6 DOF Stewart platform prototype

[StephenB]

Hello,

We are two 17-year old students from Belgium. We've designed and built a small-scale Stewart platform and created custom software for our final project. With this type of construction it is possible to achieve full 6 DOF. Here is a render of the platform and a photo:




The servo arms are mounted on the servo like this:



The acrylic pieces were all sawn, and sanded afterwards. It would've been better if we could laser-cut them, but that wasn't possible.

The platform is controlled by our software which can do all the mathematics to position the motors. Our program then sends the results using a serial over USB connection to an Arduino Mega 1280, which in turn positions the servo motors using its built-in Servo functions. The motors are powered by an external modified ATX PSU. The program can control the platform manually by modifying the 6 DOF parameters, but it can also be used as a small simulator. This is were X-Sim comes in. Using X-Sim, we can send the 6 extracted parameters from multiple games over a UDP connection to our program. These 6 parameters are then used in our calculations. We've also added a 3D simulation so we can check if our programmed calculations are working correctly.




We've used cheap servos that cost us only 10 € each. They have a torque of 10,2 kg/cm at 5V. They can move up to 180°.
They have three pins: vcc, ground and signal. The signals are connected straight to the PWM pins of the Arduino, so their position can be controlled. The vcc and ground pins are connected to the PSU. The ground of the Arduino, servos and PSU must also be connected together. We made a small board so we can plug in the servo connectors directly and plug the board upside-down into the Arduino:




Here's a video of the project:



We were able to accomplish the whole project for as little as 100 €. Only when the program was completely finished, we started designing the platform.
X-Sim has been working very well for this project. But for our presentation at the end of June, we would like to be able to demonstrate it, but we will not be able to have an internet connection. So, we are hoping to receive a stage 2 key so we can run X-Sim offline

Please comment what you think! Thanks!
Thanks to Full Motion Dynamics (http://fullmotiondynamics.com/), the platform design was inspired by their prototype.

[prodigy]

FullMotionDynamics, those are the guys from Kickstarter right?

I think that for Stage 2 Key you will need to write more details about your project.. What motors did you use, controllers, how to set them up, etc..

But I got to say, I like the compact style of this 6DOF simulator and it has good moves, just some tweaking needed.

[StephenB]

Yes, indeed. But we couldn't afford to build a real simulator like them They did a great job with their design!

I'll put some more details in my post. I must say that the movements are much better than I expected from these cheap motors. They are very smooth and the platform can move pretty quickly. Probably because it doesn't need to carry much load. The platform even reacts to small vibrations on rough terrain

[aapje06]

You've done a nice job!!!

[futuresims]

Hi,
The guys at FullMotionDynamics really did a superb job.

Here this may help fine tune your work.

Ardruino_6DOF_Motion_Platform_LoRes.pdf

Ardruino_6DOF_Motion_platform_pdf

(360.15 KiB) Downloaded 3012 times

Platform Laser Cutting File

Platform.rar

Platform_Laser_Cutting_File

(21.34 KiB) Downloaded 1744 times

Base Bottom Laser Cutting File

Base_bottom.rar

Base_bottom_laser_cutting_file

(18 KiB) Downloaded 1453 times

Base Top Laser Cutting File

Base_top.rar

Base_top_laser_cutting_file

(24.02 KiB) Downloaded 1502 times

Also the Code is in the PDF File.

I am doing my best to support the X-Sim3 community.

Thanks.

[tronicgr]

I never understood, why there is a need to stress a microcontroller perform all these math (for stewart platform) while there are the computers that fit for this job

Thanos

[StephenB]

Thank you for the document, but we had already seen this as a tutorial on instructables.com But it was deleted.
That's where our platform design was based on, such as the mounting of the motors and easy cable management. But we never wanted to "copy" their system, we did not use their code, our Arduino only receives data and outputs them. As tronicgr said, the computer does all the hard work
Next to the basic movement calculations it also has (partially finished) movement limitation calculations. Our program can also work with linear actuators, so it can do much more than an Arduino program.

[futuresims]

Hi StephenB,
I have extremely limited knowledge of the electronics as well as extremely limited knowledge of the software and no knowledge of programming or coding.

I even have a lot of trouble installing software and then trying to figure out how to set it up and even more problems trying to run it.

I don't remember where I found the files.

I do know that having the tutorial for this setup is nice and quite educational for anyone else who would like to build this unit or a similar system from which to learn from as you have done.

I do understand your approach to this system and in my opinion you are well on your way to producing a really nice simulator system yourself.

At least you are honest in saying that you in fact have seen this setup and that it was this setup that has inspired you.

99.99% of the simmers have been inspired in one way or another by someone elses work.

We are all looking forward to see your progress.

Thanks.

[Tyrion]

Hi,

I have quite a strange arduino/servos problem and I would like to ask you for help.

Thing is that when I try to select generic 2DOF profile (for lets say LFS) in extractor it wont let me do that saying that "profile could not be loaded because it is not compatible with my simulator type".

I have two servos connected to model chair through Arduino Mega.

Could you please make a short "To do" list for arduino and servos including Xsim extractor and Xsim motion converter setup.

Thank you!

Matej

[xa4123]

Hey StephenB,

I'm also from Belgium (Ghent).
Are you planning to build a real simulator like FullMotionDynamics ?
If so, I'd really like to hear about it and maybe test it one day.

xa4