Autopilot - Open Source

[rgleason]

Eval Board for mini radar $680 Analog Devices Inc. EV-RADAR-MMIC2 wow.

[Moo]

Originally Posted by rgleason

Collision Avoidance - waves not cars.
https://www.digikey.com/en/articles/...iving-vehicles

See reccommended miniature radars at the bottom.

Or point your 4G down more. 2 radars?

Radars have a minimum range, nothing to do with geometry but all to do with timing.

It is pretty short in the 4G devices, down to 200' (60m) and may be sufficient in some cases but not in rough, confused seas. - From Lowrance data.

Raymarine claims a minimum range of 6m for its CHIRP technology Quantum radar - I will be playing with a couple of these in the next couple of months and will make sure to check minimum range.

[rgleason]

Good point

pretty short in the 4G devices, down to 200' (60m) and may be sufficient in some cases but not in rough, confused seas

Too bad those auto parking, mini radars aren't fewer bucks!

[barnakiel]

Originally Posted by rgleason

Good point


Too bad those auto parking, mini radars aren't fewer bucks!

These are only few yards range.

b.

[barnakiel]

Originally Posted by rgleason

barnakiel, I was on that site. Frightened by the cost of some of that, but the
Sweep V1 360° Laser Scanner might work, but it would have to be on a gimbal up fairly high, maybe 8-9 feet?
Could you mount just one of them on the backstay to get decent reflections from oncoming waves?

Sean, see the mesh that Lasstools creates from LAS. Would it take too much HP to do that in real time?

Working over 360 degrees, this one has a lot of 'waste'. I also do not like that it rotates. Rotating sensors are more difficult to waterproof.

It would be nicer to build a sweep sensor but one that uses a fixed sensor mixed with a sweeping source. A fixed source could be even better but something is telling me a laser beam cannot be flattened with optics.

You will see on the same website they seem to offer the sensor as a stand alone. I can imagine this one could be cannibalised to build a proto.

b.

[rgleason]

What range radar would work to pick up the closest one or two big waves? 15-20 yards?

Originally Posted by barnakiel

These are only few yards range.

b.

[rgleason]

Here is a radar, 100 meters range, 40msec processing, 3mWatt or less transmission, snow and weather.
https://www.google.com/url?sa=t&rct=...2ToTcsC_fkkmb8


Build it. We had a neighbor who built them. Build a Small Radar System Course

[Moo]

Originally Posted by rgleason

What range radar would work to pick up the closest one or two big waves? 15-20 yards?

Too short, but it depends. If in a mature swell they could be a couple of hundred metres apart so you would want to be able to look out to 1/4 NM I reckon. This may require the use of a couple of different technologies to cover different ranges.

[champ8242]

You can forget LiDAR. It wil not penetrate water and you wont get returns.
I can show you a project I few with LiDAR over the pier of Scheveningen.
3dgisviewer.eu, first project.
You can see water on the sides but mostly some water patches on the pier that doesn't give returns of the surface. btw, the point cloud is clororized. This pretty picture you wont get from just LiDAR

[Moo]

Originally Posted by champ8242

You can forget LiDAR. It wil not penetrate water and you wont get returns.
I can show you a project I few with LiDAR over the pier of Scheveningen.
3dgisviewer.eu, first project.
You can see water on the sides but mostly some water patches on the pier that doesn't give returns of the surface. btw, the point cloud is clororized. This pretty picture you wont get from just LiDAR

I don't see your logic, apart from the part about maybe not getting returns; which was my point earlier.

LIDAR does penetrate water and is being used in survey for just that. Google LIDAR bathymetry or bathymetric LIDAR and you'll get dozens of hits explaining it.

The fact that it can penetrate water is what makes it useful for vision in misty, rainy environments. Makes it less useful for detecting waves though.

[barnakiel]

Originally Posted by champ8242

You can forget LiDAR. It wil not penetrate water and you wont get returns.(...)

Bingo.

b.

[barnakiel]

Originally Posted by rgleason

What range radar would work to pick up the closest one or two big waves? 15-20 yards?

I would have to look up sources but I think instrument range of 200 meters/yards would cover most but very long swell from a remote source. I have only ever sen super long super regular waves once, in the Indian Ocean. All other waves seemed shorter and faster.

Do you think at say 20 yards there would be too little time left for the core to take another look and calculate the speed?

My gut feeling is that in open water a wave 20 yards away is already picking you up.

I could possibly set up our tablet to register the waves on our next crossing.

?

b.

[champ8242]

Originally Posted by Moo

I don't see your logic, apart from the part about maybe not getting returns; which was my point earlier.

LIDAR does penetrate water and is being used in survey for just that. Google LIDAR bathymetry or bathymetric LIDAR and you'll get dozens of hits explaining it.

The fact that it can penetrate water is what makes it useful for vision in misty, rainy environments. Makes it less useful for detecting waves though.

Bathymetric liDAR systems are far more complex than topographic. Green instead of red laser, they scan slow to get the power they need and the processing is much more complex. This adds up to systems that cost a lot to run. On top of that, water clarity is a huge issue. If your signal is not strong enough you can’t see it. You can use a lot of time and money sitting on the ground waiting for clearer water. This makes bathymetric LiDAR expensive relative to topographic LiDAR.

[rgleason]

"It will not penetrate water and you will not get returns"
It looks to me like the LIDAR is working the way we would like it to. In your excellent example of the Pier of Scheveningen (upper left) which is nicely available in 3D controls we can see where the LIDAR is bouncing off the water. It think it will work for our purposes (We are not interested int the "bottom" (ground under the water)!! And I think there are enough "returns" to be useful.

Thank you for this example.

Originally Posted by champ8242

You can forget LiDAR. It wil not penetrate water and you wont get returns.
I can show you a project I few with LiDAR over the pier of Scheveningen.
3dgisviewer.eu, first project.
You can see water on the sides but mostly some water patches on the pier that doesn't give returns of the surface. btw, the point cloud is clororized. This pretty picture you wont get from just LiDAR

[champ8242]

Originally Posted by rgleason

"...Thank you for this example.

You want to by the sensor? € 89,000.00 but has less than 2cm accuracy!