JP3868098B2 - Direction control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direction control device that freely controls the direction (direction) of an object to be controlled by frictionally driving and rotating a rotor (spherical body) of a spherical actuator.
[0002]
[Prior art]
A direction control device in which a camera is held by a rotor of a spherical actuator is disclosed in Japanese Patent Laid-Open Nos. 9-6435 and 9-54356. FIG. 1 shows the structure of such a direction control device, that is, a spherical actuator holding a camera. The spherical actuator 1 has four stators 2, 2, 3, 3 arranged along the outer circumference of a substantially spherical rotor 4, and the rotor 4 is supported by these stators 2, 2, 3, 3. . Each of the stators 2, 2, 3, and 3 is composed of a rotational surface wave vibrator as shown in FIGS. That is, the elastic member 5 formed of an elastic material such as a metal has a substantially dish shape, and contact pieces 6 are projected on the surface of the outer peripheral portion at a certain pitch and arranged in an annular shape. A piezoelectric element 7 such as PZT is attached to the back surface of the outer peripheral portion of the elastic member 5 so as to face 6. The stators 2, 2, 3, and 3 support the rotor 4 so that the contact piece 6 contacts the rotor 4. Therefore, the surface of the contact piece 6 has the same curvature as the surface curvature of the rotor 4. A concave rounded surface 8 is provided. The camera 9 is fixed in the rotor 4 so as to pass through the center of the rotor 4.
[0003]
The stators 2, 2, 3, and 3 drive the rotor 4 according to the principle of an ultrasonic motor. When the piezoelectric element 7 is vibrated, flexural vibration and expansion / contraction are caused on the surface of the contact piece 6 of the elastic member 5. It generates surface wave vibration such as vibration. Since the stators 2, 2, 3, and 3 are in pressure contact with the rotor 4, the rotor 4 cannot rotate when the stators 2, 2, 3, and 3 are not driven. However, when the piezoelectric element 7 is driven in a predetermined drive mode, particles on the surface of the contact piece 6 move in an elliptical orbit by a traveling wave (flexible traveling wave) traveling in the circumferential direction on the surface of the elastic member 5, and the rotor The surface of 4 moves along the circumferential direction of the stators 2, 2, 3, 3. As a result, the rotor 4 rotates around the axis of the driven stator 2, 2, 3, 3. Further, a standing wave is generated in the stators 2, 2, 3, and 3 that do not generate a traveling wave to reduce friction with the rotor 4. Therefore, by driving and controlling the stators 2, 2, 3, and 3, the rotor 4 can be rotated and the camera 9 can be rotated in an arbitrary direction by an arbitrary angle.
[0004]
In such a direction control device 10, the directivity angle (monitoring direction) of the camera 9 can be freely and smoothly changed by driving the spherical actuator 1 and rotating the rotor 4. Further, according to such a direction control device 10, since the camera 9 can be built in the spherical actuator 1, a monitor device using the camera 9 can be reduced in size. Furthermore, if the camera 9 is arranged on the rotation center of the rotor 4, the rotation center of the rotor 4 and the center of the camera 9 can be substantially coincided with each other, so that the algorithm for controlling the direction of the camera 9 can be simplified. There are advantages.
[0005]
[Problems to be solved by the invention]
In the spherical actuator 1 used in the direction control device as shown in FIG. 1, the rotor 4 is rotated to direct the camera 9 in an arbitrary direction (directivity angle), and the tilt of the screen viewed through the camera 9 (the optical axis of the camera 9). The rotational angle of the rotor 4 can also be controlled, but the instantaneous rotation axis (that is, the rotational torque) of the rotor 4 can be controlled in the two directions (or the instantaneous directions in these two directions) connecting the opposing stators 2, 2, 3, and 3. The vector composition of the rotation axis is only in the plane including the axial direction of the four stators 2, 2, 3, 3, and the rotor 4 could not be instantaneously rotated around the optical axis of the camera 9. .
[0006]
For this reason, when the direction of the camera 9 is changed by rotating the rotor 4, the angle of the camera 9 is rotated from the substantially vertical direction, and the screen image of the monitor device is also inclined. Of course, after turning the camera 9 in the intended direction, the rotor 4 can be rotated so that the angle of the camera 9 becomes straight, but the rotor 4 does not have an instantaneous rotation axis around the optical axis of the camera 9. Therefore, it is necessary to correct the angle of the camera 9 by alternately repeating the rotations around the two stators 2, 2, 3, and 3, which causes a problem that the control is complicated and the screen moves and shakes. is there.
[0007]
In addition, if each stator is brought into contact with the rotor around a circumference smaller than the maximum circumference of the rotor so that the rotational torque acting on the rotor from each stator is directed in the three-dimensional direction, the rotor can be instantaneously rotated in any direction. An axis can be provided, and the camera angle (image) can always be kept straight.
