Not everyone defines the term "robot" the same way, according to Kiran Patel, an analyst at IHS Electronics & Media. For purposes of a report he wrote on robotics last year, Patel used the ISO 8373 standard, which defines an industrial robot as an "automatically controlled reprogrammable multi-purpose manipulator which is programmable in three or more axes."
It's that final qualifier—the three axes—that make a robot a robot, Patel said. The commonly accepted definition in China is less restrictive. What's called a robot may be "just a servo motor with an actuator," he said. "In essence it's a mechanical arm."
Even within the standard definition, there are many different types of robots. In electronics manufacturing, the most commonly used are SCARA robots for rapid pick and place as well as small parts assembly; parallel robots for pick and place; and small-payload (below 15 kilograms) articulated robots for small parts assembly, according to Patel. An emerging type of robot, called dual-arm, could work side-by-side with humans in small parts assembly.
[See related story, Robotics Renaissance Could Boost U.S. Electronics Manufacturing.]
Some common industrial robot definitions:
Articulated: A robot with arms that has at least three rotary joints.
Dual-arm: A robot with two working arms functioning alongside each other typically in small part assembly areas with high repeatability.
Parallel: A robot with arms, with prismatic or rotary axes in parallel. They have quick movement but not high accuracy.
SCARA (also called four-axis): Stands for Selective Compliant Articulated Robot Arm, a type of articulated robot with two parallel rotary joints to provide compliance in a plane.
Source: IHS report "The World Market for Industrial Robots – 2012 edition," and Wikipedia.