Oklahoma. USA. THOMAS. L. LANDERS. Univcrsiry of Arkansas. Fayeucl'illc. Arkansas. USA ..... TIle board itself was stored in a small tote, measuring approxi-.
Journal of Intelligent Manufauuring
Intelligent
tracking
ALEXANDER
BREWER
(1999) 10, 245-250
in manufacturing and NANCY
SLOAN
Univcrsiry of Oklahoma. Norma". Oklahoma. USA
THOMAS
L. LANDERS
Univcrsiry of Arkansas. Fayeucl'illc. Arkansas. USA
Dynamic scheduling is an important new innovation in manufacturing and supply chain managemenl. However. the success of dynamic scheduling will depend on real-time information. TIlis paper describes intelligent tracking technologies that provide real-time information throughout the supply chain to support kcywords a logistics planning and c;;:ecut;on. Keywords:
Intelligent tracking. RFID. virtual warehouse
Introduction
back to the ,carrier's
Intelligent tracking technologies (11'2) include global positioning systems (GPS). geographic information systems (GIS). wireless telecommunications. and radio frequency identification (RFID) as shown... in Fig. I. Today. these technologies are both intelligent and integrated. Perhaps more than any mher technology. intelligent tracking has the potential to contribute to improvements in manufacturing and to the entire supply chaitL From orders of raw materials and sub-assemblies through product assembly. testing. and distribution. intelligent tracking technologies offer opportunities for increased efficiencies and improved CUStomer service. Intelligent tracking implies that the information is gathered automatically and improves a system by reducing the time needed between value.added steps and thus improves efficiency and cycle time. Devices not only collect their own data. but they also are capable of analyzing it and pert'orming necessary actions to a process autonomously. f-or example. suppose an RFID reader is integrated with a computer attached to a wireless tclecommunications device. The result is a capability to read a tag attached to a truck on a tOil road and ;llItomatically bill the carriers account. If the truck is also outfitted with GPS. then positional information may be transmitted 0956.5515
,
1999
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home office to enhance
asset
management and customer service. /T2 may be employed to improve the efficiency and effectiveness of the supply chain.. With the increasing competitiveness and rising costs of transportation and storage, service to the customer requires information about operations status and decision tools to coordinate tfic total supply chain. Figure 2 illustrates the integrated supply chain. Historically. the supply chain was controlled in a sequential manner. Through IT2. point-of-sak transactions arc simultaneously routed to all stages of the supply chain. Since the planning for alj stages of the supply chain is initiated concurrently. the coordination between clements is increased and the logistics cycle time is reduced. When RFID is linked to other members of the group of intelligent tracking technologies-global positioning system. geographical information system. and wireless telecommunication-the potential for improvements in service and efliciency can be enhanced throughout the supply chain. A preliminary introduction to these technologies is in order. Global positioning system~ (GPS) were firs! introduced in the United States a~ a defense initiative in the 1970s. They are based on a CQnsteliation of 24 high-altitude satellites in orbit approximately 12.500 miles above the Earth. Ground-based equipment includes the transceiver (a transmitter and receiver
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Brewer. Sloan and Landers
246
Wireless telecommunications began in the 1980s with the introduction of the cellular phone and are now rapidly increasing in variety, in capability. and in size of coverage areas. Wireless communications use the radio portion of the electromagnetic spectrum, the portion in the 3000 to 300 billion cycle range. Cellular phones, perhaps the most common of the wireless devices, occupy the range of 806 to 890 MHz. With the advent of cellular phones, grpund-based networks of radio transmitters/receivers have sprung
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combined in a singlc unit) which receives and decodes information in the signals from the satellites. Through triangulation calculations based on the position and time off-set of four satellites, the latitude, longitude, and altitude of the transceiver can be determined
up across the United States in an attempt to provide nation-wide cellular coverage. An area is divided into cells ranging in diameter from one to 20 miles depending on the terrain and capacity demand. Each cell is equipped with a radio transmitter/receiver and has its own radio frequency in the 824 to 848 MHz range. In a transition so rapid that it is imperceptible to the user, calls are "handed-off" from ooe cell to another by a monitoring and switching computer as the caller moves from one cell to another. In 1998, two major networks of low or medium orbit satellites wit! be operational for telecommunications usage and will decrease the cost of satellite cellular service while
(Fig. 3). Transceivers can be located on a variety of items and arc now commonly used in the trucking industry. A geographic information system (GIS) is a computer-based mapping tool that translates the location parametcrs from the GPS into the practical information nceded ro determine a location (i.e.. nearby cities. highway numbers. street names). The databases are inregrated with a graphical user interface so the user can visually pinpoint a location.
providing world-wide coverage. Although conventional cellular service employs analog signals, digital technology is rapidly increasing in use. New means of handling digital data have been developed so that it can be more rapidly and economically transmitted through better utilization of the airwaves. An RFID system Integrates an antenna with electronic circuitry to roml a transponder that. when polled by a remote interrogatOr. will echo back an
Fig. 1. O>mponenls of ITl.