[0008]
In such a structure, it is possible to rotate the rotor around the optical axis of the camera. However, since the stator is gathered on the front surface side of the spherical actuator, the driving range of the camera direction (directing angle) becomes narrower, or the rotor In order to control the rotation position detecting means with 3 degrees of freedom. Further, the control algorithm with 3 degrees of freedom is very complicated as compared with the control algorithm with 2 degrees of freedom. This is because a motion with two degrees of freedom can be converted into a motion on one plane (a plane including the axis of the four stators), but Euler angle representation is required when the degree of freedom is three.
[0009]
The present invention has been made in view of the drawbacks of the above-described conventional example, and the object of the present invention is to freely control the direction of the control symmetry object by the spherical actuator and to control symmetry by a simple structure. An object of the present invention is to provide a direction control device that can always keep the angle of a control symmetrical object at a substantially constant angle regardless of which direction the object is directed.
[0010]
DISCLOSURE OF THE INVENTION
The direction control device according to claim 1 is a direction control device including a spherical actuator that rotates a substantially spherical rotor with a small vibration generated in a stator in multiple degrees of freedom, and an object to be controlled held by the rotor. Rotation restraint means for holding the control object rotatably on the rotor and suppressing rotation of the control object relative to a stationary object other than the rotor is provided.
[0011]
In this direction control device, the controlled object is rotatably held by the rotor, and rotation of the controlled object is suppressed by the rotation restricting means. Therefore, the rotor is rotated to rotate the controlled object. Even if the direction is changed, the angle of the controlled object can be kept substantially constant by the rotation restricting means. Moreover, in order to correct the angle of the control object, it is not necessary to move the rotor in a direction other than around the axis of the control object as in the first conventional example, so that the angle of the control object is corrected. Therefore, the direction of the controlled object does not move.
[0012]
Further, since such rotation restraining means can be constituted by mechanical means, the control of the rotor or the spherical actuator can be controlled by two degrees of freedom, and the complicated three degrees of freedom as in the case of using the three degree of freedom spherical actuator is used. A simple control algorithm can be used because it is not necessary to perform this degree of control. Further, as in the case of using a three-degree-of-freedom spherical actuator, there is no need for three-degree-of-freedom rotational position detecting means, and the rotation range of the rotor is not narrowed.
[0013]
As the rotation restraining means, one that suppresses the rotation of the control object by applying gravity to a position deviated from the rotation center of the control object can be used. In order to exert gravity, a weight or the like can be used, and the angle of the controlled object can be kept substantially constant with respect to the direction of gravity.
[0014]
Further, as the rotation restraining means, a member that suppresses the rotation of the control object by an elastic body stretched between the stationary member other than the rotor and the control object can be used. As the elastic body, a spring, a rubber band, or the like can be used, and the angle of the controlled object can be kept substantially constant with respect to a stationary member such as a casing.
[0015]
In addition, the rotation restraining means may be a member provided between a stationary member other than the rotor and the control target and having an elastic restoring force against torsion. As a member having an elastic restoring force against torsion, for example, a linear elastic body or a planar elastic body can be used. When the controlled object is to be rotated, the angle of the controlled object is substantially reduced by the elastic restoring force. Kept constant.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
3, 4 and 5 are a perspective view from the front side, a perspective view from the back side, and a cross-sectional view showing the direction control device 21 according to the embodiment of the present invention. This directional control device 21 has a camera 24 rotatably held in a rotor 23 of a spherical actuator 22, and the spherical actuator 22 has four stators 26, 26, 27, attached in a casing 25. 27, the rotor 23 is held. Further, an image photographed by the camera 24 is displayed on a display (not shown) of a monitor device installed in another place or recorded on a video film, for example. Hereinafter, the direction control device 21 of this embodiment will be described in detail. However, since the basic structure and operation of the spherical actuator 22 are the same as those of the spherical actuator (FIGS. 1 and 2), the details are omitted.
[0017]
In the figure, reference numeral 24 denotes a small camera in which an imaging CCD and a lens are housed, and is formed in a substantially rod shape. The camera 24 is press-fitted and integrated into the camera holder 28 as shown in FIG. 5, and the camera 24 held by the camera holder 28 is inserted into a through hole 29 formed in the center of the spherical rotor 23. Has been. Further, both ends of the camera holder 28 are supported by bearings 30 provided in the through holes 29 of the rotor 23 so that the camera 24 can freely rotate around the optical axis in the rotor 23.
