However, in the multi-degree-of-freedom actuator configured as described above, at least two of the remaining plurality of translation thrust elements during the period in which the drive control unit stops one of the plurality of translation thrust elements. Since the drive of the plurality of translation thrust elements is controlled so as to drive a plurality of translation thrust elements, the multi-degree-of-freedom actuator having the above configuration cannot be directly realized by the plurality of translation thrust elements. Can be realized in a pseudo manner.

  The translational thrust means a force that pushes in only one predetermined direction, and the predetermined one direction includes at least one of a positive direction and a negative direction. Therefore, the translational thrust element may be an element capable of generating a translational thrust only in the positive direction, an element capable of generating a translational thrust only in the negative direction, or a translational thrust in both positive and negative directions. The element which can generate | occur | produce may be sufficient.

  The degrees of freedom directly realized by the plurality of translation thrust elements are the degrees of freedom directly realized by one of the plurality of translation thrust elements and 2 of the plurality of translation thrust elements. This refers to the degree of freedom that is directly realized by the synthesis by driving two or more simultaneously.

  In another aspect, in the above-described multi-degree-of-freedom actuator, preferably, the drive control unit stops a drive period in which the translational thrust element is driven and driving of the translational thrust element following the drive period. When the drive of the translational thrust element is controlled by repeating a drive stop period, and a period composed of the drive period and the drive stop period following the drive transmission period is defined as one cycle, at least Controlling the plurality of translational thrust elements including one different period.

  The multi-degree-of-freedom actuator configured as described above stops one of the plurality of translation thrust elements by controlling the plurality of translation thrust elements including at least one different period. Control of the plurality of translation thrust elements that drives at least two of the remaining plurality of translation thrust elements during the period can be realized. That is, the multi-degree-of-freedom actuator having such a configuration can realize the control of the plurality of translational thrust elements by a relatively simple control of varying the period (frequency).

  In another aspect, in the above-described multi-degree-of-freedom actuator, preferably, the drive control unit stops driving of the translational thrust element and driving of the translational thrust element following the driving period. The drive stop period is repeated to control the drive of the translation thrust element, and at least one of the plurality of translation thrust elements is stopped from repeating the drive period and the drive stop period. It is to control including a blank period.

  The multi-degree-of-freedom actuator configured as described above is configured to control at least one of the plurality of translation thrust elements including the blank period, so that one translation thrust element of the plurality of translation thrust elements. The control of the plurality of translation thrust elements for driving at least two of the plurality of translation thrust elements remaining in the remaining period can be realized. That is, the multi-degree-of-freedom actuator having such a configuration can realize the control of the plurality of translational thrust elements by a relatively simple control of providing the blank period.

  In this aspect, the first aspect of controlling the plurality of translation thrust elements so as to control at least one of the plurality of translation thrust elements including the blank period, and at least one of the above-described elements And a second mode of controlling the plurality of translation thrust elements so as to control at least one of the plurality of translation thrust elements including the blank period.

  In another aspect, in the above-described multi-degree-of-freedom actuator, preferably, the drive control unit stops driving of the translational thrust element and driving of the translational thrust element following the driving period. Driving the translational thrust element by repeating the drive stop period, and when the ratio between the drive period and the drive stop period is defined as a drive stop ratio, at least one different drive is performed. Controlling the plurality of translational thrust elements including a stop ratio.

  The multi-degree-of-freedom actuator having such a configuration controls one of the plurality of translation thrust elements by including at least one different drive stop ratio, thereby allowing one of the plurality of translation thrust elements to be controlled. Control of the plurality of translation thrust elements that drives at least two translation thrust elements among the remaining plurality of translation thrust elements can be realized during the stop period. That is, the multi-degree-of-freedom actuator having such a configuration can realize the control of the plurality of translational thrust elements by a relatively simple control of varying the drive stop ratio (drive stop duty ratio).

  This aspect includes the third aspect in which the plurality of translation thrust elements are controlled including the at least one different driving stop ratio described above, the at least one different period as described above, and the at least one above-described period. A fourth aspect of controlling the plurality of translation thrust elements including different drive stop ratios, including at least one different drive stop ratio as described above, and at least one of the plurality of translation thrust elements being the blank A fifth aspect of controlling the plurality of translational thrust elements to control including a period; and at least one different drive stop ratio as described above; including at least one different period as described above; and A sixth aspect of controlling the plurality of translation thrust elements so as to control at least one of the plurality of translation thrust elements including the blank period is included.

  The multi-degree-of-freedom actuator according to the present invention can be miniaturized, and can realize a degree of freedom that cannot be directly realized by the plurality of translational thrust elements.

It is a figure which shows the structure of the multi-degree-of-freedom actuator in embodiment. It is a figure which shows the structure of the translational thrust element in the multi-degree-of-freedom actuator of embodiment. It is a figure which shows the structure of the 1st aspect of the drive control part in the multi-degree-of-freedom actuator of embodiment. It is a figure which shows the structure of the 2nd aspect of the drive control part in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating operation | movement of the direct freedom degree of the multi-degree-of-freedom actuator in embodiment. It is a figure for demonstrating operation | movement of the pseudo | simulation degree of freedom of the multi-degree-of-freedom actuator in embodiment. It is a figure for demonstrating the drive state of the 1st aspect of each translation thrust element in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the drive state of the 2nd aspect of each translational thrust element in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the drive state of the 3rd aspect of each translation thrust element in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the 1st engagement aspect of the translation thrust element and rotary body in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the 2nd engagement aspect of the translation thrust element and rotary body in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the 3rd engagement aspect of the translation thrust element and rotary body in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the 4th engagement aspect of the translation thrust element and rotary body in the multi-degree-of-freedom actuator of embodiment. It is a figure for demonstrating the other structure of the multi-degree-of-freedom actuator in embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably.

  FIG. 1 is a diagram illustrating a configuration of a multi-degree-of-freedom actuator according to the embodiment. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. Note that FIG. 1A shows the engaged state between the rotating body 1 and the plurality of translational thrust elements 2, and the rotating body 1 is shown in a transparent state and its outline is shown. FIG. 2 is a diagram illustrating a configuration of a translational thrust element in the multi-degree-of-freedom actuator of the embodiment. FIG. 2A is a side view, and FIG. 2B is an exploded perspective view. FIG. 3 is a diagram illustrating a configuration of a first aspect of the drive control unit in the multi-degree-of-freedom actuator of the embodiment. FIG. 4 is a diagram illustrating a configuration of a second mode of the drive control unit in the multi-degree-of-freedom actuator of the embodiment.

  The multi-degree-of-freedom actuator Da is a device that can move the rotating body 1 around the axes of a plurality of rotating shafts. For example, as shown in FIGS. 1 to 4, the rotating body 1 and a plurality of translational thrusts An element 2, a base 3, a driver unit 4, and a control unit 5 are provided. The structural configuration of the multi-degree-of-freedom actuator Da will be described first, and then the electrical configuration will be described below.

