The safe operation of a vessel is more and more depending on complex and critical onboard control systems, such as dynamic positioning. Because of this, those who charter the ships (e.g. major oil companies) are requesting improved performance and verification of the safety of the vessels.
"Since 2003, DNV has in cooperation with the Norwegian company Marine Cybernetics (MC) been developing a new test and certification regime called Hardware In the Loop (HIL) testing. HIL testing is a test method which can be utilized to assist in the verification of adequate performance and safety levels of the complex onboard systems. The CyberSea HIL simulator provided by Marine Cybernetics enables a wide range of detailed testing of control systems both at the factory, during commissioning, and in the sailing phase," says Knut Svein Ording, head of DNV's section for control systems.
In response to an industry request, DNV has also developed a standard for Certification of Hardware In the Loop (HIL) testing, enabling DNV to offer a certificate in line with other certificates from flag state authorities and classification societies. The Acergy Osprey is the first vessel to receive such a certificate.
"The new HIL test certification regime has proved to be a very useful instrument for carrying out deeper and broader testing on control systems. We have discovered bugs and possible bugs on the target system that are almost impossible to discover with the existing test methods within the normal class scope," says Aleks Karlsen, responsible for DP systems in DNV.
Stian Ruud, DNV's responsible for the HIL Joint Industry Project (JIP) adds: "Furthermore, we see that the HIL testing has started a discussion amongst the users and operators related to functionality, training and procedures. These experiences will form the basis for further development of class related HIL products in the Safe Computer Controlled Ship project where DNV participates."
A natural add-on
The DNV rules for classification of ships give functional requirements to the specific target systems like dynamic positioning systems, propulsion control system and power management systems. HIL test certification of a ship control system is based on general HIL requirements stated in the Standard for Certification for HIL testing, and functional requirements of the specific target system (e.g. a dynamic positioning system) as stated in the Rules.
"This means that the HIL test certification becomes a natural add-on to the existing classification and certification regime for control systems onboard ships," says Knut Svein Ording.
The certification and testing related to the upgrade of the DP AUTRO system (corresponding to IMO equipment class III) onboard the Acergy Osprey, operated by Acergy, was performed in four steps:
Following the document approval and tests all findings were listed and followed up. After implementation of necessary amendments to the DP system the comments were cleared out and the HIL test certificate was issued.
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