A question of reference

[Francis Gagné]

Hi gentlemens,

I am now a proper grown-up (I have a job) and so am posting this in the off-topic.

I am developping tools relating to vehicles. And so I need to choose a vehicle axis system. As of now there is no defined standard in the company as there was no need. I found that the two main standards are ISO 8855:2011 (Z-up) or SAE J670:2008 (Z-down). In the present case, either one seems suitable for me. Since the company is mostly european I would tend to use the ISO one.

But I have no idea which is more used in the industry (and or if it's regional), it could change the balance. If any of you have any experience with any of these please tell!

Thanks!

[DougMilliken]

I think SAE (based on General Motors work?) was first to publish a vehicle axis system, but I could be wrong. Users of ISO often seem (in my experience) to be surprised that there are any other axis systems at all!

Both SAE and ISO are right-handed, but there are other axis systems in use (particularly in simulations) that use left-handed "3D" screen display coordinates -- origin at lower left (like "1st quadrant" - positive X and Y) and Z positive into the screen. CAD may be set up with the origin outside the vehicle (not at CG). It's a mess. Depending on where you get design and test data (tire, aero, etc), you will probably have to deal with multiple axis systems for a long time.

See RCVD Chapter 4 for further thoughts on this topic.

[Edward M. Kasprzak]

It's a mess. Depending on where you get design and test data (tire, aero, etc), you will probably have to deal with multiple axis systems for a long time.

Francis, just try to avoid this: http://xkcd.com/927/

[Francis Gagné]

Thank you both for your answers!


Francis, just try to avoid this: http://xkcd.com/927/

(Note to self, bookmark the link. Theses comics might come in handy someday)

Yes indeed. This is mostly why I asked here to try to find the most common denominator!

For the time being I'll comply to the most recent ISO. It should be relatively "standard" and keep everybody on the other side of the pond happy. We don't use any outsource data for now so I can't base my decision on that. In any case, from now I will try to have everybody on the inside to be on the same page.