Patent Application
20080212840
This invention relates to optically-based methods and systems for imaging objects, and in particular for topographical/dimensional measurement of objects. This invention also relates to illumination and imaging systems, in particular accessories therefor including background media associated therewith, and more particularly to such systems and media used in optically-based methods and systems for topographical/dimensional measurement of objects.
Optical measurements of features as well as of complete manufactured objects, for example automotive metal parts, plastic parts and so on, or indeed of natural objects, can be of great value in industry. Topographical including dimensional data of manufactured objects that may be of interest may include the size, location and shape of bores, edges and the like, for example.
Some machine vision systems utilize a static global illumination system for illuminating the full object, which may be uneconomical and inefficient for some applications.
Other machine vision systems utilize lights fixed onto and carried by the camera head for illuminating the particular area of the object that is being imaged by the camera.
Many industrially manufactured objects, such as automotive metal parts, plastic parts and so on typically vary in their optical reflectance properties, some being more reflective than others for a given incident beam intensity.
Machine vision systems often utilize different illuminations to illuminate objects during such optical measurements. In such systems comprising front illumination, i.e., illumination substantially on the same side of the object to be imaged as the camera, a particular background medium may sometimes be used with respect to the object, particularly when edge measurements of the object are of interest.
When attempting to generate an image of an edge-comprising part using some standard illumination systems, the edge reflectance characteristics of the part, which may include for example specular reflections, surface texture and other forms of optical interferences near the edge, can cause the edge or part thereof in the image to appear shifted relative to where the true mechanical edge of the part should appear in the image.
The term “gain” herein includes the ratio of the reflectance of a surface of an object to the reflectance obtained from a standard white diffuser surface under the same illuminating conditions, and the ratio is often expressed in log scale.
The term “reflectance” refers to the ratio of radiant flux (total power emitted, received or passing in the form of electromagnetic radiation) reflected by a surface to the radiant flux falling on it. However, reflectance is often expressed as a percentage, i.e., the radiant flux reflected by a surface as a percentage of the radiant flux falling on it.
According to a first aspect of the invention, a system is provided for imaging, in particular for virtual reconstruction of topographical features of an object, comprising:
In some embodiments, the image acquisition system and the illumination system are each mounted for movement with respect to an independently controllable robotic arm or other motion inducing mechanism, capable of providing movement to the corresponding image devices or illumination sources, respectively, of the said image acquisition system and said illumination system, respectively, in up to six degrees of freedom.
In other embodiments, the image acquisition system and the object are each mounted for movement with respect to an independently controllable robotic arm or other motion inducing mechanism, each capable of providing movement to the corresponding image devices of the said image acquisition system and the object, respectively, in up to six degrees of freedom.
In yet other embodiments, the illumination system and the object are each mounted for movement with respect to an independently controllable robotic arm or other motion inducing mechanism, each capable of providing movement to the corresponding illumination sources of the said illumination system and the object, respectively, in up to six degrees of freedom.
In yet other embodiments, the object, the image acquisition system and the illumination system are each mounted for movement with respect to an independently controllable robotic arm or other motion inducing mechanism, each capable of providing movement to the corresponding object or image devices of the said image acquisition system or illumination sources of said illumination system, respectively, in up to six degrees of freedom.
The system according to the first aspect of the invention may comprise any one of or combination of the following features A to Q:
According to a variation of the first aspect of the invention, an imaging system is provided for imaging an object, comprising:
In some embodiments, the imaging system comprises
In particular embodiments, the image acquisition system, and the illumination system are each mounted onto separate and independently controllable robotic arms; in other embodiments the image acquisition system, and said object are each mounted onto separate and independently controllable robotic arms; in other embodiments said illumination system and said object are each mounted onto separate and independently controllable robotic arms; in other embodiments said illumination system, said image acquisition system and said object are each mounted onto separate and independently controllable robotic arms.
Optionally, the system according to this variation of the first aspect of the invention may comprise any one of or combination of the features A to Q listed above for the first aspect of the invention, mutatis mutandis.
Optionally, the imaging system may be adapted for providing image data configured for enabling virtual reconstruction of topographical features of said object.
According to said variation of the first aspect of the invention, an imaging method is provided for imaging an object, comprising:
Optionally, step (c) may comprise providing movement in at least one or in at least two or in three translational degrees of freedom, and/or providing movement in at least one or in at least two or in three rotational degrees of freedom.
Optionally, the method further comprises the step of virtually reconstructing topographical features of said ROI based on said image data.
