OGC standards enabling sensor integration in OBSEA cabled observatory
At the Polytechnic University of Catalunya, we have been advancing technology for interoperable marine sensor networks on the OBSEA cabled observatory in the Mediterranean Sea.
We are continuing our activities in an EU funded project called Nexos from the Oceans of Tomorrow call. One of the objectives of the NeXOS project is the development of different types of instruments and their integration with different types of platforms, including Autonomous Underwater Vehicles (AUVs, or gliders), buoys, drifters and cabled observatories. We are in charge of the development of smart interfaces to facilitate the integration process of instruments into marine platforms.
On the platform and vehicle side, we are working with different manufacturers to facilitate smooth integration of our instruments with their platforms, taking advantage of standards. We are working with these manufacturers to upgrade their platforms’ firmware in order to take advantage of the OGC PUCK protocol.
The instruments have RS232 serial and ethernet communication interfaces, and all of them are OGC PUCK compliant. The instruments physically contain SensorML descriptions of themselves. Commands for the instruments’ operation will be based on SCPI (Standard Commands for Programmable Instrumentation. In addition, ethernet-connected instruments feed directly into an OGC Sensor Observation Service on the Internet.
Importantly for the overall ocean observation effort, other EU funded projects under the same topic are planning to integrate the OGC PUCK protocol in their designs. We are exchanging this information between projects to ensure real interoperability between the different instruments developed and used by different projects.
The NeXOS project is developing two types of passive acoustic monitoring systems (smart hydrophones, one with very low power consumption and with signal processing capabilities, and other with no practical power constraints), three types of optical sensor systems, and fisheries management sensors systems.
Instruments are being tested, validated and demonstrated from laboratory to shallow water observatories and finally (depending on the sensor and use case) in gliders, moorings, ferry boxes and buoys. NeXOS has defined five integrative scenarios to cover the range of platforms and sensor for testing and demonstration.
OGC PUCK implementation is nearly 90% complete. Serial and IP OGC PUCK implementations are being deployed within the firmware instruments.
How it works: A marine sensor that communicates through an RS232 connection can be OGC PUCK-enabled. This means that the sensor has an internal memory containing a file with information about the instrument itself. The OGC PUCK protocol enables downloading of this file using standard commands and a well known and clear procedure.
We use the PUCK protocol to retrieve the information file from the instrument and load it to a platform over the RS232 bus (or Ethernet). The sensor description data is encoded using the OGC SWE SensorML 2.0 Encoding Standard. It is encoded using Efficient XML Exchange (EXI, a W3C standard) in order to minimize the size.
The commands that the platform needs for initializing the instrument and interrogating the instrument for new data are included in the SensorML file. The software running in the platform interprets the SensorML file in order to know which commands are needed to communicate with the instrument. We named the software running on the platform “SWE-Driver” because it uses the OGC SWE standards PUCK and SensorML at the instrument level. The SWE-Driver is able to register the Sensor into a specific SWE-SOS server to upload the measurements.
The main benefit to this approach is that the platform doesn't need to know how the instrument works and it doesn’t need to know which commands are needed to interrogate the instrument. Because the platform and the instrument are PUCK enabled, the platform knows when a new instrument is connected to one of the serial ports. It then starts all the mechanisms: read file using PUCK protocol, decode it, interrogate the instrument and upload observation data to the SOS server. It is truly “plug and play”.
The specifications of the PUCK protocol, the PUCK protocol software suits and information about the use of the PUCK protocol in Ocean Observing Systems can be found these links:
1. OGC PUCK standard - http://www.opengeospatial.org/standards/puck
2. OGC PUCK Reference Design Kit -http://www.mbari.org/pw/devtoolkit.htm, http://www.mbari.org/pw/2010-TTOSInternProject-v1.pdf
3. Use of OGC PUCK in Ocean Observing Systems - Joaquın del Rıo, et al.; "Standards-Based Plug & Work for Instruments in Ocean Observing Systems"
On October 20, the IEEE Ocean Research Coordination Network (Ocean RCN), US National Science Foundation (NSF), and Group on Earth Observations (GEO) presented a webinar, “From Sensors to Users: Applying the Open Geospatial Consortium (OGC) Sensor Web-Enablement Framework to Marine Observing Systems.” The webinar, hosted by Dr. Jay Pearlman, is summarized in this video: https://www.youtube.com/watch?v=tuuS5xT_sV8. A link to a full video of the 1-hour webinar is available at
https://cc.readytalk.com/cc/playback/Playback.do?id=c02kgx. You’ll need to register, but registration is free. A previous video is also available online: https://www.youtube.com/watch?v=a0kdYTpe1SE
For more information, see an article published in August in Earthzine:
This post was contributed by Joaquin del Rio, from Technical University of Catalonia in Spain (UPC)