JPH0714276B2 - Actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator having a movable function with two or more degrees of freedom and a robot mechanism using the actuator. The present invention relates to an actuator suitable for a device.

[Conventional technology]

As an actuator using a piezoelectric element applicable to a robot joint or the like, a method using a plurality of ring-shaped piezoelectric motor elements has been considered as described in JP-A-62-141978. This method has the advantage that a compact and lightweight actuator can be constructed.

[Problems to be Solved by the Invention]

However, since the above-mentioned conventional actuator uses a plurality of ring-shaped piezoelectric motor elements, compared with the area where the driving member and the driven member are in contact, the area that can be driven by the piezoelectric element is very small, and the driving force is small. was there.

An object of the present invention is to expand the area that can be driven by a piezoelectric element, and to configure an actuator that is compact and lightweight and that can generate a large driving force.

[Means for Solving the Problems]

The above-mentioned object is not a ring-shaped piezoelectric motor element, but a piezoelectric motor element that generates a traveling wave in one direction and a piezoelectric motor element that generates a traveling wave in a different direction, for example, an orthogonal direction, are alternately arranged to form a driving member. It is achieved by arranging on the entire spherical surface between the driven member and the driven member and controlling the magnitude and phase of the voltage supplied to each piezoelectric motor element.

[Action]

When a voltage is applied to the piezoelectric element, it expands and contracts, so that vibration is generated by applying an alternating voltage. These two piezoelectric elements are bonded by shifting by λ / 4 (λ: vibration wavelength).
Moreover, the magnitude of the voltage applied to each piezoelectric element,
A traveling wave can be generated by changing the phase. This is called a piezoelectric motor element that generates a traveling wave in one direction. Therefore, a piezoelectric motor element that generates a traveling wave in one certain direction and a piezoelectric motor element that generates a traveling wave in a different direction are alternately arranged on the entire surface between a driving member and a driven member that are in contact with each other by a spherical surface, By controlling the applied voltage, the driven member can be operated in a mechanically operable direction. By determining the piezoelectric motor elements for operating the driven members in the three orthogonal directions, movement in the three directions can be performed by simple voltage control.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an example in which the actuator of the present invention is applied to a video camera subject automatic tracking device. A video camera 2 for shooting a subject 1 is attached to an actuator 4 installed on a tripod 3. The actuator 4 is composed of a driving member 4a and a driven member 4b.

First, the image signal p of the subject 1 captured by the video camera 2 is input to the image processing circuit 5. The image processing circuit 5 stores the information of the image signal p photographed up to the previous time, compares it with the information of the image signal p of this time, and performs the image processing. For example, as a method used in image processing technology,
There are edge enhancement, difference, weighting methods, etc., and these are used to obtain information on the movement of the subject 1. Based on this information, the image processing circuit 5 calculates the movement command θ _R of the video camera 2 and inputs it to the voltage control circuit 6. The voltage control circuit 6 generates alternating voltages v _X , v _Y , v _Z of the actuator 4 in the directions of three axes orthogonal to each other based on the movement command θ _R. As a result, the actuator is driven, and the video camera 2 can be made to follow the movement of the subject 1. Although it is necessary to detect the movement of the object to be photographed most in the subject 1, there are several possible methods. For example, if the object to be photographed is always in the center of the image, the weight of the movement of the center may be increased. Also, if you want to follow the entire flow (for example, the flow of people or the flow of clouds),
If the average movement of the entire image is used as the movement command θ _R , subject automatic tracking control can be performed.

Now, the actuator 4 of the present invention will be described in detail. FIG. 2 shows a sectional view of the actuator 4. The actuator 4 is a driving member installed on the tripod 3.
4a, driven member for mounting the video camera 2b, driven member
It consists of a piezoelectric motor element 7 that drives 4b. First,
The driving member 4a has a surface whose inside is spherical. The driven member 4b having a spherical portion inscribed on this surface is a driving member.
It is inserted in 4a, and it is an orthogonal X whose origin is the center of the sphere.
Rotational movements can be made in directions around the axes, Y-axis and Z-axis.

