Abstract
Automated machines are being given greater responsibilities. Particularly in the semiconductor industry, a single work-in-process wafer may be more valuable than the machine handling it. A machine work area can be crowded with delicate and expensive tooling including microscope optics and fixtures. A single positioning mistake, such as an improperly trained point or incorrectly calculated destination, can produce a machine collision.A collision damages expensive tooling and mechanics, wastes work in process, stops system development or production, and contaminates a clean environment. Measures must be taken to avert these outcomes. Regardless of the commands sent to the motion controller, the machine should never collide with tooling, fixtures, or mechanical limits.
Once a topic of abstract research, advances in motion control technology enable real-time collision avoidance to be resident on board the motion control card itself. One or more geometric models describe safe movement areas. These models are used by a real-time monitor which anticipates collisions based on current machine position and velocity. The machine is stopped before a detected collision can occur. An example taken from industry will show the method of implementing on-board collision avoidance.