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Picture of Arduino controlled Rotary Stewart Platform

This instructable is about building a Rotary Stewart Platform. It allows to position its moving platform in six degrees of freedom. This specific platform is designed to be able to position a DSLR or any other digital camera.

This version of Stewart Platform uses instead of linear actuators just ordinary hobbyist servos for motion. Whole platform is controlled by an Arduino Uno, it computes all necessary equations to get the platform into right position and also controls servos.

Video of movement of completed platform can be seen here. Quality is not very good, but camera with better picture was at the time of capture on the platform. It was set-up for random position every 4 seconds.

Some informations about platform:

  • weight of load can be up to 2Kg (platform tested with 1.5Kg with no observable problems during moves in whole range of movements), theoretically platform should be able to cope with even higher loads, but it wasn't tested with such load
  • low power consumption - with load of 1kg was consumption of around 5W.
  • very good fineness of moves - smallest possible move is around 1mm
  • perfect ability to repeatedly achieve the same positions.
  • good stability of platform even with big loads.

All source files for platform (templates, Arduino source code, code for communication library can be found here.

Price of platform mostly depends on the price of servos and of the Arduino board. Cutting of parts, all other needed parts cost at most 50$. Total price can be around 150$.

IrDA and LCD with I2C interface were bought from ebay, they are very cheap (together around 10$)

Parts of platform are cutted from acrylic, i used 4mm acrylic.

Needed tools:

  • drill
  • screwdriver
  • tools needed for soldering and creation of PCB for connecting external power supply
  • measuring tools
  • double sided tape

In case of any questions, feel free to contact me.

 
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rmboy8627 days ago

Hi Mate, great work! :-)

One question how do I download the dxf filed from git hub? It wont let me :-(

felix.ros.71 month ago

Hi Thomas,

I'm an Industrial design student form the Netherlands and building my own stewart platform. I'm stuck at the proportions of the platform. Could you clarify how to determine the size of the base, top and legs?

I would like the top to be small enough to fit in my hand. The image shows the platform I have now, unfortunatly it runs into mechanical erros...

Cheers

Felix

IMG_2367.JPG
ThomasKNR (author)  felix.ros.71 month ago
Hi, unfortunately i cant help you very much - there is really no specific ratio. But i don't see any big problem (only that the angle of legs is at limit of ball joints), but during movement there can be some other problems, the upper platforms is way smaller than bottom platform. Have you considered inverse positioning of servos? I mean rotate them by 180°. Like this... http://www.instructables.com/id/My-Stewart-Platform-aka-the-other-kind-of-hexapod/
I think otherwise you will have to make upper platform bigger.

Thank you for your fast response!

I kinda figured it out. There is a relation between the size of the top and bottom platform as well for the length of the legs. The more the platform looks like two triangles on top of each other the better the stability, the length of the legs do determine the degree of movement. Mine seem to be too long and the platform gets tangled up because the joints can't keep up with the rotations (like you said).

I'm going to make a new one that sticks to the triangular shape, similar to your setup.

Thanks

JyB22 months ago

Hi Thomas,

First, congratulations for your work.

I was looking at your DXFs files and was wondering what should be the actual length of the servo_arms, as it shows 175 mm (6,88 inch.), which seems far too much in comparison with the plates?

JYB

ThomasKNR (author)  JyB21 month ago

That is definitely some kind of error. In program i used (QCad) it is 2cm from the middle of servo axis to the leg joint.

pallogarciiaa3 months ago

hi Thomas, i'm from Brazil.

I have a doubt about the servos:

Can I use servos with lower torque?

ThomasKNR (author)  pallogarciiaa3 months ago
hi, that depends on weight of load, with these servos the platform was strong and could handle the load for extended periods of time (hours). Therefore you can definitely use weaker servos if you won't put a lot of weight on it, also with shorter arms power of servos will be bigger.
radames ajna10 months ago

hi Thomas, where did you get the mathematics? I'm trying to use your code but would like to see the mathematics behind it, do you have any article that you can share ? thanks

craftclarity11 months ago

This is cool, I'd love to see a video of it in action...!

ThomasKNR (author)  craftclarity11 months ago

I added link for a video of platform in moves in the text, i don't have the platform right now because it's in my university, if i will get it once more, i will do better video and most probably i will expand this instructable.

me too! :)