Stochastic Estimation and Control over WirelessHART Networks: Theory and Implementation
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
There is currently a high interest of replacing traditional wired networks with wireless technology. Wireless communications can provide several advantages for process industries with aspect to exibility, maintenance and installation. The WirelessHART protocol provides a standardized wireless technology for large automation networks that explore wireless communication. However, wireless networks introduce time delays and losses in the communication system, which denes requirements for designing estimators and controllers that can tolerate and compensate for the losses and delays.
This thesis consists of several contributions. First, we develop tools for analyzing the delay and loss probabilities in WirelessHART networks with unreliable transmission links. For given network topology, routing and transmission schedule the developed tools can be used to determine the latency distributions of individual packets and quantify that a packet will arrive within a prescribed deadline. Secondly, we consider estimation and control when sensor and control messages are sent over WirelessHART networks. The network losses and latencies are modelled and compensated for by timevarying Kalman lters and LQG controllers. Both optimal controllers, of high implementation complexity, and simple suboptimal schemes are considered. The control strategies are evaluated on a simulation model of a flotation process in a Boliden mine where the wired sensors of the existent solution are replaced by a WirelessHART network scheduled for time-optimal data collection. Finally, we implement a WirelessHART-compliant sensor on a Tmote sky device and perform real experiments of wireless control on a water tank process.
Place, publisher, year, edition, pages
2010. , 87 p.
WirelessHART, Tmote, Wireless, Control, LQG, WSN, Kalman
IdentifiersURN: urn:nbn:se:kth:diva-105172OAI: oai:DiVA.org:kth-105172DiVA: diva2:570180
Subject / course
Master of Science in Engineering - Electrical Engineering