  First, the rotating body 1, the plurality of translational thrust elements 2 and the base 3 which are structural configurations will be described. The base 3 is a member that supports the rotating body 1 and the plurality of translational thrust elements 2 and is, for example, a housing or a frame. By fixing each of the plurality of translation thrust elements 2 to the base 3, the rotating body 1 and the plurality of translation thrust elements 2 are supported by the base 3. For fixing between the base 3 and each of the plurality of translational thrust elements 2, for example, adhesive fixing with an adhesive is used. For example, other methods such as screwing or brazing may be used for the fixing. Further, for example, the translation thrust element 2 may be fixed to the base 3 by integrally forming a support member 23 and a base 3 shown in FIG.

  Each of the plurality of translation thrust elements 2 is a device that generates a translation thrust. As described above, the translational thrust means a force that pushes in only one predetermined direction, and the predetermined one direction includes at least one of a positive direction and a negative direction. The plurality of translation thrust elements 2 are three or more, and in the present embodiment, the three first to third translation thrust elements 2-1, 2-2, 2-3, which are the minimum number within the above range, are used. It has. These three first to third translational thrust elements 2-1 to 2-3 are arranged so that the contact points P1 to P3 with respect to the rotating body 1 are symmetrical. In the example shown in FIG. 1, the contact points P1 to P3 are point-symmetric. To illustrate this, FIG. 1A shows a set of points equidistant from the symmetry center P0. A circle is shown by a broken line. These contact points P1 to P3 are points (point contacts) and are located on this circle. More specifically, the three first to third translational thrust elements 2-1 to 2-3 are arranged at approximately equal intervals of about 120 degrees.

  In the present specification, when referring generically, it is indicated by a reference symbol without a suffix, and when referring to an individual configuration, it is indicated by a reference symbol with a suffix.

  As the translation thrust element 2, any device that generates a translation thrust can be used so that the direction of the translation thrust and the direction of the drive vector generated by receiving the translation thrust coincide with each other. In the embodiment, the translational thrust element 2 is engaged with the rotating body 1 with a predetermined frictional force and generates the translational thrust by reciprocating in a predetermined direction. More specifically, the translational thrust element 2 is a drive device that includes a motion excitation member that engages with the rotating body 1 with a predetermined frictional force and performs asymmetric reciprocation between a forward path and a return path in a predetermined direction. is there. As an example of such a drive device, there is a drive device using an electromechanical conversion element such as a piezoelectric element, which is referred to as SIDM (Smooth Impact Drive Mechanism, “SIDM” is a registered trademark). As an example of the SIDM, there is a driving device having a configuration shown in FIG.

  The translation thrust element 2 having the configuration shown in FIG. 2 includes an electromechanical conversion element 21, a motion excitation member 22, and a support member 23.

  The electromechanical conversion element 21 is an element that converts input electrical energy into mechanical energy, that is, mechanical motion. For example, the piezoelectric element 21 that converts input electrical energy into mechanical expansion and contraction motion by a piezoelectric effect, and the like. It is.

The piezoelectric element 21 as the electromechanical conversion element 21 includes, for example, a laminate and a pair of external electrode portions. The laminated body is formed by alternately laminating a plurality of thin film (layered) piezoelectric layers made of a piezoelectric material and a thin film (layered) internal electrode layer having conductivity. In the present embodiment, the laminate has a quadrangular prism shape as shown in FIG. Each internal electrode layer is formed such that one end (one edge) thereof faces the outside. More specifically, one first internal electrode layer facing each other through the conductive layer among the internal electrode layers has one end facing a predetermined side surface (for example, the left side surface) of the multilayer body. The other second internal electrode layer is formed so that one end thereof faces the side surface (in the above example, the right side surface) facing the predetermined side surface. In this way, each internal electrode layer is configured such that a part thereof alternately faces the outside with a pair of outer peripheral side surfaces facing each other. Examples of the piezoelectric material include so-called PZT, crystal, lithium niobate (LiNbO ₃ ), potassium niobate tantalate (K (Ta, Nb) O ₃ ), barium titanate (BaTiO ₃ ), lithium tantalate (LiTaO ₃ ). And inorganic piezoelectric materials such as strontium titanate (SrTiO ₃ ).

  The pair of external electrode portions are formed on a predetermined surface of the outer peripheral surface of the multilayer body, and supply the electric energy to the multilayer body. More specifically, one first external electrode portion in the pair of external electrode portions is a thin film along the stacking direction on the left side surface so as to be electrically connected to the one first internal electrode layer. The other second external electrode portion is formed in the shape (layered), and the other second internal electrode layer is formed into a thin film (layered) along the stacking direction on the right side surface so as to be electrically connected to the other second internal electrode layer. Formed with. In this manner, the pair of external electrodes are sequentially conducted alternately with the internal electrode layers, and supplies the electric energy to the piezoelectric layers of the multilayer body.

  In the piezoelectric element 21 as an example of the electromechanical conversion element 21 having such a configuration, a predetermined voltage is applied to the pair of external electrode units from an external circuit such as a drive control unit illustrated in FIGS. When the electric energy is supplied to each piezoelectric layer of the multilayer body, the multilayer body expands or contracts in the stacking direction due to the piezoelectric effect of each piezoelectric layer.

  The motion excitation member 22 is fixed to a piezoelectric element 21 as an electromechanical conversion element 21, and mechanical energy converted from electric energy is transmitted by the piezoelectric element 21. The mechanical energy is transmitted to the rotating body 1 around a predetermined axis. It is a member that causes movement. More specifically, in this embodiment, the motion excitation member 22 is a columnar (axial) member fixed to one end of the piezoelectric element 21 in the stacking direction of the stacked body. For this fixing, for example, an adhesive such as a thermosetting adhesive is used. As the material of the motion excitation member 22, any material such as metal, ceramic, glass, carbon, and a composite material including at least one of them can be used. In the present embodiment, the motion excitation member 22 is formed of a carbon fiber composite. The cross section orthogonal to the longitudinal direction of the motion excitation member 22 may be, for example, any shape such as a rectangle, a polygon, an ellipse, and a circle. The motion excitation member 22 includes a polygonal column, a cylinder, and a weight (polygonal cone). In this embodiment, as shown in FIG. 2, the cross section of the motion excitation member 22 that makes point contact with the rotating body 1 is a chamfered rectangle. The length in the longitudinal direction of the motion excitation member 22 is appropriately determined depending on the size of the rotating body 1 and the like. However, the rotating body 1 does not move in the longitudinal direction of the motion excitation member 22, and the motion excitation member Since 22 only needs to make point contact with the rotating body 1, it can be shortened. Therefore, the translational thrust element 2 configured as shown in FIG. 2 contributes to the downsizing of the multi-degree-of-freedom actuator Da, and is suitable.

