Abstract:
The application relates to a method of inspecting an object and an inspection apparatus. The object has a plurality of features and the method includes the step of identifying a current primary feature on the object. Once the current primary feature has been selected, one or more additional features are selected, each of the one or more additional features selected having at least one common attribute with the current primary feature. The method also includes the step of capturing an image of the selected features on an image capture module.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an inspection method and an inspection apparatus. In particular, although not exclusively, the invention relates to a method of capturing images in a measuring machine environment to thereby undertake optical quality control of objects under inspection. 
     BACKGROUND TO THE INVENTION 
     In applications where parts are required to be manufactured to a high level of precision, for example in the airline and aerospace industries, highly accurate quality control mechanisms must be in place in order to ensure that parts are manufactured to specification without divergence from the design or error. Whilst highly accurate manufacturing machines are used to manufacture parts in these industries, errors may still be present in a particular part. 
     It is impractical and indeed impossible to visually inspect many of these parts by eye and obtain any degree of confidence that the part has been manufactured exactly to specification. 
     Video measurement machines are used to inspect manufactured parts. These machines generally have an image capture device, such as a digital camera or the like, and data processing and storage capabilities. The part is placed within the field of view of the image capture device and the design technical specification of a manufactured object, referred to in the art as the parts program, is stored within the storage device of the measuring machine. 
     The parts program includes a series of features associated with the manufactured object. Each feature in the parts program has a series of attributes associated therewith including the feature&#39;s geometric properties and spatial location on the object and illumination, magnification and focus settings to allow the measurement machine to capture a suitable image of the feature. 
     When the parts program is executed, instructions are provided to the operating program of the measurement machine to control the camera and move the camera relative to the object in order to measure each of the features of the object recorded in the parts program. Typically, measurement machine operating programs move through the features recorded in the parts program sequentially and capture the features on the object independently to determine whether the object has been manufactured in accordance with the design specification without error. 
     For objects that are large and/or have a large number of physical features requiring inspection and measurement, this process can be time consuming. As the measurement and inspection process is part of the manufacturing process, any reduction in the time required to perform this highly accurate quality assurance will deliver reductions in manufacturing time and hence a benefit to the manufacturer. 
     In this specification, the terms “comprises”, “comprising”, “includes”, “including” or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. 
     SUMMARY OF THE INVENTION 
     In one form, although it need not be the broadest form, the invention resides in a method of inspecting an object, the object having a plurality of features, each of the features having one or more attributes associated therewith, the method including the steps of: 
     identifying a current primary feature of the object; 
     selecting one or more additional features, each of the one or more additional features selected having at least one common attribute with the current primary feature; and 
     capturing an image of the selected features on an image capture module. 
     In a further form, the invention resides in an inspection apparatus comprising: 
     an image capture module adapted to capture a digital image of at least a portion of an object under inspection; 
     a data store having stored therein a parts list identifying a set of features on the object under inspection, each feature having one or more attributes associated therewith; 
     an operating system containing computer readable instructions for:
         identifying a current primary feature on the object under inspection;   selecting one or more additional features from the parts list, each of the one or more additional features selected having at least one common attribute with the current primary feature; and   capturing an image of the selected features using the image capture module.       

     Further features of the invention will become apparent from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       By way of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying drawings, wherein: 
         FIG. 1  shows a modular schematic of an inspection apparatus according to an embodiment of the invention; 
         FIG. 2  shows an inspection method according to an embodiment of the invention; and 
         FIG. 3  shows an embodiment of a method of selecting objects forming part of the method shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a schematic view of modules forming part of an inspection apparatus  100  according to an embodiment of the invention. Inspection apparatus  100  comprises an image capture module  110 , an operating system  120  and a data storage module  130 . 
