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Water Linked losing IMU calibration on boat

Hi,

we are using Water Linked underwater GPS with BlueRov on our boat and have a problem with IMU calibration.

Our boat setup is best visible in this topic:

We connect topside to ethernet, power supply and 4 recivers, with U1 locator mounted on BlueRov.
We get good GPS signal on topside, and calibrate IMU according to the WL manual, until GUI shows the green icon representing IMU calibration is good. When we put our topside unit on its place on the boat, in matter of 1-2 minutes IMU calibration goes from green to yellow, meaning “fair calibration”. Result of this IMU fair calibration is innacurate possition of our BlueRov in sea…

When IMU calibration drops from good to fair, local coordinate system (Y,X) rotates in global coordinate system, thus showing inncorrect ROV location.

We tried several restarts of the system and tried moving topside on different locations on the boat, to ensure there is no magnetic interference. Recivers are well bellow hull and at different depths.

Also, IMU can be recalibrated on the boat, with figure 8 movement, but works ok again for a minute, unitl IMU calibration drops to fair (yellow).

What can we do to keep IMU calibrated, since we can not use it like this??

Thank you in advance,
Mateo

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Hi Mateo!
Waterlinked IMU is a problem to calibrate, it keeps drifting.
https://waterlinked.com/forums/topic/questions-on-waterlinked-utilisation-on-a-boat/

Only way for us is to use external heading (and positioning)
One solution is: Mounting Waterlink on a moving boat

Integration via python, or WL solution: https://waterlinked.com/forums/topic/water-linked-underwater-gps-nmea-bridge/
Bo

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