  The support member 23 is a member that supports the piezoelectric element 21 and the motion excitation member 22 by holding them. As shown in FIG. 2, the support member 23 is formed in a substantially U shape (substantially C shape, substantially U shape). The piezoelectric element 21 and the motion excitation member 22 are supported by the support member 23 by fitting a connection portion between the piezoelectric element 21 and the motion excitation member 22 into the concave portion in the substantially U shape. More specifically, the connection portion between the piezoelectric element 21 and the motion excitation member 22 has three surfaces (a lower surface on the peripheral surface and a pair of side surfaces) excluding one surface (an upper surface on the peripheral surface). Each surface) is in contact with the support member 23. When the connection portion is fitted, a thermosetting adhesive is applied to the outer peripheral surface of the connection portion between the piezoelectric element 21 and the motion excitation member 22 or the inner peripheral surface of the concave portion of the support member 23, and the heating step. As a result, the adhesive is thermally cured, and as a result, the piezoelectric element 21 and the motion excitation member 22 are bonded and fixed to the support member 23. In the example shown in FIG. 2, the connection portion between the piezoelectric element 21 and the motion excitation member 22 is connected and fixed to the support member 23, but the motion excitation member 22 is connected to the support member 23. The piezoelectric element 21 may be connected to the support member 23 and fixed. The support member 23 is fixed to the base 3 on the back surface facing the concave portion in the substantially U shape. More specifically, in the side view, the three translational thrust elements 2-1 to 2-3 have the respective motion excitation members 22 with respect to the base 3 at a predetermined angle θ1 (on the horizontal plane of the base 3). It is fixed and arranged so as to be inclined at a predetermined angle θ1) from the horizontal plane as 0 degree. For the fixing between the base 3 and the support member 23 of the translational thrust element 2, for example, adhesive fixing with an adhesive is used. For example, other methods such as screwing or brazing may be used for the fixing. In the top view, as described above, the three translational thrust elements 2-1 to 2-3 are arranged at approximately equal intervals of about 120 degrees.

  Since the support member 23 substantially holds the position in this way, when the laminate of the piezoelectric elements 21 expands and contracts as described above, the expansion and contraction is transmitted to the motion excitation member 22, and the motion excitation member 22 21 reciprocates in conjunction with the expansion and contraction of the laminate in 21.

  The rotating body 1 is a member that engages with a plurality of translational thrust elements 2 with a predetermined frictional force. The rotating body 1 can be formed of any material, but in order to improve durability, the rotating body 1 should be formed of a material having excellent wear resistance such as a paper friction material used for a clutch mechanism of a car, for example. Is preferred. In the present embodiment, the rotating body 1 is formed of a magnetic material such as iron, as will be described later. The entire rotating body 1 may be formed of the magnetic body, and only the surface thereof may be formed of the magnetic body. Further, only a part of the surface on which the magnetic force acts may be formed of the magnetic material. Further, a part in the rotating body 1 may be formed of the magnetic body. In this case, the deviation may be present, but it is preferable that there is no deviation from the viewpoint of easily performing drive control of the rotating body.

  The surface that engages with the motion excitation member 22 in the rotator 1 may be a curved surface or a flat surface, and the rotator 1 may be a solid member having an arbitrary shape. Therefore, the rotating body 1 may be, for example, a polyhedron as well as a sphere, an elliptic sphere, and a hemisphere from which a part thereof is cut off. The polyhedron is more preferable as the number of faces such as a 14-hedron and a 20-hedron is larger. And in order to move the rotary body 1 more smoothly, it is preferable that the rotary body 1 is a member of the shape where the surface engaged with the some translational thrust element 2 is a curved surface. In this embodiment, as shown in FIG. 1, the rotating body 1 is a sphere or a spherical shell.

  In the configuration in which the rotating body 1, the motion excitation member 22 of the translational thrust element 2 and the base 3 are arranged in this order in the direction in which gravity acts (direction of gravity action), the translational thrust element 2 rotates. It is possible to engage the plurality of translational thrust elements 2 and the rotating body 1 with the predetermined frictional force by utilizing the weight of the body 1, but in this configuration, there are restrictions on use and design. Arise. More specifically, for example, when the multi-degree-of-freedom actuator Da is tilted, the rotating body 1 may roll down. For this reason, the multi-degree-of-freedom actuator Da must be used at a fixed location, which causes restrictions on use. Alternatively, in order to prevent the rotator 1 from falling, a fall preventing member is separately required, and design restrictions arise. In order to reduce such usage restrictions and design restrictions, in this embodiment, the multi-degree-of-freedom actuator Da engages the plurality of translational thrust elements 2 and the rotating body 1 with the predetermined frictional force. An urging member that generates an urging force to be generated is further provided. Since such an urging member can be configured more simply, for example, an elastic body such as a compression coil spring or a leaf spring may be used. Such an elastic body is obtained by considering a polygon that apexes the contact points P (P1 to P3) where the motion excitation members 22 of the plurality of translation thrust elements 2 and the rotating body 1 contact each other. Is arranged so as to generate an urging force in a direction toward the plurality of translational thrust elements 2 along the normal direction of the polygon passing through the center of gravity of the polygon. Further, for example, the urging member may be an air compressor that generates a suction attraction by air by sucking air. Such an urging member based on the attractive force attracts the air and thereby apexes the contact points P (P1 to P3) where the motion excitation members 22 of the plurality of translational thrust elements 2 and the rotating body 1 come into contact with each other. When a polygon is considered, it is arranged so as to generate a biasing force in the direction toward the plurality of translational thrust elements 2 along the normal direction of the polygon passing through the center of gravity of the polygon. For example, the biasing member may be a magnet that generates a magnetic force. In the present embodiment, the base 3 is formed by a magnet such as a permanent magnet, and the rotating body 1 is, for example, described above in order to interact with the magnetic field formed by the magnet of the base 3. Thus, it is formed of a magnetic material such as iron. As shown in FIG. 1, the magnetic base 3 acts on the rotating body 1 with a magnetic force (indicated by a relatively thick arrow in FIG. 1B) from the center point Pc toward the base 3. The magnetic force passes through the polygonal center of gravity that apexes the contact points P (P1 to P3) where the motion excitation members 22 of the plurality of translational thrust elements 2 and the rotating body 1 are in contact with each other. It acts on the motion excitation members 22 of the plurality of translational thrust elements 2 substantially equally (indicated by relatively thin arrows in FIG. 1B). Thereby, the motion excitation member 22 of the plurality of translation thrust elements 2 can stably hold the rotating body 1 by this magnetic force. Then, by using the magnetic force to generate the urging force, the plurality of translational thrust elements 2 and the rotating body 1 can be engaged with the predetermined frictional force with an extremely small structure. The magnetic body of the rotating body 1 is preferably a paramagnetic body. By forming the rotator 1 with a paramagnetic material in this way, the magnetic field of the magnet of the base 3 is similarly affected regardless of the rotation state of the rotator 1. The drive control of the rotating body 1 (control of a plurality of translational thrust elements 2) becomes easier. In the above description, the base 3 is formed of a magnet. However, a magnet such as a permanent magnet or an electromagnet may be provided separately from the base 3.

