CMS Smart System for Duke University Pratt School of Engineering
For purposes of description, the system can be divided into two separate logical functions: (1) the Smart Camera System, and (2) the Structural Monitoring System. The core components and equipment common to both functions are the Fiber Bragg Grating (FBG) Arrays and the swept laser FBG interrogation system. By looking at the plaque to the left a overview of the system is described. This system is the first to integrate cameras and fiber optic bragg gratings.
The Smart Camera System Tour
Upon entering the east hallway building W2 level 3, the tablet PC will automatically detect a wireless LAN connection and link-up with the wireless router installed in the ceiling of the hallway. By simply launching a shortcut on the tablet PC’s desktop, a live video feed via wireless connection will be established with the network camera installed on the ceiling at the end of the hallway near the bridge crossover. Along one side of the hallway floor, and gratings spaced ~3 feet apart with a tiled floor- marked to indicate a sensor region. Upon stepping or tapping on one of these designated floor tiles, the video camera will pan, zoom, and tilt to the location of that tile, and the live image will be fed to the tablet PC via the wireless connections. People near the tile will be able to see themselves in real time on the PC screen, and as they continue down the hallway to another marked tile, the camera will pan zoom and tilt to their new location. The active tiles for the smart camera system will continue around the corner and end at the bridge structure, as shown below in. During the demonstration, the faculty member can explain that the pressure exerted by standing on the tile is transferred through the tile to the Fiber Bragg Grating, causing a slight change in the reflected wavelength of the grating. This reflection signal is continuously monitored by the swept laser interrogation system (in a nearby lab). As the wavelength change is detected, a software program determines which FBG changed wavelengths, and it sends a unique signal to the camera servo.
The Smart Bridge Structural Monitoring System Tour
Located to one end of the bridge, and to one side, will be a flat screen embedded in a column support. The Fat screen will be covered with Plexiglas, and will be locked to the wall to protect the flat screen. The computer screen will display two types of information about the bridge (1) live strain/displacement information in the form of graphical indicators, and (2) time-history information about the stresses on the bridge – fed by each FBG sensor. Drawing shows the location of the FBG sensors along the fiber array to be imbedded in the concrete of the bridge floor. The structural monitoring software will probe each grating, and update the display in real-time. Therefore, as people walk along the bridge, or as gusts of wind blow against the bridge, a signal will be registered and displayed on the computer screen. The smart bridge system will not only provide an excellent application demonstration of optics, but it will be a true structural monitoring system that can provide critical stress and strain information about the bridge connecting the buildings. The structural monitoring software will allow the administrator to select different options for saving the detected information for later analysis (for example, setting the sampling rate and turning on averaging). This software is primarily designed to monitor and indicate physical stress and strain, but can also be used for monitoring temperature swings. The gratings in the hallway that are not being utilized for the camera system will be used for structural monitoring as well as temperature compensation.
Behind the scenes details of the systems
The system will be networked together on a private LAN with a wireless access point for communicating with the wireless tablet PC. The custom software for the optical FBG sensors, the camera system, and the bridge structural monitoring will run continuously and simultaneously on the main server and software computer. The tablet PC’s will act as clients to display the live data. The swept-laser interrogator by Micron Optics Inc. will have two extra channels that can be utilized for laboratory purposes while the camera and bridge systems are running, provided that the data is collected via Ethernet calls. The designated sensor tiles in the hallway will not correspond to every grating sensor in the FBG array. Half of these sensors will be used for auxiliary structural and temperature monitoring, while nearly all of the sensors in the bridge FBG array will be utilized for structural monitoring.