1 48
`
`Paper presented at the Second European Conf. on Smart Structures and Materials, Glasgow 1994, Session 3
`
`Remote Monitoring of Instrumented Structures Using
`the INTERNET Information Superhighway
`
`Peter L. Fuhr
`Dryver R. Huston
`Timothy P. Ambrose
`
`University of Vermont
`Intelligent Structural Systems Research Institute
`College of Engineering
`Burlington, VT 05405
`
`Correspondence:
`Fuhr: telephone: (802) 656- 1917, FAX: (802) 656-0696, email: fuhr@emba.uvm.edu
`
`ABSTRACT
`The requirements of sensor monitoring associated with instrumented civil structures poses potential
`logistical constraints on manpower, training and costs. The need for frequent or even continuous
`data monitoring places potentially severe constraints on overall system performance given real-
`world factors such as available manpower, geographic separation of the instrumented structures,
`and data archiving as well as the training and cost issues. While the pooi of available low wage,
`moderate skill workers available to the authors is sizable (undergraduate engineering students), the
`level of performance of such workers is quite variable leading to data acquisition integrity and
`continuity issues - matters that are not acceptable in the practical field implementation of such
`developed systems. In the case of acquiring data from the numerous sensors within the civil
`structures which the authors have instrumented (e.g., a multistory building, roadway/railway
`bridges, and a hydroelectric dam), we have found that many of these concerns may be alleviated
`through the use of an automated data acquistion system which archives the acquired information in
`an electronic location remotely accessible through the Internet global computer network. It is
`therefore possible for the data monitoring to be performed at a remote location with the only
`requirements for data acquistion being Internet accessibility. A description of the developed
`scheme is presented as well as guiding philosophies.
`
`1. Introduction
`The recent advent of advanced materials with internal sensory and reaction capabilities, i.e.
`'intelligence,' has opened the door for many useful applications in civil structures, e.g. bridges,
`buildings, dams, in contrast with aerospace structures. Structures built with intelligent materials will
`be able to sense external loads, assess the internal stresses and damage caused by the loads, and, if
`necessary, respond appropriately. Although relatively few structures are presently built with such
`materials, the potential market for the application of these materials can be quite ar1 .The most
`probable candidates for the initial application of these materials will be high-performance structures
`such as skyscrapers, including intelligent buildings, bridges, and those facilities where failure
`
`0-8194-1 700-9/94/$6.00
`
`Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/27/2015 Terms of Use: http://spiedl.org/terms
`
`Petitioners - Exhibit 1011 Page 1
`
`

