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DRIVERS of old cars know all about preventive maintenance.
The idea is that by servicing the vehicle regularly, and replacing things like the spark plugs, engine oil and wheel bearings, the car will not break down. Of course it still does, because some things go wrong unexpectedly. But what if you could build a machine that is able to detect when its various parts are about to give up the ghost and alert its operators? This is the idea behind the “virtual engineer” which David Brown of the University of Portsmouth, in England, is trying to build into production equipment.
Many of the machines in factories run day and night, stopping only for scheduled maintenance. An unplanned stoppage can be a disaster, says Luke Axel-Berg, general manager of the British subsidiary of Stork Food & Dairy Systems (SFDS), a Dutch group that makes processing equipment for the drinks, food and drugs industries. In a dairy, for instance, a breakdown means milk deliveries have to be diverted quickly to another factory, which may struggle to cope. And if repairs take several days to complete a company will start to lose customers. SFDS is therefore collaborating with Dr Brown to test some of his systems on their production lines.
It would be possible, of course, to pepper machinery with sophisticated sensors linked together by miles of wiring. But that would be complicated and expensive. Instead, Dr Brown and his colleagues have devised a way of monitoring the electric motors that drive machines for telltales of problems to come. He does this by watching the waveform of the current flowing to each motor—a product of its frequency and amplitude.
