WO2004001941A1

WO2004001941A1 - Spherical motor device

Info

Publication number: WO2004001941A1
Application number: PCT/KR2002/001202
Authority: WO
Inventors: Jung-Kee Chung; Ha-Gyeong Sung; Tae-Bin Im; Jong-Bae Lee; Young-Ouk Kim; Sung-Ho Lee
Original assignee: Korea Electronics Technology Institute
Priority date: 2002-06-25
Filing date: 2002-06-25
Publication date: 2003-12-31
Also published as: AU2002346326A1; KR20040004727A; KR100718459B1

Abstract

This invention relates to the spherical motor device that is sphereshaped and controls the three-dimensional movement. This invention is characterized with the sphere shaped outer casing that is empty inside and cut in both front side and the backside, the sphere-shaped moving part supports the moving objects, the actuator operates the moving part, the ball, the retainer, the pins and the supporting structure. This invention can be used as a pan-tilt actuator characterized with pan-tilt movement achieved by newly developed modification of contact force by piezoelectric ceramics. Also, this invention has wider driving range than the prior techniques, working in an ultrasound range, making less noise. With this spherical motor device, it is possible to manufacture miniaturized products because the device generates higher torque with a smaller size. This invention can be applied in security or surveillance cameras and actuator in joints of robots.

Description

SPHERICAL MOTOR DEVICE

Technical Field

This invention relates to a spherical motor device that can be used as a pan-tilt actuator for cameras and joints of robots, characterized with excellent pan-tilt movements achieved by newly developed modification of contact force by the transformation of piezoelectric ceramics. Also, this invention relates to a spherical motor device that has wider driving range than the prior techniques. With, this spherical motor device, it is possible to manufacture miniaturized products because the device generates higher torque with a smaller size and less noise.

Background Art

Generally, spherical motor devices have been widely used in surveillance and security cameras or in joints of robots because of its ability to transfer and control freely in three-dimensional surface of sphere. Gradually, application potentiality of such spherical motor device is on an increasing trend, and the techniques must be advanced at the same time.

A technique used in spherical motor device of prior art is primarily achieved by generating power using magnets and coils primarily. The spherical motor device of prior art applied flat linear motor on the surface of sphere. The method using the flat linear motor is commonly seen in the configuration of the prior techniques; material that transmits magnetic flux is used on the flat stator; molds are made in x and y directions of surface; moving-magnet interacts mutually to generate magnetic reluctance, moved by variation of moving-magnet that are shorten by exciting coil of being coiled moving-magnet. These principles are stabled in a fixed position with reluctance that are generated by mutual interaction of moving-magnets and plane stator, which are made up of the quality of the material that transmits magnetic flux well.

FIG. 1 is an example of applied method for said principles. FIG. 1 is a device of a prior art and protuberances are located with pattern 93 on the sphere-shaped shape-supporter 91. The pattern 93 has regular intervals (about 0.1-0.3mm), and the driving-part slider 92 moves and operates smoothly through the intervals, also making three-dimensional movement. In addition, it is possible to select pitch Px', Py' of the pattern in random on the surface of the sphere because the magnetic poles are controlled in a random pattern by making the driving-part 92 and the pattern-part 93 concentric. Namely, the sphere motor of prior art is a technology that said pattern is made at a regular solid angle from the center of the sphere and by making the device moves through the surface of the sphere.

Publication number 59-162762 of Japan relates to a complex shape of a sphere-shaped device to generate magnetic reluctance using electromagnetic power as said explanation and also patent number 5,410,232 of the United States of America relates to the device using electromagnetic power.

Problems in this sphere motor construction using electromagnetic power are to arrange magnets in over the half of sphere surface, or to make complex shapes for special purposes. And because a sphere of stator must be made up of prominence and depression like base surface of a flat linear motor and like a sphere simultaneously, that has not only difficulty in processing, but also has high inferiority possibility. And if the driving-part slider 92 is moved freely floating at regular intervals in sphere surface, another joint of sphere shape must be required for join stator and driving- part slider in the center of rotating. This shape is not only difficulty in processing but also difficulty in assembling. Particularly, a torque of prior art has limits of size because it uses electromagnetic power technology, not decelerator; if the size of torque needs to be increased, the volume of device needs to be increased at the same time.

Disclosure of Invention

This invention relates to the solutions of the problems that are mentioned above. This spherical motor device uses contact force generated by the modification of piezoelectric ceramics. Pan-tilt movement is also possible in this invention, and compared to the other prior techniques, the actuator takes less space so that the device is able to get wider movement range. Operating in an ultrasound range decreases the noise of device. The spherical motor device also generates high torque with low velocity so that the decelerator is not necessary, making the device's size smaller.

