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Title:
MINIATURE CRAWLER AND A MINIATURE INSPECTOR USING THE SAME
Document Type and Number:
WIPO Patent Application WO/2014/095091
Kind Code:
A1
Abstract:
A miniature crawler to crawl on surface of an object, comprising a chain having at least two driving units connected in series and at least a part of the driving units including piezoelectric element therein; and two anchoring elements connected with two ends of the chain, each of which is configured to be releasably fixed onto the surface. The present invention further provides a miniature inspector including a miniature crawler as described above and an inspecting device attached onto the crawler.

Inventors:
ORMAN MACIEJ (PL)
HOFSCHULTE JENS (DE)
Application Number:
PCT/EP2013/053341
Publication Date:
June 26, 2014
Filing Date:
February 20, 2013
Export Citation:
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Assignee:
ABB TECHNOLOGY LTD (CH)
ORMAN MACIEJ (PL)
HOFSCHULTE JENS (DE)
International Classes:
B62D57/02; B62D57/024
Domestic Patent References:
WO2010109534A12010-09-30
WO2012044663A12012-04-05
Foreign References:
CN100439049C2008-12-03
US20100145511A12010-06-10
DE19627927A11998-01-15
US7137465B12006-11-21
Other References:
None
Attorney, Agent or Firm:
ZIMMERMANN & PARTNER (München, DE)
Download PDF:
Claims:
CLAIMS

1. A miniature crawler to crawl on a surface of an object, comprising:

a chain having at least one driving unit and at least one of the at least one driving unit including a piezoelectric element therein; and

two anchoring elements connected with two ends of the chain, each of which is configured to be releasably fixed onto the surface.

2. The miniature crawler according to claim 1, wherein the at least one driving unit is at least two driving units connected in series.

3. The miniature crawler according to claim 1 or 2, wherein at least a part of the at least two driving units includes a mechanical amplifier and a piezoelectric element connected with the mechanical amplifier.

4. The miniature crawler according to claim 3, wherein the mechanical amplifier is flexible and in the shape of hexagon, and/or the piezoelectric element is connected with two opposite sides of the hexagon.

5. The miniature crawler according to claim 3 or 4, wherein the mechanical amplifier is made of plastics using rapid prototyping technology.

6. The miniature crawler according to any of claims 1 to 5, wherein the driving units are flexibly connected with each other.

7. The miniature crawler according to any of claims 1 to 6, wherein the anchoring elements are electric magnetic elements when the surface and/or the object are/is ferromagnetic.

8. The miniature crawler according to any of claims 1 to 7, wherein the anchoring elements are selected from suckers, controlled friction elements or electro- adhesion elements.

9. The miniature crawler according to any of claims 1 to 8, further comprising a second chain.

10. The miniature crawler according to claim 9, wherein the second chain is crossed with the chain and two second anchoring elements connected with two ends of the second chain, each of which is configured to be releasably fixed onto the surface, the second chain has at least two driving units connected in series and at least a part of the driving units include piezoelectric element therein.

11. The miniature crawler according to claim 9 or 10, wherein the chain and the second chain are perpendicular with each other.

12. The miniature crawler according to any of claims 1 to 11, wherein the crawler is used to pass through a gap between a stator and a rotor of a generator.

13. The miniature crawler according to any of claims 2-12, wherein the mechanical amplifier is made of steel, aluminum, or composite.

14. A miniature inspector, including a miniature crawler according to any one of claims 1 to 13 and an inspecting device attached onto the crawler.

15. The miniature inspector according to claim 14, wherein the inspecting device is high resolution camera, ultrasonic transducer, magnetic field sensors, or mechanical actuator.

16. A method for operating a miniature crawler on a surface, the miniature crawler including a piezoelectric element and a first and a second anchoring element, the method comprising:

powering the first anchoring element so that it sticks on the surface;

prolonging the piezoelectric element by powering it;

powering the second anchoring element so that it sticks onto the surface; and

releasing the first anchoring element.