[0018]
Four stators 26, 26, 27, 27 that generate minute vibrations are mounted in the casing 25 and are arranged along the maximum outer circumference of the rotor 23. Of the opposing stators 26, 26, 27, 27, one stator 26, 27 is mounted in the casing 25 via a leaf spring 31, and the other stator 26, 27 is a disc spring 32 and a spring receiving plate 33. And the stators 26, 26, 27, 27 are pressed against the rotor 23 by the elastic force of the leaf spring 31 and the disc spring 32, and the spring receiving plate 33 is moved by the adjusting screw 34. Thus, the elastic force of the disc spring 32 is changed so that the pressure contact force of the stators 26, 26, 27, 27 to the rotor 23 can be adjusted. Further, after the stators 26, 26, 27, 27, the rotor 23, and the like are assembled in the casing 25, the covers 35, 36 are attached to the front and back surfaces of the casing 25, respectively, thereby preventing the rotor 23, etc. from falling off. The rotor 23 and the camera 24 are exposed from the window 37 of the front cover 35 as shown in FIG. 3, and the rotor 23 and the camera holder 28 are exposed from the window 38 of the rear cover 36 as shown in FIG. ing. Reference numeral 39 denotes a hole through which a signal line for driving each of the stators 26, 26, 27, 27 is passed.
[0019]
Thus, in this direction control device 21, the spherical actuator 22 is driven to rotate the rotor 23 so that the direction (directivity angle) of the camera 24 is within the range where the window 37 of the cover 35 is open. Can be directed in any direction.
[0020]
Further, in this direction control device 21, four posts 40 are erected on the back cover 36 in correspondence with the intermediate positions of the adjacent stators 26, 26, 27, 27. The tension coil springs 41 are stretched between the outer peripheral surfaces of the rear end portions of the 28. In addition, the hole 42 of the camera holder 28 visible in FIG. 5 is for drawing out the cord of the camera 24.
[0021]
Therefore, when the direction of the camera 24 changes due to the rotation of the rotor 23, even if the angle of the camera 24 tries to rotate along with it, the tensile force of the tension coil spring 41 acts on the camera 24 via the camera holder 28. An attempt is made to hold the camera holder 28 at a position where the tension forces of the tension coil springs 41 are balanced, and as a result, the angle of the camera 24 is held so as to be substantially constant (that is, the image is always straight). The However, since the rotor 23 is pressed by the stators 26, 26, 27, 27 and a holding torque is applied, the rotor 23 is not rotated by the tension coil spring 41. If the spring constant of the tension coil spring 41 is set to the minimum constant with which the camera 24 supported by the bearing 30 can be rotated, the driving efficiency of the spherical actuator 22 is good.
[0022]
In this direction control device, even if the direction of the camera 24 is changed by rotating the rotor 23, the camera 24 is always controlled to have an almost constant angle by the elastic force of the tension coil spring 41. A good image can be obtained without tilting or blurring the image of the display. Moreover, since the stators 26, 26, 27, and 27 can be arranged on one plane, the structure is simple, and further, the structure for detecting the rotational position of the three-degree-of-freedom is not required, so that the structure can be simplified. Manufacturing costs can be reduced. Further, since it is not necessary to arrange the stator three-dimensionally unlike the three-degree-of-freedom spherical actuator, the arrangement of the stators 26, 26, 27, 27 can be made two-dimensionally. Since the rotor 23 can be controlled in two degrees of freedom without being narrowed, a simple control algorithm can be used, which can be realized with at least two stators (one of the opposing stators can be replaced with a bearing, etc.) There is an advantage that adjustment becomes easy.
[0023]
It should be noted that the effect of the spring used as the rotation restraint means is the same regardless of whether a tension coil spring or a compression coil spring is used in the direction drive range of the camera 24 as long as a spring restoring force is working. Moreover, not only a coil spring but the linear spring bent in S shape, for example can also be used. In this embodiment, the tension coil spring 41 is stretched on the back side of the casing 25, but the tension coil spring 41 may be stretched on the front side of the casing 25 to hold the angle of the camera 24.
[0024]
(Second Embodiment)
FIG. 6 is a perspective view from the back side of the direction control device 51 according to another embodiment of the present invention. In this embodiment, one tension coil spring 41 is stretched between one post 40 standing on the back cover 36 and the outer peripheral surface of the rear end portion of the camera holder 28. In this embodiment, the camera 24 is held almost straight by rotating the camera holder 28 so that the pulling force of the tension coil spring 41 is minimized. Thus, the rotation of the camera 24 can be suppressed by the single tension coil spring 41, the structure can be further simplified, and the cost can be reduced.