Here, the principle of the piezoelectric motor element 7 that generates a traveling wave will be described with reference to FIG. The piezoelectric element 8 has a property of causing distortion depending on the direction and magnitude of voltage. Therefore, FIG. 3 (a)
As described above, the piezoelectric element that expands and the piezoelectric element that contracts according to the voltage V are alternately arranged. When the voltage V is applied in the direction opposite to that in FIG. 3 (a), distortion occurs in the direction opposite to the arrow in FIG. 3 (a). By bonding such a piezoelectric element 8 to the elastic body 9,
When a voltage V is applied to the piezoelectric element 8, it deforms as shown in FIG. 3 (b). In this structure, when an alternating voltage v is applied instead of the voltage V, a standing wave is generated. Let λ be the wavelength of this standing wave. Next, as shown in FIG. 3 (c), the elastic body 9
The piezoelectric element 8a bonded to the
The piezoelectric element 8b is adhered to the piezoelectric element 8a so as to differ by λ: the wavelength of the standing wave. This is the configuration of the piezoelectric motor element 7. Then, the phase of the alternating voltage v _b applied to the piezoelectric element 8b is set to be 90 degrees later than the alternating voltage v _a applied to the piezoelectric element 8a. At this time, the waveform of the piezoelectric motor element shown in FIG. 3 (c) moves to the right with the passage of time as shown in FIG. 3 (d). If the phase of the alternating voltage v _{b leads} the phase of the alternating voltage v _a by 90 degrees, it moves in the opposite direction. This is the principle of the piezoelectric motor element that generates a traveling wave. For convenience of explanation, the voltage shown in FIG. 3C is a sinusoidal alternating voltage, but the same operation is performed if the voltage is an alternating voltage.

Then, the principle that the present embodiment rotates in three directions orthogonal to each other will be described. FIG. 4 shows how to arrange the piezoelectric motor elements, which is a feature of the present invention. FIG. 4 shows the driven member 4b in FIG.
6 shows the structure inside the drive member 4a when the above is removed. The arrow shown in each electric motor element is the direction of the traveling wave, and the adjacent piezoelectric motor elements 7a and 7b are arranged on the entire spherical inner surface so as to generate the traveling waves in directions orthogonal to each other. Next, the alternating voltages v _X , v _Y , v _Z for driving in three directions output from the voltage control circuit 6 of FIG. 1 are respectively applied to the piezoelectric motor elements of X, Y, Z shown in FIG. Is applied.
With this configuration, it is possible to independently perform the rotational movement about the three orthogonal directions with a relatively simple voltage control circuit.

Therefore, according to this embodiment, since the piezoelectric motor element for generating a driving force can be arranged on the entire surface of the driving member that comes into contact with the driving member, a small-sized and lightweight actuator having a large driving force can be configured. Further, if this actuator is used, the motion of three degrees of freedom can be configured by one actuator, so that the automatic subject tracking device itself can be made smaller and lighter. Further, when controlling the image signal by feeding back, the actuator can be directly positioned without using a gear or the like, so that the automatic follower device has no vibration and has good responsiveness. When shooting on board a ship or on a helicopter, this device can also feed back fluctuations in the floor, so stable images can be taken.

FIG. 12 shows another embodiment in which the driving force of the rotary motion about the Z axis is increased as compared with FIG. The difference from FIG. 4 is that each piezoelectric motor element does not work only for a specific one axis, but can contribute to the rotational movement of other axes. This will be described below.

In this embodiment, the alternating voltage output from the voltage control circuit
v _X , v _Y , v _Z are not directly input to each piezoelectric motor element, but are input to the voltage command switching circuit 51. In the voltage command switching circuit 51, a command is given to the piezoelectric motor driving circuit 52 so as to give a driving force suitable for rotation in each axial direction according to the values of the alternating voltages. Thereby, the voltage applied to each piezoelectric motor element is generated. Figure 2-2
One piezoelectric motor element 7c, 7d will be described as an example. For example, when rotating about the Z axis, it can be driven by generating traveling waves in the same direction. On the contrary, if a traveling wave in the opposite direction is generated, it is possible to perform the rotational movement in the direction around the X axis. As described above, by using the voltage command switching circuit 51, the voltage command switching circuit 51 can be used to generate driving force in two or more directions.

