Vision system for distinguishing touching parts
First Claim
1. In a vision system for identifying touching parts, a method for identifying an object independent of the orientation of said object, comprising the steps of(a) developing sensory data comprising an image of said object;
- (b) separating closed regions from background by connectivity analysis of the data representing said image;
(c) developing a chain encoded representation of a region boundary of each of said closed regions of said image;
(d) fitting edge segments to the chain encoded representation of each region boundary to produce a more succinct representation of the boundary of each of said closed regions of said image;
(e) fitting straight line and circular arc segments to the edge segments to create edges and corners which characterize said image;
(f) classifying said straight line and circular arc segments by feature classes, each said feature class describing a group of related features with a specific range of lengths, radii, included angles and/or angular ranges, one or more of said feature classes being associated with each of a plurality of prototypes stored in memory of said vision system to facilitate matching said image with one or more of said plurality of prototypes;
(g) proposing a match of an image of said object to said prototype based on said feature present in said object being classified in feature classes associated with said prototype; and
(h) verifying the match of the object and the prototype by translation and rotation of a region boundary of the prototype to align with the image of the object to match features of said image with features of said prototype whereby the object can be identified even when overlying another part.
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Abstract
A practical vision system for controlling the positioning of a robot arm recognizes and locates objects. The vision system processes binary images, but recognizes objects based on boundary features such as lines, arcs, corners and holes instead of "blob features" such as area and best-fit ellipse. Consequently, the vision system can process two common situations not handled by blob analysis: merged blobs due to touching or overlapping parts and incomplete blobs due to low image contrast. The microprocessor-based system is interfaced to the robot system and can recognize up to five parts per second.
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Citations
20 Claims
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1. In a vision system for identifying touching parts, a method for identifying an object independent of the orientation of said object, comprising the steps of
(a) developing sensory data comprising an image of said object; -
(b) separating closed regions from background by connectivity analysis of the data representing said image; (c) developing a chain encoded representation of a region boundary of each of said closed regions of said image; (d) fitting edge segments to the chain encoded representation of each region boundary to produce a more succinct representation of the boundary of each of said closed regions of said image; (e) fitting straight line and circular arc segments to the edge segments to create edges and corners which characterize said image; (f) classifying said straight line and circular arc segments by feature classes, each said feature class describing a group of related features with a specific range of lengths, radii, included angles and/or angular ranges, one or more of said feature classes being associated with each of a plurality of prototypes stored in memory of said vision system to facilitate matching said image with one or more of said plurality of prototypes; (g) proposing a match of an image of said object to said prototype based on said feature present in said object being classified in feature classes associated with said prototype; and (h) verifying the match of the object and the prototype by translation and rotation of a region boundary of the prototype to align with the image of the object to match features of said image with features of said prototype whereby the object can be identified even when overlying another part. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification