I did a market research project for Honeywell back around 1997 on the use of predictive maintenance for industrial and office tower HVAC systems. I was tasked with doing focus groups and interviews with persons in charge of factories and office tower facility managers to understand the economic impact of HVAC downtime. Even at that time some factories that went out of spec on temperature and humidity could cause production lines to be shut down and each hour of downtime cost hundreds of thousands of dollars in lost productivity and costs in shutting down and restarting process manufacturing equipment.

The connection to this story is that one of the techniques they had developed was vibration and audio analysis of large electric motors and other equipment I believe to determine when a motor or part was starting to go out of spec.

I sometimes wonder about systematically mining R&D ideas that where leading edge but discarded as too expensive or impractical for one reason or another from 15 to 20 years ago.