JPH01318563A - Actuator - Google Patents

Abstract

PURPOSE:To miniaturize and lighten an apparatus by arranging piezoelectric motor elements generating progressive waves in one direction and those generating progressive waves in the direction perpendicularly intersecting to one direction on the whole spherical surface through putting both piezoelectric motor elements side by side alternately. CONSTITUTION:In a video camera subject automatic tracking apparatus using an actuator, a video camera 2 photographing a subject 1 is fitted to the actuator 4 installed on a tripod 3. Also, the apparatus is equipped with a picture- processing circuit 5, to which the picture signal P of the subject 1 is inputted, and a voltage command circuit 6 generating an alternating voltage in the directions of three axes perpendicularly intersecting each other of the actuator 4. In this case, the actuator 4 is constituted by a driving member 4a, a driven member 4b fitted with the video camera 2, and piezoelectric motor elements 7. Further, the driving member 4a has a spherical surface on the inside and piezoelectric motor elements 7a, 7b generating progressive waves in the directions perpendicularly intersecting each other are adjacently arranged on the inner surface of the driving member so that the driven member 4b is moved in the directions of X- to Y-axes.

Description

[Detailed Description of the Invention] [Industrial Application Field] 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, and particularly relates to an automatic subject tracking device for a video camera, and a robot joint. The present invention relates to an actuator suitable for the device.

[Conventional technology]

As an actuator using a piezoelectric element that can be applied to the joints of a robot, a method using a plurality of ring-shaped piezoelectric motor elements has been considered, as described in Japanese Patent Laid-Open No. 141978/1983. This method has the advantage that a small and lightweight actuator can be constructed.

[Problem to be solved by the invention]

However, since the conventional actuator described above uses multiple ring-shaped piezoelectric motor elements, the area that can be driven by the piezoelectric element is very small compared to the area where the driving member and the driven member are in contact, resulting in a problem that the driving force is reduced. was there.

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

[Means to solve the problem]

The above purpose is to create a driving member by alternately arranging piezoelectric motor elements that generate traveling waves in one direction and piezoelectric motor elements that generate traveling waves in a different direction, for example, orthogonal directions, instead of using ring-shaped piezoelectric motor elements. This is achieved by arranging the entire spherical surface between the drive member and the driven member.

Furthermore, when two types of piezoelectric motor elements that generate traveling waves in different directions are arbitrarily arranged, this can be achieved by controlling the magnitude and phase of the voltage supplied to each piezoelectric motor element.

[Effect]

When a voltage is applied to a piezoelectric element, it expands and contracts, so applying an alternating voltage generates vibrations. By gluing these two piezoelectric elements with a difference of λ/4 (λ: vibration wavelength) and changing the magnitude and phase of the voltage applied to each piezoelectric element, it is possible to generate a traveling wave. can. This is called a piezoelectric motor element that generates a traveling wave in one direction. Therefore, piezoelectric motor elements that generate traveling waves in one direction and piezoelectric motor elements that generate traveling waves in different directions are alternately arranged on the entire surface between the driving member and the driven member that are in contact with each other at the spherical surface. By controlling the applied voltage, the driven member can be moved in a mechanically movable direction. By determining piezoelectric motor elements for operating the driven member in three orthogonal directions, three
Directional movement can be performed by simple voltage control. Furthermore, if the voltage of each piezoelectric motor element can be controlled independently, the direction of the traveling wave of the piezoelectric motor element can be set arbitrarily;
The position of the driven member can be moved arbitrarily.

〔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 an automatic subject tracking device for a video camera. A video camera 2 for photographing a subject 1 is attached to an actuator 4 placed on a tripod 3.

This actuator 4 includes a driving member 4a and a driven member 4b.
It consists of

First, an image signal P of the subject 1 photographed by the video camera 2 is input to the image processing circuit 5. The image processing circuit 5 stores information on the image signal p taken up to the previous time, compares it with information on the current image signal p, and performs image processing. For example, methods used in image processing technology include edge enhancement and subtraction.