     In the embodiment, image capture module  110  is in the form of a digital camera or the like able to capture images of an object under inspection  200 . Furthermore, image capture module  110  includes lighting and illumination devices, such as light emitting diodes or the like, to allow appropriate illumination and lighting conditions to allow the digital camera to capture an appropriate image of the object under inspection. 
     Image capture module  110  is in communication with operating system  120  of inspection apparatus  100  and, in the embodiment, image capture module  110  communicates digital data relating to physical features of the object under inspection  200  to the operating system  120  for processing. Furthermore, operating system  120  communicates with the image capture module  120  to control the focus and magnification characteristics of the digital camera and the illumination levels and color output of the lighting and illumination devices. 
     Operating system  120  is also in communication with data storage module  130 . In the embodiment, data storage module  130  has stored therein a parts program associated with the object under inspection. 
     The parts program stored within the data storage module  120  contains an identification of the physical features  210  present on the object under inspection  200  together with a series of one or more attributes associated with each feature. These attributes include feature&#39;s geometric properties and spatial location on the object and illumination, magnification and focus settings that are required to capture the physical features  210  of the object under inspection  200 . 
     Operating system  120  communicates the result of the inspection of the object to a user of the inspection apparatus  100  as is known in the art. 
       FIG. 2  shows an inspection method  300  according to an embodiment of the invention. The operating system  120  identifies the current primary feature from the features  210  on the object under inspection  200  (step  310 ). Suitably, the primary feature may be the first feature  210  on the object under inspection  200  in the field of view of the image capture module  110 . 
     Optionally, the primary feature may be the first feature on the parts program stored in the data storage module  130 . Alternatively, the primary feature may be the feature in the parts program that is located proximal the centre of the current field of view of the image capture module. 
     The operating system  120  then selects one or more additional features  210  on the object under inspection  200  based on the attributes associated with each feature  210  located in the parts program stored in the data storage module  120  (step  320 ) as discussed in greater detail with reference to  FIG. 3 . 
     Once the set of selected features has been compiled by the operating system  120 , the operating system  120  communicates with the image capture module  110  in order that the image capture module  110  inspects the selected features (step  330 ). Suitably this occurs by capturing an image of the selected features for processing by the operating system  120  as will be discussed in greater detail below. 
     The operating system then determines whether all of the features contained in the parts list stored in the data storage module  120  have had their respective features inspected (step  340 ). 
     If all features have not been inspected, the operating system  120  then identifies a new primary feature and the method proceeds as previously discussed (step  310 ). 
     If all features have been inspected, the operating system prepares the results of the inspection based upon the captured images (step  350 ). Suitably, this process occurs as is known in the art and the results of the inspection are then communicated for analysis to determine whether the object under inspection  200  has been manufactured to within a desired tolerance. 
       FIG. 3  shows the step of  320  in greater detail. The operating system  120  parses through the parts program and identifies all features that have identical environmental attributes as the current primary feature (step  321 ). Suitably, environmental attributes include such attributes as illumination, magnification and focus settings. 
     The operating system  120  then orders the identified features based on each feature&#39;s proximity to the current primary feature (step  322 ) with the closest feature to the primary feature heading the list. Preferably, the operating system  120  uses the spatial location attribute of each feature during the ordering process. 
     The operating system  120  then parses the list and selects the next most proximal feature (step  323 ) and determines whether that feature is able to be captured in the current field of view of the image capture module  110  (step  324 ). If the list has been exhausted the method continues from step  330  as previously described. 
     If the next most proximal feature is able to be captured in the current field of view of the image capture module  110 , that feature is selected for inspection (step  325 ). 
     If the next most proximal feature is not able to be captured in the current field of view of the image capture module  110 , that feature is discarded and returned to the parts program for later inspection (step  326 ). 
     The method and system of the invention reduces the amount of movement of the image capture device relative to the object and the number of actual image captures is reduced. In this way, time for inspection is minimized which results in subsequent cost savings to the owner. 
     Throughout the specification the aim has been to describe the present invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the present invention.