Building the business case for wireless sensors in a factory setting

With the advent of the low complexity wireless technology Zigbee, different cheaper and more energy efficient wireless transceivers became available on the market. These chipsets are gradually introduced in different small scale wireless applications. Especially in cases of wireless sensor networks, the low energy consumption and cost efficiency are a real gain. As such it is often used in small non-critical monitoring type battery powered sensor installations. In more time-critical applications, all wireless signals should be better orchestrated to avoid collisions, especially with Wi-Fi. So called spectral sensing engines are able to scan the wireless spectrum and severely reduce the probability of collisions, even between different technologies as in the Wi-Fi ⇔ Zigbee case. This paper investigates if both technologies - with or without spectral sensing engine - could lead to more cost efficient installations in more critical sensor network installations, where typically today a wired solution is used. As a realistic benchmarking case, we consider an installation in a factory in which many different types of sensors - critical and background - are scattered over the production facility and are used in controlling all processes. In this paper we constructed cost models for the wired and both wireless solutions. The results clearly show that wireless sensors could lead for smaller installations to large cost reductions (up to 50%) and give a more detailed view on the tradeoffs in a wired vs. wireless sensor network installations. This model can be used for identifying the most cost efficient sensor network for different factory installations, as well as beyond the realm of factories. The economic model is more generally applicable for sensor networks spread over large areas including mission critical and non-critical sensors.