The use of wireless devices to sense and control manufacturing processes is on its way to fulfilling its promise to cut costs, optimize processes, conserve energy, and predict equipment breakdowns.
By Gil Bassak, Technical EditorOn the shoulders of the wireless local area networks found in Starbucks coffee shops, airports, and elsewhere stands the promising technology of untethered sensing and control for manufacturing. Wireless manufacturing, while still growing into a proven technology, promises to cut costs in numerous ways. These include obviating labor-intensive wiring to sensing and control devices, paving low-cost ways to optimize processes and conserve energy, easing regulatory compliance, implementing predictive techniques, speeding plant reconfigurations, and tracking and managing assets.
For the most part, all that is needed for the technology to fully bloom are interoperable components that conform to accepted standards, the ability to ensure secure and reliable operation for a given environment and application, and educated and knowledgeable users who have the confidence to take the leap to, and hopefully reap the rewards of, wireless technology. Working toward these ends are a number of industry groups that have focused their work on making wireless manufacturing a practical reality (see adjacent article).
Costs and Benefits
Eliminating wiring costs, which can run anywhere from tens to hundreds of dollars per linear foot in a typical manufacturing setting to as much as $2,000 per foot in a nuclear power plant, is the obvious benefit of going wireless. But such one-shot savings are not where the true value of wireless is, say industry insiders such as Hesh Kagan, director of technology for the new ventures group at Invensys Process Systems. “Wireless is a fabulous enabler for a number of applications that have a tremendous return on investment,” he says. These include optimizing a plant’s process by allowing many more sensors to be installed than would normally be feasible if each had to be wired.
Wireless sensors can also save money when it comes to maintaining equipment. “Being able to Velcro low-cost wireless sensors to gather data on process equipment, you can learn how well that equipment is behaving,” Kagan says. This in turn lets plant managers perform predictive rather than preventive maintenance, which can be costly and troublesome. They can also avoid unscheduled shutdowns because a piece of equipment unexpectedly failed. Similarly, wireless sensors are an easy way to monitor emissions to ensure compliance with environmental regulations.
Still other uses for wireless sensors include tracking assets and conserving energy. Aerospace companies, for example, “have warehouses the size of football fields and, for example, until they can find the particular turbine for a specific 747, that aircraft is grounded,” says Robert Poor, chief science officer at Ember Corp., a wireless network company that is developing a technology for using wireless sensors and the science of triangulation to locate equipment quickly.
Although energy conservation is rarely cited as a benefit, it is in fact just that prospect that gave wireless sensing and control its first big push. Several years ago, the Department of Energy (DOE), through a study by the National Research Council, determined that wireless technology held the potential to cut energy consumption in the U.S. by 15 percent. That work continues under the leadership of Gideon Varga, who heads the wireless initiative at the DOE’s Industrial Technology Program Office.
That energy savings can be had through what Wayne Manges calls “ubiquitous sensing” to improve the “visibility of a process” and thereby achieve “enterprise optimization.” According to Manges, who manages the industrial wireless programs at Oak Ridge National Laboratory under a contract with UT-Battelle LLC, ubiquitous sensing gives the needed visibility into a process or pipeline to improve energy efficiency. He admits, however, that most of the energy savings from wireless sensing and control will not come from the manufacturing world but from the systems that control the heat, ventilation, and cooling in buildings.
Process-Dependent Adaptation
Currently, the most aggressive adopters of wireless technology in continuous manufacturing have been those in the oil and gas industry, according to Mike Horton, CEO of Crossbow Technology Inc., which builds wireless sensor products. In the discrete manufacturing world, says Horton, it’s the automotive industry that leads the way.
Because of their different requirements, the continuous and batch manufacturing industries have embraced wireless sensing and control more warmly than has the discrete manufacturing world. “In discrete manufacturing,” says Horton, “you have a lot of sensors that detect the presence of something that lasts only a split second, so you need lower latency.” Here, compared to their faster wired counterparts, wireless sensors and controls are at a disadvantage.
Countering that disadvantage, however, is the fact that wireless devices make it much easier to reconfigure equipment. And, “with discrete systems, reconfigurability is the name of the game,” says Ember’s Poor. “If you need to reconfigure your floor, wireless is very attractive. The fewer things you have to plug and unplug, the better.”
Nevertheless, others in the industry concur that the fast response times needed for many discrete manufacturing processes have inhibited the adoption of wireless sensing. “Customers whose processes require response times in the order of milliseconds or microseconds prefer wired solutions,” says Hector Barresi, line manager for industrial wireless products at Honeywell Inc.’s Industrial Measurement and Control Group.
In addition, for several reasons customers are more likely to move sensing rather than control functions to wireless, at least for now. For one thing, control devices such as motors and valves tend to need power lines, obviating some of the advantages of wireless control. Where more sensors give greater visibility into a process, there is no clear advantage to having more control devices. Perhaps most telling, however, is the fear among users that wireless control, still an emerging technology, might fail and bring a line to a sudden halt.
That fear, however, is diminishing with time, says Honeywell’s Barresi, who notes that 15 percent of the applications he serves with wireless technology include some level of control. “Since last year, we have noticed a tremendous turnaround,” he says. “We find the market much more open.” That’s a trend he attributes to users who are, first, increasingly informed about the technology and, second, aware of its cost-saving benefits.
Indeed, those benefits are getting easier to earn as the wireless industry moves increasingly to develop specifications and promote standards — moves that will ensure simple and successful installations as well as afford interoperability among devices from different vendors.
One radio specification being embraced by some vendors is dubbed 802.15.4 (named after the IEEE working group). Seen as an alternative to Wi-Fi and Bluetooth wireless standards, 802.15.4 combines low cost and low power consumption. In addition, the IEEE-1451.5 committee and a group called the ZigBee Alliance are pushing their versions of specifications that address higher levels of the familiar OSI network model. Still other developments are cooking in the technology of wireless networks, in particular the emergence of so-called mesh topologies, which promise higher reliability than star or point-to-point configurations.
For their part, users who want the advantages of wireless sensing and control are advised to work with vendors willing to lend their expertise by, for example, performing a site survey. Such a survey is needed to assess the impact of multipath, interference, and other radio effects. Other details that must be considered include cost, latency, application parameters, future changes to the factory floor layout, and even how often batteries will need replacement.
In the meantime, those who wait too long for wireless technology to settle may find themselves behind the curve. “Wireless sensor networking is fundamentally complex,” cautions Mark Pacelle, vice president of marketing for Millennial Net Inc., which builds those networks. “Anyone who wants to realize the benefits soon cannot wait for a standard commodity-type offering on a silver platter.”
NEXT STEPMore information on Crossbow Technology Inc. is available at www.xbow.com or by calling 408-965-3300. More information on Ember Corp. is available at www.ember.com or by calling 617-951-0200.More information on Honeywell Inc. is available at www.honeywell.com or by calling 800-423-9883.More information on Invensys is available at www.invensys.com or by calling 508-543-8750.More information on Millennial Net Inc. is available at www.millennialnet.com or by calling 781-222-1030.More information on UT-Battelle LLC is available at www.ut-battelle.org or by calling 865-220-5101.Captions:PULL-QUOTE:Those who wait too long for wireless technology to settle may find themselves behind the curve.
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