Navigation Aiding Method and Apparatus

A method for enhanced navigation of a marine platform (100) over a seafloor (200), comprising:

• performing micronavigation displacement measurements and associated coordinate frame calculations by using at least one one-sided or two-sided sonar comprising at least one transducer (20a, 20b) comprising at least one transmitter (21) configured to transmit pings and at least two parallel receiver arrays (22a, 22b) each arranged roughly parallel to a travel direction of the marine platform (100), the receiver arrays (22a, 22b) being configured to register echo of pings reflected from the seafloor (200), wherein the micronavigation displacement measurements are performed along the primary axes of two different coordinate systems in the form of a receiver array (22a, 22b) frame and a patch frame, the patch frame being located at an acoustic center of mass for an instance of seafloor illumination;
• calculating a three-dimensional orientation of the receiver array (22a, 22b) frame relative to the patch frame;
• and
• calculating accuracies for all micronavigation displacement measurements and associated coordinate frame calculations, wherein
• the micronavigation displacement measurements are processed in an estimator observation model, modelling the relationship between position, orientation, and velocity of navigation states of the marine platform (100) and the micronavigation displacement measurements, coordinate frames and accuracies, and the output of the estimator observation model is used to correct navigation data for the marine platform (100).

An apparatus (10) for providing enhanced navigation of a marine platform (100) over a seafloor (200), comprising

• at least one one-sided or two-sided sonar with at least one transmitter (21) configured to transmit pings and at least two parallel receiver arrays (22a, 22b) each arranged roughly parallel to a travel direction of the marine platform (100), the receiver arrays (22a, 22b) being configured to register echo of pings reflected from the seafloor (200), the sonar being configured to perform micronavigation displacement measurements and associated coordinate frame calculations;
• and
• a navigation processor (40) provided with means or software for calculating three-dimensional orientation of the receiver array (22a, 22b) frame relative to the patch frame and calculating accuracies for all micronavigation displacement measurements and associated coordinate frame calculations, the navigation processor (40) further comprising an estimator observation model configured to process the micronavigation displacement measurements, modelling the relationship between position, orientation, and velocity of navigation states of the marine platform (100) and the micronavigation displacement measurements, coordinate frames and accuracies, wherein
• the output of the estimator observation model is used for correction of navigation data for the marine platform (100), and
• the apparatus (10) is configured to perform the micronavigation displacement measurements along the primary axes of two different coordinate systems in the form of a receiver array (22a, 22b) frame and patch frame, the patch frame being located at the acoustic center of mass for an instance of seafloor illumination.