The Robotic Industries Association 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 as little as 15 to 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 other areas.
The costs associated with establishing manufacturing processes that rely on industrial robots initially limited the number of companies that were able to fully employ robotics. Despite the cost, however, the Handbook of Industrial Robotics reported that the population of robots in North America nearly doubled between 1990 and 2000. In addition, the world robot population was expected to grow from 677,000 in 1996 to an estimated 950,000 in 2000. Many business experts expect that, as robotics technology develops and implementation costs drop, smaller companies will increasingly be able to make use of robotics in their production processes.
Today's robotics systems operate 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.
Robots are, of course, comprised of several different elements, depending on their purpose. 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 have 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.
ASSEMBLY Assembly is one of the most demanding operations for industrial robots. A number of conditions must be met for robotic assembly to be viable, among them that the overall production system be highly coordinated and that the product be designed with robotic assembly in mind. The sophistication of the control system required implies a large initial capital outlay, which generally requires production of 100,000 to one million units per year in order to be profitable. Robotic assembly has come to be used in the production of a wide range of goods, including circuit boards, electronic components and equipment, household appliances, and automotive subassemblies.
SPRAY FINISHING OPERATIONS Industrial robots are widely used in spray finishing operations, particularly in the automobile industry. One of the reasons these operations are cost-effective is that they minimize the need for environmental control to protect workers from fumes.
Robots are also used for quality control inspections, since they can be programmed to quantitatively measure various aspects of a product's creation. In addition, the use of robots in environmental applications, such as the cleaning of contaminated sites and the handling and analysis of hazardous materials, represents an important growth market for robotics producers. Non-industrial applications for robots in security, commercial cleaning, food service, and health care are also on the rise.
FUTURE OF ROBOTICS
Recent research and development has addressed a number of aspects of robotics. Robotic hands have been developed which offer greater dexterity and flexibility, and improvements have been made in visual sensors as well (earlier generations of visual sensors were designed for use with television and home video, and did not process information quickly for optimal performance in many robotics applications; as a consequence, solid-state vision sensors came into increased use, and developments were also made with fiber optics). The use of superconducting materials, meanwhile, offers the possibility of substantial improvements in the electric motors that drive robotic arms. Attempts have also been made to develop lighter robotic arms and increase their rigidity. Standardization of software and hardware to facilitate the centralization of control systems has also been an important area of development in recent years. Indeed, "robots are simply more programmable and flexible than ever before," wrote Tooling and Production contributor Katina Z. Jones. "Multiple cells can be more easily accommodated and cybernetic gadgetry such as virtual reality and computer simulation have added a new dimension to the sales and installation of robotics." Finally, the processing speed of robotic brains was expected to increase from 10 MIPS in 2000 to 1,000 MIPS by 2003.