An analogous method is also provided for the first aspect of the invention, in which a reconstruction method is provided for virtual reconstruction of topographical features of an object, comprising, comprising:
Furthermore, the imaging system or the imaging method according to said variation of the first aspect of the invention, or the reconstruction method above according to the first aspect of the invention, may comprise any one or combination of features A to Q as listed above for the system according to the first aspect of the invention, mutatis mutandis.
A feature of at least some embodiments according to the first aspect of the invention or variation thereof is that regions of interest (ROI) of an object can be imaged in an optionally dynamic manner while being illuminated in one or more directions or axes different from the optical axis or axes of the device(s) of the image acquisition system, eliminating or minimizing specular reflection of the illumination radiation back to the image acquisition system, which may otherwise cause saturation of the image. Such saturation may in some cases cause an edge or part thereof in the image to appear shifted relative to where the true mechanical edge of the part should appear in the image.
Another feature of at least some embodiments according to the first aspect of the invention or variation thereof is that by providing an image acquisition system that is partially or fully mechanically de-coupled from the illumination system, this enables relatively large freedom of movement of the image acquisition system independently of the illumination system, while avoiding collision with the object, which could otherwise occur in some cases where the image acquisition system and the illumination system are mechanically coupled, and may thus present a relatively large imaging head.
According to at least some embodiments of the invention, systems and methods are provided for imaging and reconstructing topographical features of an object, in which an illumination system illuminates the object and images may be acquired by an image acquisition system, and wherein at least two components including the object, the illumination system, and the image acquisition system are mounted to or otherwise associated with independently controllable motion inducing mechanisms, in particular robotic arms, such as to enable at least two of the components to be independently moved, to provide optimum illumination and viewing conditions wherein to obtain image data. The image data is configured to enable topographical features of the object to be reconstructed.
According to a second aspect of the invention, a system is provided for imaging at least a region of interest (ROI) of an object including an edge, comprising:
Optionally, the imaging system may be adapted for providing image data configured for enabling virtual reconstruction of topographical features of said object. Thus, in a variation of the second aspect of the invention, the invention is directed to a virtual reconstruction system, mutatis mutandis. Thus, this variation of the second aspect of the invention is directed to measurements relating to surfaces and/or free edges of such objects, especially where the objects are highly reflective and/or textured. Further, according to this variation of the second aspect of the invention, optical data relating to surfaces and/or edges of an object are provided, which may be used for reconstructing 3D surface structure of an object.
According to the second aspect of the invention, a background system is also provided for an illuminated object to be imaged with respect thereto, comprising a visually exposed surface selectively constituting one of a plurality of interchangeable background surfaces, wherein each said background surface comprises a plurality of surface elements each of which may be reversibly moved between a first position the surface element is not comprised on said visually exposed surface, and a second position wherein the surface element is comprised on said visually exposed surface.
The background system according to the second aspect of the invention, by itself or in comprised in said imaging system or said reconstruction system, may comprise any one of or suitable combination of the following features:
Thus, according to the second aspect of the invention, a background system is provided enabling a user to selectively change the background surface in situ. According to some embodiments, the background system may be placed behind the object as an optical background. A suitable front illumination system, typically adjacent to the camera(s) or other imaging system may be used to illuminate the object and the background surface. The background device allows the user to choose between a plurality of different backgrounds with respect to the object without having to disrupt the illumination system, imaging system or the object.
Thus, at least two different optical backgrounds may be provided for imaging with the object. Optionally, two or more such background devices may be provided, wherein each said device is positioned such that the object is aligned between one such device and least one image capturing device.
A feature of the second aspect of the present invention is that by co-rotating the rotatable elements, each one of at least three alternative such surfaces may be selectively presented as background surfaces for the object O without the need to physically remove a background and replace it with another. Accordingly, this makes possible optimally matching the most appropriate of these surfaces to the object or parts thereof as required in a simple and fast manner. For example, if the object has a highly reflective surface and a non reflective surface, when imaging the former a dull or matte background surface may be preferable, while when imaging the latter, a different background may be preferred.
In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
In the present invention, the term “object” includes any two dimensional object or any three dimensional object, or a collection of two dimensional or three dimensional objects including a scene.
Dimensional data is taken herein to refer to any topographical data relating to an object, which in particular is understood herein to include any geometrical data relating to location, size and shape with respect to surfaces or edges, including internal and external surface and edges, surface geometry, or other features of an object that are capable of being imaged.
