PID Controlled Ball Balancing Stewart Platform

Motivation and Overall Concept:

As a physicist in training, I am naturally


Teacher Notes

Teachers! Did you use this instructable in your classroom?

Step 1: Get Materials

Materials Needed:


2. 6 - Servo Motors (We used HS5485HB Servo’s)

3. 6 - Threaded (Adjustable) Connecting Rods


5. 12 - Heim Joint Rod Ends

6. 6 - Rods (Adjustable)


Step 2: Prepare Materials



Step 3: Assemble Materials


Step 4: Programming


Step 5: Testing!


Step 6: Fine Tune and Enjoy!


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    13 Discussions


    Question 4 months ago

    Hello there. First of all this is a really beneficial project. You really helped us to learn many things about control, coding and mechanics. Both of you have done a great job and that is very generous of you to share your project in such an educational way.

    My question to you is that between the lines 275 and 281 which consists of the code above;

    xPrime = 0.2134*yAvg + 39.725;
    xOffset = xPrime - xMin;
    xAvg = xAvg - xOffset;

    And than you basically did the same thing for Y-axis. Could you please tell me why you did these operations? Thank you for considering your time.


    5 months ago

    Actually you used a PD controller because the parameter ki is equal to zero. Right?


    6 months ago

    where did you by the touc screen, i could not find the appropriate one online.
    please provide me with a link to purchase it.
    Best regards.


    Question 11 months ago on Step 3

    Where is the spec? Step 3 says to "Carefully assemble the materials to spec", but I don't see any spec.


    12 months ago

    where is the design?


    1 year ago on Step 1

    What servo motor can be used to substitute for HS-5485HB?


    Question 1 year ago

    How is this height determined, can it be lower?

    1 answer

    Reply 1 year ago

    The height was a bit tall. This was the case only because the adjustable threaded rods came in this length. They can very easily be cut to what ever length you would like. I chose to leave them long because that allowed an approximation for the movement to be more valid. I think you could very easily trim a 3 to 5 inches off without too much trouble. Good luck


    Question 1 year ago

    thank you so much for your quick response. bellow is a picture of the pin config for the wii controller. i was wondering if i could use them as an analog input to the system instead if the touch screen.


    Question 1 year ago

    Hello there Mustaf and Adolfo, firstly I would like to thank you for posting this DIY, it has ban really helpful. I tried to create a similar mechanism for some of my students but acquiring the resistive touch screen has been difficult (I'm currently in a very remote area in Africa) so decided to adapt it to a 4 wire Nintendo Wii Nunchuck as analog input. I would really appreciate if you could assist me, i seem to have problems adapting the code to the Nintendo. i look frward to your reply!!! thnak you

    1 answer

    Answer 1 year ago


    Unfortunately I don't know how the output of a Nintendo wii is coded. I would try to look that up online if I were you, or if you have access to some sort of an oscilloscope, you could characterize it yourself. There is a YouTube video of one that was linked to a wii controller I believe, maybe look it up and ask that person. I wish you the best of luck.