Patent Application
20080013820
In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures might not be to scale, and certain components can be shown in generalized or schematic form and identified by commercial designations in the interest of clarity and conciseness.
As used herein, a hardware system can include a combination of discrete components, an integrated circuit, an application-specific integrated circuit, a field programmable gate array, or other suitable hardware. A software system can include one or more objects, agents, threads, lines of code, subroutines, separate software applications, two or more lines of code or other suitable software structures operating in two or more software applications or on two or more processors, or other suitable software structures. In one exemplary embodiment, a software system can include one or more lines of code or other suitable software structures operating in a general purpose software application, such as an operating system, and one or more lines of code or other suitable software structures operating in a specific purpose software application.
Peripheral inspection system 102 is coupled to camera 104. As used herein, the term “coupled” and its cognate terms such as “couples” or “couple,” can include a physical connection (such as a wire, optical fiber, or a telecommunications medium), a virtual connection (such as through randomly assigned memory locations of a data memory device or a hypertext transfer protocol (HTTP) link), a logical connection (such as through one or more semiconductor devices in an integrated circuit), or other suitable connections.
Camera 104 generates image data of the periphery of an object under inspection. Lens 106 is used to focus light from mirror 108 onto an array of image sensors of camera 104. Mirror 108 is a spherical mirror section that receives image data from the periphery of the object under inspection from mirror 110. Mirror 110 is also a spherical mirror section that projects the periphery of the object under inspection onto mirror 108. Ring light 112 or other suitable lights illuminate the object under inspection.
In operation, the curvature of mirrors 108 and 110 are coordinated with the height of the object under inspection and the distance between mirror 108 and the object under inspection to allow a single image of the periphery of the object under inspection to be provided to camera 104. For example, the radius of curvature of mirror 110 and mirror 108 can be coordinated such that the object under inspection, when appropriately placed, can be seen from all sides from a single image generated at camera 104 from mirror 108 and lens 106. The radius of curvature of mirrors 108 and 110 and suitable distances can be calculated using general optics theory. In one exemplary embodiment of the present invention, the radius of the curvature of mirrors 108 and 110 are 13 mm and 31.3 mm, respectively. An aspherical profile of the mirrors 108 and 110 can be applied to reduce an image aberration.
In one exemplary embodiment, the image data generated by system 100 is polar projection data, where the distance between points around the periphery of the top of the object under inspection is less than the distance between points around the periphery of the bottom of the object under inspection. Peripheral inspection system 102 receives the image data of the object under inspection and identifies defects or other anomalies, such as by compensating for projection of the image of the object. In one exemplary embodiment, compensation is accomplished by performing conventional image data analysis (e.g. such as generation of a histogram of pixel brightness data) based on analysis of known defects in sets of projected image data. Likewise, identification of predetermined shapes within the projected image data can be performed based on a predetermined relationship between the object under inspection and the projected image data of that object. In one exemplary embodiment, compensation can include conversion of the image data from polar projection image data into a different coordinate format, or in other suitable manners.
As previously described, camera 104 generates image data of an image provided by the lens through the cone mirror 204. Spherical mirror 206 has a known spherical curvature and a radius that allows the polar projection image of the object under inspection that is generated by reflection of the image onto cone mirror 204 and generation into a set of image data by camera 104 to be inspected. The radius of curvature of mirrors 206 and angle of the cone 204 and suitable distances can be derived from general optics theory. An aspherical profile of the mirror 206 can be applied to reduce image aberration.
In operation, camera 104 generates a single set of image data for analysis by peripheral inspection system 102, such as to eliminate the need for generating multiple images of different sides of the object under inspection. The angle and size of cone mirror 204 is coordinated with the dimensions of spherical mirror 206 to allow a single set of polar projection image data of the periphery of an object under inspection to be generated.
Polar inspection system 302 receives image data that includes a polar projection of a circumferential view of an object under inspection. As previously described, such image data will typically be in polar projection format, such that items towards the center of the set of image data have a physical separation that is less than items towards the periphery of the set of image data. As such, polar inspection system 302 generates a set of image data to identify defects or other items that require an operator to be notified so that the object under inspection can be discarded or set aside for repair. Polar inspection system 302 can be used to identify predetermined metrics, such as a histogram or other statistical mapping of pixel brightness data, direct location procedures such as object mapping of known defect shapes, masking of predetermined sections of the image of the object that are not subject to inspection, indexing of features in the image data, or other suitable image inspection processes.
Cartesian mapping and inspection system 304 receives the image data in polar coordinate format and maps the polar coordinate image data to a Cartesian coordinate system. In one exemplary embodiment, the relationship between the location of individual pixels and the image data generated at those locations can be determined based on a mathematical relationship based on the dimensions of the set of mirrors that are used to generate the peripheral image data. In this manner, the polar projected image data can be mapped to a Cartesian coordinate system to allow image data inspection processes that require the use of Cartesian coordinate data to be utilized.
Peripheral location system 306 receives image data in a polar projection forma, Cartesian format, or other suitable formats, and locates one or more peripheral identifiers. In one exemplary embodiment, an object under inspection may have predetermined markings or features are identified by peripheral location system 306, to allow inspection of the object image data to be indexed. Likewise, peripheral location system 306 can use other suitable processes such as identifying external indexing features of equipment holding the object under inspection, generating histograms of pixel data for sections of the image data of the object under inspection data, locating text, applying masks, or other suitable processes. In one exemplary embodiment, peripheral location system 306 can generate error data in the event a peripheral orientation of the object under inspection can not be determined.