17. The method according to claim 16, wherein the miniature crawler is the miniature crawler according to any of claims 1-13.

Description:
MINIATURE CRAWLER AND A MINIATURE INSPECTOR USING THE

SAME

FIELD OF INVENTION

[0001] The invention relates to a miniature robotic device, more specifically a miniature crawler and a miniature inspector using the same, and a method for operating a miniature robotic device, more specifically a miniature crawler and a miniature inspector using the same.

BACKGROUND OF INVENTION

[0002] Currently the miniature crawlers are having relatively big sizes and cannot crawl inside of air gap which is smaller than for example 10 mm. Many of the existing miniature crawlers use wheel or truck as a drive mechanism. Additionally constructions of known miniature crawlers are rigid which also limits the size of air gap in which the robotic device can crawl in. This situation is particularly relevant in the case of other potential application of the crawlers like for example crawling into tubes or pipes.

[0003] Many of the existing miniature crawlers are relatively big and rigid - can only crawl inside air gap bigger than for example 10 mm. Additionally where the robotic device is used to inspect a generator field and stator core, even if the air gap is big enough to allow the crawler to come in, the rotor diameter is too small to insert the rigid crawler into the air gap.

[0004] Particularly in an exemplary application field, visual inspection of a generator filed, stator, etc. should be performed on a periodic basis, and the need for similar inspection is increasing. There are also other application fields where a miniature crawler is required. However, current solutions are not very satisfactory and it is clear that there is a long and unfilled need for a miniature crawler and an inspector using the crawler.

SUMMARY OF INVENTION

[0005] The present invention provides a miniature crawler to crawl on surface of an object, comprising: a chain having at least one driving unit and at least one of the at least one driving unit including a piezoelectric element therein; and two anchoring elements connected with two ends of the chain, each of which is configured to be releasably fixed onto the surface.

[0006] According to an embodiment, the present invention provides a miniature crawler to crawl on surface of an object, comprising: a chain having at least two driving units connected in series and at least a part of the driving units including piezoelectric element therein; and two anchoring elements connected with two ends of the chain, each of which is configured to be releasably fixed onto the surface.

[0007] According to an embodiment of the present invention, at least a part of the at least two driving units includes a mechanical amplifier and a piezoelectric element connected with the mechanical amplifier.

[0008] According to an embodiment of the present invention, the mechanical amplifier is flexible and in the shape of hexagon, and the piezoelectric element is connected with two opposite sides of the hexagon.

[0009] According to an embodiment of the present invention, the mechanical amplifier is made by plastics using rapid prototyping technology.

[0010] According to an embodiment of the present invention, the driving units are flexibly connected with each other, such as hinged with each other.

[0011] According to an embodiment of the present invention, the anchoring elements are electric magnetic elements when the surface and/or the object are/is ferromagnetic.

[0012] According to an embodiment of the present invention, the anchoring elements are selected from suckers, controlled friction elements or electro-adhesion elements.

[0013] According to an embodiment of the present invention, the miniature crawler further comprises a second chain crossed with the chain and two second anchoring elements connected with two ends of the second chain, each of which is configured to be releasably fixed onto the surface, the second chain has at least two driving units connected in series and at least a part of the driving units include piezoelectric element therein.

[0014] According to an embodiment of the present invention, the chain and the second chain are perpendicular with each other, and optionally may have one common driving unit at the crossing point.

[0015] According to an embodiment of the present invention, the crawler is used to pass through a gap between a stator and a rotor of a generator.

[0016] According to an embodiment of the present invention, the mechanical amplifier is made of steel, aluminum, or composite.

[0017] The present invention further provides a miniature inspector, including a miniature crawler as described above and an inspecting device attached onto the crawler.

[0018] According to an embodiment of the present invention, the inspecting device is a high resolution camera, ultrasonic transducer, magnetic field sensors, or mechanical actuator.

[0019] According to an embodiment of the present invention, a method for operating a miniature crawler as described herein is provided.

