Cyber Physical Systems – Situation Analysis - Energetics Meetings ...

Cyber Physical Systems – Situation AnalysisDRAFT – March 9, 2012because something can be measured does not mean that the measurement will necessarily be useful forthe purpose of determining structure health. Ideally, all data gathered by sensors should be useful.The development of ―active‖ sensors that excite and measure structural response at various locationscould enhance the capability of detecting small changes, resulting in more effective monitoring. Smartsensors should have more computing power to be able to handle large amounts of data, while notbecoming too expensive. There is the need to demonstrate the effectiveness of SHM systems, but thereare generally no real world structures on which to test them. Laboratory testing is necessary in thedevelopment of these systems but not sufficient to gauge how they will react on an actual bridge. 210Sensors for Surveillance and MonitoringThe smart buildings of the future will ideally be equipped with a variety of sensors, ranging from visual,infrared, thermal, magnetic, and others. Using such a suite of sensors, it could be feasible to monitor thelocation of anyone in the building, using some device that the person will wear or just by using visualsensors that develop models of a specific person as the person enters the building. Challenges remain inthe interpretation of the sensory data, so that the ―building‖ can monitor the activities of all (or a subsetof) the individuals inside the building. Thus, it will become feasible to detect the person who tries toforcefully open a door, as well detect that the elderly resident of apartment X21 cannot get up from thecouch and needs help. Sensors for surveillance and monitoring of building also relate to healthcare andare discussed in Chapter 5.The sensory suite and the associated network should be taken into account from building design and notafterward, as is current practice. A cultural barrier stems from the current practices of building design andsurveillance networking, which have little interaction.Data Acquisition and InterpretationToday‘s sensors do not directly measure damage or performance; they provide data from which theseproperties must be determined. Since sensors and other systems in bridges, buildings, and other structuresgather large quantities of data, there is the need to organize, process, and obtain meaningful results fromthat data in a timely and effective manner. Interpretation of data is done for the purpose of making iteasier for the end user to come to conclusions and is especially dependent upon the end user‘s level ofknowledge and training. Challenges remain in methods of data acquisition and interpretation. An increasein the amount of sensors will also increase the amount of data that is gathered and must be analyzed inorder to gain meaningful information about the structure, and networking becomes more difficult. Notonly will the amount of data increase, but there will be different types of data and sensors will supplyvarious sizes of data sets. The data from both the sensors and human inspectors should be linked andanalyzed together.Many challenges arise from the gathering, transmitting, and processing of large quantities of data.Decisions must be made about whether sensors should perform pre- and post-processing beforetransmitting data, or should the processing occur at a central node. If sensors were able to distinguishbetween useful and ―bad‖ data caused by noise or other interference, then unnecessary transmitting orprocessing of unhelpful data could be prevented. For structural health monitoring systems that are put intoplace on existing bridges, there is a challenge in establishing a baseline to which the newly collected datacan be compared. New bridges do not have this problem because data will have been gathered since theirconstruction. Existing structures have unknown levels of stress and deterioration, so there may be a210 French, C. et al. ―Report on the NSF Bridge Workshop.‖37