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Torque sensors and load cells with wireless capability are finding work in places where they were previously troublesome to wire.
The development of wireless local-area networks (WLAN per IEEE802.15.4 and the ZigBee standard) is paving the way for the wider use of sensors in applications where they had been difficult to apply. For example, ZigBee lets networked sensors (nodes) in manufacturing areas share information for immediate feedback that might improve a machine's speed and precision. A load cell or torque sensor could communicate with a temperature sensor or accelerometer within the same environment. With a temperature reading, for instance, the load cell might make an adjustment so the machine output stays accurate over a wide temperature range, or alert maintenance people that the machine needs attention now. In bottling machines, a line worker could place a fake bottle on line with a torque sensor in the cap (a torque auditor) and let it run through the capper. The torque it reads would be wirelessly sent back to the machine controls for comparison and adjustments. The sensors also provide recordable values for a particular operation, something FDA regulations often require. And if one node in the WLAN is Wi-Fi capable, the machine might use the Internet to tell a factory manager how well it's working.
Wireless features are more useful when a machine has many sensors. Wiring them for power is often not difficult but dealing with a mass of signal wires can be bothersome and a maintenance problem. Wireless sensors clean up the mess. These capabilities open new ways to control equipment.
A few applications
Torque sensors found work in auto factories in the mid 70s and quickly spread to other machines outside the industry. Examining a few of these applications may give control designers ideas for...