Beefing up wagon suspension

Beefing up wagon suspension

Postby newbouy » Fri Aug 19, 2016 11:02 am

hello does anyone know the best way to stiffen the suspension on my ingot carrier.Im assuming this is done in the bogie blueprint ,at the moment my "suspension stiffness" = 8E+09 and the "suspension damping" = 6E+07 which is the default values which most wagons have.Ive messed about with these values before and got interesting results like wagon rocking and swaying when moved and even managed to get wagon to easily tip over when going to fast around a corner.Only problem is i found other problems arise when altering these values like coupling up ect so i reverted back to the default settings.The video below will show you that when the ladle is dropped onto the ingot carrier some of the wheels sink about 100mm into the track rails which doesnt look good.Looking at some of the default wagons that carry container loads i noticed that in their blueprint cargo def sections the mass in kg entry was set to zero which means wagons which are loaded and unloaded weigth exactly the same.In my wagon i have set this value to 62994 kg which makes the ladle full of hot metal weigh the correct 62 tons which after checking in game correctly adds to the unloaded wagon mass of 7 tons to give a total mass of 69 tons but only problem is the wheels sink into the rails.if anyone could recommend values for suspension stiffness and damping or explain what they mean i would very much appreciate it.

https://www.youtube.com/watch?v=89C74RfXuHA&feature=youtu.be

thanks newbouy
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Re: Beefing up wagon suspension

Postby AndiS » Fri Aug 19, 2016 7:12 pm

If this works as in MSTS, then springs are configured like this:

1) Take mass, e.g., 69 tons.

2) Decide how far the spring should move under this load. Now if the wagon sinks in, the whole design is crooked anyway. You might consider boggies that hover 2 cm or so above the rails. Then, you could allow for 4 cm spring movement. The empty wagon would then hover 2 cm above track while the loaded one sinks in by 2 cm. Whatever, you need some length.

3) Stiffness is normally defined in N/m. That means the force in N it takes to compress the spring by 1 m. 69 tons push towards the centre of the globe with a force of almost 690 kN. If you only admit 4 cm = 1/25 m of movement, your stiffness would be 690 * 25. Result in kN, so 17250 kN or 1.7 e7 N. This is less than you used, which irritates me.

4) Damping is a force working against the velocity of the movement. So it is given in N per m/s, which is the same as Ns/m. Since N=kg*m/s², Ns/m equals kg/s. This sounds irrelevant first, but when doing the calculation, it will help.
There are springs that oscillate more than necessary and those that are too stiff. The idea is called critically damped. Then, damping is computed as:
2 * square root (mass * stiffness)
In your example, 69000 kg * 1.7e7 N equal 1.173 e12. Twice the root would be 2.15e6 in my book.

Again, this is less than what you used, so I am far from sure that this is the correct solution. At least I gave you some thoughts where to start looking. The above is a quick brain dump with the help the following Wikipedia pages.
https://en.wikipedia.org/wiki/Hooke%27s_law
https://en.wikipedia.org/wiki/Damping
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Re: Beefing up wagon suspension

Postby newbouy » Fri Aug 19, 2016 9:52 pm

Hello AndiS thanks for your quick reply

AndiS wrote: Result in kN, so 17250 kN or 1.7 e7 N. This is less than you used, which irritates me.


It does sound like the game doesnt conform to real world physics when it comes to wagons with container loads.This is proberbly why the mass in kg entry in the blueprint cargo def sections of the default wagons are always set to zero.I havnt tried this yet but If i was to set the unloaded wagon mass to 68 tons and make the full ladle mass to 1 ton i bet the sinking problem would be solved.Its a pitty because pulling just 2 unloaded ingot carrier wagons would have a whacking great mass of 136 tons :shock: instead of the correct 14 tons.Any way i shall still have a go at tweeking the suspension values and see what happens.

AndiS wrote: Result in kN, so 17250 kN or 1.7 e7 N.


Im abit confused how you actually write this value into the blueprint editor ,in the default value of stiffness = 8E+09 what does the + sign stand for ? also working from the default value which number would i increment to stiffen the suspension in small steps eg 9E+09.

Thanks alot Newbouy
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Re: Beefing up wagon suspension

Postby cjbarnes5294 » Sat Aug 20, 2016 1:28 pm

8E+09, or 8E+9 normally, is shorthand for 8,000,000,000. E+X is the same as 10^X ie. E+1 = 10^1 = 10, E+2 = 10^2 = 100, E+3 = 10^3 = 1000 etc. So you simply multiply the number in front of the E by the whole E figure: 1.7E+3 = 1.7(E+3) = 1.7 * 1000 = 1700.

Conversely, you might see something like 8E-09 or 8E-9, but it works exactly the same: E-1 = 10^(-1) = 0.1, so 8E-9 is 0.0000000008.

The blueprint editor automatically displays long numbers in the above style but thankfully you can just type in the numbers normally as well as in shorthand, so for making small incremental changes it's probably quicker just to type the full number out and forget about converting it to shorthand.