[0025]
(Third embodiment)
FIG. 7 is a perspective view from the back side of the direction control device 52 according to another embodiment of the present invention. In this embodiment, four rubber bands 53 are used in place of the tension coil spring 41 of the embodiment of FIGS. Also in this case, when the angle of the camera 24 changes as the rotor 23 rotates, the camera 24 is returned to the original angle by the elastic force of the rubber band 53. In this case as well, the rubber band 53 may be set to an elastic coefficient within a range in which the angle of the camera 24 can be corrected without suppressing the driving of the rotor 23.
[0026]
(Fourth embodiment)
FIG. 8 is a perspective view from the back side showing a direction control device 54 according to still another embodiment of the present invention. In this direction control device 54, a weight 55 is used as the rotation restraining means of the camera 24. That is, a string 56 with a weight 55 is tied to the outer peripheral surface of the rear end portion of the camera holder 28. Accordingly, when the direction of the camera 24 is changed by the rotation of the rotor 23, even if the angle of the camera 24 is rotated accordingly, a rotational moment is generated in the camera holder 28 to return to the original angle. The camera holder 28 is rotated so that the portion where 55 is connected is the lowest point. As a result, the angle of the camera 24 is always kept substantially constant. In this case as well, the driving efficiency is good if the mass of the weight 55 is set to the minimum mass capable of rotating the camera holder 28 supported by the bearing 30. The weight 55 does not need to be attached to the camera holder 28 by the string 56 as shown in FIG. 8, and is attached to a part of the outer peripheral surface of the camera holder 28 so that the center of gravity of the camera holder 28 is decentered from the axis. There may be.
[0027]
(Fifth embodiment)
FIG. 9 is a rear perspective view showing a direction control device 57 according to still another embodiment of the present invention. In this direction control device 57, a planar elastic body 58 such as a CR sponge sheet or a rubber sheet is used as a rotation restraining means of the camera 24. That is, the outer peripheral portion of the planar elastic body 58 is fixed to the periphery of the opening 38 of the back cover 36, and the inner peripheral portion of the planar elastic body 58 is fixed to the outer peripheral surface of the rear end portion of the camera holder 28. . Further, the planar elastic body 58 is not stretched in a planar shape so as to prevent contact with the rotor 23 and to be easily deformed with the rotation of the rotor. It is shaped like a bowl. In addition, in order to shape the planar elastic body into a desired shape, it may be molded into that shape, or an elastically deformable core 59 for retaining the shape is placed in the planar elastic body 58. Also good.
[0028]
Thus, when the rotor 23 rotates, the planar elastic body 58 does not hinder the rotation of the rotor 23 by deformation, but when the direction of the camera 24 changes due to the rotation of the rotor 23, the surface of the surface elastic body 58 is rotated by the rotation of the camera 24. Since the elastic body 58 is twisted around the camera 24, an elastic restoring force against the twist is generated in the planar elastic body 58, and the angle of the camera 24 is maintained as it is. In addition, you may provide this planar elastic body in the front side of a spherical actuator.
[Brief description of the drawings]
FIG. 1 is a partially broken front view illustrating a basic structure of a spherical actuator.
FIGS. 2A and 2B are a front view and a cross-sectional view showing a structure of a stator.
FIG. 3 is a front perspective view showing the direction control device according to the embodiment of the present invention.
FIG. 4 is a perspective view from the back side of the direction control device.
FIG. 5 is a cross-sectional view of the directional control device.
FIG. 6 is a rear perspective view showing a direction control device according to another embodiment of the present invention.
FIG. 7 is a rear perspective view showing a direction control device according to still another embodiment of the present invention.
FIG. 8 is a rear perspective view showing a direction control device according to still another embodiment of the present invention.
FIG. 9 is a rear perspective view showing a direction control device according to still another embodiment of the present invention.
[Explanation of symbols]
22 spherical actuator 23 rotor 24 camera 26, 27 stator 28 camera holder 30 bearing 40 post 41 tension coil spring 53 rubber band 55 weight 56 string 58 planar elastic body

Claims (4)

In a directional control device that includes a spherical actuator that rotates a substantially spherical rotor with a small amount of vibration generated in a stator in multiple degrees of freedom, and a control object held by the rotor.
A direction control device comprising a rotation restraining means for holding the control object rotatably on the rotor and suppressing rotation of the control object relative to a stationary member other than the rotor. The rotation restraining means suppresses the rotation of the control object by lowering the weight on the outer peripheral surface of the rear end portion of the control object that is off the rotation center of the control object. The direction control device according to claim 1.   The said rotation restraint means controls rotation of a control target object by the elastic body stretched between stationary members other than the said rotor and the said control target object, The Claim 1 characterized by the above-mentioned. Direction control device.   2. The direction control device according to claim 1, wherein the rotation restraining unit is a member having an elastic restoring force against torsion provided between a stationary member other than the rotor and the control target. .

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