EthOS Tips and Tricks

[Nathan]

Nathan, great posts, have you come up with or seen how to use the Flsky XR18 pitch control? I also want to figure out how to program for the Planes to offset each other to stop sub listing in turns, any idea about that? Thanks Nathan

Biggsgolf, I haven't used stability control on a sub yet, others have and might chime in.

Regarding roll control, assuming you have each plane on an independent servo, you can mix the roll into the rudder mix. And if you add in some throttle mixing.... Bob and I have discussed this sort of mix but I haven't been able to experiment. I'll spend some time on it this week and see if I can get something posted this weekend.

Nathan

[biggsgolf]

Biggsgolf, I haven't used stability control on a sub yet, others have and might chime in.

Regarding roll control, assuming you have each plane on an independent servo, you can mix the roll into the rudder mix. And if you add in some throttle mixing.... Bob and I have discussed this sort of mix but I haven't been able to experiment. I'll spend some time on it this week and see if I can get something posted this weekend.

Nathan

Thanks Nathan!

[Nathan]

Mixing Planes with Rudder to Reduce Pitch/Roll (For roll you must have the ability to control each side of the dive planes independently. The differences needed for pitch-only are included as well, towards the bottom.)

This one is a little more complicated and I don't have a boat that I can fully test this on. The exact weights and directions will have to be left up to you. I'll highlight areas where those changes can be made, but the specifics will be up to your individual boat and preferences. I suggest you make sure your output limits are set to prevent any damage from over travel and use the full values in my pictures. This will show you an exaggerated version of the changes. That will help you set up the directions of the inputs and otherwise make the secret sauce less secret.

Okay, here we go:

Set up a curve to use for mixing in the throttle. This curve is set up to only start working when the boat is moving forward. If you don't have reverse, or want the throttle's impact to start at a higher throttle then modify this curve. Most likely you won't want it to go to 100% unless you have a really large and slow moving boat. There is nothing fancy in this curve otherwise so I am not showing the config page. Do note that the curve starts at 0, not -100 - this is because 0 should be no throttle and negative is reverse. Sorry, I am not going to document how to make this work while travelling backwards!



Set up a logic switch to only activate in more extreme rudder movements. I am thinking that tiny movements of the rudder will not cause significant rolling so this logical switch sets up where in the rudder stick travel to turn on the anti-rolling function. The value (x) percentage is setpoint. The absolute value function ensures it works on both sides of the rudder input.



Create an output for our throttle mixing. This output is what links the speed of the model to the amount of correction. The "control' of this amount is through the Curve. This is just a necessary intermediary because of the way EthOS works. Make SURE you use a channel that does not have anything plugged into it. EthOS doesn't care if you use a channel above the count on your receiver. This channel NEEDS to be greater than the number of channels on your receiver. I chose 5, but you could use 10 or even 64. Just use a channel that is not physically connected to your model. The mix we will create will make this channel function.



Add the Throttle Mix. This mix ties the throttle stick (or pot, or whatever you use) to our fake output (Channel 5 for me, maybe 10 or something for you - again, a channel you are not already using. Don't break your model)




Make sure you apply the Curve and set the channel. The source is the same as you use for your throttle.

And, finally, make the anti-roll mix. This is the mix that moves the planes according to the amount of rudder and throttle. it isn't complicated once you get this far. There is a trick in the Actions, though, you have to "long press" to get the ability to choose the channel.


Here is the Action screen with a highlight for where to long press. When you do so, a screen will popup and offer a selection of "Use a source". Choose that and then select Channels and your Channel

Okay, the rest of the mix:

Note that I chose BOTH of the planes. Here is place where you might need to reverse one to get the direction of travel you need.


For pitch-only control

Use this curve instead:



And add it to the Throttle mix


That was even easier that I thought it would be!



From here you will just need to play around.

I am planning on bringing my test rig to Subfest (2024 Redux) if you'd like to try it out in person.

Nathan

[biggsgolf]

Nathan, this is much appreciated!

[NicholasRadzykewycz]

Working on a project where I'd like to send audio from a pair of microphones thru the FRSky antenna and was wondering if anyone had done that before or how to set it up in EthOS. Might have to be a custom function to write but I could save an entire large and bulky second signal antenna in my sub and reduce interference if it is possible to send audio via the FRsky

[He Who Shall Not Be Named]

Working on a project where I'd like to send audio from a pair of microphones thru the FRSky antenna and was wondering if anyone had done that before or how to set it up in EthOS. Might have to be a custom function to write but I could save an entire large and bulky second signal antenna in my sub and reduce interference if it is possible to send audio via the FRsky

You want real-time passive sonar from your model submarine. No problem.

I did that back in the day with a little FM transmitter mounted within the forward bulkhead of my 1/96 SKIPJACK's WTC.



Self noise was a problem, so I would sit on the bottom -- no aboard motor or servo noise getting in the way -- and listen. Only useful dope I got from the radio head-phones was kind-of-sound, amplitude, and doppler. No bearing or range, of course. But I could tell, without looking at the water, who was sniffing and how close they were.

You talked about two microphones/hydrophones. You're looking for relative bearing, right? The brain is not quick enough to tell the time differential in water, so you'll need an H-type detector to present bearing to you through a display. However you'll make out the amplitude differential by feeding one channel into one ear, and the second channel into the other -- that should be enough for you to skull out a rough relative bearing in real time.

My little effort was accomplished in the late 80's. With that gear no one snuck up on me!

David
High School Dropout

[NicholasRadzykewycz]

[QUOTE=He Who Shall Not Be Named;n189879]

You want real-time passive sonar from your model submarine. No problem.

Yes, I'm using a pair of Glady's hydrophones positioned at roughly 22 inches apart, so there will be enough lateral distance to get some better angle bearing with the increased speed of sound in water. Boat is being designed from the ground up for silent running, so special ESCs, Motors and Servos all ultra quiet as well as rubber cushion on every mounting bolt for further isolation.

Already have a working 900 Mhz transmitter for audio which seems to work decently. It is however very bulky and takes up a significant amount of hull room. I was mostly just noticing the port on the FRSky for headphones and the fact it played audio made me wonder if EthOS could save me a bunch of trouble of an independent transmitter and allow for audio on a single antenna system.

Boat will also be equipped with an active sonar as well in the form of a Deeper Pro castable fishfinder with a modified extended antenna. This will only work on the surface and at periscope depth

Underwater navigation to be achieved with a compass module for the FRsky.

I plan on running the sound eventually to an analyzer software on shore for more precise sound localization


The purpose of this sub is for wargaming, but more importantly the sound function will help a lot with submerged navigation, since I can visually look at the boats on the water and figure out where I roughly am at by listening to the other boats. This also allows for using things like fountains or any other fixed underwater noise source as a nav beacon so that I can puzzle out my location if I lose track of my boat underwater without having to surface and reveal where I am at.

[Nathan]

The microphone on the transmitter is designed for outputting sound files from the transmitter. I have no idea if there is a way to get audio through the telemetry signal. You'll need to call FrSky to figure that out. But I am very doubtful.

I hope you can get it working though!

Nathan