A Comprehensive Dependability Model for QoM-Aware Industrial WSN When Performing Visual Area Coverage in Occluded Scenarios

Abstract

In critical industrial monitoring and control applications, dependability evaluation will be usually required. For wireless sensor networks deployed in industrial plants, dependability evaluation can provide valuable information, enabling proper preventive or contingency measures to assure their correct and safe operation. However, when employing sensor nodes equipped with cameras, visual coverage failures may have a deep impact on the perceived quality of industrial applications, besides the already expected impacts of hardware and connectivity failures. This article proposes a comprehensive mathematical model for dependability evaluation centered on the concept of Quality of Monitoring (QoM), processing availability, reliability and effective coverage parameters in a combined way. Practical evaluation issues are discussed and simulation results are presented to demonstrate how the proposed model can be applied in wireless industrial sensor networks when assessing and enhancing their dependability.

A Survey on Monitoring Quality Assessment for Wireless Visual Sensor Networks

“…Since the monitored area is a continuous space, it is difficult to state which region has been covered by which visual sensors. Discrete solutions using grid approaches have been proposed to approximately compute area coverage for WVSN [6,17,35,38,[48][49][50]52]. That way, the area of interest can be divided into smaller regions, each one defined as identical rectangles.…”

“…Whatever the situation, area coverage problem can be approximated by manifold target coverage problems, being each one of these points of interest a target with infinitesimal size. This is a relevant approximation objecting at higher efficiency, while keeping the computational cost low [6,17,50].…”

“…Generally in the literature, a camera's field of view is divided into three regions: the closer to the camera (with high quality), the farther (with low quality) and an intermediary region (with medium quality) [6,17,67]. These configurations are depicted in Figure 5 for the regions H, L and M, respectively.…”

“…Dependable quality can be assessed using well defined methodologies to perform availability and reliability assessments in WVSN. Such evaluations assume that the application is available if some requirements are fulfilled, such as target k-coverage [27], a minimum area coverage rate [6,51,52] or even a simultaneous coverage of targets and area [35]. For this, it is considered hardware failures (hardware malfunction, battery discharging), communication failures (loss of path to a sink node) and coverage failures (loss of view, occlusion, low content quality).…”

“…Visual sensors-based networks may achieve a deeper perception of the monitored environment, leveraging the particularities of several monitoring applications [4], especially when they are operating over the Internet. Examples of such applications are surveillance [5], Industry 4.0 automation and control [6], smart street lighting [7], smart homes [8], smart grids [9], traffic and pedestrian control [10], living assistance [11], driving assistance [12], waste collection [13], emergency detection [14], among many others. For all those applications, it is fundamental to fulfill the quality requirement associated with the monitoring tasks performance.…”