Page 464 - Sensors and Control Systems in Manufacturing

Sensors in Flexible Manufacturing Systems
During the assembly task, a number of processes (executors) are 417
running, requiring synchronization of data transfer. The data may
consist of, for instance, the type, position, and orientation of a detected
part by the vision system. The communication between the processes
is realized through a shared memory lock in the VME bus.

8.12.4 Vision Sensor Software
The first step consists of a segmentation of gray-value image into a
binary image. Because backlighting is used in the system, contrast is
excellent and simple thresholding is sufficient for segmentation. Dur-
ing initialization, a threshold is calculated from the image histogram
and used until the next initialization takes place. Before the system
starts an assembly operation, the vision system must be calibrated to
the robot coordinate system. This is done by moving a ring in the
vision field. From the known robot coordinates, the ring position, and
the computed ring coordinates in the vision system, the necessary
transformation is calculated.
A drawback of connectivity analysis is that objects may not touch.
The vision package may be extended with graph-matching tech-
niques to allow recognition of touching and overlapping parts.

8.13 History of Industrial Robotics
The word robot was introduced to the public by Czech writer Karel
Capek in his play R.U.R. (Rossum’s Universal Robots), which premiered
in 1921 (Fig. 8.34). The play begins in a factory that makes artificial
people called robots, but they are closer to the modern ideas of

FIGURE 8.34 A scene from Karel Capek’s 1920 play R.U.R. (Rossum’s Universal
Robots), showing three robots.