[0020] In particular, the method may be accomplished with a miniature crawler as described herein. Particularly, the miniature crawler may include a piezoelectric element and a first and a second anchoring element. The method includes the steps of powering the first anchoring element so that it sticks on the surface; prolonging the piezoelectric element by powering it; powering the second anchoring element so that it sticks onto the surface; and releasing the first anchoring element.

[0021] Preferred embodiments, aspects, details and advantages are furthermore evident from the dependent claims, the description, and the drawings.

[0022] The invention is also directed to an apparatus for carrying out the disclosed methods and including apparatus parts for performing each described method steps. These method steps may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, the invention is also directed to methods by which the described apparatus operates. It includes method steps for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The subject matter of the invention will be explained in more detail in the following text with reference to preferred exemplary embodiments which are illustrated in the drawings, in which:

[0024] FIG. 1 shows a circumstance where a miniature crawler is used, which serves only as an exemplary application of the present invention;

[0025] FIG. 2 shows a schematic structure of a crawler according to an embodiment of the present invention;

[0026] FIG. 3 shows a schematic diagram illustrating the moving mechanism of the crawler according to an embodiment of the present invention;

[0027] FIG. 4 shows a schematic structure of a crawler according to another embodiment of the present invention;

[0028] FIG. 5 shows a perspective view of the crawler shown in Fig. 4;

[0029] FIG. 6 shows a schematic diagram illustrating the amplifying mechanism of a mechanical amplifier according to an embodiment of the present invention;

[0030] FIG. 7 shows a schematic three dimensional illustration of the mechanical amplifier according to an embodiment of the present invention; and

[0031] FIG. 8 shows a schematic structure of a crawler according to a further embodiment of the present invention.

[0032] Throughout the figures, same or similar reference numbers indicate same or similar elements. In principle, identical parts are provided with the same reference symbols in the figures. DETAILED DESCRIPTION OF EMBODIMENTS

[0033] It should be appreciated that, while this specification contains many specific implementation details, they should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0034] Hereinafter, exemplary embodiments will be referred to in describing the mechanism and spirit of the present invention. It should be understood that these embodiments are merely provided to facilitate those skilled in the art in understanding and in turn implementing the present invention, but not for limiting the scope of the present invention in any way.

[0035] Fig. 1 shows a circumstance where a miniature crawler is used, which serves only as an exemplary application of the present invention. As shown in Fig. 1, there is a gap 4 between the rotor 3 and stator 2 of a generator which needs to be inspected periodically. However, due to its small size conventional means are not applicable unless the generator is dissembled. Especially when the gap is very small such as less than 10mm, there is a strong need for such a miniature crawler 1 which can pass through the radial air gap 4 between the rotor 3 and the stator 2.

[0036] Fig. 2 shows a schematic structure of a miniature crawler according to one embodiment of the present invention. As shown in Fig. 2, the miniature crawler includes a chain having a plurality of piezoelectric elements 15 (as a driving unit as defined in the below) connected in series and two anchoring elements 13 attached respectively to the two ends 14 of the chain. Optionally, the piezoelectric elements 15 are flexibly connected with each other so that the crawler can conform to a curving surface along which the crawler is moving. For example, the piezoelectric elements 15 are hinged with each other so that the piezoelectric element 15 is rotatable around an axis parallel with the transversal direction of the piezoelectric element 15. The flexible crawler will well fit the need where the gap to be passed through is curving with a small bending radius.

[0037] In addition, as an example only, each of the anchoring elements 13 is an electric magnetic element such as electromagnet or magnetic coil which can stick onto the surface along which the crawler is moving when it is powered and can be released from the surface when the power is off. Certainly, the electric magnetic elements can only be used when the surface along which the crawler is moving or the object under/of the surface (hereinafter collectively referred to as the object of the surface and it should be understood that both are within the scope of the present invention) is ferromagnetic. Other ways may also be used such as sucker, controlled friction or electro-adhesion. Hereinafter, the anchoring elements will be similarly used and will not be repeatedly described for each embodiment.

