Discussions

Custom building or re-building RC transmitter gear

Posted by anaximander on August 23, 2010 at 2:26pm
A thought that occurred to me recently: is it possible to use the spare parts that a lot of RC shops sell, or maybe a semi-dismantled RC transmitter handset, to make your own transmitter? As in, build something from an Arduino/BeagleBoard/Gumstix/custom PCB/whatever and then connect it to the transmitting part of the RC handset, at any level - either some handset that will accept some kind of data input and send it for you, or right down on the raw electronics end, soldering bits together.

Basically, I'd like to get some computer assistance into the loop, using telemetry data to allow the system to act like fly-by-wire software, tweaking and moderating the control inputs to stop the pilot from departing from a safe flight envelope. If done right, it should make the aircraft controllable with just one two-axis thumbstick, trading separate controls for all the surfaces for basic up-down/left-right and a throttle slider. I was just wondering if it would be at all possible to build this into the actual handset (ignoring for a moment the issue of how the telemetry data would get to said handset) so that I could use the tried and tested transmission method, rather than having to fight past the latency and patchy signal issues of something like an XBee.

If not, then hey, back to the drawing board I guess. This is still early concept stages, so no great loss.

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Replies

  • Developer
    Jason Short August 24, 2010 at 4:03pm
    Why not generate PPM like a buddybox? Pipe that into a transmitter and you're good. Micheal's right. Everything else should/ is in the plane already.
  • James Turner August 24, 2010 at 3:46pm
    Looks like a great project. You might be as well to build in a standard transmitter and receiver into your diagram just in case. It's fine manually controlling the autopilot until the autopilot/ground control/Xbee (or whatever) locks up and then you have problems. I'm doing a similar project but using a GCS and there have been many times during testing when I've needed to fall back to the more "traditional" ways within seconds. you also need to be very comfortable flying your plane manually too in case you have to rescue it from a glitch. better still, have a spotter with the backup rc.
  • anaximander August 24, 2010 at 3:13pm
    Well, the diagram of the entire project plan is here, but I get the impression that's not entirely what you meant. I'm working on a diagram of dataflow, ie following the system through, starting by explaining what each sensor is reading, then seeing what's reading from the sensors, what the software does with the data it's reading, what it sends signals out to in response and what those signals make the components do. I'll post that when I've finished it, but it's pretty big - as you can see, the planned system has a lot of stuff. That's the dream, the ultimate UAV system. It's possible that I'll never actually build all of it, and parts of it might not even be achievable, but I aim to build as much of it as I can. I haven't even got my EasyStar flying autonomously yet (or flying much at all, actually) but I'm already working on designs for an airframe to carry it all...
  • Developer
    Michael Smith August 24, 2010 at 12:57pm
    Why would you want to place your anti-crash system at the mercy of your telemetry, when you could put it in the model itself?
  • Marco Glattfelder August 24, 2010 at 12:57am
    In many legislation you will need to have a "standard" rc gear that controls the plane. There are no real rules, and I guess not even a real control on that but in the case someone "official" checks your uav and/or rc he will dislike to see some wires going out to a self made box instead of a classic rc tx/rx. The reason is that you need a tested "best practice" equipment beside any uav or self made system. And that is good, because uav technology is far to be reliable as it should.
    If you have a standard rc system that can take over in case of emergency you can surely build your custom system. The best option is to use the trainer port of the rc handset itself, mostly accepting so called PPM signals. These can be modulated by an arduino board. One example of many: http://www.ianjohnston.com/content/index.php?option=com_content&amp... but there are some other projects following that path. Doing it this way allows you to use the rc gear in case the self-made solution won't work.
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