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Old Mar 31, 2015, 11:55 AM
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Getting enough channels?

In my post about minimal builds, I said I don't like to build. That's not quite true. I just don't like to build with what goes into models. I like to build with code and if I can't help it solder. Designing a part in a CAD system and 3d printing it is fun. Building it out of wood, or foam, or whatever is work. For that matter, building a CAD system is fun . Tweaking my Tx's to add channels, protocols and features is fun. Building kits and fixing aircraft is work.

So last night, I started thinking about what I'd do if I had a ship that I could do those kind of things to. Say built version of the SC&H Surprise. The first thing I noticed was: not enough channels! The most advanced RC Tx I know of - the FrSky Taranis - has 32 channels. While that's a lot for an aircraft, it seems sort of limited when I was thinking about individually controlling each gun and sail on full-rigged ship.

The DYI electronics and robotics people have systems that are designed to control hundreds or even thousands of servos individually. Getting the electronics into a model would be easier than getting the servos in, but I'm not sure about power. I did a forum search for the names of the companies that produce some of the devices as well as the names of some of the mcu's I'd use, and it turned up nothing. Well, except someone wanting to know how to spell out a raspberry.

So are there some RC systems I've overlooked that can control that number of devices? Or are people just using a few dozen channels for everything? In the latter case, is the number of available channels not a problem, or would some of you be interested in a system where the number of servos (or similar) devices was essentially unlimited?
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Old Mar 31, 2015, 05:55 PM
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I have my Byzantium running off of 4 channels, one for the rudder, one for the main sail, one for the squares and the last one controls the jibs as well as the fore sail. It would be nice to have working guns but it is not necessary for a good model. For sail control keep in mind that all the fore and aft sails forward the center of lateral Resistance can be slaved to one servo the same applies for the sails aft of the clr this also applies to the square sails but they should be rigged to separate servos than the fore and aft sails.
And yes I would be interested in unlimited channels for a future model that I have planned but that's still one and a half models (several years) away.



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Old Mar 31, 2015, 08:11 PM
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Quote:
Originally Posted by qwerty_2008 View Post
And yes I would be interested in unlimited channels for a future model that I have planned but that's still one and a half models (several years) away.
The basic idea is to approach things like you're building a floating robot instead of an RC boat.

Start with a single board computer like a Raspberry Pi for the main control system. There are some other alternatives that are smaller or more powerful if needed, but the R Pi is popular and inexpensive. People are using them as flight control boards for quadcopters, so it should be more than adequate for anything a ship would want to do.

To actually control things, you'd use some kind of servo controller. I like these because you can get them with between 6 and 24 servo connections, and can control up to 128 of them with a single serial line. Instead of having to run a servo line from the Rx to every servo, you can run one line that each one of these connects to. They are called "USB Servo Controllers" because they have a USB port, but you don't have to use except for configuration. That's not required, as they come out of the box configured for most servos, but you can fine tune things if you need to, or want to control something that's not a servo. As a bonus, they also have a scripting language on board, so you can write scripts for choreographed actions and then trigger them with a single command. For instance, if you wanted a broadside that fired with a bit of stagger so it looked more realistic than all of them going off at once, you might put all the guns on one side on one servo controller, and write a script for that.

The last bit that goes in the ship is some kind of RF module attached to the SBC. My inclination is to use a wifi dongle. Those have been used to control a number of commercial drones, but may have range problems. If that happens, you'll want something like an NRF24L01. The Wifi is a lot simpler, especially for your control box.

Of course, you are going to have to give up your RC transmitter - getting enough controls in your hands is sort of the point. If you're not interested in doing that but would like to take advantage of having an SBC or even just those servo controllers on your ship, that's also possible. However, that's all a topic for another post. And to me, that's the fun part, because I like to build things that are made with code
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Old Apr 01, 2015, 12:19 AM
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That's sorta along the lines of what I was thinking but I lack the necessary knowledge to even be begin trying to figure things out. As I mentioned before this project is years off and technology will almost certainly have changed (if I base the system around the raspberry pie now would it still be the best/easiest route 3 years down the road) by then. Also I am still not sure how I will rig everything, I was originally thinking that servos each on their own channel would be good for the recoil on the cannons but recently have been thinking about solenoids slaved to the firing system (a device similar to a car distributor) would work better, this is just an example of some of the changes that I might have a major effect on the control system.





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Old Apr 01, 2015, 08:48 AM
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What were you thinking about doing for control on your end? The wifi interface would let you use a smart phone or tablet. If you really wanted sticks as well, you could then use a bluetooth controller, or maybe a deviated Tx acting as a HID device. Going with a custom module would probably be easiest with a pi-based tablet.
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Old Apr 01, 2015, 11:53 AM
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I was thinking about using a tablet with a custom controller attached via USB. The controller would be somewhere along the lines of an overgrown playstation controller with with several knobs below the analogs and flip open covers over the triggers. Now I pretty sure that it can be done and though I can occasionally repair electronics I don't actually know much about how to make them.




PS. I cant actually draw very good either but the image down below does (hopefully) convey the idea in my head.

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Old Apr 01, 2015, 04:31 PM
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Hmm. Well, deviationTx actually has support to output to USB Hid. Using one of the Tx's it runs on (the Devo 7E can be had for $60 or so) and one of those things the FPV guys use to attach tablets to the top of a Tx would work for that.

I am biased, since I'm one of the people hacking on deviationTx these days.
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Old Apr 02, 2015, 08:01 AM
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You really ought to take this to the Homebrew Hacks for Model Boats section where it can found more easily by folks looking for this sort of thing - you might find there's folks not involved with "scale sail" that are involved in what you're talking about.
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