  Next, the drive unit 4 and the control unit 5 which are electrical configurations will be described. The drive unit 4 and the control unit 5 are drive control units that control the rotation direction, the rotation amount (rotation displacement), the rotation speed, and the like of the rotating body 1 by controlling the driving of the plurality of translation thrust elements 2. An appropriate circuit is used for the drive control unit including the drive unit 4 and the control unit 5 according to the mode of the translational thrust element 2. When the translational thrust element 2 is the SIDM drive device shown in FIG. 2, for example, the H bridge type drive control circuit shown in FIG. 3 or the half bridge type drive control circuit shown in FIG. Used as

  The H bridge type drive control circuit shown in FIG. 3 includes a driver unit 4a and a control unit 5a. The driver unit 4a is a circuit that supplies power to the translational thrust element 2 by applying a predetermined drive voltage to the translational thrust element 2, and for example, as shown in FIG. 3, a transistor Q11 as four switching elements. , Q12, Q13, and Q14. The transistors Q11 and Q12 connected in series are connected between the power source + V and the ground, and the transistors Q13 and Q14 connected in series are connected in parallel to the transistors Q11 and Q12 connected in series. Then, the piezoelectric element 21 of the translational thrust element 2 is connected between a connection point between the transistor Q11 and the transistor Q13 and a connection point between the transistor Q13 and the transistor Q14. The control unit 5a controls the on / off of the transistors Q11 to Q14 in order to control each of the plurality of translation thrust elements 2 so as to drive the rotating body 1 with a desired rotation direction, rotation amount and rotation speed. To S14. Control signals S11 to S14 for turning on and off the transistors Q11 to Q14 are supplied from the control unit 5a to the control terminals of the transistors Q11 to Q14, respectively.

  The half-bridge type drive control circuit shown in FIG. 4 includes a driver unit 4b and a control unit 5b. The driver unit 4b is a circuit that supplies power to the translational thrust element 2 by applying a predetermined drive voltage to the translational thrust element 2, and for example, as shown in FIG. 4, a transistor Q21 as two switching elements. , Q22. The transistor Q21 and the transistor Q22 connected in series with each other are connected between the power source + V and the ground, and the piezoelectric element of the translational thrust element 2 is connected between the connection point of the series-connected transistors Q21 and Q22 and the ground. 21 is connected. The control unit 5b controls the on / off of the transistors Q21 and Q22 in order to control each of the plurality of translation thrust elements 2 so as to drive the rotating body 1 with a desired rotation direction, rotation amount, and rotation speed. , S22. Control signals S21 and S22 for turning on and off the transistors Q21 and Q22 are supplied from the control unit 5b to the control terminals of the transistors Q21 and Q22, respectively.

  Next, the operation of the multi-degree-of-freedom actuator Da having such a configuration will be described. FIG. 5 is a diagram for explaining the operation of the direct degrees of freedom of the multi-degree-of-freedom actuator in the embodiment. FIG. 5A is a diagram for explaining a translation vector having a degree of freedom directly realized by each of the translation thrust elements 2-1 to 2-3, and FIG. 5B is a diagram illustrating the translation vector. It is a figure for demonstrating the rotation vector which acts on the rotary body 1 of a sphere by. FIG. 6 is a diagram for explaining an operation of pseudo degrees of freedom of the multi-degree-of-freedom actuator in the embodiment. FIG. 7 is a diagram for explaining a driving state of the first aspect of each translational thrust element in the multi-degree-of-freedom actuator of the embodiment. FIG. 8 is a diagram for explaining a driving state of the second aspect of each translational thrust element in the multi-degree-of-freedom actuator of the embodiment. FIG. 9 is a diagram for explaining a driving state of the third aspect of each translational thrust element in the multi-degree-of-freedom actuator of the embodiment. 7 to 9, those drawings (A) are time charts showing the driving state of the first translational thrust element 2-1, and those figures (B) are the second translational thrust element 2-2. FIG. 6C is a time chart showing a driving state of the third translational thrust element 2-3. The horizontal axis in each figure represents time, and the vertical axis in each figure represents the driving state. The level “0” on the vertical axis in each figure represents the stop of driving (operation), and the level “1” on the vertical axis in each figure represents driving (operation).

  In order to rotationally move the rotary body 1 of the multi-degree-of-freedom actuator Da around a predetermined axis, one or a plurality of translational thrust elements 2 in the multi-degree-of-freedom actuator Da are driven (operated) to generate a translational thrust. Due to the generated translational thrust, the rotating body 1 engaged with the translational thrust element 2 with a predetermined frictional force rotates around a predetermined axis.

  This translational thrust is generated by the following operation when the translational thrust element 2 is the driving device of the SIDM shown in FIG.

  For example, in the H-bridge type drive control circuit including the driver unit 4a and the control unit 5a shown in FIG. 3, the transistors Q11 and Q4 and the transistors Q12 and Q13 provided at diagonal positions of the H-bridge are respectively connected to the control signals S11. The transistors Q11 and Q14 and the transistors Q12 and Q13 are driven in opposite phases with each other. As a result, a rectangular wave drive signal is applied to the piezoelectric element 21 of the translational thrust element 2. By setting the duty of the drive signal to about 0.7 ([high level time]: [low level time] = 7: 3), the translational thrust element 2 causes the piezoelectric element 21 to be driven by this drive signal. By performing asymmetric stretching vibration, the asymmetric stretching motion causes the motion excitation member 22 to perform asymmetric reciprocation with a speed difference between a forward path and a return path in a predetermined direction. For example, a thrust force that pushes only in the positive direction is generated. That is, the film stretches slowly in the positive direction and contracts rapidly in the negative direction. That is, the contraction speed in the negative direction is larger than the expansion speed in the positive direction. On the other hand, by setting the duty of the driving signal to about 0.3 ([high level time]: [low level time] = 3: 7), the translational thrust element 2 causes the piezoelectric element 21 to be asymmetrically expanded and contracted. Asymmetrical stretching vibration opposite to the movement is performed, and the movement excitation member 22 performs asymmetrical reciprocating motion with a reverse speed difference between the forward path and the backward path in the one direction due to the reverse asymmetrical stretching movement. As a result, the motion excitation member 22 generates a thrust force that pushes only in the negative direction in the one direction. That is, it slowly expands in the negative direction and rapidly contracts in the positive direction. That is, the contraction speed in the positive direction is larger than the expansion speed in the negative direction.

  For example, in the half-bridge type drive control circuit including the driver unit 4b and the control unit 5b shown in FIG. 4, the transistors Q21 and Q22 are driven in opposite phases by the control signals S21 and S22, respectively. As a result, a rectangular wave drive signal is applied to the piezoelectric element 21 of the translational thrust element 2 as described above, and the duty is adjusted as described above, so that the motion excitation member 22 of the translational thrust element 2 is applied to the motion excitation member 22 of the translational thrust element 2. Produces thrust that pushes in only one direction.

  Thus, the translational thrust element 2 is in a driving state when the driving signal is supplied. On the other hand, the translational thrust element 2 is in a driving stop state when the supply of the driving signal is stopped.

  In this way, the motion excitation member 22 performs a motion in which the speed change is a so-called sawtooth shape by the H bridge type drive control circuit or the half bridge type drive control circuit, and pushes the motion excitation member 22 in only one direction. Thrust is generated. FIG. 5A is a diagram showing the thrust generated in the motion excitation member 22 only in one direction as a translation vector.