To accomplish the object stated above, the spherical motor device is composed of parts as follows. The spherical motor device's outside appearance is in sphere shape. The motor system that controls the three- dimensional movement is composed of an outer casing 10, a moving part 20, a retainer 12, a pin 13, a support 80, and an actuator 30. The outer casing 10 is a sphere with vacant inside. The moving part 20 supports the main moving object such as a camera and is positioned inside the outer casing 10. The actuator 30 operates the spherical moving part 20. The ball 11 contacts with both outer casing 10 and the moving part and when the moving part makes three-dimensional movement, the ball helps it to move smoothly. Retainer 12 holds and supports the position of the ball 11. Two pins 13 are connected to the upper part of the outer casing 10 and hold and support the retainer 12. A supporting structure 80 holds and supports the whole parts mentioned above.

According to this spherical motor device mentioned above, the moving part 20 supports the moving object such as cameras, and as the piezoelectric ceramics move in the actuator 30, the actuator operates the moving part 20. In the prior technique, slider 92 in FIG. l is applicable to the moving part 20 in this invention. Also, inner apparatus that has means to change the velocity of the exciting coils, and the regular patterns of protuberance on the surface of prior technology are applicable to the actuator 30. There are wide differences as it is stated above and the technical effect of this invention is to control the moving part 20 in pan-tilt directions from a single point using the piezoelectric ceramics. Also, because the spherical motor device can be moved in a wide range, it is very efficient when the device is used as surveillance or security cameras. Because the actuator 30 is small, the overall size of the spherical motor device can be decreased, and it is a single-point contact type, so that it operates with higher torque than the prior technology that used magnetic reluctance.

Brief Description of Drawings FIG. 1 is a perspective view of a spherical motor device of prior art.

FIG. 2 is a perspective view of a spherical motor device of this invention.

FIG. 3 is a cross-sectional view of a spherical motor device of this invention.

FIG. 4 is a combination structure drawing of ball, retainer, and pin of a spherical motor device of this invention.

FIG. 5 is a combination structure drawing of actuator of spherical motor device of this invention. FIG. 6 is a block diagram of driving driver of actuator.

FIG. 7 is a perspective view of the actuator of spherical motor device.

Reference 10: outer casing 11 : ball

12: retainer 13: pin

20: moving part 30: actuator part

31 : protuberance 32: elastic body 33: piezoelectric ceramics 34: holder

35: spring 36: sets crew

40: function generator 50: amplifier

60: sine wave generator 70: cosine wave generator

80: supporting structure 91 : shape-supporting structure 92: slider 93 : pattern

Best Mode for Carrying Out the Invention

This invention relates to a spherical motor device that can be used as a pan-tilt actuator of the devices such as cameras with pan-tilt movement, achieved by the contact force that is generated by the shape change of piezoelectric ceramics. The actuator takes less space so that the device itself can get the wider movement range. Also, this invention relates to a spherical motor device that has wider driving range than the prior techniques, working in an ultrasound range, making less noise. The best preferred embodiment of this invention is described in detail with the accompanying drawings.

FIG. 2 is a perspective view of the spherical motor device of this invention; spherical shaped moving part is positioned inside the outer casing. The outer casing 10 is sphere with vacant inside and cut in both front side and backside. The spherically shaped moving part 20 supports objects such as cameras.

FIG. 3 is a cross-sectional view of a spherical motor device. The spherical motor device is composed of small sized actuator part 30, ball 11 positioned between outer casing 10 and moving part 20, pin 13, retainer 12, and a supporting structure 80. The ball 11 is used for smooth movement of moving part 20 and outer casing 10, and the retainer 12 holds the position. Retainer 12 is supported by two pins 13 to stay solidly with outer casing 10. FIG. 4 is a combination structure drawing of the ball, the retainer, and the pins of the spherical motor device of this invention. It shows that the pin 13 supports the outer casing 10 and the retainer 12, and the ball 11 helps the moving part 20 to run smoothly with the outer casing 10.

