A new guy with new project and silly old questions

[Aloupol]

Hello all..

I'm from Liège, in Belgium, and I'm in the process of building a 3 dof dynamic simulator.
My project involves a Arduino board, DC wiper motors, Mosfet current drivers, and of course x-sim.
At the moment I've been trying to send infos through the USB port to the Arduino and turn it into servo instructions and... It works.

But at this stage my data are only keyboard events, through the RS232
monitor. The next step is to use x-sim and configure it to deliver game acceleration data to the USB.
When I'll be able to make servos move according to the game (ie rFactor) it will be a giant leap for me, although a little step for mankind...

I've tried, following the tutorial section, to configure the extractor and converter to make move the virtual simulator.
But with no success so far. Need to try again.

I hope to find here some good informations, to push my project forward.
Kind regards.
Daniel

[ferslash]

man, maybe i did not understand what you are doing... but...

i think that what you are trying to do, has all ready been done, try this links

http://www.x-sim.de/forum/viewtopic.php?t=723

it is an step by step guide for arduino, xsim and wiper motors.

if it si not what you are looking for, or if it is jus obvious that you have been seen this, sorry in advance

i hope it helps

best regards

fer

[Aloupol]

Tanks à lot. This link is one of the useful ones I had found.
At the moment I'm trying to sort the computer/firewall/x-sim parameters problem that makes the thing not work, I don't retrieve any value on the com port.

[motiondave]

using wipers for a 3dof?
Unless they are BIG wiper motors, id be surprised if you get any lift whatsoever..
Unless of course the 3rd dof is a drift and the existing frame is 2 dof with pivot.

Do you have a diagram of your build?

[ferslash]

sorry i still dont understand what your problems are...

shut the specific questions... the guys around this forum are grate and has a lot of experince...

dont be affraid about asking "where do i start"

best regards
keep building

fer

[Aloupol]

Thanks a lot for the replies, and useful links.
I didn't know what USO is (and in first, Google told me it was United States Oil fund.......) now I've got some point to start.
At this stage I'm not sure of the type of motors I will use but all the electromechanical issues won't stop me when I will be there with the computer things. It's the part that's scares me...
Shortly, I plan to reuse some material I've got. Some old DC motors of all sizes, an Arduino Mega and a power MOSFET shield featuring 3 H-bridges and ok for 30A (ok say 10A continuous and 30A peak).
This is why I think I've to go the single computer route, because the Arduino will manage the axis change and the PID regulation with no need of a second computer.
Now I've got to read, not that easy for the French speaking I am.
Apologize for my poor English....

[motiondave]

If you use the pololu JRK 12v12, they run fine off one pc.
They are controller/ hbridge in one. One per motor, one usb per board, 7 wires, NO CODE TO WRITE.
and they run 14v at 30 amps continuous.

[Aloupol]

Hi everybody.
Thanks a lot for all the interest and support. I'm not able to manage all the information in one single bite but I'll be back on it in a few days.
I'm studying all the links in your replies and as suggested, I will give more details about my project.
It's not really a motion platform but a kind of force feedback helmet. To provide some feedback of the acceleration, I had the idea of applying (moderate) forces directly on my helmet. It seems a bit silly but I'm convicted it's not.
In addition to the feeling that, when driving a real car, you feel the accelerations (actually the mass forces) with all the body but especially with the neck, because the head is the only part of the body that is not firmly strapped to the car, I've got some clues telling me it's an interesting way to test.
Firstly, a few years ago, a guy on Racesim Central followed me and tested the thing with sandows connected to the wheel and pedals through cables and pulleys (!!) and told me that, even with that archaic setup, it was incredibly immersive.
I also found an old (1980) patent from a company who produces simulators for Lockheed Martin (the F-16 warbird builder) describing more or less this kind of system.
And in addition, I read a quote of one of the former McLaren test drivers (Pedro De La Rosa, modulo my poor memory) when they started to use their state-of-the-art simulator, who said something like "they even found the way to apply mass forces on some parts of the body, to make you feel you are there".
This is why I want to go that way. Probably it's a bit too complicated as a first experience and I think I will firstly build a 2 DOF rig with all the know-how available in here.
Regards..
Daniel

[RufusDufus]

... It's not really a motion platform but a kind of force feedback helmet. To provide some feedback of the acceleration, I had the idea of applying (moderate) forces directly on my helmet. It seems a bit silly but I'm convicted it's not.
In addition to the feeling that, when driving a real car, you feel the accelerations (actually the mass forces) with all the body but especially with the neck, because the head is the only part of the body that is not firmly strapped to the car, I've got some clues telling me it's an interesting way to test....

Hi Daniel, I have also been experimenting with such an idea - nothing working yet, however I believe the idea is sound. From my point of view the important thing is that your head must still be able to move against the forces applied. Have you ever noticed while driving you tilt your head into the corner to balance the forces. If you can't move your head against the force I think it will be unnatural. So the ideal solution ends up being something like the force feedback in the steering wheel.

The reason I think it is a good idea is that the mass of the helmet while driving is subject to considerable forces that are transferred to the neck. I remember back when I used to ride a motorbike and had an inexperienced pillian on the back, you where almost guaranteed they would whack their helmet into yours the first few times you hit the brakes.

My current thoughts are to use some sort of HANS type setup to mount it all on so it is not fixed to the simulator and not constrained to one drivers height or build. I am hoping to be able to use standard servo motors used for models but not sure yet if they will provide sufficient forces. Just ideas at the moment.

[Aloupol]

The problem with servos is that they use a position control and not a force control. Force feedback wheels and joysticks use DC motors that produce a torque depending on the game value. With DC motors the torque is proportional to current. At least in stall or low speed conditions.
To lower the drag, especially when low torque is applied, I plan to use a force sensor (instead of position sensor in a servo) in a PID feedback loop.
So the motors will push, pull or release, until the resulting force value is "equal" to what the car's acceleration in the game is. An this whatever the head position, as in real life.
If the stand is strapped to the driver's body I think it could give a strange feeling: imagine you are braking: your head is pushed forward, but your shoulders are pushed backwards.