NEMOSENSE is a tailor-made IoT device that combines a vibration data acquisition device, a data logger, and a low-noise triaxial MEMS accelerometer. It is an ideal vibration monitoring solution for permanent condition monitoring of wind turbines and structures such as bridges, buildings, antennas, and stadiums. It offers a great price-performance ratio.
 
NEMOSENSE device overview
NEMOSENSE-3xMEMS-ACC is a low-power IoT device with an integrated triaxial MEMS accelerometer. It acquires the data and stores it on an internal SD card. Data is stored in CSV file format and transmitted to the server, using the MQTT protocol, when the connection is available.
 
Analog-to-digital conversion is done on the device with the onboard ADC converter. This eliminates any noise picked up in analog cabling.
 
The onboard microprocessor is used to perform simple processing tasks such as FFT and basic statistics (Min, Max, Average, RMS). This eliminates the need for an expensive external computer.
 
NEMOSENSE connectivity
NEMOSENSE is built as an Ethernet TCP/IP device. It can be connected to an existing TCP/IP network to send the data to the Dewesoft Historian service - a time-series database, for long-term data storage. If the wired-ethernet network is not available, an external 4G/5G modem can be used for the data transfer.
 
In parallel to web clients, the data can also be accessed and analyzed by an instance of award-winning DewesoftX software, typically running on a client PC in an engineering office. The DewesoftX view client includes two modules:
 
The MQTT client: MQTT client operates in DewesoftX’s measure mode and has the role of displaying live data from the measurement units.
The Historian importer: The Historian Importer plugin operates in DewesoftX Analysis mode and allows the data from a chosen time frame to be loaded into a DewesoftX data file for further in-depth analysis and reporting.
 
Device architecture
NEMOSENSE-3xMEMS-ACC is an Ethernet device and can be easily connected to an existing TCP/IP network. The MQTT Client is running onboard sending the data to the MQTT broker, a Dewesoft Historian component, installed on the server side.
 
Dewesoft Historian is a central point where data from NEMOSENSE devices, Dewesoft Measurement Units, and 3rd party MQTT clients is merged and stored into the same InfluxDB time-series database.
 
The data stored in the database can be accessed using a web browser (Grafana) or DewesoftX software.
 
Seismic noise performance
With only 25 µg/√Hz spectral noise density and 100 µg residual noise at 50 Hz bandwidth, the NEMOSENSE-3xMEMS-ACC device is a cost-effective solution for seismic measurements.
 
The FFT recorder on the image shows the residual noise of the three axes measured with an integrated accelerometer at the sample rate of 100 S/s resulting in a 96 dB dynamic range.
 
Product testing and validation
Hardware repairs or replacements are expensive on structures such as bridges. Therefore NEMOSENSE-3xMEMS-ACC was put through in-depth product validation tests that ensure reliable operation within its specifications.
 
Standard testing procedures include vibration and temperature cycle tests to check the durability and specify drifts in measured acceleration.
 
Historian database storing
NEMOSENSE dataloggers can be installed for long-term or permanent monitoring. This kind of measurement requires efficient data storage. For that, we provide Dewesoft Historian service. The Historian is a time-series database service based on the MQTT messaging protocol for the Internet of Things (IoT).
The Historian is based on an open-source InfluxDB database and is a perfect solution for long-term monitoring. Data in the Historian can be accessed in two ways:
 
Web clients: any modern web browser can be used as a web client to access real-time data stored in the Historian. The solution is based on another open-source project Grafana. It allows to set up of completely customized views and is a perfect solution for real-time dashboards.
Desktop client: the desktop client is an instance of our award-winning DewesoftX software. It allows you to import historical data from the Historian database for in-depth analysis.
 
The Historian is available to be installed on your own server (Windows, Linux, Mac OS) or as a completely managed cloud service.
 
Permanent outdoor mounting
NEMOSENSE-3xMEMS-ACC devices are supplied in a waterproof aluminum casing with RJ45 Harting push-pull connector. The enclosure is designed to be mounted outdoors and is fully waterproof and complies with IP67 environmental rating.
 
The outdoor enclosure automatically vents the air to equalize pressure inside the enclosure to the outside air pressure while it does not allow water to pass into the enclosure. This prolongs the life span of the seal and increases the durability of the enclosure.
 
Applications
NEMOSENSE-3xMEMS-ACC devices are designed for tailor-made structural health monitoring solutions and seismic monitoring solutions and are thus ideal for permanent health condition monitoring on big structures such as:
 
Wind turbines
Bridges
Buildings
Dams
Antennas
Stadiums
Structures in mines