Thus, the object to be imaged, generally designated herein as O with reference to the figures, according to the invention can comprise any mechanical or other physical object, including a scene, that it is desired to determine dimensional data, such as for example surface data or edge data, thereof. The object O may comprise for example surfaces, edges and/or other features that may be substantially three-dimensional, for example fabricated automotive parts such as die-pressed door or body panels. Alternatively the object O may comprise surfaces and edges that may be considered “two-dimensional”, comprising, for example, a thin metal sheet having a particular plan form, which may be useful in quality control of the shape of blanks before being pressed in dies or the like. Of particular interest may be the location and/or size and/or shape of free edges, internal or external, bores, holes, bosses, journals, and so on.
According to a first aspect of the invention, and referring to
The image acquisition system 150 comprises at least one image capturing device 160 mounted on a robotic arm 170. Each image capturing device 160 (only one such unit is illustrated in
The robotic arm 170 comprises a controllable mechanism for providing translations and/or rotations of a part thereof in up to five or six degrees of freedom, the part being a part of the arm onto which a desired component may be fixed or otherwise mounted, temporarily or permanently, thereby enabling the movements of the component in said up to five or six degrees of freedom. In this embodiment, the robotic arm 170 comprises a fixed base 172, fixedly mounted to a static structure such as a floor, wall, ceiling, fixed struts, and so on, or optionally to a movable structure, such as for example a trolley or gantry. The robotic arm 170 further comprises a mounting bracket 174 or gripper, i.e. a clamp or any other mechanism for gripping, clamping and so on, with respect to which the corresponding image capturing device 160 is mounted, or otherwise secured with respect thereto, optionally reversibly. A plurality of articulated links 176 are provided between the mounting bracket 174 and the base 172, in a manner enabling the bracket 174, and thus the corresponding image capturing device 160, to translate and rotate in five or six degrees of freedom in a controlled manner.
Alternatively, rather than a plurality of articulated links, the robotic arm may comprise a flexible shaft including a plurality of steering wires coupled to steering drives, and suitably connected to the flexible shaft to enable the free, operative end of the shaft (which comprises the mounting bracket or gripper) to be moved in any desired manner, for example as are used for steering endoscopes and the like, mutatis mutandis.
Such robotic arms having articulated links or endoscope type steering mechanisms are well known in the art and will not be described in any further detail herein.
Thus, the arm 170 may comprise a plurality of servomotors, controllers and so on, as is known in the art for providing such movement. The robotic arm 170 is operatively connected to, and/or comprises, a suitable power source (not shown).
Further, the arm 170 may also comprise position sensors or the like to provide positional data, or to enable such data to be determined, for the bracket 174, and thus for the corresponding image capturing device 160. Thus, the particular trajectory and specific positions and orientations of the image capturing device 160, even if set manually the first time that the system 100 is operated, may be stored by the controller, and this enables the same trajectory and specific positions and orientations of the image capturing device 160 to be repeated as often as required.
Referring to
In other embodiments of the invention, the robotic arm may be configured for providing translations and/or rotations in less than five degrees of freedom, according to the particular application of the system 100. For example, in some applications of the system 100, it may only be necessary to translate the image capturing device 160 along one direction, and/or to rotate it along one axis in order to cover all the ROI's of an object.
The robotic arm 170 is operatively connected to a controller 190 via line 179. The controller 190 is configured for controlling the movement of the arm 170 in up to six degrees of freedom, and thus of the corresponding image capturing device 160, according to preset conditions, as will become clearer below. Line 179 may be a physical line such as for example a fiber optic line, electric or electronic cable, and so on, and/or may include any other data or signal communication link, for example a suitable wireless connection between the robotic arm 170 and the controller 190, including suitable data transmitters and receivers, for example.
The illumination system 120 comprises at least one image illumination unit 130 mounted on a second robotic arm 140.
The illumination unit 130 is operatively connected to the controller 190 or to a different controller (not shown) via line 188, which may include any suitable communication link, enabling operation of the illumination unit 130, including switching the same on and off, optionally controlling intensity of illumination, as well as operation of particular illumination elements of the illumination unit 130, where appropriate. The controller 190 may also be optionally configured to control the illumination source in a manner such as to synchronize illumination of the object with the image taking process by means of the image acquisition system 150, for example as disclosed in WO 2006/080023 , assigned to the present assignee; the contents of WO 2006/080023 are incorporated herein in their entirety.
Each illumination unit 130 (only one such unit is illustrated in
The robotic arm 140 may be substantially similar to the first robotic arm 170 as described herein, including all the variations and features thereof, mutatis mutandis. Thus, the robotic arm 140 comprises a fixed base 142, fixedly mounted to a static or movable structure, a mounting bracket 144 or gripper, with respect to which the corresponding illumination unit 130 is mounted, optionally reversibly, and a plurality of controllable articulated links 146 between the mounting bracket 144 and the base 142, for providing five or six degrees of movement, or less than five degrees of movement, controlled by controller 190 via control line 149 or by a different controller. The robotic arm 140 is operatively connected to and/or comprises a suitable power source (not shown).
