Design requirements for wireless sensor-based novelty detection in machinery condition monitoring

Abstract

Wireless sensor networks are increasingly employed in a range of applications. Condition Monitoring in particular can benefit from the introduction of distributed wireless sensing solutions, operating with a high degree of autonomy. Wireless condition monitoring can extend the toolset available to the lifecycle management of engineering assets, offering ease of installation, flexibility, portability and accessibility. A significant hurdle for the adoption of wireless condition monitoring solutions in industry is related to the extent that such solutions can operate over long time periods, while providing adequate monitoring. Wireless sensor nodes extend the sensor functionality by providing on-board CPU, memory, power management and communications capabilities. Yet these are inherently limited due to the small form factor of the devices. Even in cases of sensor nodes with power harvesting capabilities, the minimization of the node energy consumption is sought at a premium. Apart from making the hardware design more energy efficient, sensor nodes can operate more efficiently if they achieve to minimize their energy-consuming activities, while meeting condition monitoring performance requirements. Low-level power management should be dealt with at the level of the sensor operating system. At the application end, a sensor node must feature some form of smart behaviour, enabling it to recognize events that deserve further attention. This is of profound importance as engineering assets equipped with embedded novelty detection capabilities would lend themselves for enhanced and sustainable operation. In this paper we study the design requirements for developing Novelty Detection techniques, as middleware components embedded on a single sensor board. Such smart components would enable the detection of events that signal the presence of unusual behaviour in the monitored equipment. On the basis of the identified design requirements, a conceptual architecture for the development of wireless sensor – board level novelty detection is discussed.