System Level Health and Environmental Monitoring for Automatic Test Equipment

Sensor technology has enabled seemingly unlimited ability to monitor temperature, humidity, air flow, power, voltage, current, etc. with small, inexpensive, and reliable devices. These devices are small enough to fit anywhere inside of just about every assembly/subassembly of a piece of Automatic Test Equipment (ATE). The question is what kind of measurements need to be made, where should they be located, and what benefit are they to the system and the operators? Like all engineering tasks, adding environmental monitoring sensors to ATE should be based on requirements, cost, and benefits. Operational requirements such as temperature, altitude, and humidity are the primary drivers. Next are operational interface requirements such as input power, shock, vibration, and Electromagnetic Interference (EMI)/ Electromagnetic Compatibility (EMC). Finally, reliability and maintainability (R&M) requirements are often overlooked in the selection and placement of environmental sensors. Just as important as the sensors themselves is finding a way to present the data in a logical fashion focused on creating an intuitive interface for the operators of the equipment as a part of comprehensive Health Monitoring approach at the system level. Too much data presented without consideration towards the operator could detract from the primary mission to repair and verify the Units Under Test (UUTs). The data must also be logged and stored in such a way to be able to understand and recreate scenarios to help track the environmental effects on the ATE over time. This paper discusses the design approach taken to evaluate system level requirements to determine the overall environmental monitor architecture. It also discusses the cost and complexity trade-offs mandatory to ensure a focused operator experience without affecting system reliability and system maintainability requirements. Finally, the paper will discuss the overall system level benefits of the environmental and health monitoring schemes as they are employed on several ATE systems.