WO2010055496A1

WO2010055496A1 - A device and method for detecting or generating a curvature

Info

Publication number: WO2010055496A1
Application number: PCT/IB2009/055088
Authority: WO
Inventors: Andrea Schneider
Original assignee: Stardax S.R.L.
Priority date: 2008-11-17
Filing date: 2009-11-16
Publication date: 2010-05-20
Also published as: ITFI20080223A1

Abstract

The present invention relates to a reaction chamber of an epitaxial reactor, consisting essentially of a hollow quartz piece; the hollow quartz piece comprises a quartz piece section (1) having the shape of a cylinder or a prism or a cone or a pyramid and an axial through hole (2) provided in said quartz piece section (1 ); the quartz piece section (1 ) is adapted to define, according to two of three directions, a reaction and deposition zone (3) and to house at least one susceptor (4) to be heated inside the axial through hole (2). The chamber is provided with a reflecting layer (5) made of a quartz-based material and adapted to reflect back infrared radiations emitted by the susceptor (4); the reflecting layer (5) is applied to said quartz piece section (1 ) and/or to a quartz component of the reaction chamber.

Description

TITLE A DEVICE AND METHOD FOR DETECTING OR GENERATING A CURVATURE

DESCRIPTION Field of the Invention The present invention concerns a new device and method for detecting or generating a curvature, advantageously, but not exclusively, intended as a detector of the working configuration taken up by a sail of a boat, Background of the invention

Presently, various systems are known for facing the problem of the detection of a flexed element, In a first method, use is made of electrical resistance strain gauges, or similar deformation sensors (for example based on optic fiber) applied to the body that undergoes the curvatur®. The axial deformation of the sensor corresponds to a measurable variation in the electrical or optical properties of the same, In case of a linear elastic deformation, once obtained the field of axial deformation in a number of points of the convex and the concave side of the body, it is possible to reconstruct the deformed configuration thereof.

Laser scanning systems can also be used, which allow a geometry in space to be detected through the measurement of the flight time of the light radiation emitted by an analyzing device, Feeler systems are also foreseen, with feeler probe machinery of the surface to be detected, actuated to as to provide coordinates in space with respect to a predetermined origin.

Furthermore, it is possible to make use of simple topographical surveys, which exploit punctual measurements and trigonometric relationships, or of photogrammetric relationships (through the analysis of one or more photographs).

All of these systems generally have limitations (of constructive complexity, costs, accuracy of the measurement, reading speed) which leave various fields of use uncovered. For example, in the field of sailing, in which the possibility of detecting the deformation of the sail surface and/or of the mast in real time would provide extremely important Indications on the efficiency of the aerodynamic profile, none of the known systems is really suitable for use. Topographical and photogrammetric detections do not allow reading in real time. Similar considerations apply to feeler devices, the mechanical interaction of which with a sail is actually impossible, and which in addition are not suitable to obtain a reading in dynamic conditions.

Laser and strain gauge systems can be unacceptably complex and expensive, having problems of electricity consumption and of efficiency in critical weather conditions (wind, thermal dilatations that can disturb the measurement, etc.). Moreover, they can interfere, due to their bulk and functionality (considering that they generate an additional strain), with the deformation of the body of which the curvature detection is being carried out. Summary of the invention

The object of the present invention is to overcome the problems just indicated, by providing a new device and method for detecting and measuring a curvature that is suitable for performing accurate detections in real time in critical conditions like the working conditions of a sail surface, all by means of structurally simple and relatively cost-effective solutions.

A particular object of the present invention is to provide a device and method of the aforementioned type, which make it possible to not significantly interfere, from the point of view of stress and bulk, with the inflection of the body on which the detection is being carried out. These and other objects are achieved with the device and method for detecting or generating a curvature according to the present invention, the essential characteristics of which are defined by the attached claims 1 , 17 and 18. Brief description of the drawings

The characteristics and advantages of the device and method for detecting or generating a curvature according to the present invention shall become clearer from the following description of embodiments thereof, given as examples and not for limiting purposes, with reference to the attached drawings, in which:

- figure 1 schematically represents a perspective view of a detection device according to a first embodiment of the invention, in a non-deformed configuration; - figure 2 shows, in an analogous way to figure 1 , the device of the first embodiment in a deformed configuration; - figure 3 schematically represents a perspective view of a detection device according to a second embodiment of the invention, in a non-deformed configuration;

- figure 4 shows, in an analogous way to figure 3, the device of the second embodiment in a deformed configuration; - figures 5a to 7c are diagrams representing the working principle of the device and of the method according to the invention, showing respectively, for each of three flexion conditions of the device (figures 5a, 6a, 7a), the progress of a relative sliding function (figures 5b, 6b, 7b) and the derivative function thereof (figures 5c, 6c, 7c); and

- figures 8 and 9 schematically show, respectively, perspective and side views (outlining a further and identical adjacent module), of a module according to a further embodiment of the device.