  As shown in FIG. 5A, in the multi-degree-of-freedom actuator Da having the structure shown in FIG. 1, first, when the translational thrust element 2-1 operates, the translational thrust element 2-1 causes the translational thrust element 2-1. -1 in the direction from the piezoelectric element 21-1 toward the motion excitation member 22-1. As a result, the rotating body 1 engaged with the motion excitation member 22-1 of the translational thrust element 2-1 with a predetermined frictional force performs a rotational motion about the axis orthogonal to the translation vector V1. As shown in FIG. 5A, the X axis is set in the direction from the motion excitation member 22-1 to the piezoelectric element 21-1 in the translational thrust element 2-1, and the Y axis is set to be orthogonal to the X axis. When the XYZ coordinate system in which the Z axis is set so as to be orthogonal to the X axis and the Y axis is provided and the positive direction of the X axis is 0 degrees and the counterclockwise direction is the positive direction, the translation vector V1 is The rotation axis is in the +30 degree direction.

  When the translation thrust element 2-2 operates, the translation thrust element 2-2 causes a translation vector V2 in the direction from the piezoelectric element 21-2 to the motion excitation member 22-2 in the translation thrust element 2-2. Arise. As a result, the rotating body 1 engaged with the motion excitation member 22-2 of the translation thrust element 2-2 with a predetermined frictional force performs a rotational motion around the axis orthogonal to the translation vector V2. In the XYZ coordinate system, the translation vector V2 is in the 0 degree direction, and the rotation axis is in the +90 degree direction.

  When the translation thrust element 2-3 is operated, the translation thrust element 2-3 generates a translation vector V3 in the direction from the piezoelectric element 21-3 to the motion excitation member 22-3 in the translation thrust element 2-3. Arise. As a result, the rotating body 1 engaged with the motion excitation member 22-3 of the translational thrust element 2-3 with a predetermined frictional force performs a rotational motion around the axis orthogonal to the translation vector V3. In the XYZ coordinate system, the translation vector V3 is in the +60 degree direction, and the rotation axis is in the -30 degree direction.

  When a plurality of these three translational thrust elements 2-1 to 2-3 operate simultaneously, a composite vector of a plurality of translation vectors V generated by the plurality of translational thrust elements 2 operating is obtained. Acting on the rotator 1, the rotator 1 performs a rotational motion about an axis orthogonal to the combined vector. For example, all of these three translational thrust elements 2-1 to 2-3 are simultaneously operated with the translational thrust element 2-2 and the translational thrust element 2-3 in the same phase and the translational thrust element 2-1 in the opposite phase. In this case, as shown in FIG. 5B, a composite vector V is generated in the direction (X-axis direction) from the motion excitation member 22-2 to the piezoelectric element 21-2 in the translational thrust element 2-2. Then, with this composite vector V, the rotator 1 rotates around an axis (Y axis) orthogonal to the composite vector V. That is, the rotation vector in this case is in the Y-axis direction.

  When the rotary body 1 is rotated around the desired rotation axis, the translational thrust element 2 that does not contribute to the rotary movement may be in a stopped state, but may be in a slip state with respect to the rotary body 1. preferable. For example, when the translational thrust element 2 is the SIDM drive device shown in FIG. 2, the duty of the drive signal is about 0.5 ([high level time]: [low level time] = 5: 5). By doing so, the translational thrust element 2 is in a slip state with respect to the rotating body 1. As a result, the translational thrust element 2 is engaged with the rotating body 1 not by static frictional force but by dynamic frictional force, so that the rotating body 1 can smoothly rotate.

  By operating in this way, the multi-degree-of-freedom actuator Da in the present embodiment can move the rotating body 1 around the axes of a plurality of rotating shafts. And since the multi-degree-of-freedom actuator Da in this embodiment uses the several translational thrust element 2 which can be reduced in size, it becomes possible to reduce in size and to contact a rotary body in multiple places, Therefore A bigger driving force is given. Can be obtained. In addition, the multi-degree-of-freedom actuator Da in the present embodiment can be driven with high resolution of, for example, several hundred nanometers or less, and precise position control is possible.

  On the other hand, since it operates in this way, there is a degree of freedom that cannot be directly realized by the plurality of translation thrust elements 2 due to the arrangement positions of the plurality of translation thrust elements 2 with respect to the rotating body 1. There is a case. For example, in the configuration shown in FIG. 1, when a polygon that apexes the contact point P (P1 to P3) is considered, the rotation is performed with the polygon normal P0Pc passing through the center of gravity P0 of the polygon as the rotation axis. Motion (degree of freedom) cannot be directly realized by these three first to third translational thrust elements 2-1 to 2-3.

  For this reason, in the multi-degree-of-freedom actuator Da of the present embodiment, the drive control unit (drive unit 4 and control unit 5) is directly operated by the three first to third translational thrust elements 2-1 to 2-3. In order to realize a degree of freedom that cannot be realized automatically, the remaining plurality (in the period in which one of the first to third translational thrust elements 2-1 to 2-3 is stopped, These first to third translational thrust elements 2-1 to 2-3 are controlled so as to drive at least two of the two translational thrust elements 2 in the present embodiment. is there. As described above, the drive control unit controls the driving of the first to second translational thrust elements 2 so that the multi-degree-of-freedom actuator Da having such a configuration is directly realized by the plurality of translational thrust elements 2. The degree of freedom that cannot be realized can be realized in a pseudo manner.

  More specifically, when the drive of the first to third translational thrust elements 2-1 to 2-3 is controlled in this way, the movement of the rotating body 1 is restricted at the contact point with the translational thrust element 2 that has stopped driving. As a result, the rotating body 1 has only a rotational movement with a contact point with the translational thrust element 2 that has stopped driving as a fulcrum and a line segment passing through the fulcrum contact point and the center P0 of the rotating body 1 as a rotation axis. The translational thrust of the translational thrust element 2 being driven is canceled by the frictional force at the contact point where the other components except for the component contributing to the rotational motion serve as the fulcrum. Thus, the degree of freedom that cannot be directly realized by driving the plurality of translational thrust elements 2 is realized in a pseudo manner. For example, as shown in FIG. 6, during the period in which the driving of the third translational thrust element 2-3 is stopped and the remaining first and second translational thrust elements 2-1 and 2-2 are driven, the rotating body 1 is a rotary motion with a contact point P3 with the third translational thrust element 2-3 stopped driving as a fulcrum and a line segment P3P0 passing through the contact point P3 serving as the fulcrum and the center P0 of the rotating body 1 as a rotation axis. The translational thrusts of the first and second translational thrust elements 2-1 and 2-2 that are being driven can be obtained at the contact P3 where the other components excluding the component that contributes to the rotational motion are the fulcrums. Canceled by frictional force. Thus, a degree of freedom with the line segment P3P0 as the rotation axis that cannot be directly realized by driving the first to third translational thrust elements 2-1 to 2-3 is realized in a pseudo manner.

