Suspension Calculation (Suspension Speed)?

[B3ntley]

Hello! Does anyone know or have an idea on how to calculate the speed of the suspension or springs?
Would I take the frequency and convert it to a linear speed (with some algebra included)?
or
Would I take the energy transferring through the spring and applying some variant of the General Kinetic Energy equation? This would also include a free-body diagram of the spring and dampers. Caster angle may factor into suspension speed.

Any ideas or is this calculation useless or redundant?

[Schnizz58]

Spring rates are given in N/m/s, so if you know the force applied, you should be able to divide the spring rate by the force and get the speed in m/s. Of course that ignores the dampers, which will resist the motion of the springs. Someone send up the bat signal for Jussi. He's probably down in his basement sniffing his airlocks.

[Jussi Viljami Karjalainen]

What do you mean by suspension speed in this case? What are you trying to calculate?

Spring rates are given in N/m/s

That's dampers. Springs only react to displacement so they are N/mm, dampers react to velocity.

He's probably down in his basement sniffing his airlocks.

I don't have a basement, the bucket is in the backroom. =)

Reminds me that I "need" to go sniff it...

[Schnizz58]

Thanks for the correction. Something didn't seem right with that after I re-read it.

[B3ntley]

I'm trying to determine the amount of energy in the springs under accel, braking, and average over bumps

[Diamond_Eyes]

I'm trying to determine the amount of energy in the springs under accel, braking, and average over bumps

Force = stiffness(spring rate) x distance (suspension travel)

Integrate this and you will get the 'work' done or the elastic energy, E

Multiply half spring rate by travel squared to get the elastic energy (work done)

So a 200 N/mm spring compressed (or stretched) by 20mm, covert to values consistent SI units Newtons and metres

E = 1/2 x 200,000 x 0.020squared = 40 J

Interrogate the datalogging to get distance travelled

Don't know how dampers fit in to the equation as they only dissipate energy and don't store it.....

Out of interest, energy recovery from suspension travel
http://www.autoblog.com/2013/08/30/z...ry-suspension/

[Jussi Viljami Karjalainen]

I think doing that effectively would really require you to be able to log the suspension travel info, and that's unfortunately not something that's fed into the API, so no programs can use it AFAIK. Which sucks, because I would have been using it to make suspension histograms for ages now if it did.

[Diamond_Eyes]

Didn't realise that travel isn't in the API - you can only see it telemetry HUD. It's a must have datalogging trace IRL.

[RacingManiac]

More things filed under "games have done this years ago why didn't pCARS do it"...

[Jussi Viljami Karjalainen]

Didn't realise that travel isn't in the API - you can only see it telemetry HUD. It's a must have datalogging trace IRL.

More things filed under "games have done this years ago why didn't pCARS do it"...

Actually it's my mistake, it wasn't in the original Shared Data API, but it looks like it has been included in the new UDP API. It even looks like there's a straight up suspension velocity value there, so all you'd need is to log those and count the occurrences to make a suspension histogram.

  f32   sRideHeight[4];               // 392
  f32   sSuspensionTravel[4];         // 408
  f32   sSuspensionVelocity[4];       // 424