I have quite a few zigbee modules of various powers. I've used them for serial communication of environmental data and found them perfect for that. I am looking to do some sort of UAVS but I am loath to spend hundreds of Euro on a decent radio system when I have the zigbee modules.

I wonder has anyone built a full RC system for an aircraft using zigbee for comms. Components of the system would be
airborne zigbee, arduino, servos
ground zigbee, computer , software, joystick, mouse or keyboard for controller

The advantage is that no RC radio or receiver would be required, saving cost and weight, while extending range but of course the disadvantage is potential unreliability.

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It plugs into a Digi Xtend rather than an XBee, but it does have an 8 channel Pololu-compatible serial servo controller built-in. And a few other bits and pieces that might come in handy, such as a 2 amp switching power supply. You can disable the timeout completely and just use it as a telemetry platform.

You can send it serial garbage all day long and it wont crash.

http://www.millswoodeng.com.au/failsafe_device.html

Scroll to the bottom of the web page - there's a block diagram.

Andrew.
Sounds like you're planning something similar to what I'm currently researching. My plan was to get the InputShield that's available for Arduino, and build it into a ground station of some sort. The InputShield has a nice little Playstation-style thumbstick, so with a little coding it could easily be used to fly a plane, provided you don't want to do anything too fancy. I'm still trying to work out how I'd code it all to run on an Arduino or two; I'm kinda new to Arduinos in general and I haven't quite figured out where how much they're capable of. I can think of a few more powerful systems that would be able to handle it, but I don't really want to have to buy even more kit, especially seeing how expensive some of those other systems are... Do you think an Arduino (or two; one airborne and one groundside) would be enough to handle manual control, autopilot command uplink, telemetry, photo and video downlink? Would one XBee have the bandwidth, or would it need two?
I've been trying to implement my own RC system using a couple of arduinos and some APC220-43 RF units. The actual modules themselves are pretty easy to use, but they are just too high latency for RC stuff - a quick test showed 120ms for 8 bytes, ~130ms for 16byte packet, 180ms for 32byte. So now I'm going to look into XBees as those results seem a lot more promising!
Hey any way your drone design could.maybe possably go into a hover or short range glide mode while awaiting for the latency to catch up.or your not designed to hover like copter??
Joe, do you have any more info on your XBEE serial to pololu servo controller setup? I'm trying to do something very similar. Do you have a null modem adapter between the two?
How do you plan on getting video back on a single line? XBee's can't handle that kind of bandwidth...Video can be 2+ mbps and an xbee is only 15kbps!
Hi Jeffery,

Generally I think some sort of graceful recovery from a comms failure (either permanent of intermittent) should be built into every UAV flightplan. Either a return to base and loiter or in the case of 'copter craft , a hover and descend mode. That said, If you think you are going to have significant latency, then an alternative coms method should be used. The idea of using zigbee was to save having to buy the radio hardware (and I bet that digital comms is the way forward anayway) . By using a zigbee for the comms, an onboard micro is needed in the UAV , so loads of different failure modes are possible.

In my development, the biggest latency was between the UI and the serial code, not the actual transmission stuff. But that was because I was trying to abstract the UI from the comms method and that didn't work for RT control.
Diarmuid
yeah i got you completly now. thats was one thing i was considering also to completly cut out original rc transmitter/reciever . and just have a set of paired xbees or like devices to do complete control from my pc if needed. but as you mentioned the issues with falures that would come up are to many to think about..and i apologize for my random question im still new to all the electronics behind the autopilot..but i do agree your control layout should be further experimented with . good luck testing

Hi,

I build the BreezeUAV project without radio system and now that the project become good enough to fly, I regret it.

Firstable XBee are great, but sometime the communication is lost and my failsafe capability is not good enough.

Secondly, it's always better to have two links of communication and be able to switch from one of them automatically.

In my project, I don't control the plane directly. A joystick is used to define the pitch roll yaw and speed, those data are send to the UAV which try to achieve that attitude and speed goals.

I'm updating data from ground station to UAV at 30 Hz, while telemetry from UAV to GS is download at 1 Hz. Using a radio, I'll be able to increase the telemetry data rate.

It feels good to build cheap system, but when they crash ... Safety is always better :)

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