Optionally, and as may be the case for other embodiments of the invention as well, mutatis mutandis, the illumination unit 130 may comprise a light reflecting medium 131 and an illumination source 132, as illustrated in
Alternatively, the light reflective medium may comprise a background device that is configured for selectively presenting one of a number of alternative optical media at a time to face one or more of the object O, illumination system 120, and optical image acquisition system 150. Each of the alternative media may comprise different light reflection properties. Such a background device may comprise, for example, the dynamic background device as disclosed herein according to a second aspect of the invention and illustrated in
A “retro-reflective surface” herein refers to a surface which bounces incident light back towards the source of the light, in other words, a light beam that has a certain incidence angle with respect to the layer will exit the layer at approximately the same angle back to the illumination source. Such retro-reflective surfaces are well known and may be formed, for example, using spherical reflective beads, or the like, and compositions of retro-reflective layers and methods for their production are disclosed in U.S. Pat. Nos. 2,432,928, 2,440,584, 2,543,800, 2,397,702, 4,104,102, for example, the contents of which are incorporated herein in their entirety by reference. Retro-reflective surfaces typically provide a gain of more than 2.
In the embodiment illustrated in
Referring back to
Such optimal position(s) and orientation(s) for the of the image acquisition system 150 may in general depend on the nature of the ROI itself, or may be preset for example, according to criteria, for example.
The criteria for optimally positioning and/or orienting the illumination system 120 may be similar to or different from those for the image acquisition system 150. In particular, the illumination provided by the illumination system 120 to an ROI may be optimized such that for each image acquisition position/orientation of the image acquisition system 150 with respect to an ROI of the object O, the illumination system 120 provides maximum uniformity and intensity of illumination for every part of the ROI being imaged, minimizing shadows and/or high contrast between different parts of the ROI. Again, in general, the position and orientation of the illumination system 120 may be coupled to the position and/or orientation of the image acquisition system 150 at any particular ROI, and may in general depend on the nature of the ROI itself, or may be preset for example, according to criteria, for example. This coupling, though, is non-mechanical, and the robotic arms 140 and 170 may move independently one from the other. Rather, this coupling refers, in some embodiments, to controlling the movement of both robotic arms 140 and 170 such that they maintain a particular spatial relationship or follow a particular variation in spatial relationship, according to the particular application of the system 100.
By way of example, for ROI's relating to substantially planar features such as for example planar walls, trimmed sheet metal, edges, and the like it may be sufficient to have an optical axis of the image acquisition system 150 generally perpendicular to the ROI, and spaced therefrom so that the field of view thereof encompasses the ROI. If the ROI is relatively large, better resolution may be obtained by providing a plurality of sets of image data taken successively from adjacent parts of the ROI, each of which may be considered as an ROI, and the data subsequently stitched. The illumination provided by the illumination system 120 may be such as to provide an illumination direction to illuminate the ROI such as to optimize the illumination, and to minimize specular reflection, for example. On the other hand, where the ROI is a highly complex three-dimensional shape, the image acquisition system 150 may be positioned and/or oriented in a variety of positions relative to the ROI to obtain sufficient cover therefore, and the illumination system 120 provides illumination in a suitable manner to avoid or minimize specular reflection of the illumination to the image acquisition system, and avoid or minimize saturation of the image. Optionally, this may be determined in a theoretical manner for each ROI. For example, optimal methods for imaging and illuminating standard shapes, for example cubes, cylinders, spheres, etc, may be derived from basic concepts in physics relating to optical reflection, for example. Alternatively, the optimal relative positions of the image acquisition system 150 and the illumination system 120 may be determined in an empirical manner, e.g. by trial and error. Alternatively, any suitable combination of theoretical and empirical methods may be used.
Alternatively, the image acquisition system 150 may be preset to obtain image data at spaced angular intervals in azimuth and elevation around the object O, according to any polar or other coordinate system, and the illumination system 120 provides illumination in an appropriate manner, assuming an appropriate spatial configuration, i.e., position and orientation, relative to the image acquisition system 150 and the object O, by independently operating and moving the robotic arm 140. Alternatively, the image acquisition system 150 may be preset to obtain image data according to predetermined criteria.
Control of the position and/or orientation of the image acquisition system 150 and/or of the illumination system 120 may be provided by the controller 190 via lines 179 and 149, respectively, for example in an automated manner. In variations of this embodiment wherein one or more of the image acquisition system 150, illumination system 120, robotic arm 170, robotic arm 140 may be controlled by separate controllers, such controllers may optionally be operatively connected so as to coordinate the operations thereof.
