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Remote control with an XBee and a Propeller

If you’ve been playing with electronics for long enough, eventually you’ll need a nice remote control transmitter to control your RC car, airplane, or any other robotics project you have lying around. With these robotics projects comes the problem remote control, and the XBee Handheld Controller may be just the ticket to remotely control any project that comes off your workbench.

This isn’t the first remote controller we’ve seen that does just about everything, but it is the first one to include an XBee wireless transceiver to easily interface to your robotics project. The controller comes in two models, the Q4, which uses four Playstation-like joysticks, and the Q2, which uses proper remote control gimbal joysticks. Both the controllers have a slew of buttons, toggle switches, four rotary pots and a 2×20 LCD display.

After the break you can check out [Paul]‘s pitch explaining what these controllers can do and showing off a hexapod robot under the control of his Q4 controller. A very neat project, and we can’t wait to see this controller out in the field.

Comments

  1. wardy says:

    Looks like they’ve put a lot of thought into this design. I’m a big fan of the Propeller / XBee platform, those two products go together very well. My current project is vaguely similar to this and in fact this would interface with my build quite nicely I think.

    This controller looks quite amenable to being modified to add a good deal of project-specific extra functionality.

    Good luck with this project guys, it’s neat.

  2. my2c says:

    Sweet! – These look very nice! – I’ve gutted rc controllers and swapped in atmel/xbee radio interfaces before for similar purposes, this would be much easier / nicer…

  3. SpydaMonky says:

    Omg that is the most beautiful TX I have ever seen!

  4. Shadowmite says:

    It’s nice, and I strongly considered buying funding and buying one. However $200!? It doesn’t even include the xbee or assembly! For 50 in parts and a nice case essentially.

  5. martinmunk says:

    I’m really not impressed with the responsiveness of this :(

  6. rud says:

    it looks like there is quite some lag ? or is it just me ?

    • Haku says:

      Not just you, I looked at the video frame by frame when he was showing the Q4 with the test board, when he flipped the two switches at the top of the Q4 it was 8 frames before the test board responded, with the video running at 29.97fps that translates into 267ms (over 1/4 second) delay.

      I would hope that’s just a software issue which can/will be fixed, because that’s an extraordinary amount of lag for a something which is designed to control things in realtime.

    • exHomunculus says:

      The Xbees have a “sleep” setting to conserve power. They will sleep for a set amount of time before waking up to see if any anything is being transmitted to them.

      So the lag is usually on the receiving Xbee. The transmitting Xbee will send its data as soon as you tell it to.

      It’s not really a software issue in terms of propeller code, but how you setup the receiving Xbee.

      Basically, you can have it never sleep to reduce lag to a minimum. Depending on the Xbee module you are using, you may have to adjust your power requirements. There are some that are 1W IIRC.

  7. Paul says:

    In original demo video the test station had a form interpolation running the servos.

    We have posted a new video on our Youtube Channel. The new video shows the test station with the interpolation disabled. Instead of smoothing/ramping the movement of the servo from it’s current position to its next the servos go exactly to it’s next position. There is a small delay for the reaction of the LED’s on the servo test fixture. Due to them being shifted thru a four 74HC595 shift register. All the led’s are controlled thru 3 pins on the test station.

    Each channel takes ~0.87ms to transmit from the controller. In the video we used 6Ch’s so the whole transmission takes ~5.17ms at 57.6kBd. All 32Ch’s take 28.23ms to transmit.

    Servo’s being used are http://www.servodatabase.com/servo/hitec/hs-475hb
    There running at 6V at .18s /60 degrees. Upgrading to faster servos like a http://servocity.com/html/hs-5565mh_servo.html would increase the response time as well.

    @Haku: We recorded the video in 720 60P

    Paul
    Quantum Robotics

  8. Paul says:

    Here’s the link to the new video.

  9. Haku says:

    @Paul, your 720p videos when downloaded from YouTube come in as 29.97fps mp4 videos.

    I took a look at the 2nd video and the lag seems even worse, the servos are only changing position ever 1/2 second – completely inadequate for a lot of RC cars/planes/bots.

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