  Further, in the plurality of translation thrust elements 2, a rotational motion obtained by synthesizing the rotational motions restricted by the respective contacts is realized by sequentially switching the translation thrust elements 2 to be stopped in a clockwise direction or a counterclockwise direction. Thus, a degree of freedom that cannot be directly realized by the plurality of translational thrust elements 2 is realized in a pseudo manner. More specifically, in the first period, the driving of the first translational thrust element 2-1 is stopped and the remaining second and third translational thrust elements 2-2 and 2-3 are driven. As a result, this In the first period, the rotating body 1 has a contact P1 with the first translational thrust element 2-1 that has stopped driving as a fulcrum, and a line segment P1P0 that passes through the contact P1 serving as the fulcrum and the center P0 of the rotator 1. In the second period following the first period, the translational thrust element 2 that stops driving is switched, the driving of the second translational thrust element 2-2 is stopped, and the remaining The third and first translational thrust elements 2-3 and 2-1 are driven. As a result, in this second period, the rotating body 1 contacts the second translational thrust element 2-2 that has stopped driving. And a line segment P2P passing through the contact P2 serving as the fulcrum and the center P0 of the rotating body 1 Only in the third period following the second period, the translation thrust element 2 that stops driving is switched, and the drive of the third translation thrust element 2-3 is stopped, The remaining first and second translational thrust elements 2-1 and 2-2 are driven. As a result, in this third period, the rotating body 1 is in contact with the third translational thrust element 2-3 that has stopped driving. Only a rotational motion is generated with the contact point P3 as a fulcrum and the line P3P0 passing through the contact point P3 serving as the fulcrum and the center P0 of the rotating body 1 as a rotation axis. And control of these 1st thru | or 3rd period is repeated sequentially. As described above, the first to third translational thrust elements 2-1 to 2-3 are driven by cyclically performing the control of the first to third periods, so that the three first to third translational elements are driven. A rotational motion (degree of freedom) about the normal line P0Pc that cannot be directly realized by the third translational thrust elements 2-1 to 2-3 is realized in a pseudo manner.

  Then, during the period when one of the plurality of translation thrust elements 2 is stopped, at least two of the plurality of translation thrust elements 2 are driven. In addition, examples of a method for controlling the plurality of translational thrust elements include the following methods.

  The first method is a method of controlling the drive of the translation thrust element by repeating a drive period for driving the translation thrust element 2 and a drive stop period for stopping the drive of the translation thrust element 2 following the drive period. Then, when a period composed of the drive period and the drive stop period following the drive transmission period is defined as one period, a method of controlling a plurality of translational thrust elements 2 including at least one different period. is there. Such a multi-degree-of-freedom actuator Da using the first method cannot be directly realized by the plurality of translational thrust elements 2 by a relatively simple control of varying the period (frequency). Control of the plurality of translational thrust elements 2 for realizing the above can be realized.

  FIG. 7 shows driving patterns of the first to third translational thrust elements 2-1 to 2-3 in the multi-degree-of-freedom actuator Da configured as shown in FIG. 1 when such a first method is used. Yes. In the drive pattern shown in FIG. 7, the first and second translational thrust elements 2-1 and 2-2 are controlled at the same period (frequency), and the third translational thrust element 2-3 is controlled by the first and second translational thrust elements 2-3. The second translational thrust elements 2-1 and 2-2 are controlled with a period (frequency) different from the period (frequency).

  The second method is a method of controlling the driving of the translational thrust element 2 by repeating the driving period and the driving stop period following the driving period, and at least one of the plurality of translational thrust elements 2 is controlled. This is a method of controlling the unit including a blank period in which the repetition of the drive period and the drive stop period is stopped. The multi-degree-of-freedom actuator Da using the second method realizes a degree of freedom that cannot be directly realized by the plurality of translational thrust elements 2 by a relatively simple control of providing the blank period. Therefore, control of the plurality of translational thrust elements 2 can be realized.

  FIG. 8 shows driving patterns of the first to third translational thrust elements 2-1 to 2-3 in the multi-degree-of-freedom actuator Da configured as shown in FIG. 1 when such a second method is used. Yes. In the drive pattern shown in FIG. 8, the first to third translational thrust elements 2-1 to 2-3 are controlled with the same period (frequency), and the third translational thrust element 2-3 is connected to the drive period. Control is performed including a blank period in which the repetition with the drive stop period is stopped at a predetermined time interval.

  The third method is a method of controlling the driving of the translational thrust element 2 by repeating the driving period and the driving stop period following the driving period, and a ratio between the driving period and the driving stop period. Is a method for controlling the plurality of translational thrust elements 2 including at least one different drive stop ratio. Such a multi-degree-of-freedom actuator Da using the third method is directly realized by the plurality of translational thrust elements 2 by relatively simple control of varying the drive stop ratio (duty ratio of drive stop). It is possible to realize control of the plurality of translational thrust elements 2 to realize a degree of freedom that cannot be achieved.

  Further, a plurality of methods among these first to third methods may be combined. For example, the fourth method combines the first and second methods, includes at least one different period (frequency) as described above, and includes at least one of the plurality of translational thrust elements 2 as described above. In this method, the plurality of translational thrust elements 2 are controlled so as to be controlled including the blank period.

  Further, for example, the fifth method is a combination of the first and third methods, including at least one different period (frequency) as described above, and including at least one different drive stop ratio as described above. This is a method of controlling the translational thrust element 2.

  Further, for example, the sixth method is a combination of the third and second methods, includes at least one different drive stop ratio as described above, and at least one of the plurality of translational thrust elements 2 as described above. In this method, the plurality of translational thrust elements 2 are controlled so as to be controlled including the blank period.

  Further, for example, the seventh method is a combination of the first to third methods, includes at least one different driving stop ratio as described above, includes at least one different period as described above, and further, as described above. The plurality of translational thrust elements 2 are controlled such that at least one of the plurality of translational thrust elements 2 is controlled including the blank period.

  FIG. 9 shows drive patterns of the first to third translational thrust elements 2-1 to 2-3 in the multi-degree-of-freedom actuator Da configured as shown in FIG. 1 when the fourth method is used. Yes. In the drive pattern shown in FIG. 9, the first and second translational thrust elements 2-1 and 2-2 are controlled at the same period (frequency), and the third translational thrust element 2-3 is controlled by the first and second translational thrust elements 2-3. The second translational thrust elements 2-1 and 2-2 are controlled with a period (frequency) different from the period (frequency) of the second translational thrust elements 2-1 and 2-2. Control is performed including a blank period for stopping the repetition at predetermined time intervals.

  Control of the plurality of translational thrust elements 2 by each of these methods is performed by the drive control unit including the drive unit 4 and the control unit 5. Since the period (frequency) and the drive stop ratio in each method cannot be directly realized by the plurality of translational thrust elements 2, a desired rotational direction and a desired degree of freedom realized in a pseudo manner are obtained. It is appropriately set according to the rotation speed, the desired rotation axis, and the like.

  In the multi-degree-of-freedom actuator Da in the present embodiment, the plurality of translational thrust elements 2 are arranged such that the contact points P (P1 to P3) with respect to the rotating body 1 are point-symmetric. For this reason, since the rotary body 1 is equally supported by the plurality of translational thrust elements 2, the posture of the rotary body 1 can be stably maintained, and the rotary body 1 can be stably driven and controlled. . In addition, the drive control is also facilitated when arranged symmetrically in this way.

