Steering Design

[umairraan]

I am designing the steering system for FSAE car for a little project, i have gotten the steering angle and steering ratio. But now I cant find a way to relate that to the rack motion and also how to get the gears and pinion values from there. Much will be appreciated if anyone can tell me properly how to calculate all these, since we are not given much technical education here in classes rather just theoretical plus I cannot find it in books or online regarding my problem.

[Thibault HUGUET]

Hum... google is your friend guy !!

But i'm friendly today so i will say : V=w.R ...

[MCoach]

Rack and pinon = steering ratio. Think about that. There's a relationship made through gears.

You can write it out in equations and draw a picture, make sure to watch your units. If your steering wheel changes (+5 degrees), how far does the linear motion of the rack move? How far does this then move the tie rod (this is the easy one)? From there, how far does the tie rod move the wheel assembly (in degrees)?

If you can answer each of these steps. You can answer your problem. Thibault gave a hint that's valuable.

[dynatune]

This is the bible of suspension design. Here you will find every answer to every possible question on suspensions: http://www.amazon.de/Radf%C3%BChrungen-Stra%C3%9Fenfahrzeuge-Kinematik-Elasto-Kinematik-Konstruktion/dp/3540641556. The only catch to it is that it is written in German and that you need to understand the basics of vector algebra. The good news is that soon a special module of dynatune will be available that does all the calculations that you are looking for :-)

By the way the hint V = w. R is good but not completely correct, it should be: vector V = Vector Vo + angular velocity vector Omega vectorcrossmultiplicated with distance vector R

cheers,
www.dynatune-xl.com

[jlangholzj]

This is the bible of suspension design. Here you will find every answer to every possible question on suspensions: http://www.amazon.de/Radf%C3%BChrungen-Stra%C3%9Fenfahrzeuge-Kinematik-Elasto-Kinematik-Konstruktion/dp/3540641556. The only catch to it is that it is written in German and that you need to understand the basics of vector algebra. The good news is that soon a special module of dynatune will be available that does all the calculations that you are looking for :-)

By the way the hint V = w. R is good but not completely correct, it should be: vector V = Vector Vo + angular velocity vector Omega vectorcrossmultiplicated with distance vector R

cheers,
www.dynatune-xl.com


AAAANnnnnddd this is why we need a separate section of the forum.

Is vector algebra the "most correct" form of the calculation? Yeah. Will the additional 2 hours you spend on it be worth the 2% difference it makes? Nope.

[MCoach]

This is the bible of suspension design. Here you will find every answer to every possible question on suspensions: http://www.amazon.de/Radf%C3%BChrungen-Stra%C3%9Fenfahrzeuge-Kinematik-Elasto-Kinematik-Konstruktion/dp/3540641556. The only catch to it is that it is written in German and that you need to understand the basics of vector algebra. The good news is that soon a special module of dynatune will be available that does all the calculations that you are looking for :-)

By the way the hint V = w. R is good but not completely correct, it should be: vector V = Vector Vo + angular velocity vector Omega vectorcrossmultiplicated with distance vector R

cheers,
www.dynatune-xl.com

I don't think a driver would ever be able to tell the difference.

[Big Bird]

Dynatune, I am not the only one here who is getting a little tired of your use of these forums for the promotion of your commercial software tool. Please refrain. I am sure your tool is very capable, but I do not need to read about it every time someone raises a dynamics question. Thank you.

[dynatune]

Big Bird, I did not know that you or some of your friends were annoyed by the contributions. If you find the comments or contributions not worthwhile I am sorry, but looking at the number of positive reactions, people were/are quite happy about the contributions and eager to learn about new/different ways of doing things. This might not be applicable to you but certainly to some other people here in the forum. By adding a link to the comments I am following the "usual" standards in blogs to indicate clearly to any readers, that there is commercial interest and that seems to me by all means correct, as do also quite a few other people here. Seems fair ?

Personally I am a little bit offended however by the fact that you mention that I am using these forums just for promotion, implicating that the comments are not valid or do not matter, and nothing could be further from that. I am more than passionate to convince young engineers to enhance their skills and follow the best teachers and find the best literature out there. Forgive me again Big Bird, I do not know your experience, but if you hold an open wheel FIA race license, if you are capable of running and managing a workstation with multi-body dynamics software and understanding it, or better able to write it yourself, if you have developed in the last 25 years everything from a 20 wheeler 40t truck to an F1 car and all variants in between, if you have driven a car 4 times to the moon and back, hold a suspension patent, if you have designed championship winning cars, if you have a proven track record of having developed cars that changed the world of vehicle dynamics, I can understand your point, if not I'd suggest maybe a bit more respect for those who did all of that and want to share their knowledge with people willing to learn. Thank you

Paul

[dynatune]

AAAANnnnnddd this is why we need a separate section of the forum.

Is vector algebra the "most correct" form of the calculation? Yeah. Will the additional 2 hours you spend on it be worth the 2% difference it makes? Nope.

Trust me. Read the book, I have heard that there is an English version of it. You will be amazed ! Btw. the author is the head of suspension design of BMW and creator of all their multi-link suspensions ! Why do you guys think that Bimmers are so good ? And yes vectoralgebra is "unfortunately" the best calculation. Take it from an old fox.

Cheers
dynatune

[dynatune]

I don't think a driver would ever be able to tell the difference.

those who win yes, those at the end of the grid not ....

Cheers,
dynatune

[Z]

While I am not happy with the never-ending tsunami of advertising on this Interweb-thingy (even all those pretty girls who want to be my friends don't quite do it for me...), I don't see Dynatune's (Paul's) posts as being too OTT.

Frankly, it is posts like the OP's original post that have me most worried!


I am designing the steering system for FSAE car ...
... tell me properly how to calculate all these ...
... I cannot find it in books or online ...

Grrroooaaaannnnn!!!!! :(
~~~~~o0o~~~~~

BTW1. Using V=WxR (bold = vectors, x = cross product) is NO HARDER, and much more RIGOROUS, than "V=w.R". Today's engineers could do with a bit more rigour.

BTW2. That must be one cracker of a car you have there, Paul. Four times to the Moon and back! Obviously not an air-breathing engine, so what sort of batteries does it use? :)

BTW3. Bimmers are crap!!!!!

Z