Control of 6 DOF Stewart platform

It could always be bolted to the ground. I have access to large machinery and if I wanted to build one in the future I would have the tools to do so. Anyways I dont want to build a full sized model. I just wanted to build a miniature one.

Its very hard to make such motion systems efficient cause they are based on pyramid method. Each motion axis element that encapsule a minor motion axis element must be twice as large as the previous stage to be able to support the encapsuled motion element weight as well its motion path structure. For example Yaw axis motor must be larger, to be able to support both Bank and Pitch motors structure. Now imagine that a heave axis motor must be HUGE, to be able to support the weight of all bank, pitch and yaw motors and their structures. No matter how balanced you keep a motion platform, you will alway face this problem.

Here is an example in numbers:

Bank motor load = 10kg
Pitch motor load = 20kg
Yaw motor load = 60kg
Heave motor load = 180kg

I intentionally limited the possible axis to 4, cause after this number of axis, you will need to make the platform also portable on a X-Y sliding table to be able to also have the lateral and longitude motion and there lies a more serious problem than motor size. You need to have a POWER CABLE following the simulators on its travel! :lol:

Not wondering why this guy has nothing more but the idea so far. If he ever tried to build even a minor axis model he would faced the problems earlier: http://morsim.net/


On the opposite a 6DOF Stewart platform has six identical motor/drive systems that share the weight and the required structure is far less complicate in the end! :thbup:

Regards, Thanos

I completely agree with you that the standard system is mechanically simpler and more efficient.I just want to know whether the software planmix is working on could work with such a motion system. If it could, I would like to experiment with this for just the sake of experimentation. Whether its better or worse does not matter to me, I just want to try it.

You can define as much axis as you want, as long as they are independant from each other. If you want to use dependent axis like a stewart platform for example, you have to make a movement algorithm for it by yourself. Yet, there is no algortighm for dependant axis implemented in X-Sim. But we appreciate contribuitions ;D

regards

...do you mean that the platform would not have to be designed as a hexipod top motion platform and could really be designed in any way that would provide you 6DOF?...

Yes Lazyman, it could. The cueing algorithm calculates the position and the rotation of our body in every step of the program (0.05sec), in such a way so to feel what pilot feels. If we use stewart platform for the motion, then we feed those data to the kinematic model of the stewart platform to drive the motion.
If we use another design, for example: a platform like Thanos's (pitch,roll) on a fast lift (heave) and all these on a wheels (surge,sway,yaw), then we feed the output data to the kinematic model of the new design and tune the parameters of the algorithms with the new distances and velocities for each axis of our new design.

Thank you for your response planmix. I really appreciate it.

The new version of the software:

Limiting Settings


Cueing/Washout Settings

Any more news on the progress of your project?

I look foward to when it is available for purchase. 8)

I'm looking forward to built the big scale platform and sit on it and calibrate the software with me on the platform at last

I designed a new low cost actuator (1m drive distance, 70cm/sec speed and load 100Kgr).
I'm going to built it as soon as I can and test it.

Hi John, THANKS for your explaining, they are so clear.. Any news in your project? Sorry but I have no more nails to bite!! Don´t forget of us, at least tell us if you did something new..
Regards,
Carlos.

Hi planmix,

Fascinating stuff. I currently have a 2 DOF platform prototype, but have decided to go for a 6 DOF platrform using powered steering boxes.

is this control software available as a x-sim2 plugin, or are you keeping it private currently?

I have a copy of Matlab along with simulink. If you need anyone to test the setup with the latest version of matlab, just let me know.

Many thanks

TJ

hi! Could you show the original data in the picture? Thank you.

Hi...
I'm a Newbie to the 6Dof model...
I'm planning to implement a 6DOF Model using stewart platform
I have managed to read the data from software simulator model using MATLAB.
I would be really glad if any one one of you could suggest some method or a procedure from which i can get a clear idea of how to convert the orientation to Lengths of the the Linear Actuators...

Thanks in Advance

And Advance New year wishes..

- I have access to the hydraulic components..., now in stock I have 6 cylinders, size 850mm (closed) plus + 630mm (stroke) I flashed a crazy little idea to make Stewart platform, theoretically make such a platform is not difficult, 2-steel constructions, the 6-cylinder, 12- active joint located 120 degrees relative to each other.
- the fact is that I do not use AutoCAD or Matlab, if someone who use this programs, can help calculate the optimal location points for this size of hydraulic cylinders, I will be very grateful
Thank you.