Description of the preferred embodiments

With reference, for the time being, to figures 1 and 2, a detection device according to the invention is a flexible body 1 , developing basically in a single direction, along an axis S. The body 1 has a length that may vary, chosen on a case by case basis so as to be at least equal to a portion of the curvature that it is wished to detect, said curvature being taken up by the surface of a deformable structure (not represented), for example a sail surface, onto which the device itself is stuck as shall be made clearer hereafter. The body 1 comprises at least a pair of wire-like or, preferably (like in the illustrated example), laminar elements 2, 3, extending along the axis S and mutually linked so as to remain parallel to one another, or in any case at a distance H that varies along the same axis S according to a predetermined and known relationship. The two elements 2, 3 are made from flexible and longitudinally inextensible material, for example fiberglass plates. They are integrally connected to one another at an end 1a of the body 1 , whereas otherwise they are free to carry out reciprocal sliding along the axis S, said sliding occurring, as made clear by figure 2, following a flexion of the body 1 in response to the deformation of the structure to be detected.

From a purely mechanical point of view, this result can be obtained through a distribution of spacer columns 4, fixedly connected to an element 2 and slidably engaged (only in the direction of the axis S) with the other element 3. The device also comprises means for detecting the relative sliding of the two elements, in its projection along the direction S, which can be mathematically defined in terms of a curvilinear abscissa. Such detection means, schematically represented in the figures and indicated at 5, can for example consist of a distribution of linear displacement sensors, of the magnetic type (by magnetic induction, Hall effect or magnetoresistive), potentiometer, optical sensors and in general according to what is available on the market for similar uses. The sensors are arranged in regular intervals along the axis S, with a frequency such as to provide an adequate sampling of the relative sliding of the two elements, in any case to be optimized according to the specific applications.

The configuration of the device is finally completed by electronic microprocessor means, preferably arranged at an end 1a of the body 1 , for the acquisition of the data/signals emitted by the detection means, along with means for the transmission of the acquired data/signals to an external processing apparatus (PC, palmtop, mobile phone, etc.) which, through suitable software, is adapted to process the data and make it available for the user in digital and graphical format. The acquisition means, the transmission means (preferably via radio, Bluetooth^®, infrared etc.), the possible battery means and the entire relative circuitry are not represented or described in detail, being - as such - obvious to implement. Operatively, in the main and most typical form of use, the device according to the invention is connected to a deformable structure of which the deformed configuration one wishes to detect. The device is made integral with the same structure along one of the two wire-like or laminar elements 2, 3, through gluing or mechanical attachment. Clearly, when the structure becomes flexed, the device, and specifically the body 1 , flexes correspondingly, and the flexure (figure 2), generates a relative sliding of the two elements along the curvilinear abscissa S, measured by the sensors 5 and transmitted to the external processing apparatus.

The processor is thus able to reconstruct the relative sliding as a discrete or continuous mathematical function m(S) of the curvilinear abscissa S, i.e. the position along the axis S. Since the value H (distance between the elements) is also known, possibly variable according to a known function H(Sj, it will be possible to work out the local radius of curvature, keeping in mind that the derivative of m(S) with respect to S is inversely proportional to the radius of curvature, with a correction factor of direct proportionality to the local distance H(S) between the two flexed elements.

From the local radius of curvature (as a function of the curvilinear abscissa) it is then possible to reconstruct the deformation of the detector (and therefore of the structure) on a Cartesian plane x,y, by obviously solving a known mathematical problem.

