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Topic: Optimal actuator to move an analog stick (Read 1 time) previous topic - next topic

lollinopil

Sorry for the delay, Vince. Very busy at work :(

My task is that joystick and 3 buttons. I am in a good shape with the 3 buttons, but the joystick is way more hard to control.

vinceherman

Now the delay was on my part.  :)  Just got back from vacation.

I did order some of the sparkfun thumb joysticks.  When they get here, I will print up a clip and see if I can arrange the servos and write a simple script to move the joystick.

I might even see if I can work some PID logic in to it.

Kaliber84

Might be a bit late already. But have you thought about using a servo and cord? The idea is similar to what a drive belt does. But instead of continuous rotation it's able to transmit force along one axis. Right now I can't post a hand-drawn sketch but tried to make do with the chat (see below).
The servo pulls the cord attached to it when turning. The cord pulled transmits the momentum/force along it's path which is why it needs to be redirected with 2 wheels so that it can be lead to the analog stick. The cord should prove to be easily attachable to the analog stick with a simple knot.

The drawback of this is, that while you need few single parts, you will need to attach the wheels to something. If you can solve this then it is easy to implement this 2 times for 2-axis movement and if the servo is a digital one you can accurately control the control stick. Using an additional gearbox for a servo will greatly improve the accuracy. In the end it all comes down to whether you can create static points for your wheels and servo that won't move in relation to the joystick.

 
  __X__
O____O
     T


X - servo wheel
T - analog stick
O - wheel
__ - cord


A simpler but also more inaccurate solution similar to this would be 2 servos placed to the sides of the joystick. Each servo pushes/pulls a stick that is attached to the servo as well as the joystick. The sticks work as a connection in the shape of a parallelogram.
If the radius of your servo is equal to the radius of the joystick then you're even able to directly transmit the servo angle to the joystick angle 1:1.

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