Rangefinder over the ocean and PX4LOW as backup

ArduCopter Copter 4.0
1

hi all i have two questions:
I’m in need of flying my hexa above water. and i need it to maintaine altitude (5m) as accurate as possible. and i need to figure out some protection agains GPS blocks/Failures. is it possible to connect a PX4FLOW as backup for navigation if GPS fails? and set somekind of parameter to make the drone fall back to it?

  1. is it possible to use the SF20 rangefinder above a water source? or the reflectivness of the water will make the sensor go crazy?

  2. is it possible to use optical flow as backup? i mean only if i experiance GPS jams and it becomes unrelaiable, is it possible to make the quad fall back to the PX4FLOW and get it out of failsafe?

TIA

2

I think booth sensors PX4 and laser rangefinders doesn’t work over the water. You should think about blending GPS option or GPS RTK.

3

I think the best range finder above water is to use radar . But I personally don’t have experience using radar.

4

Hi, lightware have some additional configuration for the lidar. I simply can’t remember in which thread it was.
However what’s important is that it’s possible.
Sorry I can’t remember more.

5

we have a couple Lightware LW20 units…they are hit and miss over water. I would say 70% of the time they give an accurate distance, but the other 30% they produce 100 m value. We are plainning on trying one of the US-D1 Altimeters or the NRA24…