Image data obtained by the image acquisition system 150 may be transmitted to the controller 190, for example via line 189, or indeed any other suitable data analysis and manipulation system, for analysis and manipulation as required, to provide the desired dimensional data, including for example surface or edge data, or other geometrical data relating to the object O.
In other embodiments of the invention, the robotic arms for the imaging system and/or for the illumination system may be replaced with other controllable suitable motion-inducing mechanisms adapted for providing movement in a desired number of degrees of freedom, optionally including suitable translation and/or rotation systems, for example a suitable gantry system. However, while gantry systems and the like may provide movement with up to 6 degrees of freedom, robotic arms also have the feature of not requiring a relative large frame and rails, which can otherwise sometimes collide with the object, image acquisition devices or illumination sources, or indeed similar components of the second (and/or third) motion inducing mechanisms when these are also gantries. Robotic arms may be configured for enabling the particular component mounted or otherwise associated therewith—the image acquisition system, the illumination system or the object—to be moved in three dimensional space in a manner that may in general prevent collision with other components or robotic arms of the system 100 when the sequence of movements of the robotic arm is properly coordinated.
The system 100 may be operated in a number of different ways, and some non-limiting examples thereof will now be described.
In such an example the general topography of the nominal object may be known, for example from a CAD model of the object.
The controller 190, or other suitable computer, may first divide the CAD model or datum, in a virtual sense, i.e., within the computer environment, into a plurality of ROI's such as for example to minimize the number of different images that may be required to be taken, and to minimize the number of different movements required for the image acquisition system and/or the illumination system, to provide a series of coordinated instructions for moving the image acquisition system 150 and illumination system 120 with respect to a known position and orientation of the object with respect to the stand 112.
Then, each object of the series of objects is in turn placed on the stand 112 in a known datum position and orientation, and the image acquisition system 150 and illumination system 120 are operated according to the series of coordinated instructions. The image data obtained may then be processed by the controller 190 to provide desired surface data of the particular object being imaged. Optionally, the surface data at each ROI may be compared with nominal data, and deviations therefrom determined and provided in a suitable manner, for example as disclosed in WO 2005/010627, assigned to the present assignee and the contents of which are incorporated herein in their entirety. Further optionally, the controller 190 may be configured for automatically alerting a user whenever the surface data for a particular ROI differs from the corresponding nominal data beyond a preset threshold. For example, if the object is a manufactured item such as a car door, for example, having a plurality of bores, an alert may be generated by the system 100 if the radius and/or position of each bore in the particular item being imaged is off with respect to the nominal radius and/or center, respectively, of the CAD model or datum model.
Alternatively, there may be cases in which it may be desired to check various ROI's in relation to each other, for each of the series of objects, against a nominal relative position and/or size and/or shape of the ROI's, without reference to a CAD model, and the procedure may be similar to that described above in this example, mutatis mutandis.
the Controller 190 may Optionally be Programmed with Preset Relative Positional and orientation settings of the image acquisition system 150 and illumination system 120 with respect to certain standard topographic features, for example bores, planes and so on. When a new object is being inspected by the system 100 for the first time, the object may be mounted to the stand 112, and the imaging system 150 may be manually brought into proximity with features thereof that may correspond topographically to such as those contained in the controller memory. The user can then indicate, via a suitable interface such as a keyboard and screen, and software operating drop down menus, for example, the type of feature being scanned, and the controller then brings the illumination system 120 into the appropriate position with respect to the imaging system 150 for that feature.
Referring to
The image acquisition system 250 comprises all the features as described herein for the image acquisition system 150 first embodiment, mutatis mutandis, and thus comprises at least one image capturing device 260 mounted on a robotic arm 270, similar to the corresponding elements described for the first embodiment, mutatis mutandis. The system 200 further comprises controller 290, for example similar to the controller 190 described for the first embodiment, mutatis mutandis, which controls operation of the robotic arm 270 and of the image capturing device 260 via lines 271, 261, respectively.
The illumination system 220 comprises at least one image illumination unit 230 as described for the image illumination unit 130 of first embodiment, mutatis mutandis, but in contrast to the first embodiment, rather than being mounted to an independently movable robotic arm, the illumination unit 230 is statically mounted, or mounted for movement with the image acquisition system. For example, the illumination unit 230 may be mounted on a stand 212, or to a mounting block, clamps, table or any other suitable device or structure, preferably such that the position and orientation of illumination unit 230 may be fixed and knowable.
