It’s Octagonal!

It's Octagonal!

Apparently, I didn’t have enough challenges, so now I have a cold. Great. Anyway, it’s driving me to bed a lot earlier than usual (it’s midnight now, and I’m up with the kids at about 6) and maybe I’ll pop some nyquil on the way. So, tonight, I cut the corners off of the table. This allows for a greater range of motion when two axis are active (i.e. towards the CORNERS). I also turned up the power and speed a bit and sat on the platform for a ride. Finally I moved the pitch heim joint to a new location to help accommodate the further range of motion. Success!

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First full test

Finished the software and ran it for the first time. I need to adjust the text file that contains the pitch and roll (and time) data for a better experience, and I need to increase the throw a little. In order to do that, I need to trim the corners, but it looks good!

Enough wiring for one night

Just about done.  Those .1″ sockets aren’t really suited to permanent wiring.  Still need to wire up:

  • Output to fan control
  • Output to motor control
  • Rewire on/off switch (my wire is too short)

Should make for quick work tomorrow night.  Then I can move on to either making the cart seat or programming!

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Fan control

What’s the point of flying down a steep drop off in a roller coaster if you can’t feel the wind in your face?  Here’s how I’m taking care of that.  Solid state relay controlled by the bullduino to run a fan on command.  I’ve got one of those squirrel-cage carpet drying fans, I think that’s what I’ll use.

BTW- be careful if you use this mounting method.  It isn’t exactly up to code.

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Servo feedback

I mentioned below that I made a giant high torque servo (160 in-lb) but I didn’t explain the feedback loop at all.  You need to know your position, so I hose-clamped a bracket onto my motor and drilled  a hole for a standard 5k linear pot.  put + and – on the ends, and the wiper gives you a voltage that corresponds to position.  When I finish tuning the pid, I’ll post the arduino (bullduino) code to make this work.  Note there are 2 servos present on the device, which makes it a little tricky, as you’ll have to switch A/D converters and give it a little dwell time between reads.  Here’s a picture of my linkage between the motor and the pot.  Note the masking tape component.  If this thing flails out of control during development, I don’t want anything damaged besides the sacrificial tape.

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