Bereitstellung der weltweit energieeffizientesten drahtlosen Überwachungslösung mit Hilfe der elektrolytischen Neigungssensoren von Fredericks
Einführung
There are over 612,000 bridges in the United States and as of February 2017, almost 10% of them need to be repaired or replaced according to The American Road and Transportation Builders Association. That means that there are currently over 55,000 bridges that require real-time monitoring in order to avoid a catastrophe like the 2007 bridge collapse in Minneapolis, Minnesota.
Was ist Resensys?
Resensys bietet kosteneffiziente und skalierbare Lösungen, um die strukturelle Stabilität dieser und anderer Autobahnbrücken zu bewerten, so dass strukturelle Probleme erkannt und notwendige Instandhaltungen und Reparaturen geplant werden können, um die Sicherheit und Langlebigkeit der Brücken zu gewährleisten.
Die drahtlose Lösung SenSpot™ zur Überwachung des Bauwerkszustands ist für bestehende und im Bau befindliche Brücken gedacht und verfügt über kleine, kostengünstige und einfach zu installierende Funksensoren, die eine Vielzahl von Variablen messen, die die Leistungsfähigkeit einer Brücke beeinflussen.
Entstanden aus der Forschung von Präsident und CTO Dr. Mehdi Khandani an der University of Maryland, ist Resensys führend im Bereich der geostrukturellen Echtzeit-Überwachung und bietet das langlebigste drahtlose Brückenüberwachungssystem mit einer erwarteten Lebensdauer von mindestens 10 Jahren. Für weitere Informationen besuchen Sie http://www.resensys.com.
The Challenge
Obwohl es auf dem Markt auch andere Sensoren zur Überwachung von Infrastrukturen gibt, unterscheidet sich ein Resensys-Gerät durch seinen extrem niedrigen Stromverbrauch: Es verbraucht nur etwa 4 Mikrowatt, also etwa 100 Millionen Mal weniger als eine typische Glühbirne. Das bedeutet, dass ein SenSpot-Sensor eine Mindestlebensdauer von 10 Jahren hat und nur eine kleine ½-AA-Batterie benötigt.
Um ein solch effizientes und genaues Überwachungssystem anbieten zu können, musste Resensys einen Neigungssensor mit einer Auflösung von bis zu einem Tausendstel Grad finden, der gleichzeitig einen geringen Stromverbrauch, eine lange Lebensdauer und eine Produktlebensdauer von mindestens 10 Jahren bietet.
Die Lösung
Dr. Khandani and his team thoroughly evaluated a variety of MEMS and other electrolytic tilt sensors and concluded that the Fredericks Single-Axis Narrow-Range Electrolytic Tilt Sensor (PN 0703-0711-99) significantly outperformed competing products in terms of long term repeatability and resolution.
“Qualitatively, Fredericks’ devices were an order of magnitude better than both MEMS and competing electrolytic sensors,” says Dr. Khandani. “In our application, repeatability is very important and none of the competing products did as great as Fredericks products did.”
Die Ergebnisse
With the help of Fredericks’ electrolytic tilt sensors, Resensys is able to offer the world’s most energy-efficient wireless monitoring solution that helps keep travelers safe with around 5,000 SenSpot™ tilt units in use in the US and around the world.
“Our decision to use Fredericks products was driven by the excellent accuracy and durability of their tilt sensors,” Dr. Khandani adds. “Such long term and high-quality measurements help capture the smallest movement and instability on critical bridge components.”
SenSpot™ in Aktion: Brücke über den Patapsco River
In the Spring of 2014, cracks were spotted in the girders and piers of the I-70 Patapsco River Bridge near Baltimore, Maryland. Engineers found that non-responsive bearings had caused damage to piers and steel girders of the bridge, which led to its closure in June 2014.
Repairs were made, retrofits were applied, and a SenSpot™ monitoring system was installed in July 2014 to detect any further changes. More than 40 SenSpot™ units were mounted on the bridge, including 12 tilt sensors located on the bridge’s rocker bearings to monitor the movement pattern and detect non-responsiveness or over-responsiveness. In addition, six high-resolution tilt sensors were mounted on the bridge’s piers to monitor the deflection and rotation of the bridge rocker bearings caused by cold temperatures.
Early results from August to November 2014 found that the bearings on two piers were non-responsive to temperature changes and an additional bearing saw only 20% of expected movement. Data collected through Spring 2015, however, showed that the bearings had an unprecedented response to the robust retrofits (combined with especially cold winter), and by March 2015 all piers and respective bearings were fully responsive.
Dr. Khandani notes, “After more than four years of continuous monitoring, we are pleased that the Fredericks devices used in SenSpot™ sensors produce very consistent, repeatable, and high-quality measurements of tilt and inclination at sub-arc-second resolution.”
Before alerting the Maryland State Highway Administration, the Resensys team worked with engineers at Fredericks to confirm the data. At Fredericks, we take a partnership approach to our relationships with customers, and customer satisfaction is a priority. We have dedicated representatives and engineers committed to providing highly responsive service, and our customers have anytime-access to our leadership team, made possible in part by our “not too big, not too small” operation.