There are various weighting methods, and information on the movement of the subject 1 is obtained using these methods. Based on this information, the image processing circuit 5 calculates a movement command θR for the video camera 2, and the voltage control path 6
Enter. This voltage control path 6 generates alternating voltages V X r V Y r V Z in three orthogonal axes directions of the actuator 4 based on the movement command OR. Thereby, the actuator is driven, and the video camera 2 can be made to follow the movement of the subject 1. In addition,
It is necessary to detect the movement of the object most desired to photograph among the objects 1, and there are several possible methods for this. For example, if the object to be photographed is always placed at the center of the image, weighting of the movement of the center may be increased. Also, if you want to follow the overall flow (for example, the flow of one person or the flow of clouds),
If the average movement of the entire image is used as the movement command θR, automatic subject 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 4 installed on the tripod 3.
a, a driven member 4b to which the video camera 2 is attached, and a piezoelectric motor element 7 that drives the driven member 4b.

First, the driving member 4a has a spherical inner surface. Driven member 4b having a spherical portion inscribed in this surface
is inserted into the drive member 4a, and can rotate in directions centered on the X-axis, Y-axis, and Z-axis, which are perpendicular to each other with the center of the sphere as the origin.

Here, the principle of the piezoelectric motor element 7 that generates traveling waves will be explained with reference to FIG. The piezoelectric element 8 has the property of causing distortion depending on the direction and magnitude of voltage.

Therefore, as shown in FIG. 3(a), the piezoelectric elements that expand and the piezoelectric elements that contract are arranged alternately depending on the voltage V. Figure 3 (
When voltage V is applied in the direction opposite to a), distortion occurs in the direction opposite to the arrow in FIG. 3(a). Such a piezoelectric element 8
When the piezoelectric element 8 is bonded to the elastic body 9 and a voltage V is applied to the piezoelectric element 8, the piezoelectric element 8 is deformed as shown in FIG. 3(b). In this configuration, if an alternating voltage V is applied instead of the voltage V, a standing wave is generated.

Let the wavelength of this standing wave be λ. Next, Figure 3 (Q)
The piezoelectric element 8b is bonded to the piezoelectric element 8a so that the strain is different from the piezoelectric element 8a bonded to the elastic body 9 by λ/4 (where λ is the wavelength of the standing wave) as shown in FIG. This is the configuration of the piezoelectric motor element 7. The phase of the alternating voltage (2)5 applied to the piezoelectric element 8b is made to be 90 degrees slower than the alternating voltage Va 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 as time passes, as shown in FIG. 3(d). Further, when the phase of the alternating voltage Vb is 90 degrees ahead of the phase of the alternating voltage Va, the phase shifts in the opposite direction. This is the principle of piezoelectric motor elements that generate traveling waves. For convenience of explanation.

Although the voltage shown in FIG. 3(c) is a sinusoidal alternating voltage, the same operation will occur if the voltage is an alternating voltage.

The principle by which this embodiment rotates in three orthogonal directions will now be described. FIG. 4 shows how piezoelectric motor elements are arranged, which is a feature of the present invention. Figure 4 shows the driven member 4 in Figure 2.
It shows the structure inside the drive member 4a when b is removed. The arrow shown inside each electric motor element indicates the direction of the traveling wave, and adjacent piezoelectric motor elements 7a and 7b are arranged on the entire surface of the spherical inner surface so as to generate traveling waves in mutually orthogonal directions. Next, the alternating voltages vx, vy for driving the three directions output from the voltage control circuit 6 in FIG.
vz is applied to the x, y, and z piezoelectric motor elements shown in FIG. 4, respectively. In this way, rotational motion around three orthogonal directions can be independently performed using relatively simple voltage control paths.

