BACKGROUNO OF THE INVENTION

T is invεntion relates to the use of optics to definε an object contactεo by a sensor devicε-

Existing mεthods of dεfiniπg an object cαntacted by a sensor devicε utilize electrical transducers. Such transducεrs arε complex, ^' iriherently expensive and prone to failures espεcially when used in a manu acturing environment.

SUMMARY OF THE INVENTION

It is an object of this invention to provide inexpensive but highly rεliable apparatus for defining the configuration of an object.

It is a further object of this invεntion to provide apparatus for a rαbotic device to identify objεcts it cαntacts.

It is a further object of this invention to provide apparatus for part iαsntification in a manufae uring environment.

This invention rεprεsents a major advance in thε arεa of pressure imaging because it utillzes a novel arrangs ent of optical components to acπievs a high rεsolutiαπ description or picture of an cojeet at very low cost.

Tne simplicity of oεsign, comparsd to other electrical methαds of oefining an object, means high reliability because tnerε ars fe-w parcs to fail. Additionally, any repairs that are needed can be pεrformeα quickly resulting in a significant increase in opεrating time as comparεd to electrical Systems which arε innerently ore complex and thεrefore, requirε mer≤ εxpεrtisε and time to repair.

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The high reliability and si plicity of thε invention ake it well suited to a manufacturing εnvironmεnt wherε it can be incorporated into a robotic devicε or used as a part idεπtification systεm.

In geπeral, thε invεntion fεaturεs, in one aspect, a pressurε imaging system for describing the configuration of an object brought in contact with the system. The system includes means for producing coilimatεd light, an optical bεam Splitter which is arrangεd to receivε the collimatεd light, a sεnsor plate, which is light transparent, flexible and located adjacεnt to thε bεam Splitter so that the collimated light reaches the plate after the light passεs thrαugn the beam Splitter, a atrix in contact with the sensor plate whicn has a flexible top surface and a rough undεrsurfacε which is in contact with the sensor plate, and is arranged so the object can be brought in contact with the top surface of the matrix to deform the matrix, εans for rεceiving thε light rεflεcted by the top surface of the sεnsor plate, and means for detεrmining thε configuration of thε objεct basεd on thε reflεctεd light.

In prεferred embαdimencs, the means for producing collimated light includes an incandescent light bulb and a lens; thε bεam splitter is cuöε shaped; thε bεam splitter is adε of glass; the bεam splitter includεs a diagonal intεrfacε which bisεcts the splitter aloπg a diagonal plane όf thε splitter; the sensor plate is a siliconε elastα er; tnε matrix is a silicone elastomer witn a flat top surfacε and a plurality of pyramidal projections on its undεrsurfacε; thε mεans for rεceiving rεflected light includes a photodetεctαr airay, such as CCD camera or vidiccn which detεr iπes thε configuration of thε objεct basεd on thε distribution of thε rεflectεo light; tnε focusing lens receivεs thε rεflεctεd light, and focuses the light on the photodεtector array; the pnσtαdεtectαr providεs means for convεrting the two dimεnsiαnal lignt distribution

into electric signals for dεtermining the configuration of the * object; mεans for producing a videα display of the object, created from the electric signals.

5 In ancther preferred e bodiment, the system includes mεans for producing a video display of the object creatεd from thε electric signals.

^■ In anσtnεr prεferred embodiment, the pressure imaging system is an 10 integral part of the contact surface of apparatus for coπtacting objects, which can detεr ine the configuration of thε object contacted; thε apparatus is an integral part of a rαbotic dεvicε.

Othεr fεaturεs and advantagεs of the invention will be apparent from 15 the following description of the preferred embαdi eπts, and from the clai s.

For a füll unoerstandiπg of the prεsent invention, referεncε should now be ade to the following detailεd description of preferred 20 embodimεnts of thε invention aπo to the acco paπying drawings.

8RIEF 0ESCRIPTI0N OF THE ORAWINGS

Fig. 1 is a diagrammatic viεw of thε prεfεrrεd embodiment.

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Fig. 2 is a diagrammatic view of the prεferrεd embodiment that is in contact with an object.

* Fig. 3 is an enlarged diagrammatic viεw of the matrix shov>- ^* in Fig. 0 2. .

DETAILED DESCRIPTION OF THE PREFERRED EM30DIMENTS

A prefεrrεd ε bodimεnt of the invention will now be dεscribεd with rεferεncε to the drawings.

Rεfεrring to Fig. 1, a prεssurε imaging systεm is shown. Thε systεm has light sourcε IQ which providεs light bεam 11 that passεs through and is colii atεd by lεns 12. The light source can be an incanoεscεnt light bulb or a light e itting diode.

Collimated light bεam 14 strikes mirror 16 and is r≤flected as a parallεl hεam into bεam splitter 18. The bεam splitter is typically glass with a. diagonal iπterfacε 20 bisecting it.

The light bea entering thε bεam splittεr strikεs intεrfacs 20, which rεflects part of thε incident light 22 to thε lεft side of the bεam splitter and passes re aining light 24 through to the top of the splittεr. Light 22 is absorbed by- black surface 26.

Lignt 24 passεs through sensor plate 28, which is a transparent silicαne elastomεr or rubbεr located on top of the beam splitter.

The lignt strikes contact surface 30, which is the uppεr surface αf thε sεnsor plate.

The contact surface reflεcts thε impinging lignt back to intεrfacε 20 as rεflectεα light 32. Thε intεrface dirεcts reflected light 32 to lens 3-Ü which focuses thε light onto photodetεctor array 36.

The photodetεctor dεvelops electrical signals from thε light that cαrrεspcno to thε amount of impinging light.

