Keywords : navigation

Navigation

The Nautile uses 2 different systems permanently operational: in-vehicle navigation and surface navigation.

In-vehicle navigation

Sensors :

  • Anschutz gyrocompass, standard 20, 110-222 type
  • RDI doppler log, 300 kHz,
  • The distancemeter for all acoustic data acquisition of distances to beacons and digital filtering.

3 modes of navigation :

Three softwares are used to obtain the navigation curves:

  • Long baseline navigation in bottom-track mode using the distancemeter data regardless of the log data
  • Dead reckoning navigation using the gyrocompass data and the log and heading data ; it requires regular manual adjustment
  • Hybrid navigation using all the available sensor data

Performance for in-vehicle navigation:

Long base navigations in hybrid or bottom-track mode are reliable,

Navigation in bottom-track mode can be checked immediately after diving due to the high user-friendliness of navigation tools and VEMO+ software (navigation route graphic design)

A ± 2-m accuracy was calculated on an area spotted between 3 beacons without acoustic masking. This precision is not related to immersion.

Surface navigation:

Surface calculator: Poséidon

The calculator software is translated in a current language. It is used to:

  • Calibrate the beacons area: beacons absolute positioning,
  • Position the ship, the Nautile and an elevator in the beacons area,
  • Supply the surface navigation results and configuration parameters on Ethernet.

The scientific station provides real-time monitoring of the long baseline surface navigation on the VEMO+ screen,

The user-friendly Man Machine Interface makes it simpler to implement the system,

The long baseline system accuracy is related to immersion and so less reliable than navigation in bottom-track mode. However it is used redundantly for navigation results.