An industrial robot is generally an arm with a gripper and some capacity for movement such as straight lines and rotations. Japan has been successful with robots capable of two straight movements and two rotations; whereas, the US is going for all 6 degrees of freedom. More advanced robots have microprocessors as brains. Sequences of motion for the robot can be programmed into memory by leading the robot through the desired sequences or programming the robot. Even more advanced robots have artificial senses such as sight, touch, force.
A fundamental problem in the assembly of industrial products is fitting pieces with close tolerances together such as gears or placing a weld in exactly the correct place. A human is an excellent assembler because we automatically make minor adjustments in position to fit parts together correctly. If a robot without sight tries to do the same it must know exactly where the two parts are in space and the sequence of motions to fit them together. Lacking the ability to make corrections, the robot can easily jam or wedge the two parts together. The initial progress in assembly automation was with robots without senses. These initial successes required considerable effort to overcome the orientation problem.
Robots without senses are currently used in painting and welding automobiles. In painting, the robot is superior to the human because the robot does not need a fresh air supply and protection from dangerous chemicals. Moreover, painting is tolerant to deviations in the positioning of the paint gun with respect to the automobile frame. In welding auto frames together, the robot is also superior given the strength required to handle the welders and the adverse conditions under which the welds must be made. The equipment to have the frames exactly aligned to make the welds costs much more than the robots. Also, Kawasaki was able to program a robot without senses to assembly a motorcycle gearbox by having the robot gripper vibrate slightly to compensate for inaccurate positioning.
Advances in the use of robots in assembly have required the development of robots with senses. When a human assembles a product of component of a product he can usually identify the component parts instinctively without much thought. To create a program which gives a robot the capacity to pick up randomly arranged parts is a major undertaking. To provide a robot with a camera so that he can see is no problem. What is a problem is providing the robot with the machine intelligence to interpret the input from the camera. One solution is to have the parts to be assembled arrive in exactly the right orientation. This is expensive; thus, while acceptable for mass production, it is inefficient for batch production. Some success is being achieved at creating machine intelligence which can recognize parts in an arbitrary setting. Work is progressing to give robots such senses as sight, touch, force. With these sense a robot can be programmed to make minor corrections to the sequences of steps it makes.
Much current success in assembly by robots with senses is achieved by greatly simplifying the task of identifying alternatives. In production this can be achieved by using bar codes similar to the ones used in grocery stores. Bradly-Allen has a plant which automatically assembles many kinds of controllers for electric motors on the same assembly line. Robots know which sequence of operations to perform on each product coming down the assembly line by reading the bar code on the product. Robots with senses are also used for quality control checking in this plant.
IBM created a plant here in Austin which employed robots with senses to assemble laptop computers. The robots were controlled by PC-ATs. This technology will probably be used to assemble all IBM personal computers in the near future. Without significant labor costs, IBM can compete with the clones. Robots, once programmed, put the right chip in the right slot - something humans do not always do. As the number of component parts in electronic goods is generally small, robotic assembly in this area will proceed quickly.
Robots can currently assemble electronic products such as laptop computers, gear boxes, electric motors, and other components. With each new plant to assemble a product such as an auto more and more of the assembly will be automated. Since robots are not humans the jobs they do best differ from humans. Furthermore the best assembly by robots frequently requires a complete redesign of the product and manufacturing procedure to take advantage of the capabilities of robots. This product redesign usually involves simplification and reduction of the number of parts and consequently, usually results in greater reliability.