Alternatively, and for example for some variations of this embodiment in which the illumination system 220 comprises a light reflecting medium and an illumination source analogous to the components illustrated and disclosed with reference to
The illumination unit 230 is operatively connected to controller 290 (or optionally to a different, suitable controller) via line 219, and controller 290 controls operation of the illumination unit 230 in a similar to that described for the first embodiment mutatis mutandis.
The object O is mounted onto said mechanism 210, which comprises a robotic arm substantially similar to the robotic arm 170 as described herein for the first embodiment, including all the variations and features thereof, mutatis mutandis. Thus, the mechanism 210 comprises a fixed base 242, fixedly mounted to a static structure, a mounting bracket 244 or gripper, for reversibly mounting the object O thereto, and a plurality of controllable articulated links 246 between the mounting bracket 244 and the base 242, for providing five or six degrees of movement, or less than five degrees of movement, controlled by controller 290 (or optionally to a different, suitable controller) via control line 249.
Alternatively, and referring to
Operation of the system 200 is similar to that of system 100, mutatis mutandis, the main difference being that while in the first embodiment, the illumination system and the image acquisition system are moved, while the object remains stationary, in the second embodiment the image acquisition system and the object may be independently moved, while the illumination system remains stationary or part thereof is mechanically coupled to the image acquisition system, mutatis mutandis.
Referring to
The image acquisition system 350 comprises all the features as described herein for the image acquisition system 150 or 250 of the first or second embodiments, mutatis mutandis, but in contrast to the first or embodiments, rather than being mounted to a movable robotic arm, the image acquisition system 350 is mounted on a stand 312, or to a mounting block, clamps, table or any other suitable device or structure, preferably such that the position and orientation of image acquisition system 350 may be fixed and knowable. The image acquisition system 350 is operatively connected to controller 390 (or optionally to a different, suitable controller) via line 319, and controller 390 controls operation of the image acquisition system 350 in a similar to that described for the first and second embodiments mutatis mutandis.
The illumination system 320 comprises at least one image illumination unit 330 as described for the image illumination unit 130 of first embodiment, mutatis mutandis, mounted on a robotic arm 370, similar to the corresponding elements described for the first embodiment, mutatis mutandis. The controller 390 may be similar to the controller 190 or 290 described for the first and second embodiments, mutatis mutandis, which controls operation of the robotic arm 370 and of the illumination unit 330 via lines 371, 361, respectively.
Referring to
The object O is mounted onto said mechanism 310, which may be similar to the mechanism 210 described for the second embodiment, mutatis mutandis, and thus comprises a robotic arm substantially similar to the robotic arm 170 as described herein for the first embodiment, for example, including all the variations and features thereof, mutatis mutandis. Thus, the mechanism 310 comprises a fixed base 342, fixedly mounted to a static structure, a mounting bracket 344 or gripper, for reversibly mounting the object O thereto, and a plurality of controllable articulated links 346 between the mounting bracket 344 and the base 342, for providing five or six degrees of movement, or less than five degrees of movement, controlled by controller 390 via control line 349.
Operation of the system 300 is similar to that of system 100 or system 200, mutatis mutandis, the main difference being that in the third embodiment part or all of the illumination system and the object may be independently moved, while the image acquisition system remains stationary mutatis mutandis.
Referring to
The image acquisition system 450 comprises all the features as described herein for the image acquisition system 150 or 250 of the first or second embodiments, mutatis mutandis, for example, and thus comprises at least one image capturing device 460 mounted on a robotic arm 470, similar to the corresponding elements described for the first or second embodiments, mutatis mutandis. The system 400 further comprises controller 490, similar to the controller 190, 290, 390 described for the first, second or third embodiments, mutatis mutandis, which controls operation of the robotic arm 470 and of the image capturing device 460 via lines 471, 461, respectively.
The illumination system 420 comprises at least one image illumination unit 430 as described for the image illumination unit 130 or 330 of first or third embodiments, mutatis mutandis, for example, mounted on a robotic arm 480, similar to the corresponding elements described for the first or third embodiment, mutatis mutandis. The controller 490 may also control operation of the robotic arm 480 and of the illumination unit 430 via lines 481, 431, respectively, or alternatively, different controllers may be provided for each component.
The object O is mounted onto said mechanism 410, which may be similar to the mechanism 210 or 310 described for the second and third embodiments, mutatis mutandis, for example, and thus may comprise a robotic arm substantially similar to the robotic arm 170 as described herein for the first embodiment, for example, including all the variations and features thereof, mutatis mutandis. Thus, the mechanism 410 comprises a fixed base 442, fixedly mounted to a static structure, a mounting bracket 444 or gripper, for reversibly mounting the object O thereto, and a plurality of controllable articulated links 446 between the mounting bracket 444 and the base 442, for providing five or six degrees of movement, or less than five degrees of movement, controlled by controller 490 via control line 449.