  The multi-degree-of-freedom actuator Da according to the present embodiment further includes a biasing member that generates a biasing force that engages the plurality of translational thrust elements 2 and the rotating body 1 with a predetermined frictional force. For this reason, in the multi-degree-of-freedom actuator Da in the present embodiment, usage restrictions and design restrictions are reduced. In this embodiment, the urging member is a magnet, and the rotating body 1 is formed of a magnetic body that acts on the magnetic force generated by the magnet. For this reason, the multi-degree-of-freedom actuator Da in the present embodiment can be miniaturized, and it is not necessary to separately input energy from the outside to generate the urging force.

  Moreover, in the above-mentioned embodiment, although the urging | biasing member was comprised with one member, you may be comprised with a some member. For example, a plurality of magnets may be used as the urging member, or a magnet and an elastic body may be used.

  In the above-described embodiment, the three translational thrust elements 2-1 to 2-3 are fixed so that the motion excitation member 22 is inclined at a predetermined angle θ1 with respect to the base 3 in a side view. In the top view, the three translational thrust elements 2-1 to 2-3 are arranged at approximately equal intervals of about 120 degrees, but the plurality of translational thrust elements 2 may be arranged in a desired plurality of freedom. Under the premise that the degree can be realized, the rotating body 1 can be engaged with a predetermined frictional force in various manners. Hereinafter, an engagement mode between the translational thrust element and the rotating body will be described.

  FIG. 10 is a diagram for explaining a first engagement mode between the translational thrust element and the rotating body in the multi-degree-of-freedom actuator of the embodiment. FIG. 11 is a diagram for explaining a second engagement mode between the translational thrust element and the rotating body in the multi-degree-of-freedom actuator according to the embodiment. FIG. 12 is a view for explaining a third engagement mode between the translational thrust element and the rotating body in the multi-degree-of-freedom actuator of the embodiment. 10A is the same as FIG. 1B, and FIG. 10 to FIG. 12 are cross-sectional views taken along the line AA shown in FIG. 1A, as in FIG. 1B. It is. FIG. 13 is a view for explaining a fourth engagement mode between the translational thrust element and the rotating body in the multi-degree-of-freedom actuator of the embodiment. FIG. 13 shows the rotating body 1 in a transparent state in order to show the engaged state between the rotating body 1 and the plurality of translational thrust elements 2 as in FIG.

  First, in the first engagement mode, the translational thrust element 2 may be arranged such that the motion excitation member 22 is fixed to the base 3 at an arbitrary angle θ (where θ includes 0 degrees). For example, like the multi-degree-of-freedom actuator Da shown in FIGS. 10A and 1B, the translational thrust element 2 is fixed so that the motion excitation member 22 is inclined with respect to the base 3 at an angle θ1. For example, like the multi-degree-of-freedom actuator Db shown in FIG. 10B, the translational thrust element 2 has its motion excitation member 22 tilted with respect to the base 3 at an angle θ2 larger than the angle θ1. It may be fixed and arranged. Of course, although not shown in the drawing, the translational thrust element 2 may be fixed and disposed so that the motion excitation member 22 is inclined with respect to the base 3 at an angle θ3 smaller than the angle θ1.

  The direction from the piezoelectric element 21 toward the motion excitation member 22 may be a direction from the outside toward the center point Pc ′ along the radial direction, as shown in FIG. ), It may be a direction from the center point Pc ′ toward the outside along the radial direction. Here, the direction from the piezoelectric element 21 toward the motion excitation member 22 is the direction from the piezoelectric element 21 toward the motion excitation member 22 when the piezoelectric element 21 and the motion excitation member 22 are projected onto the base 3. The radial direction is a radial direction of a projected circle (a circle formed by the outer peripheral contour of the rotating body 1) of the rotating body 1 formed when the spherical rotating body 1 is projected onto the base 3. The center point Pc ′ is the center point of this circle (projection point of the center point Pc formed when the center point Pc of the rotating body 1 is projected onto the base 3). The following description is also the same.

  Further, in the second engagement mode, each of the plurality of translation thrust elements 2 may be fixed and arranged so that each motion excitation member 22 is inclined with respect to the base 3 at a different angle θ. For example, like the multi-degree-of-freedom actuator Dc shown in FIG. 11A, one of the three translational thrust elements 2 has a motion excitation member 22-2 on the base 3. The remaining one of the three translational thrust elements 2 is arranged so as to be inclined at an angle θ42, and the motion excitation member 22-3 has an angle with respect to the base 3 in the remaining one of the three translational thrust elements 2. Although the remaining translational thrust elements 2-1 of the three translational thrust elements 2 are not shown in the figure, the motion excitation member 22-1 is attached to the base 3 while being fixed so as to be inclined at θ43. It is fixed and arranged so as to be inclined at an angle θ41. In the example shown in FIG. 11A, the angle θ43 is different from the angle θ42, and in this example, is larger than the angle θ42. And in this 2nd engagement aspect, like the multi-degree-of-freedom actuator Dd shown to FIG. 11 (B), one translation thrust element 2-2 of the three translation thrust elements 2 is the motion excitation member. 22-2 may be fixed to the base 3 at an angle of 0 degrees. Although not shown, one of the three translational thrust elements 2 may be arranged such that the motion excitation member 22-2 is fixed to the base 3 at an angle of 90 degrees.

  Of course, each of the plurality of translational thrust elements 2 is fixed so that each motion excitation member 22 is inclined with respect to the base 3 at the same angle θ as shown in FIGS. 10 (A) and 10 (B). May be arranged.

  Further, in the third engagement mode, each of the plurality of translation thrust elements 2 may be fixed and arranged so as to come into contact with the rotating body 1 at an arbitrary position of the rotating body 1. For example, like the multi-degree-of-freedom actuator De shown in FIG. 12, one translation thrust element 2-2 of the three translation thrust elements 2 has a motion excitation member 22-2 having an angle of 0 with respect to the base 3. The remaining one of the three translational thrust elements 2 is arranged so that the motion excitation member 22-3 is inclined with respect to the base 3 at an angle of 90 degrees. And a line segment connecting the contact point P2 of the translation thrust element 2-2 with the rotating body 1 and the center point Pc of the rotation body and the contact point of the translation thrust element 2-1 with the rotating body 1 The angle formed by the line connecting P1 and the center point Pc of the rotating body is fixed so that the angle is 90 degrees, and the remaining translation thrust elements 2-3 of the three translation thrust elements 2 are arranged. Is a line connecting the contact point P1 of the translational thrust element 2-1 with the rotating body 1 and the center point Pc of the rotating body. And an angle formed by a line segment connecting the contact point P3 of the translational thrust element 2-3 with the rotating body 1 and the center point Pc of the rotating body is an angle of 90 degrees, and the translational thrust element The line segment connecting the contact point P2 with the rotating body 1 of 2-2 and the center point Pc of the rotating body, the contact point P3 with the rotating body 1 of the translation thrust element 2-3, and the center point Pc of the rotating body. Are fixed and arranged so that the angle formed by the line segment connecting the two becomes an angle of 45 degrees.

