Wireless sensor ingenuity applied to public washrooms

The core of the washroom information service are the sensors which are battery-powered and monitor the fill levels.

Washrooms are among the highest-maintenance rooms in both public and commercial buildings, but now, a connected sensor system from researchers in Europe could make their upkeep much more efficient.

Researchers from Fraunhofer Society in Germany have come up with a washroom information service which uses sensors that are connected wirelessly to automatically monitor soap, cotton towel and toilet paper levels.

With advanced insight into the stock levels of consumables in each washroom, cleaning staff will be able to plan their maintenance rounds much more effectively, ensuring on-time replenishment of soap, hand-towels and toilet paper.

Professor Thomas Wieland, head of the Fraunhofer Application Centre for Wireless Sensor Systems, worked with service provider CWS-boco International to create the system.

The core of the washroom information service are the sensors, which are battery-powered and monitor the fill levels of soap dispensers, cotton towel rolls and toilet paper. In the case of the soap dispenser, an optical sensor keeps an eyes on the fill level, while the sensor module gathers the data from the meter in the soap dispenser, which records every portion dispensed. For toilet paper, optical systems monitor their stock level, while a portion meter monitors the usage of the hand towel dispenser.

The information from the dispenser sensors is transmitted to a Washroom Control Unit via Bluetooth 4.0 LE communications, which helps lower the energy required for data transmission from the sensors. Each Washroom Control Unit is a collection point and communication node, and multiple units are distributed around the entire building and networked with each other.

Together, these Washroom Control Units form a self-configuring network, with each node deciding autonomously what device to send its data to. This means that even if some modules are out of order or cannot be reached, the data from the remaining Washroom Control Units can still be communicated through the network.

Once all the data has been collected, the final unit in the transmission chain sends the entire data package to a gateway. From there, the information is forwarded via a cellular network to the cleaning service provider's server.

Each washroom operator has access to a visual user interface which displays the relevant information for them. A visual user interface displays the information for each individual washroom operator. The shift supervisor can then print out the washroom information as a shift plan or send it to the cleaning staff’s tablets. Another option would be to have a display at the entrance to the washrooms that shows what the washroom requires.

The Fraunhofer researchers say the technology will not be just applicable to washrooms. Wirelessly networked sensor technology makes many applicataren’t only thinking about washroom services.

"The system is ideal for any situation where sensor data has to be gathered and transmitted,” Wieland explains.

The self-organisational network technology in particular provides extreme reliability. With its transmission frequency of 868 MHz, the wireless signals can penetrate walls with ease, which is especially useful in complex buildings.

Possible applications include uses in the agricultural sector to monitor crops. In cities, sensor networks can keep track of the water quality in rivers, bridge stability, and other constructions. Further applications include the use of networked sensors for supervising production plants and monitoring the status of machines or workpieces.