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247
Intelligent tracking
'//':':'/:-::::"':::"~~:~:':::'~:>"\ GPS Satellite I GPS Satellite 4
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identification number. A wireless provides the following benefits:
. ..
RFID
system
Identification at a distance . Continuous or intennittent tracking Real-time control
Operations in a harsh environment . Hands-free operation . Versatile memory and processing requirements Other fonns of infonnation may be added to the ID number in the tag. Read/write memory is an option. allowing dynamic infonnation to be stored with the associated asset being tracked. Varying degrees of complexity inside the controller chip of the tag also allow for error correction. longer read distance. and security of the infonnation. RF lechnology has been successfully used in some portions of the supply chain. Copperweld. a Pitlsburgh-based steel tubing and wire manufaclUrer. has laken the first steps toward RFID. They have implemented an infrastructure of RF unils 10 handle a
barcode-based inventory system. Through the use of a contactless system to read a variety of barcodes. they have managed to reduce the time needed to complete their original tracking process by two thirds. Currently. the system builds the manifest of outgoing goods by simply scanning a product's barcode and entering an amount. Future plans include the use of this system in their receiving department as well (Copperweld. 1995). The United States Postal service uses RHD to track cycle times in their sortation centers. Working with the RHD supplier. a new tag specification was created so that the tag would be the same size as a nonnal post card. The post card is introduced into the system by 'mailing' it to someone. Antennas are strategically setup in the centers to keep track of the tag as it moves around the facility. When the tag reaches ils destination. the infonnation on its path is tabulalcd and used [0 assess the now of mail through the poslal system (Brewer and Landers. 1997) Wacker Chemilronik ill Berghausen. Germany uses
248
Brewer, Sloan and Landers
TIRIS to achieve a zero-fault production process for silicon wafer manufacturing. RFIO tags are attached to plastic trays that hold the wafers. A comprehensive automation system called CarMas (Carrier Management System) from the company HERMOS. collects data as the trays go through various process steps. Nine RFIO rcad points are included on cach etching machine. Every step of the process is tracked and managed. This process now only requires one operator and eliminates all faults. Sincc the production environment includes high temperatures and harsh chemicals, the RFIO ,tags must be reliable and durable (TlRIS News. 1996) BMW and Vauxhall use RFIO tags to enable accurate customization of individual customer orders. A read/write smart tag is programmed with the customer order. The tag is then attached to and travels with the car during the production process.
This tracking ensures that the car is manufactured with the correct color, model, interior. and any other option the customer specifies. Some of the major advantages cited for this system are: . . . . .
Read without direct line of sight. Reprogrammed to reflect different requirements. Integrated into a complete systcm. Reused at the end of assembly. Used under harsh conditions because they are maintenance-free and battery-free (Brewer and Landers. 1997).
United Biscuits attaches RFIO transponders to the stainless steel carts. which are used to carry material throughou£ the processing facility. Raw material and
finished products are tracked as they travel through the entire-plant. TIle goals of the system were to improve stock management, increase control over material usage, and improve product trace-ability and reporting. The factory uses the system to track bin movement from initial weighing through preparation. mixing. and baking. This ensures that the correct bin is in the correct location throughout the process. Since the tags are virtually maintenance free, the reliability of the system is very high (TlRIS News, 1996)
Intelligent
tracking
in the supply chain
A variety of wireless options. such as RFIO. may be combined with a GPS to provide detailed information about materials in transit. Table I identifies potential data and their uses. Such data include expected lime of arrival and perhaps the load manifest, depending on the capabilities of tracking utilized. With this information about an in-bound order for raw materials. the manufacturer can assign a truck to the correct dock and schedule unloading and manpower requirements. The event times can thus be more accurately determined. Further. the information obtained by the hybrid RFIO/GPS system can then be combined with a production scheduling algorithm on a shop floor. The production directives can be changed real-time in response to information obtained from earlier in the supply chain. Production quotas can be changed based on the availability or quality of raw materials in transit.
Table L (Sloan et aL 1997) Feature
Funuion
Location and identification
More efficient load assignment. routing. and dispatching; monitor status of shipment; beller emergency response; greater security: decreased insurance costs for carrier and for shipper; beuer match of equipment type and need
Expected time of arrival (ETA) Load manifest
Assignment 10 correct dock: scheduling of unloading: beller customer service Location and ETA of a particular shipment item; tracking hazardous cargo; dedication of containers to hazardous cargo; take advantage of postponement transportation and merge-in-transit opportunities
Engine parameters
Trouble.shooting and maint:;nance scheduling; prevention of breakdowns: safety considerations
Breakdown or emergency
Fasler response time: greater security for driver and load
Bill of lading information and conlimlation
(nstant invoicing
Document imaging or FAX capabilily
Continnation
of licensure. fees paid. etc.
