A method of feature extraction for 3-D objective surface by circular range acquisition is proposed and investigated. In the experimental system, circular range acquisition is realized by moving an optical range sensor mechanically along a circular path.
A prototype of an optical range sensor, which adopting a 2.0mW He-Ne gas laser as a light source, 342mm (length)×130mm (width) ×174mm (height) body size and 5kg weight was manufactured. This range sensor is mounted on the wrist of a SCARA robot (A 3020, Hitachi).
The range sensor is positioned sequentially at a point along the circular path with a given radius around the axis passing through the target point and detects the range to the corresponded point on the surface of an object.
The surface feature around the target point is identified by investigating the variation of the acquired range data along the circular path. Applying the above operation to the surface of an object to be tested, surface features of an object can be extracted. Surface features, such as planes, vertices and edges, are represented as a polar coordinates representation of the range variation along the circular path. Thus, the circular range acquisition and the feature extraction of the surface are applied to the different types of vertices on a polyhedra.
Moreover, the circular range acquisitions tracing on the edge line are carried out over the surface of an object and experimental results are reported.