Defect notification system 308 receives inspection data from polar inspection system 302, Cartesian mapping and inspection system 304, peripheral location system 306, or other suitable systems and generates and defect notification data. In one exemplary environment, the defect notification data can cause an object under inspection to be extracted for further analysis, such as for manual inspection, to determine whether the object under inspection can be repaired, to determine whether the object must be discarded, or for other suitable purposes. Likewise, defect notification system 308 can generate control data to cause the object under inspection to be discarded by suitable mechanisms, such as where the object under inspection is a low cost part and the cost of repair is greater than the cost of disposal. Likewise, other suitable notification data can be generated by defect notification system 308.
In operation, system 300 allows peripheral image data of an object under inspection to be analyzed. Such peripheral image data is typically in a polar projection format, and may be mapped into a Cartesian system for inspection or can be inspected in its polar projection format. Indexing of features of the object under inspection may be required, and notification of an operator or generation of other control data for processing of potentially defective components can be performed by system 300.
At 404, it is determined whether Cartesian mapping of the object under inspection is to be performed. In one exemplary embodiment, the image data can be generated in a polar projection format, such that mapping to Cartesian coordinates may be performed in order to perform inspection processes on the image data. If it is determined that Cartesian mapping is not to be performed, the method proceeds to 404 where the image data is analyzed using one or more polar projection inspection processes. In one exemplary embodiment, histograms or other suitable data can be used to analyze the pixels generated by the inspection image, identification of groups of pixels having predetermined characteristics can be performed, detection of projected text or other features can be used, or other suitable polar projected image data inspection methods can be applied. The method then proceeds to 412.
If it is determined that Cartesian mapping is to be performed at 404, the method proceeds to 406, where the image data is converted from polar projected data to Cartesian coordinate data. In one exemplary embodiment, the mathematical relationship between the object under inspection and mirrors that are used to project each side of the object under inspection into a single image can be used to map from the polar projection data to Cartesian coordinate data. Other suitable processes can also or alternatively be used. The method then proceeds to 408.
At 408, the mapped image data is analyzed using one or more Cartesian inspection processes. In one exemplary embodiment, the image data can be analyzed using histogram analysis, location of predetermined features or letters in the image data, indexing of the image data based on a map of features in the image data, blocking of areas from processing that are not under inspection, or other suitable processes.
At 412, it is determined whether a defect has been located. If no defect has been located, the method proceeds to 416, otherwise the method proceeds to 414 where notification data is generated. In one exemplary embodiment, notification data can include data that notifies an operator that a object under inspection needs to be checked for damage. Likewise, the notification data can include control data to a suitable device to remove the object under inspection. Likewise, other suitable notification data can be generated. The method then proceeds to 416.
At 416, the next inspection piece is advanced. In one exemplary embodiment, inspection can be formed “on the fly”, such that advancement to the next inspection piece occurs in a continuous process. Likewise, the next inspection piece can be advanced upon completion of inspection of the current inspection piece, such as where the inspection piece is discarded upon generation of notification data. Likewise, other suitable processes can be used. The method then proceeds to 416.
At 416, image data of the new object under inspection is generated. In one exemplary embodiment, a single camera can be used to capture a projected peripheral image having projected polar coordinates. Likewise, other suitable processes can be used. The method then returns to 402.
In operation, method 400 allows a single set of image data to be analyzed that contains image data from all sides of an object under inspection. In one exemplary embodiment, mirrors can be used to generate a projected polar coordinate view of all sides of an object under inspection, such that image data generated is taken at a single spot so as to reduce the number of sets of image data that need to be generated. Likewise, other suitable processes can be used.
Furthermore, it is noted that the letters of “Microv” from the side-on image are themselves projected onto a cylinder, such that the spacing of the letters on the side of the cylinder is less than the spacing of the letters that directly face the image data generating device. As such, even if multiple sets of side-on image data were used, it might still be necessary to either convert that data from the cylinder projection plane to a Cartesian coordinate plane, or to take a larger number of sets of side-on image data such that the areas of the image data set where the areas having unacceptable variation due to projection onto a cylinder can be masked. As such, the present invention allows a single set of image data to be analyzed that provides a larger segment of the periphery of an object under inspection than side-on viewing, which reduces the number of sets of image data that must be generated and analyzed and increases the inspection speed of the system.
Dimensions for one exemplary embodiment of the present invention are provided in Table 1:
Dimensions for another exemplary embodiment of the present invention such as that shown in
A camera such as model A102f from Basler AG company or other suitable cameras can be used to generate the image data.
Dimensions for one exemplary embodiment of the present invention that includes an object cylinder diameter range of 22 mm are provided in Table 3:
Dimensions for another embodiment of the present invention using a cone mirror and having an object cylinder diameter of 22 mm are provided in Table 4:
The “sag” or z-coordinate of the standard surface is given by:
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where:
Although exemplary embodiments of a system and method of the present invention have been described in detail herein, those skilled in the art will also recognize that various substitutions and modifications can be made to the systems and methods without departing from the scope and spirit of the appended claims.