The self-explanatory diagrams of figures 5a-7c clarify, with some examples of discrete detection, the above mentioned correlation. Figure 5a shows a device in non- deformed configuration, corresponding to a function m(S) which is constantly null, along with its derivative (figures 5b and 5c), this corresponding in fact to an infinite radius of curvature. In figure 6a the curvature of the device is shaped like an arc of circle. The function m(S) is a straight line (figure 6b) the constant derivative of which (figure 6c) is indeed the response to a constant radius of curvature. Finally, figure 7a represents a deformation of the device with variable curvature, and it can be seen (figures 7b and 7c) how a point of null curvature corresponds to a maximum of the function m(S), a null derivative function, and therefore an infinite radius of curvature; the progress of the derivative function thus represents a true representation of the evolution in shape of the flexed structure. Clearly, many devices arranged in various parts of the structure and simultaneously communicating with the processing apparatus will allow information to be obtained on the configuration of the structure as a whole. According to the above described embodiment, relative sliding is observed between the two elements 2, 3 exclusively when the curvatures to which the device is subjected lie on the local plane containing the mutually sliding elements. In order to reconstruct the deformation in space, further elements then need to be used, arranged on an orthogonal or in any case transversal surface, so that it shall be possible to determine the deformation in space from the combination of the two reconstructed deformations.

A single device, based on the same constructive principle, can also directly be made suitable for three-dimensional measurements, with a generically elongated matrix, for example a body 1 shaped like an extruded cylinder or prism, with a plurality of longitudinal elements, for example three laminar or wire-like elements arranged on respective vertices of a triangle, typically an equilateral triangle. In this case, the differential sliding detected in sets of two between couples of elements, again through distributions of suitably arranged sensors, will be able to provide information on the spatial curvature.

Remaining however in the two-dimensional field, with reference to figures 3 and 4, a variant embodiment can provide that one of the two longitudinal elements, wholly indicated at 13, has a discontinuous configuration, being made up of a plurality of laminar segments 13a - 13n each with a first end fixedly connected, through a column 14a, to the other longitudinal element 12 (the one intended for connection with the structure to be detected), and a second end that is free, although constrained to slide like in the previous embodiment through a spacer column 14b.

This solution has the advantage that the relative sliding along the axis S does not mechanically add up along the body 11 , for which reason the same body does not undergo any increase in longitudinal extension due to the deformation. In fact, the displacement of each segment 13a - 13n, each one corresponding to a detection point (and to a sensor), is compensated and taken up thanks to the interruption that distances the segment from the next one.

The body 1 can have a coating, preferably made from elastomeric material such as silicon rubber so as to make the device take on the shape of a shock-resistant flexible stick and with the internal components suitably protected from atmospheric agents and from mechanical stresses.

With regard to the detection means, according to a more basic solution, but which is still within the scope of the invention, they can simply consist of notches or reference marks formed in the elements, adapted to provide an immediate visual indication, possibly "recordable" with the help of graphic markers. The detection of the sliding can in this case be left to a subsequent step, in general using measuring instruments such as a common gauge. Of course, it is thus also possible to do without the processing and transmitting means, realizing a purely "manual" version of the device.

The advantages achieved by the device according to the invention are clear from the above, in terms of structural simplicity and cost-effectiveness of the technology used, these being characteristics that make it easy to manufacture the instrument and to use it, even in critical conditions, where more delicate and expensive (or bulky) apparatuses cannot be applied. In practice, there is the possibility of reconstructing the shape of the deformed structure in real time and with a high sampling frequency over time, making it possible to study the deformation dynamics in depth. The deformation can be reconstructed with very high time frequencies, gathering details on the variation in curvature helping anybody interested in the temporal dynamics of the deformation (for example deformations to be associated with events studied in parallel, or caused by the observer).

Compared with strain gauges, in the device according to the invention the effects of thermal distortions are intrinsically cancelled out, because the at least two longitudinal elements shrink or dilate by the same amount without relative sliding. The possibility of sliding between the two flexed elements allows their distance H to be increased while keeping the flexional rigidity unchanged. In this way, it is possible to amplify the sliding readings and use linear sliding sensors with even relatively low resolution, like linear encoders (absolute or relative) or potentiometers, which is thus simple and cost-effective technology. With strain gauges, for deformations to be measured, it is necessary to exploit the inflection of a monolithic element (stick). In order to obtain the same amplification result the thickness of the flexed element should therefore be increased, increasing its rigidity and therefore the perturbation on the structure measured. It would also be more difficult to make the instrument adhere to the deformed structure to be measured. For example, in the shape detection of a sail surface, a stick that is too rigid would create an unacceptable perturbation, and also one that has a low thickness would make the measurement of deformations inaccurate and difficult. According to the invention, this conflict of needs is overcome.

