iXBlue GAPS - 7.2 Coupling Principle

GAPS - User Guide
7.2 Coupling Principle
The coupling with an INS (+DVL) is the optimal solution for positioning a deep water vehicle.
GAPS locates itself in a field of fix transponders and is bidirectionally coupled with an INS.
The physical link can be made via an umbilical, with an acoustic communication system
(modem for example) or with a MTB transponder (see section 7.4). The two devices exchange
their own navigation and transponders positioning. They correct themselves respectively. The
distances to the transponders provided by GAPS feed the Kalman filter of the INSpreventing
the drift of the inertial navigation. The provided navigation is therefore very precise and drift
free even with the use of a single transponder or depending of the trajectory of the vehicle
among some sparse transponders (sparse array application, i.e. pipeline tracking).
Figure 63 - Coupling GAPS and an INS
In this section, is detailed how to connect GAPS to the INS in order for GAPS to provide to the
INS the needed absolute positioning. GAPS must be configured to output data to the INS and
the INSmust be configured to input data coming from GAPS. The protocols that must be used
are the following:
● GAPS STANDARD: this protocol has several drawbacks :
> ASCII format (not optimal in term of bandwidth in an umbilical or acoustic modem)
> Many telegrams are not used by the INS
> Standard deviation is estimated in INS
> Positions are time stamped so it is mandatory that PHINS and GAPS receives ZDA
● IXSEA USBL INS 1:
> Binary (optimal in term of bandwidth in an umbilical or acoustic modem)
> Positions are time stamped so it is mandatory that the INSand GAPS receives ZDA
> Standard deviation is estimated by USBL
● POSIDONIA 6000:
> Binary (optimal in term of bandwidth in the umbilical or acoustic modem)
MU-GAPS-AN-005-H - November 2019 129