FIG. 5 is a combination structure drawing of the actuator of the spherical motor device of this invention. Cross-shaped elastic body 32 with hemispheric protuberance 31 is positioned at the top. At the bottom of four corners of the cross-shaped elastic body, piezoelectric ceramics of layer structure are positioned, and four holders 34 support layered piezoelectric ceramics. At the bottom of the holders, there are spring 35 and the setscrew 36 in order. The electric signals sent by four layer-built piezoelectric are transferred to the protuberance 31 , which then point- contacts with the sphere shaped moving part 20, then the moving part operates. Four piezoelectric ceramics of layer structure are grouped by two, and a piezoelectric ceramic in a group receives amplified electric sine waved signal and the other piezoelectric ceramic in the group receives the amplified electric cosine waved signal, which are 90 degrees of phase difference. After the piezoelectric ceramics get signals, one group makes movement in one way, and two groups make two-way movement. In combination, these piezoelectric ceramics are designed to make circular movement. The holder has cylinder-shaped protuberance in center for easy assembly with the spring 35. The spring 35 supports the actuator's 30 movement with flexible elasticity. The setscrew assembles the actuator 30 parts with the outer casing 10, and it has screw to put force on the spring 35. FIG. 6 is a block diagram of driving driver of actuator. The signals from the function generator 40 are divided into the sine wave generator 60 and cosine wave generator 70. The signals are amplified by the amplifier 50 and transferred to the piezoelectric ceramics 33. FIG. 7 is a perspective view of an actuator's movement. Four layered piezoelectric ceramics 33 are grouped by two. The signals from the function generator 40 are divided into the sine wave generator 60 and the cosine wave generator 70, and transferred to the piezoelectric ceramics 33 after the amplifier 50 amplifies the signals. In one group of piezoelectric ceramics that is composed of two piezoelectric ceramics, one piezoelectric ceramic receives sine waved amplified electric signals, and the other one receives cosine waved amplified electric signals, then the elastic body 32 changes its shape by the group of piezoelectric ceramics and the protuberance 31 positioned on the elastic body 32 makes elliptic motion with time. And as the protuberance 31 moves, the moving part 20 operates. As the FIG. 7 shows, the protuberance 31 makes elliptic motions with time by the transformation of the elastic body 32 with the shape change of one group of piezoelectric ceramics. Applying this principle, the other group of piezoelectric ceramics in perpendicular position will make the same movement, allowing the moving part 20 a pan-tilt movement. Also, if the two groups of the piezoelectric ceramics are operated simultaneously, the circular movement by pan-tilt operations will achieve three-dimensional movement.

This invention relates to a fixed outer casing 10 with operating moving part 20. This invention can be applied to another formation as following; the actuator 30 is positioned inside the moving part 20, moving part is fixed, and operates the outer casing 10. In other words, because this device is using the actuator 30, which is small in size with high torque, it is possible to change the formation of the device depending on its purpose. Industrial Applicability

This spherical motor device is using the piezoelectric ceramics to make three-dimensional movement such as pan, tilt, and circular ways. Also, because the actuator is small, the overall size can be decreased. Furthermore, because this device uses point-contact method, it generates higher torque than other prior spherical motor devices that use magnetic reluctance. The spherical motor device also operates in a ultrasound range and makes less noise. Therefore, this device can be used in surveillance or security cameras and in actuators of joints of robots.

Claims

What is Claimed is:

1. A spherical motor device that is sphere shaped and controls the three-dimensional movement comprising: an outer casing that is in sphere shape, empty inside and cut in both sides; a moving part that supports moving objects; and an actuator that operates said moving part.

2. The spherical motor device as claimed in claim 1, further comprising: at least one ball that supports the smooth movement of said outer casing and said moving part; - a retainer that holds the position of said ball; and at least one pin that holds the position of said retainer with outer casing, connected by the molds in outer casing.

3. The spherical motor device as claimed in claim 1, further comprising: a supporting structure that supports said outer casing, said moving part, and said actuator.

4. The spherical motor device as claimed in claim 1, said actuator comprising: a hemispheric protuberance that spot-contacts with spherical shaped moving part; an elastic body that contacts with the hemispheric protuberance; several piezoelectric ceramics positioned between the elastic body and the holder; a spring that supports the protuberance, elastic body, the piezoelectric ceramics, and the holder; and a setscrew that assembles the said actuator and the outer casing.

5. The spherical motor device as claimed in claim 4, wherein said elastic body is characterized by special movement by the shape change of the piezoelectric ceramics.

6. The spherical motor device as claimed in claim 4, wherein said holder is characterized with the cylinder-shaped protuberance in center for easy assembly with the spring.

7. The spherical motor device as claimed in claim 4, wherein said setscrew consists of screws in circumference so that said setscrew can put force on said spring.

8. The spherical motor device as claimed in claim 4, wherein said piezoelectric ceramics operates by the electric signals different in phases that are generated from a function generator, an amplifier, a sine wave generator, and a cosine wave generator.

9. The spherical motor device as claimed in claim 4, wherein said piezoelectric ceramic has a layered structure, two piezoelectric ceramics compose one group, and several groups cooperate to make a three-dimensional movement.

10. The spherical motor device as claimed in claim 9, wherein in a group of piezoelectric ceramics, one piezoelectric ceramic of the group receives an amplifying electric signal and the other piezoelectric ceramic of the group receives another amplifying electric signal, 90 degrees different in phase, so that the group of piezoelectric ceramics moves in elliptic motions with time.