A Wireless Toolkit for Monitoring Applications

Monitoring the behavior of physical structures and processes gives valuable information about their condition and performance. This information can be used to improve safety, reliability and performance of the monitored physical structure. Complex systems of today require efficient and intelligent monitoring strategies which will help forming cause-effect relations between certain variables and problems. Wireless sensing is a promising technology for monitoring applications due to its advantages, e.g., in installation times and costs. Many systems were successfully implemented over the last decade. However these systems are often hard to use and designed for a specific purpose. Moreover, high sampling rate data collection with these systems can take long times due to limited bandwidth of the wireless networks. In this thesis, a wireless monitoring toolkit is developed and it can be defined as a portable, easy-to-use, simple-to-setup and fast monitoring system to be used for simultaneous multi-parameter monitoring of physical structures and processes. The toolkit consists of user interfaces, a novel data acquisition system which optimizes wireless communication speed in the network, a real-time monitoring application, a communication test application, a high sampling rate application, and wireless sensors hardware equipped with multiple sensors and IEEE 802.15.4 radios. Real-time monitoring application has a flexible, reliable and efficient structure due to its dynamic and multi-task operation. These two features distinguish this application from other wireless monitoring applications. Tests on a wooden bridge, a laboratory scale trolley crane, and an industrial bridge crane show that the developed system works seamlessly in industrial environments as well as in laboratory environments. Data collected in these case studies provide valuable information about the condition and performance of the monitored structures and systems, as shown by the data analysis performed. The thesis includes a review of state of the art wireless monitoring systems and determines framework of a general purpose wireless monitoring system to be used for condition monitoring and performance optimization purposes

A-Stack : a TDMA framework for reliable, real-time and high data-rate wireless sensor networks

The reduced size, power consumption and cost of wireless sensors make them an excitingtechnology for many monitoring and control applications. However, developing reliable, realtimeand high data-rate applications is challenging due to time-variations and interference inwireless channels and the medium access delays. For high data-rate and real-time applications,time division multiple access (TDMA) based medium access approach performs better ascompared to carrier sense multiple access (CSMA) based approach. On the other hand,implementation of TDMA in resource constrained wireless nodes requires difficult designdecisions. This document presents A-Stack, a real-time protocol stack for time synchronized, multichanneland slotted communication in multi-hop wireless networks. The stack is developed tomeet the reliability and accuracy requirements of real-time applications such as wirelessautomation and wireless structural health monitoring. A-Stack provides a flexible developmentenvironment for such applications by ensuring deterministic reliability and latency. It includesMAC, routing and time-synchronization protocols as well as a node-joining algorithm. Thestack is further supplemented with PC tools for optimizing the network as per the targetapplication for easy prototyping. This document explains the design and operational aspects ofA-Stack. Various deployment scenarios as well as long term system and communicationreliability tests are presented in the document