Semi-autonomous data collection for the IoT

May 10, 2016 // By Mikel Choperena
Latest technology advances bring wireless and battery-free sensors based on RFID technology to act as a data source for the Internet of Things.

RFID has long been associated to identification. No wonder why: RFID stands for Radio Frequency Identification and it was developed with the idea to identify assets. As such, the technology has become widely popular for its usage in logistics and supply chain applications, providing advantages over bar codes to uniquely identify items – this allows for track & trace services without the need of line of sight, at distances up to 10 meters and readings of up to 700 items per second.

As such, RFID is a good source of data for IoT just as an identification tool. As an example, items at retails stores are tagged with RFID devices so that companies can take inventories in a fast and reliable fashion and replenish stores to avoid out of stock losses.

 

Adding sensors to the mix

One of the greatest advantages of RFID – if not the biggest – is the possibility of working battery-free. Obviously, there are active RFID solutions that can communicate over kilometres of distance but being able to track RFID tags at some meters without using batteries at all is very convenient. Now, the IoT is not just about identification. There is a triad to successful IoT systems: data collection, data processing and data delivery. RFID systems are included in the data collection part but… why limit this to identification?

Latest advances in RFID technology have resulted in wireless and battery-free devices. RFID tags basically harvest RF energy to power up a chip that replies back with a unique identification number. New developments use that harvested energy to power up external devices such as sensors or actuators – which is a new source of data for the IoT.

Temperature sensors, pressure sensors, humidity or soil moisture sensors, voltage or current sensors… you name it. Any of these can be wireless and battery-free and provide an important set of data. Even LEDs can be flashed, mechanical relays switched or displays changed wirelessly and without batteries.

As pointed out previously, IoT is also about processing all the data and delivering it correctly. RFID hardware can provide lots of data. However, the true potential of the RFID systems lies in the combination of data collection and data processing, converting data into meaningful and actionable information.


Rotor temperature monitoring system.

As an example, RFID is a great technology to collect data of hot spots inside motor and generator rotors. In these motors, winding temperature or permanent magnet temperature are key but, as a rotating device, wiring sensors to the rotor is not a possibility. Battery powered wireless devices are technically feasible but the cost of changing batteries is too high when having to stop the motors for this purpose, sometimes affecting the production of a whole manufacturing line. RFID temperature sensors can be placed on the rotor to collect data from hot spots. These sensors will never require a battery change so the solution works fine.