Therefore, according to this embodiment, the piezoelectric motor element that generates the driving force can be disposed on the entire surface of the driving member that comes into contact with it, so that it is possible to configure an actuator that is small, lightweight, and has a large driving force. Further, if this actuator is used, operations with three degrees of freedom can be configured with one actuator, so the automatic subject tracking device itself can be made smaller and lighter. Furthermore, when performing control by feeding back image signals, the actuator can be directly positioned without using gears, resulting in an automatic tracking device with no vibration and good responsiveness. When photographing on a ship or a helicopter, this device can provide feedback on the shaking of the floor, allowing stable images to be taken.

FIG. 12 shows another embodiment in which the driving force for rotational movement around the Z axis is increased compared to that in FIG. 4.

The difference from FIG. 4 is that each piezoelectric motor element does not work only on one specific axis, but can also contribute to the rotational movement of other axes. This will be explained below.

In this embodiment, the alternating voltage V output from which voltage control path is
X, VY, and VZ are not directly input to each piezoelectric motor element, but are input to a voltage command switching circuit 51. The voltage command switching circuit 51 applies driving force suitable for rotation in each axial direction according to the values of these alternating voltages.
A command is given to the piezoelectric motor drive circuit 52. This generates a voltage that is applied to each piezoelectric motor element.

This will be explained by taking two piezoelectric motor elements 7c and 7d in FIG. 12 as an example. For example, when rotating around the Z-axis, driving can be done by generating traveling waves in the same direction. vice versa.

By generating a traveling wave in the opposite direction, it is possible to perform rotational movement in a direction centered on the Z-axis. In this way, by using the voltage command switching circuit 51, it can be used to generate driving force in two or more directions.

Therefore, by using this embodiment, the driving force for rotational movement in a 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 that determines the shooting position of a video camera by remote control.

FIG. 4 shows two things: a remote controller 12 is used instead of the image processing circuit 5, and the structure of the actuator 4 is different.
This figure differs from Figure 1 in several points.

First, a photographer who is inside the subject 1 or at a point away from the video camera 2 operates the three remote control levers 13 on the remote control device 12 to send the up/down signal UD and the left/right signal LR.
, generates a 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. Further, the up/down signal UD and the left/right signal LR are input to a voltage control path 6. Voltage control number 6
Then, according to these signals, alternating voltages V UD and V LR to be applied to the piezoelectric element of the actuator 4 are generated.

Next, the structure of the actuator that is different from that in FIG. 1 will be explained using FIG. 6. FIG. 6 is an exploded view of the actuator 4 shown in FIG. 5 into a driving member 4C and a driven member 4d. A rotation piezoelectric motor element 14 for rotating the video camera 2 around the coordinate axis Z-axis of the drive member 4C is attached to the drive member 4C. Further, in order to move the video camera 2 up and down, a vertical piezoelectric motor element 15 is attached to the driven member 4d so as to rotate around the coordinate axis X' axis of the driven member 4d. By inputting the alternating voltage VLRtvuo to the rotational and vertical piezoelectric motor elements 14 and 15, respectively, it is possible to take pictures with the video camera by remote control while always maintaining the vertical relationship on the image and the vertical relationship of the actual subject. 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 directly below.

Therefore, according to this embodiment, images can always be photographed in all directions with the correct vertical relationship without performing complicated coordinate transformation. Furthermore, only two piezoelectric motor elements are required, and the number of voltage control paths can be simplified. Furthermore, by attaching the piezoelectric element not only to the driving member but also to the driven member, the area in which the piezoelectric motor element is arranged can be further expanded, and an actuator with a large driving force can be constructed. Using this device, the photographer himself can become the subject. In particular, this device has the advantage of being inexpensive to construct.

FIG. 7 shows an embodiment in which the actuator of the present invention is applied to an assembly work robot. This transfers the part 17a placed on the workbench 16 to the part 17b on the belt conveyor 18.
This figure shows the process of inserting the paper into the container using a robot. Part 1
When inserting 7a into component 17b, the positional deviation detector 19 detects the deviation in the fit. As the positional deviation detector 19, for example, there is a method using image processing.