Operation of the system 400 is similar to that of system 100, or system 200, or system 300, the main difference being as follows. While in the first, second and third embodiments, two of the three main elements of the system are movable (the main elements being the illumination system, the image acquisition system, and the object (or the stand onto which the object may be mounted)), while the third main element is static, at least during operation of the corresponding system, the illumination system and the image acquisition system are moved, while the object remains stationary, in the fourth embodiment the illumination system, the image acquisition system and the object may each be moved independently of one another, mutatis mutandis, enabling greater flexibility in operation thereof.
According to a second aspect of the invention, and referring to
Alternatively, such a background device 15 may be used with any suitable optical system. A generalized example of such an optical system, generally designated with the numeral 10, is illustrated in
The background device 15 is configured for selectively presenting a visually exposed surface comprising one of a number of alternative optical media at a time to face one or more of the object O, illumination source 11, and optical image capturing device 12. Each of the alternative media may optionally comprise different light reflection properties, for example: at least one such media may present a substantially monochromatic colored background, optionally that provides a desired contrast with the object O being imaged; at least one such media may comprise a two dimensional image or pattern, for example a company logo; at least one such media may have high reflectivity or gain, particularly relative to the reflectivity or gain of the object O.
In the embodiment illustrated in
When one set of facets, say facets 91, are co-planarly aligned, they form a generally continuous planar background surface, collectively referred to as surface 99, which is effectively perceived as the background surface for the object O.
The elements 90 may be substantially identical to one another, or may vary in size and form from one another in any particular said device 15.
a illustrates a variation of the background device of
In operation of the optical system 10, an object O to be imaged is placed in front of the background device 15, and arranged such that it is located between the background device 15 and the illumination source 11, and also between background device 15 and the image capturing device 12. In particular, the illumination source 11 may be spatially arranged with respect to the object O and background device 15, such that, at least during operation of the system 10, the object O, for example a portion of the surface thereof comprising edges (internal or external), and a part of the background device 15 surrounding the object's edges are illuminated by the source 11.
Similarly, the image capturing device 12 may be spatially arranged with respect to the object O and background device 15, such that, at least during operation of the system 10, an image of the object O, or at least a portion of the surface, and a part of the background device 15 may be obtained with the image capturing device 12.
In operation, the illumination source 11 illuminates the object O and background device 15, or at least a portion of the surface of the object O, for example including edges thereof of interest, and a part of the background device 15 surrounding the edges, as seen by the image capturing device 12, and the image capturing device 12 then captures one or more images of the object, possibly including a part of the background device 15.
The said image capturing device 12 and the illumination source 11 may be similar to the image capturing device 160 and the illumination unit 130 as disclosed with respect to the first aspect of the invention, mutatis mutandis, for example.
Suitable image data obtained by the image capturing device 12 may be provided to a suitable microprocessor, and processed in any suitable manner to reconstruct two-dimensional or three dimensional data relating to surfaces and/or edges of the object.
Optionally, the background device 15 may be statically mounted with respect to one or more of the object O, illumination source 11, and optical image capturing device 12. Alternatively, the background device 15 may be movable in a controllable manner with respect to any one or more of the object O, illumination source 11, and optical image capturing device 12, for example the background device 15 may be mounted to a robotic arm.
The elements 90 may be arranged with respect to the frame member 80 such that the longitudinal axes 70 are vertically or horizontally oriented, or indeed oriented along any desired direction.
Optionally, the background device 15 may be provided as modular unit that is optionally configured for being assembled with other such modules to provide backgrounds of varying sizes as required.
Optionally, the background device 15 may be configured for providing a non-planar background surface rather than planar surface 99, for example a concave or convex curved background surface. In such cases, the axes 70 are arranged in parallel formation, but arranged on an arc. Optionally, the sides of the triangular cross-section of the elements 90 may be curved inwards or outwards, and the corresponding facets of the elements 90 may be concavely or convexly contoured to form part of a cylindrical surface.
Optionally, at least one said background surface 99 may optionally comprise a retro-reflective surface, wherein the corresponding facets of the elements 90 may each comprise a retro-reflective layer, while other background surfaces formed by the background device 150 may comprise a reflective surface, a semi reflective surface, a matte surface, for example matte white or matte black, or indeed any other surface.