Regarding this, and to further emphasize the conceptual difference with respect to strain gauges, it should be noted that the device according to the invention can be based on a completely labile structure. A further example embodiment, particularly significant from this point of view, is provided by figures 8 and 9, to which reference will I be made hereafter. In this case, the device comprises a core 101 consisting of a linkage of units 106 adapted to be freely articulated on a plane. A certain number of units 106 makes a single module 107 of the core 101 , which represents the sampling range, i.e. the device segment on which a discreet sliding detection is carried out. As a matter of fact, the sliding is realized by inextensible wire-like elements 102,

103, in turn practically without a flexional resistance, arranged so as to slide, respectively, on the concave and on the convex side of the curvature of the module 107. The detection can therefore in this case also take advantage of a simple rotation sensor, for example acting on a roller 105 with which the wire-like elements 102, 103 engage translating the sliding into a rotation. The wire-like elements are conceptually distinct but physically they can be joined, one representing the continuation of the other. The roller 105 is obviously supported by one of the end units 106 of the module 107 of the core 101 , and rotates around an axis parallel with the axis of curvature. A module 107 will be consecutively connected, again in a freely articulated manner, to many identical modules to form a single device (figure 9).

Compared to optical systems (photogrammetry) in the case of the invention there is an extremely simple shape reconstruction algorithm. Moreover, the measurement is independent of the lighting conditions of the object to be detected, for which reason the invention is perfectly compatible with night-time use, as well as with a time frequency which cannot be reached by the aforementioned known systems.

Compared to laser scanners, the solution according to the invention is drastically more simple and cost-effective, since laser systems make it necessary to use expensive and delicate optical technology with obvious limitations of use outdoors in unfavorable weather conditions, little possibility of miniaturization, and electricity consumption not compatible with battery power supply units available on the market.

Furthermore, compared to topographical detection methods, besides to the fact that in these known methods the measurements are made sequentially and processed later on, and they are not suitable for dynamic detections and reconstructions in real time, the invention is suitable for making detections even on a small scale. There are therefore multiple applications of the device according to the invention, one of which, of particular interest, is that of telemetry in the sports sector (achieving ideal aerodynamic profiles during competition). For example, in sailing competitions any adjustment of the rig can be correlated to the deformation of the profile of the sails, both during the regatta and in training, to monitor the aerodynamic profile of the sails in real time. By using many devices it is possible to detect the profiles at various heights.

Other typical applications will be the real time monitoring of structural elements (testing, reaching critical deformations), quick testing of 3D models in the design field, biometric applications (detection of anatomical configurations), the manufacture of templates in the fields of manufacturing and building, and so on. Still with the same configuration, the device can also be exploited for use as a reference and/or "copying" instrument of a shape, even static, detected previously. In this case, the indications on the progress of the function m(S) associated with a certain deformed configuration can be stored and reproduced, to make the device return to the same deformed configuration at a later time. Possibly, reference graphs or databases can also be created, which are capable of providing the amount of sliding to be reached at every detection point in order to obtain a certain curvature.

Precisely in relation to this last proposed use, without affecting the possibility of a deformation by simple manipulation (especially in the aforementioned "manual" version), the device can also advantageously be equipped with a series of micro- actuators adapted to be controlled from a remote position, manually or automatically, for acting between the longitudinal elements so as to recreate the desired relative sliding conditions, precisely based on the curvature to be reproduced. The actuators can in general allow for control and correction off the shape in real time, in practice making the device a truly active instrument, for use in the manufacturing industry as the control of a press that deforms a plate by adjusting the closing parameters according to the deformation progressively obtained, of a motorized winch that reacts to the deformations of the element to which it applies tension etc..

The present invention is not limited to the embodiments described and illustrated, provided only as examples and not for limiting purposes, but it comprises all variants and modifications covered by the scope of the appended claims.

Claims

1. A device for detecting or generating a curvature, characterized in that it comprises a body (1 , 101) with at least two longitudinal elements (2, 3, 12, 13, 102, 103) extending along an axis (S), said elements (2, 3) being made of a flexible and inextensible material and being linked so as to be mutually slidable along said axis (S) while remaining spaced, in parallel fashion or in any case at a distance (H) that varies along said axis (S) according to a predetermined relation, the device further comprising detection means (5) for detecting the relative sliding (m) of said elements (2, 3) along said axis (S) in at least a plurality of sampling points, in response to said body (1) taking on said curvature, so as to establish a correspondence between the local curvature and the local sliding detected in at least said sampling points, considering also said distance (H).

