The design and control of a micron-accurate robot arm

A simple Cartesian robot has been designed to achieve micron precision in manufacturing through sophisticated control strategies rather than through massive rigid mechanical components. Advantages of the lightweight design include lower cost and greater versatility. Problems that have to be addressed by the controller include vibration of the members and backlash in all moving parts. The robot developed consists of precision lead screws driven by simple DC motors. The motors are controlled by a computer that receives feedback from the optical encoders of the motors, as well as from laser interferometers that provide information on the motions actually occurring. The interferometer system is capable of measuring both position and direction of motion