Intelligent
249
lrackinR
Two relatively new concepts which can be more easily implemented as a result of tracking technologies are postponement transportation and merge-in-transiL- With postponement transportation, a shipment that is not tied to a specific order is dispatched in a general direction, and when anorder occurs, the shipment is then routed to the proper destination. Merge-in-transit involves combining the various segments of an order at a common site, such as a truck depot or distribution center, so the total order can be delivered as a whole to the customer site. Merge-in-transit may also include some assembly en route to the final destination. Intelligenl tracking can also expedite the flow through customs gates, thus decreasing delivery times. The utilization of real-time data can provide instantaneous decision-making responses to variations in the supply chain. Communication throughout the supply chain is of foremost importance in order for decision-making to be truly responsive to events. Supply chain management software focuses on matching up the supply and demand portions of a business. The software is usually based on forecasting methods for demand planning, production planning, and scheduling. The modeling, problem-solving, and optimization techniques include time-series analysis, linear programming, mixed integer programming, and simulation. Software suppliers inciude Manugistics, Numetrix, i2 Technologies, and Chesapeake Decision Sciences (Hicks, 1997). Optimization tools focus on transportation resource optimization, vehicle routing and scheduling, inventory allocation, and manufacturing scheduling optimization. The software utilizes operations research and mathematical techniques to model and solve specific operations issues. These techniques include linear programming, mixed integer programming, optimization and network modeling, and simulation. Software suppliers include Red Pepper Software Co., i2 Technologies, and CAPS Logistics (Hicks, 1997).
RFID pilot test in manufacturing The usefulness of RFIO in manufacturing is being assessed by The Logistics Institute at the University of Arkansas. A pilot study of TIRIS technology was completed at an electronics manufacturing facility in
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November 1997. The purpose of the study was to assess (I) the feasibility of the technology as a tool for real-time shop floor control and (2) the role of an RHO integrator. In this application of RHO, small printed circuit boards were tracked. Each set of boards of a particular type, or lot, was identified by a unique batch number. Each lot could contain one or more boards. TIle board itself was stored in a small tote, measuring approximately 8 inches wide by 12 inches long by I inch deep. Multiple boards could be placed in each tote if they were in the same lot. As the boards went through the manufacturing process of adding parts, inspection, testing, and confomlal coating. Boards could be split off of the main lot if they were faulty or required special attention. In this test, only three types of boards were tracked. One antenna was placed at each of the four workstations. The RHO reader, stationed remotely from the antennas, polled each of the four antennas once per second, for a total of four potential reads per second. Hardware and software limited the RFIO reader to only four reads per second. It was the responsibility of each worker to pass the RHO tag, attached to an accompanying paperwork folder that was unique to each lot, by the antenna in that area. In this way, the times when the lot entered the workstation and when it ieft couid be tracked. Though small scale, consisting of only two readers and four antennas, the stUdy was a good example of the complexities of RHO technology in practice. Among other considerations, read range, tag presentation, and ambient conditions were taken into account during the study. One of the primary hurdles in the study was the participation of workers in the shop. As in any new technology, it is important to stress that the technology is being installed to help the workers and improve productivity, not to reduce jobs or increase workload. Preliminary results indicate that, due to the complexities of RFlO technology, a system integrator is recommended. In so far as the improvement of the work center itself, algorithms are being developed to mesh the output of the RFlO system into the existing systems of the work center, to better improve process flow and scheduling of the workers. In the tasks of designing the system, developing the software, and installing the hardware and software of the system, specific knowledge is required in each
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Brewer. Sloan and Landers
area. Making the various components of the system work together correctly can be considered an art. The full results of this research will be published in a subsequent article.
program just as easily as upgrading infrastructure to a new technology.
the entire
References Conclusions The real innovation in RHO is not in the technology itself, but in its application in real-world situations. The end goal of any project, such as introducing RHO, Bar-code, or Data-matrix into an alreadyexisting system, must be to reduce cost. Reduction of waste, production cycle time, other non-value added time, or inventory is the purpose of a new technology, not the introduction of the technology itself. Conversely, innovation could be considered as making a decision not to upgrade to a new technology. The introduction of a new program to drive existing technology can have a large effect on the workings of an existing system as welL New real-time algorithms could draw statistical data from the output of existing hardware to drive a real-time production control
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Brewer, A. and Landers, T. (1997) Radio Frcqucncy ldclllification: A Survcy and Asscssmelll of the Technology, University of Arkansas Department of Industrial Engineering Technical Report. Copperweld Turns to Mobility on the Manufacturing Floor, (1995) Industrial Engineering. 27. Flynn, L. J. (1996) Post Offices Using Radio-ID Tags to Monitor Row of Mail, The New York Times CyherTimes. Hicks, Donald A. (1997) The Manager's Guide to Supply Chain and Logistics Problem-Solving Tools and Techniques: Tools, Companies, and Industries, liE Solutions, 29( iO). Sloan, Nancy, Carikcioglu. L, Landers T and Taylor, G. D. (1997) lntelligefll Tracking Technologies for the Trucking Industry, University of Arkansas Department of Industrial Engineering Tcchnical Report. TlRIS News (1996), (16).
