Coordinate System Standards? 2

[type26owner]

I've nearly completed a 3D computer model of the chassis and suspension bits for a Lotus 41 but have realized I don't know what's used as the origin point or the orientation of the Cartesian Coordinate System that's normally used in the automotive industry. Is there any standard and what is it?
Keith

 

[GregLocock]

I don't know if there is a standard, in the chassis world of a big 3 company we use X say 1000 mm forward of the front of the body, positive backwards, Y central, negative to the left, Z about 200 mm under the ground plane, positive up.

I have seen Z=0 at the bottom of the body, but that would introduce changes of sign for a lot of chassis work, so it is not a smart move. Cheers

Greg Locock

 

[brad]

Greg,
That is the GM standard, and I believe Ford and DCX also use it. There is another known automotive standard (I want to attribute it to SAE, but I could be wrong). I remember seeing it about a decade ago and thinking it was quirky, but if it wasn't SAE it was an equally reputable source.

I recall this one had origin in about the same location as yours. Positive x was pointing to the drivers' left ("driver's side" in US, "passenger's side" to you Aussies), and positive y pointed toward rear of car. +z was "up"

The standard you describe is what I am most familiar with. If somebody can add or correct my 10-year-old recollection, please chime in.
Brad

 

[GregLocock]

FEA/modal analysis guys used to use that, I think, it may come from the aerospace industry. Oh well, at least the big 3 agree on something! Cheers

Greg Locock

 

[brad]

This was early-90's FEA. However, the FEA guys at least at GM did not use that system. And what are you doing posting so early? Isn't it 7:00 a.m. for you?
Cheers,
Brad

 

[harmony]

Three dimensional reference systems used for European type approval is based on ISO 4130-1978. The gist is as follows:

The vehicle is divided into three planes X,Y,Z
Zero X plane (vertical transverse zero plane) runs roughly across the engine bulk head. Therefore X+ is to the rear of the vehicle. X- to the front of the vehicle.

Zero Y plane (Vertical longitudinal zero plane) runs through the longitudinal median of the vehicle. When facing the vehicle front Y+ is to the left of the zero plane and Y- to the right.

Zero Z plane (horizontal zero plane) runs roughly through the centre line of the wheels. Z+ is upwards, Z- is downwards.

Check the ISO standard for the exact positions.

 

[type26owner]

Thank you! I had it headed off in the wrong direction!
Keith

 

[Berserk]

For GM
X starts from the front of the car with positive direction towards the back of the car.
Z starts from the ground (bottom of wheels)
Y is at center of vehicle with positive direction toward the passenger side and negative is driver side