Optionally, the minimum gain or reflectance provided by at least one background surface 99 of the background device 15 may be related to the gain or reflectance properties of the object O itself. In such a case, the more reflective the object O itself is, the higher the reflectivity or gain of the background surface 99 needs to be in order to provide adequate contrast when viewed by the image capturing device 12. Thus, the gain or reflectance of the object O, in particularly the edges or the zones or areas of free edges of the object O is substantially lower than the gain or reflectance of the background surface 99. For example, the object O may have a gain of less than unity and/or reflectance less than about 5%, while the background device 15 may have a gain of unity or greater, including 2, 3, 4, and so on, and/or reflectance of more than 5%, say 10%, 15%, 20%, 30%, 40% and so on. Alternatively, the object may have a gain of 1 or greater than 1, e.g., 1.3, and/or a reflectivity of greater than 5%, say 10%, wherein the background device 15 is chosen having a gain of substantially more than 1.3, say 2 or greater than 2, and/or a reflectivity of substantially more than 10%, say 20% or greater. In other words, the ratio of the background gain GM to the object gain GO may be greater than 1, i.e., the ratio of background reflectance RM to object reflectance RO may be greater than 1. Said differently, for a given radiant flux falling on this background surface 99 and object O, the ratio of radiant flux emitted by this background surface 99 to the radiant flux emitted by the object O (herein referred to as the “radiant flux ratio”), in particular the surface thereof close to an exposed edge of the object O, is greater than 1.
Optionally, the illumination source 11 may be located relatively close to the one or more image capturing devices 12, and thus illumination light from the illumination source 11 may be captured at relatively high intensity by the image capturing devices 12 after being reflected by a particular background surface 99.
Alternatively, if the illumination source(s) 11 and the image capturing device(s) are located at significantly spaced spatial positions, such that a retro reflective surface would not reflect most of the light incident on it to the image capturing device(s), then the background surface 99 may be changed by rotating the elements 90 appropriately to align a different set of facets that each comprise a reflective surface that is configured for reflecting a significant portion of the incident light thereon towards the image capturing device(s).
Optionally, and in cases where there are a plurality of image capturing devices 12, all of which are located in significantly different positions relative to the source 11, the background surface 99 may be adapted for reflecting the incident light in all the required viewing directions, each defined by the viewing axis of a corresponding image capturing device 12, so that the background surface 99 is perceived by each device 12 as being highly reflective.
By way of further example, the background device 15 may comprise three sets of facets 91, 92, 93 that selectively provide one or another of a suitable reflective, semi reflective or matte background surfaces, the actual background surface that is used optionally depending on the reflectance of the object O itself or of part thereof. Non-limiting examples of suitable materials for the background device 15 may include the Matte White, High Contrast Matte White, Video Spectra, Glass Beaded, Silver Matte, High Power, and Silver Vision screen fabrics manufactured by Da-Lite (USA); Mocom 20× screens provided by Mocomtech; and so on.
The facets of the prism members 90 may each comprise a rigid planar or non-planar screen having a suitable retro-reflective, reflective, semi reflective or matte surface or any other suitable background surface on a suitable substrate, for example glass or plastic.
The facets may be made from a material having suitable reflectance properties, and/or comprise a coating having suitable reflectance properties, and/or comprise an outer layer configured such as to exhibit (and/or made from a material having) suitable reflectance properties.
Optionally, it is possible to operate the background device such as to provide a background surface 99 that is a composite of facets 91, 92, 93, for example such that some elements 90 will be oriented with facets 91 outermost and facing the object/illumination system/image acquisition units, while other elements may have facets 92 outermost, while optionally other elements 90 will have facets 93 outermost. The background surface 99 presented by the background device 15 may thus comprise any desired combination or permutation of the prismatic element facets.
Referring to
The plate elements 190 essentially comprise two facets, 191 and 192, facing in generally opposite directions, and are pivotably mounted to the frame member (not shown) along axes 170, enabling the elements 190 to be selectively rotated by 180 degrees to present one or another of facets 191, 192, and thus together the elements 190 present one of several possible background surfaces for use with an object being imaged.
It should be noted that the word “comprising” as used herein is to be interpreted to mean “including but not limited to”.
It should be noted that in the following claims, alphanumeric characters and/or Roman numerals used to designate method steps are provided for convenience only and do not imply any particular order of performing the steps.
While there has been shown and disclosed example embodiments in accordance with the invention, it will be appreciated that many changes may be made therein without departing from the spirit of the invention.
(This application was filed under 35 U.S.C. 119(e) and claims the benefit of U.S. Provisional Applications 60/843,700 and 60/858,998, which were filed on Sep. 12, 2006 and Nov. 15, 2006, respectively.)
| Number | Date | Country | |
|---|---|---|---|
| 60843700 | Sep 2006 | US | |
| 60858998 | Nov 2006 | US |
