Not 3DOF but now 2DOF Motion Rig - Planing/Prototyping

Hi folks.

As some might have mentioed I'm lurking around the forum for a week or two now. Not without a reason.
After building two non-moving rigs I thought it would be time to go a step further and go for a 3DOF racing-rig.

My plan is to move the whole cockpit part of the rig, which includes the seat, wheel and pedals.
I don't like those 2DOF builds where the distance to the wheel reduces while breaking ... :thbd:

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Update 2011-01-23:
Well well, after some responses to my 3DOF sketches I think I need to trust the old guys here. More power isn't a real option currently, so I reduced the planned rig and start with a 2DOF-seatmover. It's easier to realize and an upgrade to 3DOF is still possible at a later time. :highfive:

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• Hardware, Shops and URLs

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electronic parts

• FEZ Panda Microcontroller board - ~35€
• 12V 30A power supply - ~50€
• Pololu Dual VNH2SP30 - ~50€
• 2 x VW Passat wiper motors - 15€/each

construction parts

• no details yet

Sources & Sketches

• Sketchup v0.1

Prototype - WIP


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Re: 3DOF Motion Rig - Planing/Prototyping

Hi,

braking effect can be very easely adjusted to your liking and can even be setted to null ... So don't base your design choice on that ... :thbd:

The idea is to fool your brain by creating muscles tension on your arms, legs, shoulder... to simulate G-forces... And it's works pretty damn well!

Good luck with your build,



Regards


Bleco

Re: 3DOF Motion Rig - Planing/Prototyping

I thought that braking effect would be simulated by moving the chair down with the front and so use gravitation to get some g-force on your body. Wondering if I can get enough angle for that though ... :?

Re: 3DOF Motion Rig - Planing/Prototyping

Why don't you like 2DOF seatmovers? Have you even tried one before? Have you tried one with a good profile?

A 3DOF platform like in your plan requires a lot more engineering, and a lot more money. 360W of power is not going to move a sim like that + a driver anywhere.

I would reconsider those plans. You have to size up the power, or size down the platform.

Re: 3DOF Motion Rig - Planing/Prototyping

You won't get any kind of muscle tension or gravitation effect with your design ... and also no gravitation effect with a seat mover, just pure brutal racing feeling ... :yes:


Bleco

Re: 3DOF Motion Rig - Planing/Prototyping

Nope, haven't used anything, neither 3DOF or 2DOF seatmovers.

Rotating the platform around a stabilized center point with being able to have some movement up/down was the main idea and I thought/hoped the power would be sufficient to do that. As well as the effects resulting of that.
I should possibly first finish the painting before publishing here. :?

Re: 3DOF Motion Rig - Planing/Prototyping

I hope our posts haven't dampened your spirits, but the above posters are on the money:

1. - If you move the wheel and pedals too, you need to move quite a distance to get anything near the sensation of a seat mover.
2. - If your stuck on this design anyway, Frakk is correct that you're going to need more power
3. - Rotation from a center point feels good for flight, but is very unrealistic for racing IMHO.

Just some things to consider while you're still in the design phase.

Re: 3DOF Motion Rig that might become a 2DOF

Well, the responses made me rethink what I had in mind and how it would be possible to achive those ideas. Started to sketch a 2DOF solution.
I think I will give that a try and see how it works out.

Thanks for the opinions, thats why i posted my plans here.

Re: 3DOF Motion Rig - Planing/Prototyping

That is a wise decision. I rather see you succeed with a simple 2DOF seatmover project than get stuck and give up on a 3DOF sim after you invested tons of time and money.

Re: 3DOF Motion Rig - Planing/Prototyping

We'll see if i succeed. A lot of coding and testing needs to be done with the ARM-based hardware. Though the possibilities the FEZ microcontrollers bring with them got me to use them.
Maybe tronic opens up some of his code for me to get a peak into it. 8)

What kind of (cardan-)joints are you guys using underneath the seat?
Is there something simple to get from ebay?

Bye, buk

Do you have experience programming the FEZ, or other types of controllers? You can always fall back on other controllers if you can't get it working.

There have been tons of posts about u-joints on the forum. Search for universal joint or u-joint
Ebay is full of them too, search for the same.

My prototype is working with an Arduino fed with 3 joystick axles via USO from Xsim controlling three servos.
I haven't got my hands on a FEZ but am familiar with .NET/C# which is the reason I ordered the FEZ Panda. Besides that I'm curious about those things and don't need to finish the project in a few weeks.

Will search for the joints, thanks.

Question:
Does a front bal joint like that has enough angle to be mounted underneath the seat?
http://cgi.ebay.de/FRONT-BALL-JOINT-LAN ... 1c13e46f67

Hello Buk, the seat of my simulator is mounted on a front ball joint (recycled from an old renault), works perfect!!! :yippiee:
Some photos (Sorry about the quality)




Regards

Hey!

How much angle can you achive with such a joint? I'm unsure if it is enough to move the seat with it. :

Bye, buk


Update: External brain (aka dad) told me that the angles are sufficient, so I'll go with that solution. Thanks guys. :clap:

With a ball joint you have to take care of the rotation with 2 extra rods as you can see in the picture.

A universal joint solves this problem without any additional parts. It will be easier to build and probably cheaper in the end.

Re: 3DOF Motion Rig - Planing/Prototyping

I have not ridden neither a 2DoF nor a 3DoF - a passenger car though.
From calculation of the accelerations I would expect in an average car easily 0.5 - 1 g through curves or when braking. With the 150 mm stroke of a typical SCN5 I estimate one can only achieve 0.2 g approx by tilting the seat and thereby using the gravitational field to simulate acceleration.
The acceleration of the SCN5 (during 0.4 sec of a full stroke) for me sounds more like quickly shaking the seat.

From what you say it sounds like shaking the seat results in a fairly satisfactory experience and game immersion. Have you ridden a 3DoF? Would you say that the >0.5 g one can simulate with such a device isn’t making the difference?

That's exactly the background of my questions. I have not found an affordable way of implementing a 3DoF including heave - won't give up though yet