Matrix 42, consisting of numerous flexible projections 44 connected by top surface 46, rests on contact surface 30. The top surface must be very thin and flexible so that deformation of an arεa of thε . surfacε ^' in response to placement of an object on that area has only . 5 minimal effect on the surrounding surfacε arεa.

Typically, this matrix is made of silicone elastomer with a flat top surface and an undersurfacε consisting of a rεgular twα-di ensional array of any small pyramids. The spatial dεπsity of ^" the pyramids 10 determines thε resolution of the pressure Image.

A typical matrix has dimεnsions of one inch by one inch, and a thickness of twα to thrεe millimεtεrs, with a 100 by 100 array of pyramids on its undεrsurfacε. 15

Rεfεrring to Figs. 2 and 3, thε Operation will now be dεscribed in detail.

An oojεct will come in contact with surfacε 46 and the surfacε will 20 oεform in relationship to the object. Sensor plate 28,._whose uppεr contact surfacε 30 is in dirεct contact with matrix 47. will also deform. The deformation of the sensor plate will be in ccπformancε with the deformation of thε matrix. Soth matrix 42 and sεnsor plate 28 arε shown in thεir dεfor εd pαsitipns in Figs. 2 and 3. Both thε 25 sensor plate and thε matrix will return to undεformed positiαns when contact with the object eπds. "

If thε matrix has a rough underside created by numercus points 44, the defor ed portion of the sensor plate will confor to this rough 30 unoεrside and light striking the deformed arεa will be scatterεd by ■« the rdughnεss of thε surfacε. This scattεring will rεduce thε a cunt of light 32 reflected to Interface 20 by the deformed

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portions of sεπsor 28. Light 32 reflectεd by thε undeformεd portions of thε sεnsor platε will bε rεflεctεd dirεctly without any subs antial scattεring, and therefofε, it will bε of grεater intensity thaπ the scatterεd light that is rεflεctεd.

Rεfεrring to Fig. 3, light 32 rεflectεd by the deformed portioπ of sensor 28 is shown in morε dεtail.

Portion 48 of uppεr contact surfacε 30, locatεd bεtween adjacεnt projections, provides an optically s ooth concavε surfacε which cαπcεntratεs reflεcted light 32 at point A.

Light striking porticn 50 of the upper contact -surface, which is In contact with a prα εction 44, is scattεrεd so this portion of rεflected light 32 is of lessεr intεnsity than the light rεflectεd by portion 48 of thε sεnsαr plate.

Reflεcted light 32 is dirεcted by intεrfacε 20 to lεns 34 which focusεs thε light onto various portions of the photodetεctor array.

Using conventional tεchniquεs thε photodεtεctor array producεs εlεctric Signals in rεsponse to thε incident light, which arε proportional tα thε amount cf lignt incidεnt on portions of thε phόtαoetεctor.

Tnεsε Signals arε rεiateo to the defdrmation of sεnsor ^' plate 23, and therεforε, tney arε proportional to the prεssurε distribution crεatεo across thε sεnsor platε by the object placεd on it. Photoσεtεctαr Output 38, crεatεc from thεse signals, can bε usεo to efine the size and shapε of tnε objεct placεd on the sensor platε, and to prooucε a vidεα i age of tne object on a conventional cathode ray tube display (not snow-) .

The pressure image obtaineo directly from photodstectαr array 36 is a regulär array of dots, with each dot corrε≤ponding to onε point of contact of a projectiαn's pin-hεad with the sεnsor plate. Bεcausε the contact arεa bεtween the peak of the ^' projection and the top surface of the sensor ^* plate is approximatel proportional to the pressurε εxεrtεd on thε projεction, thε dots havε variable ^' area, which define the pressurε Variation appliεd to the matrix. Therεforε, thε prεssurε Information is εncodεd in thε area of the rεsulting i agε. This kind of arεa-modulation i agε is commαπly callεd a "nalf-tonε" image, and it is just like a picturε printed on a newspapεr.

If a continuαus tonε prεssurε image is dεsirεd rather than thε half-tonε imagε, wε can smεar thε image by oefocusing it. This is acccmplished by moving lens 34 so the image becomes slightly out of focus so that the rεgular pattern of dots will bεcomε a gray scale imagε which corrεsponds to thε pressurε Variation. Essentiaiiy, this is a conventional spatial low pass filtεring Operation.

in a preferred e bddimεnt thε prεssure imaging systεm can bε incorpαratεd inte thε fingertip of a robot's hand such that sεnsor platε 28 is locatεd on thε εxterior surfacε of thε flngεrtip.

V-'hen thε fingertip co es in contact with an object, the sensor plate will deform and the robot will bε ablε to use Output 38 to determine the objεcts configuration basεd on tnε prεssurε distribution crεatec across the sensor.

In another emoodimεnt thε photodεtεctor Output can be usεd to display a viαεα imagε of the αbjεct on a cathode ray tubε display

(not snownj using convεntional tεchniques, for the identification of parts in a manufacturing environment.

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Thεre has thus been shown and described a novεl apparatus for a pressurε imaging systεm which fulfills all the objects and advantagεs sought therεforε. Many changes, modificatlons, variatioπs and othεr usεs ano applications of thε subject invention will, however, become apparent to those skilled in the art after considering this spεcificatioπ and the accompanying drawings which disclose prefεrrεd ε bodlmεnts therεof.. All such changes, modificatlons, variations and other usεs and applications which do not dεpart from thε spirit and scopε of thε Invεntion arε dεεmεd to. bε covered by the invention which is limited only by thε Claims which follow.