DIY Seatbelt tensioner with simtools

[HoiHman]

A lot guys that have build the SFX100 are thinking about adding a seat belt tensioner to their rig.

Even though i would have prefered to use one the SFX100 servos doing the work, i have decided to order the parts servo seatbelt tensioner and will start building as soon as the parts arrive.

Parts needed:
Servos
https://hobbyking.com/de_de/turnigy...-servo-33kg-0-21sec-154g.html?___store=de_de1

Turnigy 5A (8-40v) SBEC für Lipo :
https://hobbyking.com/de_de/turnigy-5a-8-40v-sbec-for-lipo.html

Aduino uno
https://nl.aliexpress.com/premium/a...SB_20190116083039&origin=y&catId=0&isViewCP=y

Power supply:
Still need to order one, or if the specs of the servos allow it, i will use the 6v power supply of my GS-4

I will be copying the build from @Ringorian and @saxxon66 who have already a topic with complete instruction on the german forum.

https://forum.virtualracing.org/sho...ffer-100-Euro-(auch-Ohne-Motion-realisierbar)

Jochen en Micha, feel free to jump in and educate us

 

[HoiHman]

I guess another option might be to have a row of several springs that you can add or remove to adjust tension, just like Charles Atlas used to do with his old-skool chest expander. I obviously only ever used it with all five intact, so I have to take others word on this.

That was my plan initially, so i orderd 6 springs.

Turned out that one is almost strong enough to keep the SFX100 to the ground

 

[Stevie_007]

That was my plan initially, so i orderd 6 springs.

Turned out that one is almost strong enough to keep the SFX100 to the ground

out of all the springs i received these were the best just the right amount of tension
https://www.ebay.co.uk/itm/Tension-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[HoiHman]

out of all the springs i received these were the best just the right amount of tension
https://www.ebay.co.uk/itm/Tension-spring-1-84mm-x-16mm-x-162mm/122088626655?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Thanks Steven, i ordered something similar. I really have no idea if me having a GS-4 influences the spring strength needed. Time will tell.

 

[anton_Chez]

I wouldn't think so. Nothing on the GS 4 is pulling on the spring from what I would imagine.

 

[HoiHman]

The springs are only temporary until we get second controller support in Simfeedback.When it's released i'm going to use the 5th servo i already have laying on the shelf.

So let's discuss what we are trying to simulate here:

When you brake, the G-forces move your upper body forward into the seatbelts and away from the seat. We try to simulate this by pulling on the seatbelts.

This pulling of the seatbelts actually pushes you further back into the seat, which is the opposite from a real life situation.

To combat this, you should have a seat with moving panels that move backwards under braking.
Simulating your body moving away from the seat.

That's exactly what the GS-4 does.

I wouldn't think so. Nothing on the GS 4 is pulling on the spring from what I would imagine.

Of Course this effect can be turned of, but the play in the seat belt as a result from the backwards panel movement can definitely impact how the tension is felt, what the spring strength is needed or the preferred initial load on the spring.

 

[saxxon66]

Hm, Gseat and belt?
I think these effects are antagonistic and could even cancel each other out.
Maybe you can dial/tune it, by stoping the seatbelt if it has reached a position and will not pull further.

My approach is to use gravity by tilting forward when braking and tightening the belt.

The back is relieved and you feel the pressure on your shoulders and hands.

 

[anton_Chez]

Agree. I think we're getting way too technical with it all and have been a little overwhelmed with the level of feedback we've been able to achieve with the SFX-100. Now we want ALL the feedback, ever....

A floor mounted harness will work perfectly under brake pitch with the actuators tuned for brake dive. Passive, cheap, effective and as it would be in real life.

 

[HoiHman]

Time will tell and if so it's just a matter of which effect feels better, so the other one will be turned off.

 

[Specialist68]

The springs are only temporary until we get second controller support in Simfeedback.When it's released i'm going to use the 5th servo i already have laying on the shelf.

I hope they wil make a second controller support
But not alone for a Belt but also for tractie loss
I wish they could connect it to the same leonardo and same software

 

[anton_Chez]

Arduino is already tapped out and will need another one to support more controllers.

I think we need to appreciate what SimFeedback and Saxxon have been able to achieve and deliver within the confines of itself. I mean most of us are running 20 grande motion platforms for pennies on the dollar and here we are disappointed that we can't enable another controller with the current setup, tensioner is providing tension the incorrect way, etc.

The SFX-100 system as a whole is a modern marvel by, from what I can tell, a very smart and thoughtful sim racing enthusiast. Being able to share in his experience is something I am very grateful for. We could have been relegated to just watching Youtube videos of him showing off his project.

We get to drive it now.

 

[HoiHman]

Don't worry second controller support will come when it's ready.

Back on topic:

Big thanks to @sdubbin, you put in the right direction Steve

I just received the springs and they feel really good. Now i still have to find a "mobile solution" since i can't bolt them to the ground. Also there's a large buttkicker Advance sticking out at the back of my seat that also make things a bit more complex.

 

[Lotusman]

Agree. I think we're getting way too technical with it all and have been a little overwhelmed with the level of feedback we've been able to achieve with the SFX-100. Now we want ALL the feedback, ever....