Kind regards,
Chris
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Re: Beefing up wagon suspension

Postby newbouy » Sun Aug 21, 2016 10:21 am

Hello Chris thanks for the in depth reply :shock: ,im not going to pretend that i understand what it all means thou :lol: maths wasnt my best subject.I understand bits of it so maybe if i keep reading it over and over again it might click.Looks like im going to resort to a try it and see what happens method and report back with the outcome.Thanks for you help.

thanks alot Newbouy
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Re: Beefing up wagon suspension

Postby AndiS » Sun Aug 21, 2016 11:00 am

Sorry about the sloppiness. 1e4 = 1E4 = 1E+4 = 1E+04.
The number after the E tells you how far the coma is shifted. So 1E4 is 1 with 4 zeros, i.e. 10,000.
Negative numbers shift to the left.

How that all is interpreted by the game is something I never tried out. And how far my formulas are off the mark is the other thing I don't know as I am sort of off-line currently.

At any rate, I would first try it with an empty wagon and see if I can correlate the visible sinking in with the numbers entered for stiffness (in connection with Mass, of course). Then, I would go for a load that is as heavy as the empty wagon. Now the amount of sinking in should double, or something is fishy.

I assumed that you already established the current mass that the game sees, e.g., by logging TotalTrainMass or something like that. I for one never established that for myself. So it could well be that the game does something unrealistic. At least for wheel slip, such behaviour is documented.
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Re: Beefing up wagon suspension

Postby newbouy » Sun Aug 21, 2016 10:57 pm

AndiS wrote:The number after the E tells you how far the coma is shifted. So 1E4 is 1 with 4 zeros, i.e. 10,000.
Negative numbers shift to the left.


Now that bit i do understand abit better AndiS.Any way i did abit of try it and see what happens testing and even with high suspension values the wheels still sunk into the rails when the ladle was dropped onto the wagon.High suspension damping values gave some very weird results where the unloaded wagon was actually tipped on its side :shock: .So in the end i reverted back to the default suspension stiffness and damping values and decided to lower the weight of the ladle while at the same time increase the weight of the ingot carrier.

AndiS wrote:I would go for a load that is as heavy as the empty wagon

This worked fine no sinking problems with both wagon and ladle each weighting 7 tons.
After quite abit of testing i reached the following weight values which didnt cause the wheels to sink into the rails :
Ingot carrier wagon = 40 tons
Ladle = 29 tons
Total loaded wagon mass in game shows 69 tons.

The video link below shows the result of the above values with only a very slight sinking but i can live with it.Thanks AndiS and Chris for your help.
https://youtu.be/AP5b5zTALG0

Thanks Newbouy
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Re: Beefing up wagon suspension

Postby VictoryWorks » Mon Aug 22, 2016 8:58 am

I think the issue is probably the way that suspension and motion has been implemented in TS.
Remember it was never part of the core so like most things it's been hacked in afterwards and I guess the way they did it was to simply allow the entire item of stock to move up and down (and left and right?) very slightly so as to look like it's shaking around as it travels. Ideally it should have just been everything but the bogies but that appears to not be the case. For a coal wagon etc it creates a reasonable visual effect but for something like this you see the trickery, that the whole thing sinks into the track.

Is there a way to fake this instead? Detect in script whether the item is loaded or not with Call("GetTotalMass") - note: you would need to test if this does detect the change in mass when an item is loaded - and then do you own manual animation of the body and other parts lowering.
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Re: Beefing up wagon suspension

Postby newbouy » Tue Aug 23, 2016 1:00 am

VictoryWorks wrote: Is there a way to fake this instead?


Hello Pete i originally wanted to be able to fill the ladle while it was loaded on the ingot carrier and then have the ladle lifted off later by the overhead crane but i could not find a way to do it.Filling the ladle uses the bulk freight cargo and the lifting off of the ladle uses the container freight cargo and i couldnt see a way of using both on the same wagon so ive had to do 2 seperate versions.

VictoryWorks wrote: Detect in script whether the item is loaded or not with Call("GetTotalMass") - note: you would need to test if this does detect the change in mass when an item is loaded


Yes the Call("GetTotalMass") does detect the weight of the ladle when its loaded onto the wagon.

BTW Pete the TPO`s are fantastic the animation for those mail bags landing in the catch net must have took some doing , im just thinking i assume you have to hit the "T" key as your passing the catch nets then???

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Re: Beefing up wagon suspension

Postby VictoryWorks » Tue Aug 23, 2016 12:02 pm

Yeah that sounds tricky, mostly due to how you'd have to make sure it was 100% aligned to do those transfers manually.
You could still do the animation though as that GetTotalMass call works - the truck just needs to check it's own mass periodically and then when it increases/decreases you run an animation that raises/lowers the chassis quickly with a "bump".

Thank you, we're REALLY pleased with the TPO's. It's been in my head for years and I've shelved it frequently due to a lack of capability of the sim and then a year or so ago the solution came to me.
The system is actually totally automatic, you just need to drive the train within the correct speed limits. It couldn't be a game registered fuel/cargo transfer as they can't happen at speed (the water troughs fill is all script using a function that just adds water) so the TPO is a metric ton of smoke and mirrors to get the job done - but we think it turned out pretty good :)
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