Therefore, according to the present embodiment, the driving force of the rotational movement in the desired direction can be further increased.

FIG. 5 shows an embodiment in which the actuator of the present invention is applied to a remote-controlled video camera device which determines the shooting position of the video camera by remote control.

FIG. 5 is different from FIG. 1 in that the remote controller 12 is used instead of the image processing circuit 5 and the structure of the actuator 4 is different.

First, a photographer in the subject 1 or at a point away from the video camera 2 operates the three remote control levers 13 on the remote controller 12 to generate the up / down signal UD, the left / right signal LR, and the zoom signal ZM. . The zoom signal ZM is input to the video camera 2, and the size of the image is changed by moving the position of the lens. The up / down signal UD and the left / right signal LR are input to the voltage control circuit 6. The voltage control circuit 6 generates alternating voltages v _UD and v _LR to be applied to the piezoelectric element of the actuator 4 according to these signals.

Next, the structure of the actuator different from that of FIG. 1 will be described with reference to FIG. FIG. 6 is an exploded view of the actuator 4 of FIG. 5 into a driving member 4c and a driven member 4d.
For the driving member 4c, the video camera 2 is used as the coordinate axis Z of the driving member 4c.
A rotating piezoelectric motor element 14 for rotating about an axis is mounted. The driven member 4d has a video camera 2
In order to move up and down, a vertical piezoelectric moker element 15 is attached so as to rotate around the coordinate axis X'of the driven member 4d. By inputting alternating voltages v _LR and v _UD to the rotary and vertical piezoelectric motor elements 14 and 15, respectively, the video camera is remotely operated while maintaining the vertical relationship between the image and the actual subject. be able to. Further, due to the structure of the actuator, the video camera 2 can have a movable range of 180 degrees or more in the vertical direction, and can photograph in all directions including directly above and below.

Therefore, according to this embodiment, it is possible to always perform the correct shooting of the vertical relationship of images in all directions without performing complicated coordinate conversion. Also, only two piezoelectric motor elements are required, and the voltage control circuit can be simplified. Further, by mounting the piezoelectric element not only on the driving member but also on the driven member, the arrangement area of the piezoelectric motor element can be further expanded, and an actuator having a large driving force can be configured. By using this device, the photographer himself can be the subject. In particular, this device has a feature that it can be constructed at low cost.

FIG. 7 shows an embodiment in which the actuator of the present invention is applied to a robot for assembly work. This shows a step of inserting the component 17a placed on the workbench 16 into the component 17b on the belt conveyor 18 using a robot. Part 17a to Part 17b
When inserting into the position deviation detector
Detected by 19. Examples of the position deviation detector 19 include a method using image processing. The deviation signal ε obtained from the position deviation detector 19 is input to the robot controller 20. The robot controller 20 performs control calculation so as to reduce the deviation of fit, and outputs the applied voltages v ₁ , v ₂ , v ₃ of the actuators that are joints of the robot. By these applied voltages v ₁ , v ₂ , v ₃ , the first, second and third actuators 21, 22, 23 are operated, and the tip arm 24
Thus, the component 17a can be inserted into the component 17b.

Next, the structure of the actuator, which is a feature of this embodiment, will be described with reference to FIG. The robot shown in this embodiment is composed of a three-degree-of-freedom arm actuator 25 whose cross section is shown in FIG. 8 (a), except for the first actuator 21 and the tip arm 24 which serve as a mount. . The piezoelectric element that drives the three-degree-of-freedom arm actuator 25 is attached to a portion having a spherical inner surface.
It has the same configuration as the piezoelectric motor element shown in the figure.
Therefore, it is possible to rotate in any of the three orthogonal axes, which allows the number of actuators to be at least equivalent to that of a conventional robot constituted by 6 axes. If a standard of the size of the three-degree-of-freedom arm actuator 25 (the diameter of the sphere, the inner diameter of the inner sphere, the length of the arm) is created and mass-produced, an inexpensive robot can be easily constructed. The robot's arm can be increased by simply adding an arm actuator 25 with 3 degrees of freedom, and it can be applied to a robot like an elephant's nose. A two-degree-of-freedom arm actuator 26 is also conceivable as shown in FIG. 8 (b). It operates with three piezoelectric motor elements 27, 28, 29, but the basic principle is the same as the three-degree-of-freedom arm actuator 25.