  In the fourth engagement mode, each of the plurality of translational thrust elements 2 may be fixed and arranged so as to come into contact with the rotating body 1 in an arbitrary direction. That is, each of the plurality of translation thrust elements 2 may be fixed and arranged so that the longitudinal direction (direction of the translation vector) of each motion excitation member 22 is in contact with the rotating body 1 in an arbitrary direction. Each of the translational thrust elements 2 may be arranged so that the direction from the piezoelectric element 21 toward the motion excitation member 22 (direction of the translation vector) is in contact with the rotating body 1 in an arbitrary direction.

  For example, like the multi-degree-of-freedom actuator Df shown in FIG. 13 (A), in the top view, each of the three translational thrust elements 2-1 to 2-3 has the longitudinal direction of each motion excitation member 22 in the radial direction. The two translational thrust elements 2-1 and 2-3 out of the three translational thrust elements 2-1 to 2-3 are piezoelectric elements. While the direction from 21 to the motion excitation member 22 is from the outside to the center, the remaining one translational thrust element 2-2 has a direction from the piezoelectric element 21 to the motion excitation member 22 from the center point Pc ′. The direction is toward the outside. Thus, each of the plurality of translational thrust elements 2 may have different directions from the piezoelectric element 21 toward the motion excitation member 22.

  Further, for example, like the multi-degree-of-freedom actuator Dg shown in FIG. 13B, each of the three translational thrust elements 2-1 to 2-3 has a diameter in the longitudinal direction of each of the motion excitation members 22 in a top view. Although it is along the direction, they may be arranged at unequal intervals (intervals different from each other). The translation thrust element 2-1 and the translation thrust element 2-2 are arranged at an interval of an angle of 135 degrees, and the translation thrust element 2-2 and the translation thrust element 2-3 are arranged at an interval of an angle of 90 degrees, The translation thrust element 2-3 and the translation thrust element 2-1 are arranged at an angle of 135 degrees.

  Further, for example, like the multi-degree-of-freedom actuator Dh shown in FIG. 13C, each of the three translational thrust elements 2-1 to 2-3 has a diameter in the longitudinal direction of each motion excitation member 22 in a top view. It does not necessarily have to be along the direction, and is along the tangential direction of a circle having a predetermined radius with the point on the line passing through the center point Pc of the rotating body 1 as the center point, and from the piezoelectric element 21 to the motion excitation member 22. The direction to go is arranged in the clockwise direction.

  For example, like the multi-degree-of-freedom actuator Di shown in FIG. 13D, each of the three translational thrust elements 2-1 to 2-3 has a diameter in the longitudinal direction of each motion excitation member 22 in a top view. The one along the direction and the one along the tangential direction of a circle having a predetermined radius with the point on the line passing through the center point Pc of the rotating body 1 as the center point may be mixed. Each of the two translation thrust elements 2-1 and 2-3 is along a tangential direction of a circle having a predetermined radius with a point on the line passing through the center point Pc of the rotating body 1 as a center point, and a piezoelectric element. The direction from 21 to the motion excitation member 22 is arranged in the clockwise direction, and the longitudinal direction of the motion excitation member 22 is arranged along the radial direction of the translation thrust element 2-2.

  As described above, the plurality of translational thrust elements 2 can be arranged in an arbitrary manner as long as they are arranged to engage with the rotating body 1 with a predetermined frictional force. For this reason, the plurality of translational thrust elements 2 can be arranged so that the multi-degree-of-freedom actuator D is the smallest. Alternatively, the plurality of translational thrust elements 2 can be arranged so as to achieve the simplest drive control in order to realize a desired degree of freedom of the multi-degree-of-freedom actuator D. Alternatively, the plurality of translation thrust elements 2 can directly realize the degree of freedom most frequently used among the desired degrees of freedom of the multi-degree-of-freedom actuator D with one translation thrust element 2. It can also be arranged according to the most frequently used degree of freedom.

  In the above description, the multi-degree-of-freedom actuators Da to Di include the three first to third translational thrust elements 2-1 to 2-3, but the four or more translational thrust elements 2 are included. It may be provided. For example, an example of a multi-degree-of-freedom actuator D including four first to fourth translational thrust elements 2-1 to 2-4 is shown in FIG.

  FIG. 14 is a diagram for explaining another configuration of the multi-degree-of-freedom actuator according to the embodiment. FIG. 14A shows a first other configuration, and FIG. 14B shows a second other configuration. As in FIG. 1A, FIG. 14 shows the rotating body 1 in a transparent state in order to show the engaged state between the rotating body 1 and the plurality of translational thrust elements 2.

  For example, like the multi-degree-of-freedom actuator Dk shown in FIG. 14A, in the top view, each of the four translational thrust elements 2-1 to 2-4 has the longitudinal direction of each motion excitation member 22 in the radial direction. Are arranged at substantially equal intervals of about 90 degrees.

  Further, for example, like the multi-degree-of-freedom actuator Dl shown in FIG. 14B, each of the four translational thrust elements 2-1 to 2-4 is a line passing through the center point Pc of the rotating body 1 in a top view. Along the tangential direction of a circle with a predetermined radius centered on the minute point, the direction from the piezoelectric element 21 toward the motion excitation member 22 is arranged in a counterclockwise direction. These four translational thrust elements 2-1 to 2-4 are arranged at substantially equal intervals.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

D, Da to Dl Multi-degree-of-freedom actuator 1 Rotating body 2 Translation thrust element 4, 4a, 4b Drive unit 5, 5a, 5b Control unit

Claims (4)

A plurality of three or more translation thrust elements that generate the translation thrust such that the direction of the translation thrust and the direction of the drive vector generated by receiving the translation thrust coincide with each other;
A rotating body that engages the plurality of translational thrust elements with a predetermined frictional force;
A drive control unit for controlling the drive of the plurality of translational thrust elements,
In order to realize a degree of freedom that cannot be directly realized by the plurality of translation thrust elements, the drive control unit is configured to stop one translation thrust element among the plurality of translation thrust elements. A multi-degree-of-freedom actuator, wherein the plurality of translation thrust elements are controlled so as to drive at least two of the plurality of remaining translation thrust elements. The drive control unit controls driving of the translation thrust element by repeating a drive period for driving the translation thrust element and a drive stop period for stopping driving of the translation thrust element following the drive period. When the period composed of the drive period and the drive stop period following the drive transmission period is defined as one period, the plurality of translational thrust elements are controlled including at least one different period. The multi-degree-of-freedom actuator according to claim 1. The drive control unit controls driving of the translation thrust element by repeating a drive period for driving the translation thrust element and a drive stop period for stopping driving of the translation thrust element following the drive period. 3. The method according to claim 1, wherein at least one of the plurality of translational thrust elements is controlled including a blank period during which repetition of the drive period and the drive stop period is stopped. The multi-degree-of-freedom actuator described. The drive control unit controls driving of the translation thrust element by repeating a drive period for driving the translation thrust element and a drive stop period for stopping driving of the translation thrust element following the drive period. When the ratio between the drive period and the drive stop period is defined as a drive stop ratio, the plurality of translation thrust elements are controlled including at least one different drive stop ratio. The multi-degree-of-freedom actuator according to any one of claims 1 to 3.

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