The deviation signal ε obtained from the position deviation detector 19 is input to the robot control bag [20]. Robot control bag W20
In this case, a control calculation is performed to reduce the deviation of the fit, and the applied voltage Vl,'/2. Outputs V3. These applied voltages VL, V2. By V3, the 1st. The second and third actuators 21, 22, 23 are operated so that the tip arm 24 can insert the part 17a into the part 17b.

Next, the structure of the actuator, which is a feature of this embodiment, will be explained using FIG. The robot shown in this embodiment is entirely composed of a three-degree-of-freedom arm actuator 25, the cross section of which is shown in FIG. 8(a), except for the first actuator 21 and the tip arm 24, which serve as a pedestal. The piezoelectric element that drives the three-degree-of-freedom arm actuator 25 is attached to a portion having a spherical inner surface, and has the same configuration as the piezoelectric motor element shown in FIG. 3. Therefore, it is possible to rotate in any of the three orthogonal axes, and thereby the robot can perform operations equivalent to or greater than a conventional robot having at least six axes of actuators. Furthermore, by creating a standard for the size of the three-degree-of-freedom arm actuator 25 (diameter of the sphere, inner diameter of the inner sphere, length of the arm) and mass producing it, an inexpensive robot can be easily constructed. The robot's arms can also be increased by simply adding 3-degree-of-freedom arm actuators 25, and can also be applied to robots like elephant trunks. Note that, as shown in FIG. 8(b), a two-confession variable arm actuator 26 is also considered. This consists of 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 assembly work robot can be configured with a simpler configuration. In addition, it is easy to standardize arm actuators, so it is possible to manufacture robots that are inexpensive and can be configured with any number of arms. Since the arm actuator is easy to replace, it also has the advantage of shortening the repair time in the event of a failure. Furthermore, since this actuator is operated by frictional force,
Even in the event of a power outage, it can maintain the same posture as before the power outage, which is excellent from a safety standpoint.

FIG. 9 shows an example in which the actuator of the present invention is applied to a screw-fastening robot. FIG. 9 shows a device for screwing the screw 17c into the screw hole of the component 17d by a robot, but the difference from FIG. 7 is that the intermediate arm 30 is used instead of the third actuator 23 and the tip arm 24. I have used the tip actuator 31. In the case of screw fastening work, after the tip actuator 31 reaches a certain position, it is necessary to rotate the tip actuator 31 at high speed about an axis whose coordinate is the arm of the tip actuator 31. Therefore, among the piezoelectric motor elements installed in the tip actuator 31, it is sufficient to apply a voltage only to the piezoelectric motor element that rotates around an axis whose coordinate is the arm of the tip actuator 31. In contrast, in order to perform the same operation in the embodiment shown in FIG. 7, three piezoelectric motor elements of the third actuator 23 must be operated.

Moreover, the robot controller 2 performs the coordinate transformation calculations for this purpose.
It is necessary to do it at high speed with 0. Therefore, in the embodiment shown in FIG. 9, since the tip actuator 31 on the side that performs the work is operated, coordinate transformation in the screwing work is not necessary.

Furthermore, if various arms as shown in Fig. 10 are used,
It is also possible to reduce the number of coordinate transformations required for robot control. In other words, in addition to the intermediate arm 30, there are arm actuators 32, 3 with various actuators attached to both ends.
3.34 is possible. By combining these arms with the arms shown in FIG. 8, it is possible to construct robots with even different structures.

Therefore, by using this embodiment, it is possible to construct a robot that can perform screw fastening work at high speed. Furthermore, by using various types of arms, it is possible to create a robot that is optimal for each task.

FIG. 11 shows 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 solar heat/solar collector 3 that collects heat and light from the sun 35.
This is a device whose purpose is to collect the light at 6 and transfer it to the required place using the light/heat transfer device 37.

