Original Date: 11/03/1996
Revision Date: 01/18/2007
Information : Wireless Technology
Wireless technology has already revolutionized the communication systems for business, personal, and recreational use. The next stage of wireless systems involves using sensors and actuators to improve manufacturing process control and impact predictive maintenance data acquisition. Oak Ridge Centers for Manufacturing Technology (ORCMT) is investigating methods to transmit distributed sensor data through wireless networks.
Predictive diagnostics rely on traditional sensors such as accelerometers and thermocouples or thermography. Typically, either a technician gathers data from sensors throughout the facility on a scheduled basis, or a central collection computer records data which is transmitted across wires from each sensor. The former method may miss failures because of infrequent sampling intervals, while the latter requires high initial costs for wiring each sensor. Wiring a facility can run from $40 per foot of wire for a chemical plant to $2,000 per foot of wire for a nuclear power plant.
Wireless systems already use radio-frequency tags on components and machinery to automatically track inventory and notify subsystems throughout a manufacturing operation. In addition, new developments in spread-spectrum radio frequency technology have eliminated earlier problems (interference, multi-path, and line-of-sight constraints) commonly associated with narrow-band FM devices. Spread-spectrum radio frequency technology now offers direct sequencing, frequency hopping, and high immunity to interference by using a high bandwidth (2 megabits per second) and built-in encryption.
Power scavenging, access control, and high initial costs still present challenges to wireless systems. However, ORCMT has successfully developed and demonstrated wireless systems in some research projects, such as microwave telemetry for sensors in hazardous environments; wireless controls for the Athens Utility Board; and a fully- integrated, self-powered microcircuit which was glued to a bee to monitor its location for the Department of Agriculture.
Wireless technology provides several benefits over traditional methods for condition monitoring and process control. Benefits include flexibility, remote accessibility, and increased electrical reliability. Possible long-term advantages are reduced operational costs and increased system availability.
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