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TwitchFinger robot build notes

Arduino Robotics
TwitchFinger robot build notes

I’m converting a Twitchie kit into a finger-controlled robot arm. I built a little servo breakout on some perfboard, and added pin headers to plug a flex sensor into it, making a voltage divider circuit for the Arduino. This means the angle of the servos changes (rapidly!) as you bend the sensor. I’ll be attaching the sensor to the finger of a glove.

Running low on time (I’m building this for a demo on G4TV’s Attack of the Show) I bought some PC fan connector cables for a buck each, rather than solder together my own. They have the same pin spacing (and color even) as the servo cables and the Arduino pin headers, so they are a perfect plug-and-play extender. I sheathed the wires in braided sleeves, mostly for looks.

I used nylon screws and nuts to attach my breakout board to the Arduino, and put it all in an aluminum project box, along with a battery pack and on/off switch. I’ll need to throw some more weight in there (lead sinkers?) to prevent it from tipping.



It’s a lot of fun to play with; the control is pretty responsive, and whipping the snake-like arm around is very entertaining. I may leave it at that, but if anyone can think of something more to do with it I’d love to hear it. Rob Bullington, from the Maker Shed, suggested it throw a flaming tennis ball! They’d allow that on set, right?

In the Maker Shed:

Twitchie is available at the Maker Shed, and you can find out more at Teuthis.

4 thoughts on “TwitchFinger robot build notes

  1. jqpubliq says:

    I like the fan cable idea. I’ve bought some cheap servo extension cables and repurposed them to the same end. Pin pitch is the same, and the cables are cheap and easy to find.

  2. John Park says:

    jqpubliq, cheap and easy is good. I have to fight the urge to build every little last thing myself — got to value my limited time more than that!

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John Edgar Park likes to make things and tell people about it. He builds project for Adafruit Industries. You can find him at and twitter/IG @johnedgarpark

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