According to this embodiment, by using the arm actuator, the assembling robot can be constructed with a simpler structure. In addition, the standardization of arm actuators is easy, so it is possible to manufacture a robot that is inexpensive and can be arbitrarily set by the number of arms. It is easy to replace the arm actuator, and it has the feature that the repair time in case of failure is short. Furthermore, since this actuator operates by frictional force, it can maintain its posture before a power failure even in the event of a power failure, and is excellent in terms of safety.

FIG. 9 shows an example in which the actuator of the present invention is applied to a robot for screwing work. A device for screwing the screw 17c into the screw hole of the component 17d by the robot is shown in FIG. 9, but the difference from FIG. 7 is that the third actuator 23 and the tip arm 24 are replaced by the intermediate arm 30. I used the tip actuator 31. In the case of screwing work, after the tip actuator 31 reaches a certain position, it is necessary to rotate the tip actuator 31 at high speed around an axis having the arm of the tip actuator 31 as a coordinate. Therefore, among the piezoelectric motor elements mounted in the tip actuator 31, it is sufficient to apply the voltage only to the piezoelectric motor element that rotates about the axis having the arm of the tip actuator 31 as a coordinate. On the other hand, in order to perform the same operation in the embodiment shown in FIG.
The three piezoelectric motor elements of the actuator 23 of FIG. Moreover, it is necessary for the robot controller 20 to perform the coordinate conversion calculation for that purpose at high speed. Therefore, in the embodiment shown in FIG. 9, since the tip actuator 31 on the work side is operated, the coordinate conversion in the screwing work becomes unnecessary.

Also, by using various arms as shown in FIG. 10, the number of coordinate exchanges required for robot control can be reduced. That is, in addition to the intermediate arm 30, arm actuators 32, 33, 34 having various actuators at both ends can be considered. A robot having a different structure can be constructed by combining these arms with the arm shown in FIG.

Therefore, by using this embodiment, it is possible to construct a robot capable of performing screwing work at high speed. Also, by using various kinds of arms, it is possible to create a robot most suitable for each work.

FIG. 11 is an embodiment in which the actuator of the present invention is applied to an automatic tracking device for collecting solar heat and sunlight.

This is a device for collecting heat and light from the sun 35 in a solar heat / sunlight collector 36 and transferring them to a necessary place by a light / heat transfer device 37. First, solar heat / solar collector
The solar position detector 38 is used because the surface of 36 can collect most heat and light when it is perpendicular to the sun 35. The length and direction of the shadow of the sun position detector 38 is read by the image sensor 39, and based on this, the tracking controller 40 performs a control calculation so that the position of the solar heat / sunlight collector 36 coincides with the sun 35. To do. Next, the tracking actuator 41 operates by the voltage v output from the tracking control device 40, and the sun 35 automatically
The solar heat / solar collector 36 can be aligned in the direction of. The tracking actuator 41 may have the same principle as the actuator shown in FIG.

According to this embodiment, since the same posture can be maintained by the frictional force when no voltage is applied to the actuator, it suffices to apply the voltage to the actuator only several times an hour to control it, and the cost for operation can be very low. be able to. In particular, this actuator is small, can generate a large torque, and has a strong holding force even when the power is not supplied, and is thus suitable for such a device.

The above is the description of the embodiments of the present invention, but it goes without saying that the present actuator can also be applied to a device for moving a lighting device such as a spotlight, a pitching machine, or the like. Further, in the embodiment, the actuator which can rotate in two degrees of freedom and three degrees of freedom is described, but it is naturally possible to combine it with a mechanism which moves linearly. Furthermore, for convenience of explanation, although each piezoelectric element is described as being used only when it is moved in one predetermined direction, it can be used for driving in multiple directions. When applied to a tracking device, it is effective not only for the sun, but also for stars, artificial satellites, flying objects, and the like.

