Realistic case studies of wireless structural control

Abstract

Wireless Structural Control (WSC) systems can play a crucial role in protecting civil infrastructure in the event of earthquakes and other natural disasters. Such systems represent an exemplary class of cyber-physical systems that perform close-loop control using wireless sensor networks. Existing WSC research usually employs wireless sensors installed on small lab structures, which cannot capture realistic delays and data loss in wireless sensor networks deployed on large civil structures. The lack of realistic tools that capture both the cyber (wireless) and physical (structural) aspects of WSC systems has been a hurdle for cyber-physical systems research for civil infrastructure. This advances the state of the art through the following contributions. First, we developed the Wireless Cyber-Physical Simulator (WCPS), an integrated environment that combines realistic simulations of both wireless sensor networks and structures. WCPS integrates Simulink and TOSSIM, a stateof-the-art sensor network simulator featuring a realistic wireless model seeded by signal traces. Second, we performed two realistic case studies each combining a structural model with wireless traces collected from real-world environments. The building study combines a benchmark building model and wireless traces collected from a multi-story building. The bridge study combines the structural model of the Cape Girardeau bridge over the Mississippi River and wireless traces collected from a similar bridge (the Jindo Bridge) in South Korea. These case studies shed light on the challenges of WSC and the limitations of a traditional structural control approach under realistic wireless conditions. Finally, we proposed a cyber-physical co-design approach to WSC that integrates a novel holistic scheduling scheme (for sensing, communication and control) and an Optimal Time Delay Controller (OTDC) that substantially improves structural control performance.

Sensor Placement with Multiple Objectives for Structural Health Monitoring

“…The decision on structural state is made offline. Many existing WSN approaches use the flat architectures [Bocca et al 2011;Whelan and Hietbrink 2012;Peckens and Lynch 2013;Araujo et al 2012;Li et al 2013Kim et al 2007]. The way of raw data transmitting and processing at the sink makes it practically difficult to achieve the high quality of monitoring, because of WSN constraints.…”

“…Cyber-Physical Systems (CPS) have recently been proposed by Li et al [2013] and Hackmann et al [2013], considering both the constraints of the underlying WSNs and the SHM requirements, where a distributed damage detection algorithm is suggested under a hierarchical cluster-based WSN [Hackmann et al 2013]. Although it offers a trade-off between the computation and communication capacities, it does not reveal the details, such as connectivity, or coverage in the hierarchical architecture.…”

“…Only a few justify the use of WSNs, where sensors are often required to transmit data to a central server (or a sink) [Ceriotti et al 2009;Araujo et al 2012;Hackmann et al 2012;Li et al 2013;Linderman et al 2010;Farrar and Worden 2012]. By using either single-hop or multihop communication techniques, data transmission over a large structure is extremely difficult and costly.…”

Incorporating emergency alarms in reliable wireless process control

“…Gisso in [6] is a recent simulator for wireless control systems based on Cooja, but the wireless link model in Cooja simulation remains to be improved. WCPS [19] connects Simulink and TOSSIM. WCPS 2.0 as a further development in this paper has incorporated substantial changes including a new WirelessHART protocol stack.…”

“…In this section, we firstly introduce our Wireless CyberPhysical Simulator [2] [19]; we then describe our WirelessHART stack implementation; we finally we present our real-time emergency communication protocols, and other major changes in WCPS 2.0. …”