A floor mounted harness will work perfectly under brake pitch with the actuators tuned for brake dive. Passive, cheap, effective and as it would be in real life.

The springs are only temporary until we get second controller support in Simfeedback.When it's released i'm going to use the 5th servo i already have laying on the shelf.

So let's discuss what we are trying to simulate here:

When you brake, the G-forces move your upper body forward into the seatbelts and away from the seat. We try to simulate this by pulling on the seatbelts.

This pulling of the seatbelts actually pushes you further back into the seat, which is the opposite from a real life situation.

To combat this, you should have a seat with moving panels that move backwards under braking.
Simulating your body moving away from the seat.

That's exactly what the GS-4 does.



Of Course this effect can be turned of, but the play in the seat belt as a result from the backwards panel movement can definitely impact how the tension is felt, what the spring strength is needed or the preferred initial load on the spring.

 

[Lotusman]

Folks, I had a passive belt system with D-Box and moved to SeatTime's active system. There is no comparison the active one is so much better. I have also now added a GS5, they work seamlessly and don't cancel each other out at all.

In fact due to the feeling of "G" force with the seat and belt I've upped the force I use for braking as for the first time I have enough feel to stamp on the brake and modulate it.

 

[HoiHman]

Folks, I had a passive belt system with D-Box and moved to SeatTime's active system. There is no comparison the active one is so much better. I have also now added a GS5, they work seamlessly and don't cancel each other out at all.

In fact due to the feeling of "G" force with the seat and belt I've upped the force I use for braking as for the first time I have enough feel to stamp on the brake and modulate it.

Thanks @Lotusman for confirming

This makes the wait for the second controller support even harder

Slowly i'm making progress with my passive solution to tie me over untill then.




I have a set 5 springs with in 2 different strengths. This will give me plenty options to find the right combo needed.

Having a CNC machine is always handy. Of course so is a 3D printer, which is currently printing the guidance rolls i need.




Something else that might be great to consider:

If the second controller works in the same way as the current SFX100, there's another great advantage:

You easily put on your seatbelt, because they are long enough, you press "START" and the controller goes to the central position, automatically adjusting your seat belt in the normal position so it's thight. When you want to get out of your rig, press "Stop" and it will be easier to take the seat belts of.

Same also applies right now with the passive solution, since lowering the platform will give you 5cm extra play.

 

[anton_Chez]

Nice to hear some feedback regarding the active tensioner. I will wait for Hugo to give his impressions as well before making a decision. I'd settled on not worrying about it since I've finally managed to make my shoulder straps stay tight. Also wanted to try a static passive solution before putting even more electronics onto the rig.

 

[HoiHman]

I did an initial test this morning and decided to put this project on a hold.

Because the rig is not permanent, there's no way to really anker the seatbelts on the floor or wall. I tried a box with heavy weight and even though it holds the belts in place, it does not provide me with enough immersion to proceed.

Some WIP foto's






With belts tightened i need at least a 2" surge to get a good feel of the effect, which is way too much.

I can feel the belt tighten lightly at lower surge settings, but i'm looking for something more drastic. If i thighten the belts more, the surge effect is increased but so is the idle load on my shoulders which is too uncomfortable.

I tried a "limiter" on the springs which worked quite wel. The first inch of surge is spring based, after that the tieraps even lift the heavy box. This puts a pretty good load on the shoulders, but..... it will do the same with a 2" heave.

Just imagine playing Dirt Rally with that.

I put in a lot time to get this working, made special rolls on bearings to get past the buttkicker advance, but in the end the result is disappointing. Even more so it ads complexity and more set up time to my rig, which is something i do not need.

You probably need to move the mounting point of the seat belt tensioner further backwards to have more surge and less heave movements, but that's not an option for me.

At least i got a good feeling how a seat belt tensioner feels and i'm not sure yet it that's the route i want to go. As Micha already mentioned, you feel the pressure on your shoulders when it thightens.

But is that the same feeling as in real life. Shouldn't we feel the front of the seatbelt pushing againt you chest and bellty?

Just thinking out loud and appriciate feedback.

Anyway the seat belt tensioner is of the rig again, i went back to fixed mounting of the seat belts to the GS-4.

 

[anton_Chez]

I think you're only going to be satisfied with an active tension. But then, they are still probably going to be putting pressure most on your shoulders.

 

[HoiHman]

I think you're only going to be satisfied with an active tension. But then, they are still probably going to be putting pressure most on your shoulders.

Yeah, i think so to Anton. At least the work i have done so far can be used to install an active seat belt tensioner faster when the time comes.

 

[HoiHman]

Yesterday i did a simulation and to me it feels much much more natural when the lower 2 belts are being pulled back by a tensioner instead of the 2 top ones.

The forces are immediately felt in the front your body, instead of your shoulders.

Because this is more difficult to implement, could this be the reason why most seat belt tensioners go for the tension on the shoulders?

 

[anton_Chez]

Interesting thought. I wonder if I will be able to try connecting the lower belts with my tensioner once it's built. Waiting for payment request from the bloke Hugo bought off. I wonder how far away his is? @HugoB