My SimXperience style motion project

Hi guys

I've pretty much finished my plans for my motion rig and want to show it off and see if I get your approval
Here's my current rig - it's diy as well:




Yeah, I did put lots of thought in my new rig, but it's possible I've missed something of course and changing an ACAD model is easier than cutting a steel tube longer;-)
That's what it is gonna be made of anyway. It will be welded up and only the frame which takes the steering wheel is bolted on. I wouldn't get it into my sim room if it was one piece. The monitor stand which takes my 3 24'' BenQ XL2420T's is separated. The centre screen will be just about 60mm behind the steering wheel rim (so it's gonna be a bit closer than it is now on my current rig).
The pedals are gonna be mounted on seat rails. I'm using SimX SCN5 actuators for the seat and the rear traction loss module.
Here some pics of the bits and pieces:

So here some isometrics of my new rig:
This is how it started







Hope you think it's ok...and if there are issues please let me know

Thanks

(pics updated 9/8/2013)

Hello Thirsty !

So, it will be a 3DOF seat mover !
Nice drawings ! Nothing wrong for me at the moment
but it will depend on
- how much Yaw angle do you intend to get
- where will you actuate the yaw effort

I'm eager to see the next steps !
Mat

Hi Thirsty, great build ideas. As a matter of fact it is very similar to what I built, my first trial was today; worked fantastic.

Good luck and keep us posted.

Design looks good except for rear swing arm arrangement, they are usually an arc, not straight , where the rollers sit on the back for the yaw.

Hi Mat

Cheers for your feedback.
I've done some work on my file and modeled the rear traction loss actuator bracket (all isometrics have been swopped). The actuators are on their way and should be delivered next week sometime. Depending on the exact size of the actuator I might have to revise the design slightly, but the location will remain the same.
I'd think it's pretty close to where SimX is having their actuator located as well.
You think it's ok?

Cheers

Cheers for your feedback
Yeah, the flat steel bit is 40mm wide. I rotated the rig around the pivot when placing it and figured the wheel is just using a strip 30mm wide. That means I've got either side a minimum of 5mm to the edge of the flat steel.


I've got a question and hope you can help me with that.
It's about balancing the seat / locating the steering shaft knuckle under the seat. I built a bit of a device which helped me finding the lets call it centre weight point. However, I wonder if it's better moving the pivot in relation to the seat back a bit to compensate for the pressure you put on the brake which works against the actuators tilting the seat forwards.
You know what I mean?

Cheers

Hi Thirsty,

Centre weight point= Center of Gravity or CG

I was testing this very thing last night. My CG is adjustable, it is mounted with clamps so I can loosen it and slide the sled forward and backward to adjust it.

I tried sliding the CG forward (moved the sled backward) in order to counteract the forward force of, as you mention, braking. I have surge setup so when I hit the brakes the entire sled tilts forward, I had thought that this would aid the motors by reducing the torque on them. I didn't find that there was any difference at all.

Thanks mate
This might be a silly question, but how did you figure out it didn't make a difference?
Can you tell me by how much you moved your pivot back? With the device I'm using I can locate the CG within an estimated accuracy of +/-10mm. It's my missus standing behind the seat moving the back rest back and forth and telling me which direction is easier. I actually think 10mm don't make much of a difference and this is just having the legs idle with the pedals. I've got a sort of heavy duty pedal set and think the actuators have a bit of work to do to counteract these forces.
My pivot is located 70mm in front of the very bottom of the back rest. I'm just guessing, but in order to give the actuators some relief I think I would have to move the pivot back by at least 20mm without making it too hard to pull me back when accelerating - are you agreeing on these ballpark figures or am I completely off here?

Cheers

Hi Thirsty,

I moved my CG about an inch and measured the amp load on the motors, they barely moved from 4 amps to hold the sled stationary. I assumed that if I were far off the CG that it would take more amperage to have the motors hold the sled level than if the CG is dead on. It might be that I am using winch motors which have a tendency to hold the weight without the need for the motors because of the gearing.

I would like to do the same test while the winches are in motion but I would need to relocate the gauges in order to see them. Too much trouble right now

Hi Thirsty, if I understand your question... you want to know (for a seatmover) how much pushing on the brakes effects the seat movement because you are effectively pushing the seat backwards?

If you think about the tangential distance (A in diagram below) that this force is being applied it will probably be pretty short in relation to the actuator tangential distance (B) therefore you are getting a greater lever force from the actuators than from your leg braking pressure. So theoretically yes you are correct, however in practice I can't imagine it would be that important to worry about.

(Sorry for the crude drawing - I didn't do a good job at drawing the line B at a tangent but I hope it explains what I mean)


I have a seatmover and can't adjust the seat position but it seems to work fine no matter what size or weight person is in it. I would suggest your approach to test with someone seeing how easy it is to move the seat while pushing on the brake is a good approach!

Centre of gravity for a 2 DOF needs to be almost spot on. Even for seat mover. I have attached a pic of best way to find balance, use this for seat mover and full frame. ( Thanks Matt for pic).
If you find the motors are having trouble lifting the frame from a big braking motion and its balanced, you may need to look at mounting the motors at more of an angle. Or try increasing power to the motors and reduce the percentage of the force for braking.

Cheers mate. That makes sense and I agree getting data when the seat is in motion would be great. An inch should make a difference anyway. I'd think that might be a good distance to change the pivot by - not too much out of balance, but on the other side a bit to compensate for brake forces.
Dunno - this is about figuring out what the general consensus is.
Cheers

Hi mate
Cheers for the feedback. You got it exactly right - that's what I mean...and the sketch certainly does the job :thbup:
You're right: better check it properly. I will have to modify my balancing tool a bit and let my missus do the braking to see what's happening. I understand there's not much leverage on the break force's side - I've got about 100mm - and that makes it less critical.
See how we go with that anyway.
Cheers

Thats interesting about the balancing. Granted I have had 3 seat movers, got one current using big worm gear motors but used wipers , and big worm gear motors though, not SCN5. I think mine is a tad off balance , but it seems to react well.
I think there is a weight moving difference between motors and actuators.
Have you had a look at your buddies sim to see where pivot is?

Cheers for that mate. That's a pretty simple solution...and I'm sure it works
The brake forces won't have any effect on the actuators on that one of course.
Yeah, judging by the response it doesn't seem like motion rig builders are considering this point and aren't concerned about it anyway.
On the other hand not everyone is using a 60kg or 100kg load cell brake either. I'm on combination socks/G27 atm (my braking on iracing without assists is just crap), but that will change with my new rig when I start using my load cell brake and start wearing shoes. Just talking about gear here, my braking might still be crap after the change;-)
Cheers

My mates pivot is a bit further back, but that's because he's got a bucket seat with a very thin back rest. Taking that into account our pivots are pretty much the same. Even though he is using CST F1's he didn't consider brake forces at all. He's a socks racer though and therefore our pedals are gonna be calibrated differently.
He's been using his SCN5's for 3 years now and they still go well, but they do show signs of wear as well.