[0038] Fig. 3 shows a schematic diagram illustrating the moving mechanism of the crawler according to an embodiment of the present invention. For the purpose of simplifying the description, only one piezoelectric element 15 is shown here, and the moving mechanism of a crawler having more than one piezoelectric element remains same which will not be described repeatedly. As shown in Fig. 3, arrow 16 indicates the direction along which the crawler is moving. At step SI, the crawler is put onto the surface to be moved along. At step S2, the anchoring element 13 at left side is powered so that it can stick onto the surface. At step S3, by powering the piezoelectric elements 15, it will be prolonged in its longitudinal direction when an external electric field is applied thereto, and thus the anchoring element 13 at right side will move rightwards since the anchoring element 13 at left side is sticking onto the surface. At step S4, the anchoring element 13 at right side is powered so that it can stick onto the surface while the anchoring element 13 at left side is released by removing the electric field applied thereto. At step S5, the electric field applied onto the piezoelectric elements 15 is removed and thus the piezoelectric elements 15 will be shortened in its longitudinal direction, and then the anchoring element 13 at left side will move rightwards since it has been released while the anchoring element 13 at right side is sticking onto the surface. Comparing the position of the crawler at SI with the position at S5, the crawler has been moved rightwards. By repeating the foregoing process, the crawler can move rightwards to a further extent. By reversing the order of powering the anchoring elements 13 at left side and right side, the crawler can move leftwards. Usually, the piezoelectric element 15 can be powered by a high frequency electric signal, such as at 1000 Hz, and thus the actual moving distance of the crawler will be visible even though a single deformation of the piezoelectric element 15 may not be visible.

[0039] It should be understood that although the crawler includes a plurality of piezoelectric elements 15, not all of them need to be powered at same time, and the circumstance where only part of them are powered at same time is also within the scope of the present invention, although it will not be specifically pointed out every time. Also, in the above example, the piezoelectric element 15 will be prolonged in its longitudinal direction when an external electric field is applied thereto. However, it should be understood that the present invention is also applicable where the piezoelectric element 15 will be shortened in its longitudinal direction when an external electric field is applied thereto, and only the moving direction of the crawler or the order of powering the anchoring elements will be changed.

[0040] Since usually the deformation amplitude of piezoelectric element is quite small, and thus the crawler may not be very efficient in situation where the distance to be moved is very long. To speeding move of the crawler, all or most of the piezoelectric elements in the crawler may be provided with a mechanical amplifier so that the moving distance of one piezoelectric element per powering may be increased.

[0041] Figs. 4 and 5 show schematic structure of a crawler according to another embodiment of the present invention. As shown in Fig. 4, the miniature crawler includes a chain including a plurality of driving units 12 connected in series and two anchoring elements 13 attached respectively to the two ends 14 of the connected driving units 12. Each driving unit 12 includes a mechanical amplifier 21 and a piezoelectric element 15 connected therewith. Optionally, the driving units 12 are flexibly connected with each other so that the crawler can conform to a curving surface along which the crawler is moving. For example, the driving units 12 are hinged with each other so that it is rotatable around an axis perpendicular with the longitudinal direction of the crawler. The flexible crawler will well fit the need where the gap to be passed through is curving with a small bending radius. Same as Fig. 2, as an example only, each of the anchoring elements 13 is electric magnetic elements which can stick onto the surface along which the crawler is moving when it is powered and can be released from the surface when the power is off.

[0042] FIG. 6 shows a schematic diagram illustrating the amplifying mechanism of a mechanical amplifier according to an embodiment of the present invention. In this example, the amplifier is flexible and in shape of a hexagon, and the piezoelectric element 15 connected therewith is located between two opposite sides of the hexagon, thus leaving two jointed sides at both transversal sides of the piezoelectric element 15. As shown in left side of Fig. 6, the piezoelectric element 15 is in its original position between two opposite sides 211 and 212, and two jointed sides 213 and 214 are located at left side of the piezoelectric element 15 while the two jointed sides 215 and 216 are located at right side of the piezoelectric element 15. As shown in right side of Fig. 6, the piezoelectric element 15 will be prolonged in its longitudinal direction by applying electrical field thereon, and thus the two sides 211 and 212 will move away from each other and the jointed sides 213 and 214 and the jointed sides 215 and 216 will respectively buckle inward, reducing the transversal size SI of the hexagon. The reduced size of the hexagon could be, for example 3mm, triple of the deformation amplitude of the piezoelectric element 15. Based on the design of the hexagon or even other shapes or designs, the extent of amplifying could be different and will not be described in detail here. Since a single move of piezoelectric element is small and may not well serve the need of a quick move even with the high frequency electric signal, this embodiment provides an even advantageous solution.

