Robotics

Related Terms: Automation

The Robotic Industries Association (RIA) defines robot as follows: "A robot is a reprogrammable, multifunctional manipulator designed to move material, parts, tools or specialized devices through variable programmed motions for the performance of a variety of tasks." Recently, however, the industry's current working definition of a robot has come to be understood as any piece of equipment that has three or more degrees of movement or freedom.

Robotics is an increasingly visible and important component of modern business, especially in certain industries. Robotics-oriented production processes are most obvious in factories and manufacturing facilities; in fact, approximately 90 percent of all robots in operation today can be found in such facilities. These robots, termed "industrial robots," were found almost exclusively in automobile manufacturing plants 20 years ago. But industrial robots are now being used in laboratories, research and development facilities, warehouses, hospitals, energy-oriented industries (petroleum, nuclear power, etc.), and, above all, in research.

According to RIA, some 160,000 robots were installed and operating in the U.S. in 2006. In 2005, 19,594 robots valued at $1.18 billion were shipped to North American companies. In the first quarter of 2006, orders by RIA members (about 90 percent of the industry) were valued at $272 million and represented 3,722 such machines. Robotics thus is already a well-established and one might say mature industry—and yet its future is unimaginably large and diverse.

TECHNOLOGY

Today's robotics systems operate like most machines by way of hydraulic, pneumatic, and electrical power. Electric motors have become progressively smaller, with high power-to-weight ratios, enabling them to become the dominant means by which robots are powered. The crucial element in robotics is the artificial intelligence carried in the programmable circuitry of the machines.

Robots are comprised of elements that differ depending on end use. The hand of a robot, for instance, is referred to in the industry as an "end effector." End effectors may be specialized tools, such as spot welders or spray guns, or more general-purpose grippers. Common grippers include fingered and vacuum types. Another central element of robotics control technology is the sensor. It is through sensors that a robotic system receives knowledge of its environment, to which subsequent actions of the robot can be adjusted. Sensors are used to enable a robot to adjust to variations in the position of objects to be picked up, to inspect objects, and to monitor proper operation (although some robots are able to adjust to variations in object placement without the use of sensors, provided they have sufficient end effector flexibility). Important sensor types include visual, force and torque, speed and acceleration, tactile, and distance sensors. The majority of industrial robots use simple binary sensing, analogous to an on/off switch. This does not permit sophisticated feedback to the robot as to how successfully an operation was performed. Lack of adequate feedback also often requires the use of guides and fixtures to constrain the motions of a robot through an operation, which implies substantial inflexibility in changing operations.

Robots are programmed either by guiding or by off-line programming. Most industrial robots are programmed by the former method. This involves manually guiding a robot from point to point through the phases of an operation, with each point stored in the robotic control system. With off-line programming, the points of an operation are defined through computer commands. This is referred to as manipulator level off-line programming. An important area of research is the development of off-line programming that makes use of higher-level languages, in which robotic actions are defined by tasks or objectives.

Robots may be programmed to move through a specified continuous path instead of from point to point. Continuous path control is necessary for operations such as spray painting or arc welding a curved joint. Programming also requires that a robot be synchronized with the automated machine tools or other robots with which it is working. Thus robot control systems are generally interfaced with a more centralized control system.

COMMON USES OF ROBOTICS

Industrial robotics has emerged as a popular manufacturing methodology in several areas in recent years, including welding, materials transport, assembly, and spray finishing operations.

Spot and Electric Arc Welding

Welding guns are heavy and the speed of assembly lines requires precise movement, thus creating an ideal niche for robotics. Parts can be welded either through the movement of the robot or by keeping the robot relatively stationary and moving the part past the robot. The latter method has come into widespread use since it generally requires less expensive conveyor systems. The control system of the robot must synchronize the robot with the speed of the assembly line and with other robots working on the line. Control systems may also count the number of welds completed and derive productivity data.

Pick-and-Place Operations

Industrial robots also perform what are referred to as pick-and-place operations. Among the most common of these operations is loading and unloading pallets, used across a broad range of industries. This requires relatively complex programming, as the robot must sense how full a pallet is and adjust its placements or removals accordingly. Robots have been vital in pick-and-place operations in the casting of metals and plastics. In the die casting of metals, for instance, productivity using the same die-casting machinery has increased up to three times, the result of robots' greater speed, strength, and ability to withstand heat in parts removal operations.

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