Motion simulator with the universal joint at the top?

@hooshang, well you're right, it is different from the real world, i understand that...but we are of course trying to achieve the closest possible feeling to the real thing as possible within given limitations...
You mention sway with roll...and surge with pitch - this is exactly for the reason i described in 1. and 2. picture of my previous post (leaning seat is pitch motion - center of rotation may differ from one example to another though).
As for the forces in stewart platform...it is 6DOF, and that is the maximum possible degrees of freedom within a robot mechanism, adding more actuators is redundant and will only add to more range of motion at best, but it still stays only 6DOF.
That being said, with stewart we can do every possible motion that can be done with 2DOF or 3DOF simulator if the range of motion is within platform's moving limitations. I must say though that the biggest disadvantage among robot mechanisms with the use of stewart platform is range of motion...but obviously it is enough for simulators, since there are so many even professional ones based on this kind of platform...

Regards,

Pawks

Hi @Pawks
everythings has its own limitation and you know the concept.
you are smart and hope you will be more active in this community.
regards
Hooshang

Hi @hooshang
Well, being smart is a relative term...i may know more about some things than others, but i am dumb at many other things where others are more knowledgeable...
But that is the greatest thing of being a part of a community - a lot of people with small amount of knowledge adds to a lot of knowledge and better final product...
So yeah, since i found this forums i mostly was just browsing through, cause there are tons of good information here... and hopefully i'll be able to contribute at least part of it back to the community some day...

Regards,

Pawks

@Pawks , build a sim with your ideas and SHOW US that it works well. Simple

Hi @bsft ...i can feel a bit of aggressiveness in your post...but i've been browsing this forums for a while now and i know that i'm not the only one - this is what i get for being a newcomer i guess...
Anyway, to explain some things you might have missed...
- first of all this wasn't my idea, i just entered this thread cause i had the same idea as OP... and secondly - you can see in my first post ITT that i realized from people's answers to OP, that it's not worth it...
- another thing is that if i would have built this kind of simulator, then i could post a video showing it in action, but it would be pointless since you can't feel any forces from a video, which is the only reason to build it this way in the first place...
- my other posts ITT are just discussions and explanations of what i understand about motion and forces that go with it ... i know that this doesn't mean much to you but i can guarantee you that any posts coming from me explaining something will be only about things i believe i understand very well - otherwise there will be a question mark at the end, or will be clearly stated that i don't understand it good enough ... feel free to ignore, dislike or disagree with anything i post, but if you disagree please explain why - i'm always open for a discussion...
- i know that i haven't earned any trust and respect from members around here yet unlike you have - i respect that. And i also know that my posts will often be overlooked just for that reason and things i post about will be treated untrustworthy, but i will continue to post if i feel someone could find it useful and be sure that i'll stop posting if i get only negative response...
- also i haven't noticed anywhere that one isn't allowed to discuss/explain things if they don't have a simulator built to back it up (added this cause this is the kind of feeling i get from your post)...

No hard feelings, Regards,

Pawks

ok , apologies for the remarks, I can be blunt sometimes,
Lets carry on
Dave.

Ahhhhhhh! I totally agree with your ideas Pawks.
I have come to the same conclusions independently. But alas someone have already thought of it first!. The head high pivot point seems the most logical approach to maximise the correct physics of our 2 DOF sims. ( as a side idea, a rotation platform for yaw???) As an added bonus to this arrangement, your head (and eyes) will not be thrown all over the place by the violent movements of the sim.
I am definitely going down this track for my next sim project. I am working on the long through fast moving linear actuators at the moment. Once I have that sorted, the sim shouldn't be that difficult to build. One of the main problems with this concept is compensating for the weight needed to be supported by the actuators. I have been designing my rig for a while now and I think I have overcome most of the problems ( I hope?)

hope you have a go to.

Hi @Bruceaust , nice to hear from someone with the same ideas...
Although a lot of people here are saying that a rig with universal joint at the bottom feels ok, I'm still thinking about how to build one the other way...
I have another idea how it could be done, but there are some problems i need to overcome first...currently I'm still building the upper part (seat + pedals + wheel), so after that is done i'll see which way i'll go...
As i see that @noorbeast offered you a try on his bottom mount sim. If you do try it, it would be nice to hear from you about how it feels. I respect everybody's opinion, but since we have the same ideas, it would be much more meaningful to hear about it from you.

Regards,
pawks

I built a scn5 100 back in 2008 with a universal under the seat. I'm more than happy with it as it enhances game play 10 fold. I'm not into a lot of motion and have it set up more to replicate what the car is doing more than trying to reproduce g-forces. I'd be surprised if it moves more than inch in any direction. Speed and smoothness of the actuators is more important to me then the total distance of travel.

Of course we're all different and have different expectations!

great idea get it built and see what happens but i guess you can compare it a swing. i like new ways of thinking but i do feel there not any force involved at the right parts from a top mount.
the body moves mostly in a seat from butt upwards and the forces are so would need to be pushed and pulled to get the feel of force at that point and above.
if you put a mount on the top you lose the top forces and becomes a swing type, i don't see it putting enough umph to the head be abit like a frame mover i guess, also what happens to the pedals and steering wheel as a seat mover does not move you that much to effect the driving part if you get seating right.
the most movement would be the feet and would defo be a problem with pedals.
but like i say you have to go with it and explore these things.
that is how i see it and if you put a race seat on a swing then push from the bottom it might give you an idea then push it from the top and feel which puts more force on the top and you might be close to what it might do ?
i just see your sat not pushed about in the seat and thats what the forces are the most force should go from your head to you legs.
if you take you belt off in a car then brake hard you body pivots at waist follows the car movement on it spring moevments left right forward back you will always pivot.
i can only see the other way round not giving enough force kinda what happens when you change to frame mover you lose some forces.
we could all be wrong and the only way is build it and build a thread so we can see how it is going and how it work by the end of it be very informative for everyone and you could end up being the top one that changed the ways.
all for this to be built

i drive a gwiz so i no what happens to my body driving as it drives like a bike round corners and leans alot and i have no seat support as its such a basic thing to drive around in and i pivot from waiste up everyway i go so feels the same via forces tbh and not far out.
the best way is take you belt off and drive work out what your body does with car inputs and work out how you can replicate it with a frame or seat mover.
your car has all the info you need and you can test it free other than petrol as hard and as much as you like.
start there and see what you come up with.
this is very intresting to build.

As I have built 2 Sims I have come to these ideas thru the experience of these Sims.
I favor a sim with a lot of movement because it gives much more flexibility when making motion profiles.
One of the things I do is have quite a bit of pitch and roll feeding into both axies. This gives very good effects when the angle of the road changes. Fantastic as you go up thru The Cutting or down thru Forrest Elbow at Bathurst! I like many things about the sim I have now but I am keen to try the head pivot point as I believe it will give the most realism. I will be trying to maximize the throws to get about it 20 deg on both axies.
Another reason for trying this arrangement is to stop your head being thrown all over the place as the sim reacts to quick movements. Because my current sim moves very fast it is quite hard to focus when your head is rattling around! ( My screens move with the rig). As an addition to trying the "new" pivot position, I also would like to try a seat belt tensioning system. This will tighten the belts when braking.

So much to do and so little time.

this can not be far off an end result from a high mount.
http://www.cmsstrategic.com/news/2377/itec-2015-showcasing-the-spectrum-of-simulation/

go find one of these in the arcades we have them over here in most of them, must say ive not been on one which is not like me ! doh

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