`

`Second European Conference on Smart Structures and Materials I 149
`
`presents large safety concerns, such as nuclear waste containment vessels, bridge decks, dams, and
`structures under construction.
`Large scale structures that have actually had fiber optic sensors embedded into them are still
`relatively few. Hoist and Lessing2 have installed fiber optic displacement gages in dams to measure
`shifting between segments. Fuhr et a!.3 report the installation of fiber optic sensors into the Stafford
`Building at the University of Vermont. Similar installations have been completed at the Winooski
`One dam in Winooski, VT4, in the newly constructed physics building on the campus of the Dublin
`City University in Ireland5, and in a railway overpass bridge in Middlebury, VT6. Researchers at
`the University of Toronto, in conjunction with City of Calgary (Alberta, Canada) officials, have
`embedded fiber optic strain gauges into the prestressed concrete support girders on a highway
`overpass7.
`A major challenge to building and using a comprehensive sensor system is that a variety of
`physical parameters must be measured using sensors that are often spatially distributed across the
`span of a large structure. The sensing and data processing requirements are complicated by most of
`the measurands exhibiting dynamic behaviors with time scales that vary over several orders of
`magnitude. An additional concern is that modern data acquisition hardware collects enormous
`amounts of data, only a small fraction of which may be useful.
`In the case of an instrumented civil structure questions regarding the data acquistion and
`frequency of monitoring of the embedded sensors arise. In parallel, labor concerns ranging from
`training of sensor "inspectors" to who actually performs the processing and analyzing of the acquired
`data are legitimate matters in the practical field implementation of such developed systems.
`
`2. Data Acquistion from Instrumented Structures
`We have been concerned with the acquistion of data from embedded and surface attached sensors
`which are placed throughout a potentially large instrumented civil structure. Two issues predominate
`our activities: (1) collection of the sensors' data at a single central location within (or near) the
`instrumented structure; and (2) development of a method for remote monitoring of this sensor
`information. With respect to issue 1 , we have proceeded to use radio telemetry for data acquistion
`and concentration at a single central location8. Issue 2's requirements are currently being met
`through the use of system software resources associated with the Internet global computer network.
`The Internet is actually a collection of approximately 30,000 computer networks. There is a vast
`array of network software utilities that manage and control network node-to-node communications.
`We have found that for simple data archiving and subsequent remote locale retrieval, the use of an
`"anonymous" File Transfer Protocol (FTP) site is optimal. This allows raw, time history data from
`each embedded sensor to be archived on an Internet networked computer in a file (or folder) that may
`be accessed using FTP. Information security may be obtained by requiring a password to access this
`data, or, complete world-wide Internet access may occur if the sensor data is archived in an
`anonymous FTP accessible file/folder. Power frequency data acquired from fiber optic vibration
`sensor #16, located within turbogenerator #3's support mount is displayed as Figure 1 . This data
`was accessed remotely using a modem equipped Macintosh LCII microcomputer from the
`"WinOneDam@emba.uvm.edu" anonymous FTP data site located on a Sun Microsystems computer
`at the University of Vermont. A portion of the raw data is shown in this Figure as well as the
`associated frequency power spectra.
`In conjunction with the monitoring of the status of the embedded sensors is the need to
`concurrently monitor the electric power generation status as well as the water level and flow rates.
`Two methods are used for this data acquistion: (1) traditional analog-to-digital (ND) conversion of the
`electrical values associated with each turbogenerator's water flow rate, turbine rotation rate (RPM),
`
`Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/27/2015 Terms of Use: http://spiedl.org/terms
`
`Petitioners - Exhibit 1011 Page 2
`
`

`

`1 50 1 Fuhr, Huston, Ambrose
`
`generation efficiency and generator output electrical power; and (2) simple TV camera video capture of
`the operator's consoles associated with each turbogenerator. In the first case, the acquired individual
`voltage levels are interfaced to a unique channel on a microcomputer's A/D board, sampled, scaled,
`time-tagged and stored in memory for transmission to the Internet host computer. This information is
`then formatted on the Internet-host and placed in an anonymous FTP account for worldwide Internet
`access. In the second case, the acquired video frames, (1 for each console display plus the outside
`camera) are transmitted to the Internet-host computer's "WinOne-video" Mosaic file for worldwide
`Internet access and viewing using Mosaic or a comparable video display program.
`
`Point
`
`fiber_freq.y
`6.1583e-05
`3.3713e-08
`8.6179e-08
`3.6841e-08
`1.6613e-07
`3126eMg
`
`0
`1
`2
`3
`4
`5
`
`freqs.y
`
`.1o
`
`0
`12
`24
`36
`48
`61
`
`0
`
`1000
`
`Frequency (Hz)
`
`Figure 1. FTP accessed embedded sensor data obtained from the Winooski One dam.
`
`In a manner somewhat similar to the FTP site, the use of the Internet network utility program
`"Mosaic" has been chosen for the visual display of video frames acquired from video cameras
`positioned at the Winooski One dam. Mosaic is an Internet-based global hypermedia browser that
`allows the user to discover, retrieve, and display documents and data from all over the Internet. It is
`part of the World Wide Web project, a distributed hypermedia environment originated at CERN and
`collaborated upon by a large, informal, and international design and development team. Mosaic,
`which can be copied for free from many Internet software archives, organizes information into a so-
`called "home page", which serves as a table of contents about a particular topic or group of topics.
`In the context of instrumented civil structures information, we have configured a multimedia
`(video/audio) equipped microcomputer for acquiring and preprocessing of the video images obtained
`from the cameras located at the instrumented structure, in this case, the Winooski One hydroelectric
`dam. Near realtime video images are placed into the appropriate Mosaic source location home page.
`All video images are not archived, due to limited physical disk space, but rather have the last 30
`frames temporarily stored. Viewing of the video frames is achieved using Mosaic on an Ethernet
`configured Internet accessible (IP - Internet Protocol addressed) microcomputer.
`The images shown as Figure 2 represent the Mosaic video viewing of the Winooski One dam on
`April 6, 1994 at 2:20 PM EST. Specifically, Figure 2.a shows the outside video view of the water
`flowing over the dam at this time. Figure 2.b shows the associated video frame of the camera's view
`of the control monitor for turbogenerator number 2. From this frame the operational values and river
`level and flow rate data of this generator are readily apparent (please note that the full screen sized
`video frames have been reduced for this publication).
`
`Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/27/2015 Terms of Use: http://spiedl.org/terms
`
`Petitioners - Exhibit 1011 Page 3
`
`

