Page 441 - Sensors and Control Systems in Manufacturing

Sensors in Flexible Manufacturing Systems

FIGURE 8.10 Result of applying edge extraction operation. 395

however, to reset each edge point as it is traced. The tracing of a com-
plete object thus removes it from the frame and ensures it will not be
subsequently retraced.

8.7 End Effector Camera Sensor Detecting Partially
Visible Objects
A new method of locating partially visible two-dimensional objects
has been developed. The method is applicable to complex industrial
parts that may contain several occurrences of local features, such as
holes and corners. The matching process utilizes clusters of mutually
consistent features to hypothesize objects and uses templates of the
objects to verify these hypotheses. The technique is fast because it
concentrates on key features that are automatically selected on the
basis of detailed analysis of CAD-type models of the objects. The
automatic analysis applies general-purpose routines for building and
analyzing representations of clusters of local features that could be
used in procedures to select features for other locational strategies.
These routines include algorithms to compute the rotational and mir-
ror symmetries of objects in terms of their local features. The class of
tasks that involve the location of the partially visible object ranges
from relatively easy tasks, such as locating a single two-dimensional
object, to the extremely difficult task of locating three-dimensional