First, since the solar heat/sunlight collector 36 can collect the most heat and light when its surface is perpendicular to the sun 35, the solar position detector 38 is used. The length and direction of the shadow of the solar position detector 38 are read by the image sensor 39, and based on this, the tracking control device 40 performs control calculations so that the position of the solar heat/sunlight collector 36 matches the diameter 535. conduct.

Next, by the voltage V output from the tracking control device 40,
The tracking actuator 41 operates and automatically tracks the sun 35.
The solar heat/sunlight collector 36 can be aligned in the direction of . Note that the tracking actuator 41 may be of the same principle as the actuator shown in FIG.

According to this embodiment, when no voltage is applied to the actuator, the same posture can be maintained by frictional force, so it is only necessary to apply voltage to the actuator several times per hour for control, which greatly reduces operating costs. be able to. In particular, this actuator is small, can generate large torque, and has strong holding power even when power is not supplied.

It is ideal for such devices.

The above is a detailed explanation of the present invention, but it goes without saying that the single actuator can also be applied to devices that move lighting equipment such as spotlights, pitching machines, etc. In addition, in the example, there are two degrees of freedom.

Although we have described an actuator that can rotate with three degrees of freedom, it is of course possible to combine it with a mechanism that moves linearly. Furthermore, for convenience of explanation, each piezoelectric element has been described as being used only when moving in one predetermined direction, but it is also possible to use it to drive in multiple directions. When applied to a tracking device, it is effective not only for the sun but also for star 9 artificial satellites, flying objects, etc.

〔Effect of the invention〕

According to the present invention, the piezoelectric element that generates the driving force can be disposed in most of the area where the driving mechanism and the working movement mechanism are in contact, so that it is possible to configure an actuator that is small and lightweight and can generate a large driving force.

[Brief explanation of the drawing]

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. 3 shows the operating principle of the piezoelectric motor element. FIG. 4 is a cross-sectional view when the driven member of FIG. 2 is removed, FIG. 5 is a configuration diagram of an embodiment applied to a remote-controlled video camera device, and FIG. Fig. 7 is a configuration diagram of an embodiment applied to an assembly robot, Fig. 8 is a schematic diagram of the actuator used in Fig. 7, and Fig. 9 is a screw fastening robot. Fig. 10 is a schematic diagram of an actuator that can be applied to a robot, and Fig. 11 is a schematic diagram of an actuator that can be applied to a robot.
FIG. 12 is a configuration diagram of an embodiment applied to an automatic tracking device for collecting sunlight, and FIG. 12 is a sectional view of a driving member showing another embodiment different from FIG. 4. 1... Subject, 2... Video camera, 3... Tripod, 4... Actuator, 5... Image processing circuit, 6
...How many voltage control paths, 7...Piezoelectric motor element, 8...
・Piezoelectric element, 9... Elastic body, 12... Remote controller,
13...Remote control lever, 14...Rotation piezoelectric motor element, 15...Vertical 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 degrees of freedom actuator, 2
6...2 degrees of freedom actuator, 27, 28.29.
... Piezoelectric motor element, 3o... Intermediate arm, 31...
・Tip actuator, 32° 33.34...Arm actuator, 35...Sun, 36...Solar heat・
Solar collector, 37... Light/heat transfer device, 38...
Solar position detector, 39... Image sensor, 40...
Tracking control device, 41... Tracking actuator, 51
... Voltage command switching circuit, 52 ... Piezoelectric motor No. 1 Prisoner 2 Figure 3 Exit (a) CC) Dormitory 4 Enryo 7 ward $q Side t0 Group 12m

Claims (9)

