Saturday, 14 June 2014

My Servo has now arrived.

posted 24 Dec 2010 15:52 by David Taylor

It's been a busy week now that I think of it:
My Servo, some nuts and bolts and spare gears for my servo arrived yesterday (See the updated Parts List). I'm only seen normal servo's before. These Micro Servos really are tiny. I'm amazed that this little thing is rated to 1.1kg of torque.

Anyway, I created a scale model of my servo and imported this into my TriRot model and noticed that I would have to make a little more space available than initially anticipated, but that's all sorted out now as well. Luckily I only need about 3 more millimetres on each side to protect the ESC's (Electronic Speed Controllers).

The next issue I noticed was that the hex nuts I ordered (You can't by these from a hardware store longer than 30mm - I need about 35mm ;-) only have thread on about 2 thirds of their length. I sorted this out by using some rubber fish-tank pipe (which seems to be just stiff enough) as a spacer. I'm hoping that this also provides some vibration dampening from the motors during flight. (I've noticed a couple of guys building tricopters and quadcopters that this seems to be a problem for the accelerometers and gyros.)

I've also been researching how to get some telemetry back from TriRot and monitor this once I try to liftoff for the first time.
This is a screen shot of the telemetry screen I've built so far for TriRot. I've wanted to get my head around Microsoft WPF and XAML for a while now, and this gave me the perfect opportunity and excuse to do just that. I've built the screen above from scratch. Graphics where done in Paint.Net and each guage consists of a Background, The needle and a Glass cover. I then animate the needle graphic. Once this is final I will replace the sliders (used for testing) with output from TriRot via USB initially. (GHIElectronics have a USB CDC driver that I can use with my FEZ Mini 1.3 board) I'm still debating whether I should use something like an Xbee or one of the 2.4GHz telemetry systems you can get with the radio control. Some of them seem to have a PC interface cable and the documentation mentions a user customizable serial port to send things like GPS data.
To this I will be adding graphs to show output from the Gyro's and Acc's per channel.

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