Page 30 -

1.3 Commercial Robot Controllers 11

logic in a single control platform compatible with Windows 98 & Windows
NT/2000. Adept motion controllers can be configured to control other
robots and custom mechanisms, and are standard on a variety of systems
from OEMs.

Motion/Process Integration and Sequencing. Motion/process integration
involves coordinating manipulator motion with process sensors or other
process controller devices. The most primitive process integration is through
discrete digital input/output (I/O). For example a machine controller external
to the robot controller might send a one bit signal indicating that it is ready
to be loaded by the robot. The robot controller must have the ability to read
the digital signal and to perform logical operations (if then, wait until, do
until, etc.) using the signal. That is, some robot controllers have some
programmable logic controller (PLC) functions built in. Coordination with
sensors (e.g. vision) is also often provided.
Human Integration. The controller’s human interfaces are critical to the
expeditious setup and programming of robot systems. Most robot controllers
have two types of human interface available: computer style CRT/keyboard
terminals for writing and editing program code off-line, and teach pendants,
which are portable manual input terminals used to command motion in a
telerobotic fashion via touch keys or joy sticks. Teach pendants are usually
the most efficient means available for positioning the robot, and a memory
in the controller makes it possible to play back the taught positions to execute
motion trajectories. With practice, human operators can quickly teach a series
of points which are chained together in playback mode. Most robot
applications currently depend on the integration of human expertise during
the programming phase for the successful planning and coordination of robot
motion. These interface mechanisms are effective in unobstructed workspaces
where no changes occur between programming and execution. They do not
allow human interface during execution or adaptation to changing
environments.
More recent advanced robot interface techniques are based on behavior-
based programming, where various specific behaviors are programmed into
the robot controller at a low level (e.g. pick up piece, insert in machine
chuck). The behaviors are then sequenced and their specific motion
parameters specified by a higher-level machine supervisor as prescribed by
the human operator. Such an approach was used in [Mireles and Lewis
2001].
Information Integration. Information integration is becoming more
important as the trend toward increasing flexibility and agility impacts
robotics. Many commercial robot controllers now support information
integration functions by employing integrated PC interfaces through the

Copyright © 2004 by Marcel Dekker, Inc.