〔The invention's effect〕

According to the present invention, since the piezoelectric element that generates a driving force can be arranged in most of the area where the driving mechanism and the driven mechanism are in contact with each other, it is possible to configure an actuator that is small and lightweight and that can generate a large driving force.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention applied to an automatic subject tracking device, FIG. 2 is a sectional view showing the structure of the actuator used in FIG. 1, and FIG. FIG. 4 is a structural view showing the principle of operation of the piezoelectric motor element, FIG. 4 is a sectional view when the driven member in FIG. 2 is removed, and FIG. 5 is a configuration diagram of an embodiment applied to a remote control video camera device. 6 is an exploded view of the actuator used in FIG. 5, FIG. 7 is a configuration diagram of an embodiment applied to a robot for assembly work, FIG. 8 is a schematic diagram of the actuator used in FIG. 7, and FIG. Fig. 1 is a block diagram of an embodiment applied to a robot for screwing work, Fig. 10 is a schematic diagram of an actuator applicable to the robot, and Fig. 11 is an example applied to an automatic tracking device for collecting solar heat and sunlight. FIG. 12 is a configuration diagram of an embodiment, and FIG. 12 is a drive section showing an embodiment different from FIG. It is sectional drawing of a material. 1 ... Subject, 2 ... Video camera, 3 ... Tripod, 4 ...
... Actuator, 5 ... Image processing circuit, 6 ... Voltage control circuit, 7 ... Piezoelectric motor element, 8 ... Piezoelectric element, 9 ...
… Elastic body, 12 …… Remote control device, 13 …… Remote control lever,
14 …… Rotating piezoelectric motor element, 15 …… Upper and lower piezoelectric motor element, 16 …… Workbench, 17 …… Parts, 18 …… Belt conveyor, 19 …… Position deviation detector, 20 …… Robot control device,
21,22,23 …… Actuator, 24 …… Tip arm, 25…
… 3-DOF actuator, 26 …… 2-DOF actuator, 27,28,29 …… Piezoelectric motor element, 30 …… Intermediate arm, 31 …… Tip actuator, 32,33,34 …… Arm actuator, 35 ...... Sun, 36 ...... Solar heat / solar collector, 37 ...... Light / heat transfer device, 38 ...... Sun position detector, 39
...... Image / sensor, 40 ...... Tracking control device, 41 ...... Tracking actuator, 51 ...... Voltage command switching circuit, 52 ...... Piezoelectric motor drive circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideki Nihei 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Kyoki Katayama 4026, Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. (72) Inventor Hiroshi Nagase 4026 Kujimachi, Hitachi City, Hitachi, Ibaraki Hitachi, Ltd. (72) Inventor Toshihiko Matsuda 4026, Kujicho, Hitachi, Ibaraki Hitachi, Ltd., Hitachi Research Institute, Ltd. (72) Inventor Kenzo Kamiyama 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Co., Ltd. Omika Plant (56) References JP-A-62-228392 (JP, A) JP-A-62-141978 ( JP, A)

Claims (3)

[Claims] 1. A piezoelectric motor element for generating a traveling wave by changing the magnitude and phase of a voltage applied to a piezoelectric element, and a spherical shell having an opening part in one part and a holding part in the other part. An actuator comprising: a drive section having a plurality of piezoelectric motor elements arranged on an inner wall thereof; and a spherical driven section that is housed in the spherical shell and driven by the piezoelectric motor element, wherein: An actuator characterized in that two types of the piezoelectric motor elements that generate traveling waves in different directions are alternately arranged adjacent to each other in all directions on the entire inner wall of the spherical shell inscribed with the outer periphery of the surface. 2. The actuator according to claim 1, a tracking device connected to the driven part of the actuator, a detection circuit for detecting a signal in response to the movement of a moving object, or a signal according to the movement of the moving object. And a control circuit that controls the drive unit to operate the tracking device according to the output from the detection circuit or the commanding device. 3. The actuator according to claim 1, an arm of a work robot connected to the driven part of the actuator, a detection circuit for detecting a signal in response to the position of the work object, or the work object. And a control circuit for controlling the drive unit so as to operate the arm of the work robot in accordance with an output from the detection circuit or the command unit. Robot for work.