6DOF Joystick

by i-make-robots Apr 23, 2013
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making a joystick from this means solving the forward kinematics which is very hard to do. However! If you can pull it off then I want to read your code. make your life simple, get 4-wire servos from adafruit and then you don't have to hack anything.

Which servos are you using? Are you using any different ones on the master platform?

The servos are all the same. I modified the master servos to act as sensors only. If you want off the shelf solution, try 4-wire servos: http://www.adafruit.com/products/1450

Awesome, thanks for the link. Do you know if those servos can be easily back-driven, or would I have to disconnect the motor/gears inside of them to use as a plain sensor?

EDIT: Just looked at the video on that page, looks like their servos are backdrivable but are a little tight. Maybe I can detect if a servo starts accelerating and help slightly push it along until the user stops accelerating... hmm (I haven't looked at your master code yet so I don't know if you're doing anything like that with your servos).

I'm building one right now for my engineering class and I've got everything down except the wiring. Could you help with that? Or post a clearer picture of the wiring job you did here? Thanks!

All the reds go to 5v. All the blacks go to GND. All the left servos have been modified to be just potentiometers, and they go to analog pins 0-5. The right are normal potentiometers and they go to digital pins with PWM. Then it's a 1:1. You could also record the values to an SD card and play it later, or send them over the web... that parts kinda boring for me, so I didn't bother.
There are also 4-wire servos (adafruit?) that will let you record and playback on the same servo.

When you get it working, tweet a pic to @MarginallyC so I can share it on my blog.

To get it to work on Windows as a joystick why not use a Teensy? I'm currently working on a joystick platform for KSP that uses a plugin and a Teensy to look like a gamepad/joystick.

Could do. Board is not a big issue; software is. The math for Stewart Platform forward kinematics is h-a-r-d.

Nice, maybe good for 3d printer platform too, if servos could be more accurate ;)

yes. Like the Rostock, but with more options.