SensorSA Data Acquisition System

The SensorSA Data Acquisition System (SensorSA DAS) is a network capable appliance developed by AIT, which allows seamless integration of various sensors in a Sensor Service environment based on SensorSA. The main characteristic of SensorSA is the exclusive use of OGC SWE interfaces for all communication.

SensorSA DAS exposes sensor data, management data, and history of alerts over a Sensor Observation Service (SOS) interface. The sensor configuration is performed via Sensor Planning Service (SPS) interface, and the configuration of events and alerts is performed through a Sensor Alert Service (SAS) interface.

AnySen Driver

AnySen driver has been back-ported to existing UWEDAT monitoring system and used in production environments. Companies interested in integrating AnySen in their own products are kindly asked to contact AIT.

The AnySen driver is a software component for low level data acquisition, which can be used to connect sensors to a Data Acquisition System. It controls the sensor, interprets measurement streams and parses measurements.

AnySen is a part of the Time Series Toolbox and can be easily combined with other toolbox components. The main advantage of AnySen is its capability to read and interpret data from many sensor nodes equipped with a digital interface (e.g. RS232 or LAN). This is achieved by abstracting the sensor protocols and reading the concrete description out of a simple sensor description file. All commands necessary for configuring and retrieving data from an analyser can be configured at run time. When a new sensor is attached to the DAS, the AnySen can trigger an automated configuration process, leading to the sensor level ‘Plug and Measure’.

The configuration can either be read from a central Database, or from the SensorSA Smart Sensor. The configuration possibilities include the protocol description, structure of the measurements, and various meta-information such as the name and unit of the measured phenomenon. This is a significant difference to current DAS concepts, where this meta-information is injected in higher levels, often as part of the application logic.

GeoMotes and GeoCubes

The GeoMotes are mini-GPS devices (about 30 x 40 x 10mm, antenna included) that provide an accuracy better than one centimeter, thanks to a post data processing based on a differential calculus.

These devices can be embedded in self-powered systems which are connected wirelessly to each other in order to set up a network. Each node, named GeoCube, can continuously provide GPS data to one PC. Furthermore, GeoCube is equipped with a three axis MEMS accelerometer which is able to detect high frequency displacements. Therefore GeoCube is able to send a warning, then GPS data are being recorded and new positions are computed with one hour delay.

A network of GeoCubes is a mesh with wireless links that can monitor a local area of about one square kilometer. This network is small, easy to install and a low cost solution for geohazard predictions. Each node, i.e. each Geocube, is geo-localized with a relative positioning accuracy better than one centimeter in planimetry and two centimeters in altimetry. Moreover, time accuracy of each GeoCube is better than 50ns: it can easily and precisely date or initiate events.

Microns

Microns are wireless ad-hoc sensor communication nodes developed by SDA. As opposed to the Geocube, the Micron is a sensor node and not an actual sensor. Up to eight sensors can be connected to a Micron, which in its turn stores and relays observations to the sensor network.

The Micron smart sensor nodes have an integrated battery, which allows a guaranteed autonomy of 2 years. This autonomy may vary depending of the sensors attached and the frequency of measurements. An external power source can be connected, so e.g. photovoltaic panels could also be deployed to power the sensor nodes, and take over the battery powering.

The sensor nodes support different network topologies and are organised ina self-healing network, which means that if a node fails, the other nodes will automatically find another communication route. When several routing paths are possible, they will chose the most efficient path for their data communication.

SensorSA Data Acquisition System allows seamless integration of Microns in SensorSA networks.

SensorSA Smart Sensor Adapter

The SensorSA ‘Smart Sensor Adapter (SSA)’ is a simple device which allows the user to connect a simple RS-232-based measuring device with automatic identification and registration to the station computer.

The SensorSA SSA has a possibility to provide all information required for automatic configuring of a SensorSA DAS, including e.g. capabilities of the sensor, resolution, accuracy and type of the measurements (units), sensor location, owner, proposals for information processing and more.

When attached to an USB port, the SSA allows the DAS to download its configuration data. In a next step, the DAS uses this information in the similar way it would use the configuration data obtained from the ‘sensor types’ database. Finally, the SSA switches to the ‘transparent’ mode and allows direct communication between the SensorSA DAS and the SSA RS-232 interface.

The current implementation of the SSA is based on a Microchip evaluation board shown above and the firmware supports following operations:

• setTransparent=0 or 1switch to Command mode or RS232-USB
  converter mode

• getCapabilities outputs the Sensor-ML file to USB
  
• getTemperature outputs the local temperature of the adapter (demo-value)
  
• getSwitchStates outputs the logical states of two digital input lines
  
• getPoti outputs the value of the on-board potentiometer (demo-value)

These commands can be sent over the USB connection and will be interpreted by the board until it enters the transparent mode (setTransparent=1 command). Once in transparent mode, the SSA acts as a simple USB to RS-232 bridge, which allows re-using of the existing sensor drivers with no or minimal changes.