[0043] To be noted, by following the steps shown in Fig. 3, the crawler shown in Fig. 5 will move leftwards, but it should be understood that the crawler can move rightwards by various other ways, such as by reversing the order of powering the anchoring elements at left side and right side.

[0044] Fig. 7 shows a schematic three dimensional illustration of the mechanical amplifier according to an embodiment of the present invention. As shown in Fig. 7, the mechanical amplifier 21 is a three dimensional hexagon having a length L, width W, and height H. The mechanical amplifier 21 can be made of various materials, such as plastics, steel, aluminum or composite, and can be produced by rapid prototyping (RP) technology which enables quick and cheap adjustment to macro scale shape of the mechanical amplifier 21. For example, for an piezoelectric element with a size of 5mm x 3mm x 3mm, the height H could be about 3mm only, while the length L and width W could be about 5.5 mm and 3.5 mm respectively, which means the height of the miniature crawler could be as small as 3mm, and thus satisfy the application need where the gap to be passed through is quite small. Depends on the size of the piezoelectric element, the mechanical amplifier 21 can be made even smaller.

[0045] The above describes the hexagon as an example of mechanical amplifier, but the mechanical amplifier can also be implemented in other ways such as employing lever principle or connecting rod structure.

[0046] It should also be understood that although the crawler in Fig. 2 includes a plurality of piezoelectric elements 15 while the crawler in Fig. 4 includes a plurality of driving units 12 with mechanical amplifier 21, the solution mixing the piezoelectric elements with driving units having mechanical amplifier in the chain is also within the scope of the present invention, and the solution mixing the piezoelectric elements and/or the driving units having mechanical amplifier with other elements in the chain of connection is also within the scope of the present invention, although it will not be specifically pointed out every time, and hereinafter the piezoelectric element 15 in Fig. 2, the driving unit 12 including the piezoelectric element and the mechanical amplifier in Fig. 4, and other elements in the chain of connection are collectively referred to as driving unit(s).

[0047] Fig. 8 shows a schematic structure of a crawler according to a further embodiment of the present invention. In the previous embodiments, the crawler can only move in one dimension, i.e. in the direction of right and left shown in the drawing. In Fig. 8, two one-dimensional crawlers as described above are crossed with each other and optionally may have one common driving unit at the crossing point, and a payload 17 is located at the crossing point. By having two one-dimensional crawlers on different direction, the payload 17 can be moved in either right-and-left direction or up-and-down direction. For example, the payload 17 can move in right and left direction with the help of the left and right anchoring elements 13, and the payload 17 can move in up and down direction with the help of top and bottom anchoring elements 13. Certainly, the two directions do not have to be perpendicular with each other.

[0048] In some application fields such as inspection of stator core and field surface of a generator, the above crawler can carry a high resolution camera, ultrasonic transducer, magnetic field sensors and/or other sensors to provide a clear view of the stator core laminations, stator wedges, field wedges and inboard ends of the retaining rings. Further, the above crawler can carry mechanical actuators to conduct maintenance work or the like.

[0049] Although the above makes reference to miniature inspector including sensors having sensing function only, the crawler as described can certainly be applied to circumstances where other functions are required such as to make repair or maintain an object. For the sole purpose of saving words, the present application uses the term "inspector" or "inspecting device" to cover all these situations and shall not be construed as device having inspecting function only.

[0050] Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no way limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.