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

lignes062.gif (8656 octets)

In-vehicle navigation:

fleche_verte_d.gif (689 octets) Sensors:

puce1.gif (88 octets) Anschutz gyrocompass, standard 20, 110-222 type
puce1.gif (88 octets) RDI doppler log, 300 kHz,
puce1.gif (88 octets) The distancemeter for all acoustic data acquisition of distances to beacons and digital filtering.

fleche_verte_d.gif (689 octets) 3 modes of navigation:

Three softwares are used to obtain the navigation curves:

puce1.gif (88 octets) Long baseline navigation in bottom-track mode using the distancemeter data regardless of the log data
puce1.gif (88 octets) Dead reckoning navigation using the gyrocompass data and the log and heading data ; it requires regular manual adjustment
puce1.gif (88 octets) Hybrid navigation using all the available sensor data

navigation fond.jpg (33212 octets)
© Ifremer

fleche_verte_d.gif (689 octets) 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.

lignes062.gif (1070 octets)

Surface navigation:

fleche_verte_d.gif (689 octets) Surface calculator: Poséidon

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

puce1.gif (88 octets) Calibrate the beacons area: beacons absolute positioning,
puce1.gif (88 octets) Position the ship, the Nautile and an elevator in the beacons area,
puce1.gif (88 octets) 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.