2. The device according to claim 1 , wherein said elements (2, 3) are laminar elements mutually connected via a distribution of spacers (4).

3. The device according to claim 2, wherein said spacers (4) are integral with one of said elements (2) and engaged slidably in the direction of said axis (S) with the other element (3).

4. The device according to claim 2, wherein one of said elements (13) has a discontinuous configuration, being composed of a plurality of laminar segments (13a- 13n) each with a first end integral with the other laminar element (12) via a first spacer (14a), and a second end engaged slidably in the direction of said axis (S) with a second spacer (14b) integral with the other laminar element (12).

5. The device according to claim 1 , comprising a plurality of longitudinal elements arranged within an elongated matrix, such as three elements arranged on respective corners of a triangle, said detection means (5) being adapted to detect the relative sliding between couples of elements.

6. The device according to any of the previous claims, wherein said detection means comprise reference signs formed in said elements.

7. The device according to any of the claims from 1 to 5, wherein said detection means (5) comprise a distribution of linear displacement sensors (5) arranged along said elements.

8. The device according to claim 1 , wherein said body comprises a core (101 ) consisting of a linkage of units (106) freely hinged on a plane, said longitudinal elements comprising wire-shaped elements modularly arranged in couples of elements (102, 103) slidable respectively on the curvature concave and convex sides of said core (101), said detection means comprising rotation sensors adapted to detect the rotation induced by said relative sliding (m) as a result of the engagement between said wire-shaped elements (102, 103) and a rotating member (105) arranged on said core (101).

9. The device according to claim 7 or 8, wherein said sensors (5, 105) are chosen among the group comprising: magnetic induction sensors; Hall effect sensors; magneto-resistive effect sensors; potentiometers; optical sensors.

10. The device according to claims 7, 8 or 9, further comprising: microprocessor electronic means for acquiring data/signals emitted by said sensors (5), and transmission means for remotely transmitting the acquired data signals to external processing means.

11. The device according to claim 10, further comprising battery means for said sensors, said microprocessor means and said transmission means.

12. The device according to any of the claims 7 to 11 , further comprising actuator means remotely controllable according to automatic or manual instructions, for operating on said longitudinal elements so as to generate desired relative sliding conditions, based on a curvature to be reproduced or generated.

13. The device according to any of the previous claims, further comprising means adapted to allow its connection to a structure of which the deformation status is to be detected or generated.

14. A device according to any of the previous claims, wherein said body (1 , 101 ) is provided with a protective coating made of an elastomeric material.

15. A system comprising a plurality of devices according to any of the claims 10 to

14. and processor means communicating with said transmission means and adapted to process the data/signals of relative sliding so as to the explicate the representation of said curvature in a graphic and/or digital format.

16. The system according to claim 15, wherein said processor means are adapted to control the actuator means, when present.

17. A method for detecting the curvature of a structure, characterized by: connecting to said structure a body (1 , 101) with at least two longitudinal elements (2, 3, 12, 13, 102, 103) extending along an axis (S), said elements (2, 3) being made of a flexible and inextensible material and being linked so as to be mutually slidable along said axis (S) while remaining spaced, in parallel fashion or in any case at a distance (H) that varies along said axis (S) according to a predetermined relation; detecting the relative sliding (m) of said elements (2, 3) along said axis (S) in at least a plurality of sampling points, in response to said body (1) taking on said curvature; obtaining indications on the local curvature based on the local sliding detected in at least said sampling points, considering also said distance (H).

18. A method for generating a curvature, characterized in that: providing a body (1 , 101) with at least two longitudinal elements (2, 3, 12, 13, 102, 103) extending along an axis (S), said elements (2, 3) being made of a flexible and inextensible material and being linked so as to be mutually slidable along said axis (S) while remaining spaced, in parallel fashion or in any case at a distance (H) that varies along said axis (S) according to a predetermined relation; establishing a correspondence between the relative sliding (m) of said elements (2, 3) along said axis (S) in at least a plurality of sampling points, and the curvature locally taken on by said body (1) in response to said sliding, considering also said distance (H); deforming said body by imposing, in said sampling points, the relative sliding (m) generating a desired curvature according to said correspondence.