[Claims] 1. Alternating one or one group of piezoelectric motor elements that generate a traveling wave in one direction and another one or one group of piezoelectric motor elements that generate a traveling wave in a direction different from the traveling wave,
interposed between a driving member and a driven member that are inscribed on a spherical surface,
An actuator comprising a power source that supplies voltage to the piezoelectric motor element. 2. Alternating one or one group of piezoelectric motor elements that generate a traveling wave in one direction and another one or one group of piezoelectric motor elements that generate a traveling wave in a direction different from the traveling wave,
interposed between a driving member and a driven member that are inscribed on a spherical surface,
an actuator having a power source that supplies voltage to the piezoelectric motor element; a detection circuit that detects a signal in response to the movement of a moving object; A moving object tracking device comprising: a voltage control circuit that controls voltage supplied to the actuator so that the actuator is movable. 3. Alternating one or one group of piezoelectric motor elements that generate a traveling wave in one direction and another one or one group of piezoelectric motor elements that generate a traveling wave in a direction different from the traveling wave,
interposed between a driving member and a driven member that are inscribed on a spherical surface,
an actuator having a power source for supplying voltage to the piezoelectric motor element; a detection circuit for detecting a signal responsive to the position of the object to be worked; A working robot, comprising: a voltage control circuit that controls voltage supplied to the actuator so that the actuator can move more than 100 degrees. 4. Optionally, one or one group of piezoelectric motor elements generates a traveling wave in one direction, and another one or one group of piezoelectric motor elements generates a traveling wave in a direction different from the traveling wave.
interposed between a driving member and a driven member that are inscribed on a spherical surface,
The driven member has a power supply that supplies voltage to the piezoelectric motor element, and controls the magnitude or phase of the voltage supplied from the power supply to the piezoelectric motor element, so that the driven member can move in two or more degrees of freedom. An actuator characterized by: 5. Optionally, one or one group of piezoelectric motor elements generates a traveling wave in one direction, and another one or one group of piezoelectric motor elements generates a traveling wave in a direction different from the traveling wave.
interposed between a driving member and a driven member that are inscribed on a spherical surface,
The driven member has a power supply that supplies voltage to the piezoelectric motor element, and controls the magnitude or phase of the voltage supplied from the power supply to the piezoelectric motor element, so that the driven member can move in two or more degrees of freedom. a detection circuit that detects a signal responsive to the movement of a moving object; and a detection circuit that supplies signals to the actuator so that the driven member can move in at least two degrees of freedom in response to the output from the detection circuit. A moving object tracking device comprising a voltage control circuit that controls a voltage. 6. Another method in which one or a group of piezoelectric motor elements that generate a traveling wave in one direction is arranged in a ring shape or on the entire surface of a spherical driving member, and generates a traveling wave in a direction different from the traveling wave.
An actuator characterized in that a piezoelectric motor element or a group of piezoelectric motor elements are disposed on an inner surface of a driven member that is spherically inscribed with the driving member, and the actuator has a power supply that supplies voltage to the piezoelectric motor element. 7. Another method in which one or a group of piezoelectric motor elements that generate a traveling wave in one direction is arranged in a ring shape or on the entire surface of a spherical driving member, and generates a traveling wave in a direction different from the traveling wave.
A piezoelectric motor element or a group of piezoelectric motor elements are disposed on an inner surface of a driven member that is spherically inscribed with the driving member, and an actuator having a power supply for supplying voltage to the piezoelectric motor element, and a signal generator that generates a signal according to the movement of a moving object. a means for outputting
a voltage control circuit that controls a voltage supplied to the actuator so that the driven member is movable in at least two degrees of freedom in accordance with the output from the signal output means; Device. 8. One end of the connection member has a drive member with a piezoelectric motor element arranged on its spherical inner surface, and the other end of the connection member has a spherical driven member or a drive member with a piezoelectric motor element arranged on its spherical inner surface. A single arm for a robot characterized by having a member. 9. One end of the connection member has a drive member with a piezoelectric motor element arranged on its spherical inner surface, and the other end of the connection member has a spherical driven member or a drive member with a piezoelectric motor element arranged on its spherical inner surface. a robot arm having a plurality of actuators connected to each other; a detection circuit for detecting a signal responsive to the position of the object to be worked; and a detection circuit for detecting a signal responsive to the position of the object being worked; A robot comprising: a voltage control path for controlling the voltage supplied to each of the actuators so that the robot can move in at least two degrees of freedom.