In order to ensure a safe berth-to-berth navigation of vessels the harbors as start and end points of a voyage as well as way points of a trafficable route should be determined. Position data (P) specify such points in a global usable reference system in unambiguous manner. Navigation data (N) such as rate of turn, heading, course and speed over ground are used to plan and control the movement of ships during the voyage. Time data (T) serves the scheduling of voyages and the synchronizing of communication and information processes between stakeholders of the maritime traffic system.
PNT data belongs to the group of nautical data used for planning, realization and monitoring of vessel navigation in time and space. Therefore PNT data plays an important role for the early detection of incident risks and for the avoidance of collisions and grounding. In consequence, a reliable provision of PNT data should be ensured, which meets performance requirements varying in dependence on traffic area, nautical tasks and successive applications. User needs such as “resilient PNT data provision”, “improvement of reliability”, and “indication of reliability” are causes to continue the development and enhancement of the maritime PNT system. However till today whether achieved level nor target level of reliability of the maritime PNT system are specified in an unambiguous manner using technical performance parameter (e.g. accuracy, integrity, continuity, and availability). Harmonized technical requirements are necessary prerequisites for the identification of technical gaps within the current PNT system and a target-orientated improvement.
The generally admitted processing chain for PNT data provision is composed by Global navigation Satellite Systems (GNSS), PNT relevant terrestrial services as well as ship-side sensors (see Fig. 2).
A consolidated architecture is necessary to match the classic solution up to multi-system, multi-service, and multi-sensor based approaches on current and future performance requirements. For this purpose a modular and extendable architecture design should be aimed to support a scalable liability of instrumentation as well as a fast roll-out process of modernized components. Furthermore the architecture describes the framework, within the fusion of data coming from different sources can be realized to meet overarching requirements on provision of PNT data and related reliability information.
A consolidated architecture allows that data products and data interfaces can be specified in a next step. Experimental trials in sufficient maritime test bed should be realized to verify the capability of PNT technique under application conditions and to decide at least about its usability within the maritime PNT system.
During ship’s voyage the performance requirement on PNT data provision varies as well as the availability of PNT data sources usable for this purpose. In consequence, an overarching PNT system concept is necessary, which manages the PNT system by implemented monitoring and control functionalities in such a manner that the best PNT data set can be provided taking into account the current usable PNT data sources.
Resilience is a requirement especially applied on safety-critical data and systems. Resilience describes the ability of such systems to identify internal and external disturbances and to compensate resulting adverse effects. That means that a loss of functionalities or a decrease of product performance can be avoided in case of typical disturbances and malfunctions (see Fig. 3). Only an aim-orientated extension of the maritime PNT system (data sources: sensors, services) creates the needed redundancy within the data base, which enables a resilient PNT data provision by enhanced techniques. A consequence is a system redesign covering architecture, data interfaces, and functionalities.
Finally, consolidated versions of the maritime PNT system and recognized components should be described by performance standards or guidelines, which are provided by International Maritime Organization (IMO) and supporting associations. In addition, training measures should be offered to the nautical staff to create the necessary familiarity in use of new techniques, services and facilities.
A scope of our research and development activities focuses on resilient provision of PNT data in the maritime traffic system. Results of our work
With a PNT data provision as needed in all phases of ship’s voyage we contribute to a comprehensive and reliable situation observation, which helps to continue the risk reduction of collisions and groundings.