`

`Second European Conference on Smart Structures and Materials I 11
`
`(b)
`(a)
`Figure 2. Internet accessed, Mosaic displayed realtime "snapshots" of: (a) from an outside deck
`video camera showing the current water flow level at the Winooski One hydroelectric dam; (b)
`powerhouse control console associated with turbogenerator #2. The actual display has been
`reduced from its full screen size for this publication.
`
`3. Summary
`The requirements of sensor monitoring associated with instrumented civil structures poses
`potential logistical constraints on manpower, training and costs. The need for frequent or even
`continuous data monitoring places severe constraints on the monitoring performance given real-world
`factors such as available manpower, geographic separation of the instrumented structures, and data
`archiving as well as the training and cost issues. We have found that many of these concerns may be
`alleviated through the use of an automated data acquistion system which archives the acquired
`information in an electronic location accessible through the Internet. It is therefore possible for the data
`monitoring to be performed at a remote location with the only requirements being Internet accessibility.
`
`4. References
`1. D.R. Huston, Smart Civil Structures - An Overview, SPIE Paper No. 1588-21, Proc. SPIE
`Fibers '91 Symposium, Boston, MA, Sept. 1991.
`2. A. Holst and R. Lessing, "Fiber-Optic Intensity-Modulated Sensors for Continuous Observation
`of Concrete and Rock-Fill Dams", Proc. 1st European Conf. on Smart Structures and Materials,
`Glascow, 1992, p. 223.
`3. P.L. Fuhr, D.R. Huston, P.J. Kajenski, and T.P. Ambrose, "Performance and Health
`Monitoring of the Stafford Medical Building Using Embedded Sensors", J. Smart Materials and
`Structures, 1, (1992), 63-68.
`4. P.L. Fuhr and D.R. Huston, "Multiplexed fiber optic pressure and vibration sensors for
`hydroelectric dam monitoring", J. Smart Materials and Structures, 2 (1993), 320-325.
`5. B. McCraith, Dublin City University , Ireland, personal communication to P.L. Fuhr, 1993.
`6. D.R. Huston, P.L. Fuhr, T.P. Ambrose, "Intelligent Civil Structures - Activities in Vermont", to
`be published in the J. of Smart Materials and Structures, 1994.
`7. R. Measures, et al, "Strain gauge measurements obtained from an instrumented bridge girder",
`Smart Materials and Structures Conference 2, Orlando, FL, Feb. 1994.
`8. P.L. Fuhr, D.R. Huston and T.P. Ambrose, "Interrogation of multiple fiber sensors in civil
`structures using radio telemetry", J. Smart Materials and Structures, 2, (1993), 264-269.
`
`Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/27/2015 Terms of Use: http://spiedl.org/terms
`
`Petitioners - Exhibit 1011 Page 4
`
`