4WS?

[darienphoenix]

Have any teams ever tried using four-wheel steering? I was wondering if there would be any real benefits (would help getting around the hairpin at FSAE-A which we couldn't do last year).

[darienphoenix]

Have any teams ever tried using four-wheel steering? I was wondering if there would be any real benefits (would help getting around the hairpin at FSAE-A which we couldn't do last year).

[Steve Yao]

Using the search feature will help you a lot.
For instance:
http://fsae.com/eve/forums/a/tpc/f/125607348/m/70560057...056005743#7056005743 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/7056005743?r=7056005743#7056005743)

BTW, What university are you with?

[darienphoenix]

Adelaide.

I won't be in final year for a good few years yet, but I'm learning as much as possible in the meantime.

[D-Train]

In theory, it only works in transients - you'd want opposite steer (relative to front wheels) in corner entry, and parallel steer in corner exit.

If you were having trouble with the hairpin, try running more steering lock. No other teams seemed to struggle that badly in the hairpin, and only one car at the (Aus) comp last year ran 4WS.

Firenze (an italian team i believe) run have run an active RWS system previously. There's some good pics of it on their site, but i'm not even sure they ran it at the comp.

Don't even bother looking at Washington's efforts of some time ago.

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">If you were having trouble with the hairpin, try running more steering lock. </div></BLOCKQUOTE>

I'm not that much of a newbie. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[PatClarke]

DP,
Perhaps having the worlds stiffest rear anti rollbar contributed to the problems at the hairpin? And then giving one of the worlds greatest race car designers the flick when he suggested a cure was far from clever.
There is more to competing successfully than building a car and just driving it.
Regards
Pat

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
DP,
Perhaps having the worlds stiffest rear anti rollbar contributed to the problems at the hairpin? And then giving one of the worlds greatest race car designers the flick when he suggested a cure was far from clever.
There is more to competing successfully than building a car and just driving it.
Regards
Pat </div></BLOCKQUOTE>

Pat,

I have no idea what you're referring to with the "one of the world's greatest race car designers" comment - I wasn't at the comp last year. Care to elaborate?

And yes the DeDion rear did inherently cause understeer, or at least that's what I understand of it. But the same rear suspension setup won design in 04, so go figure.

You seem like you're trying to tell me off, which seems a little pointless since I'm completely new to the game and wasn't involved in any past decisions. If you have criticism of Adelaide's previous year designs or attitude, I'd love to hear it, but cryptic comments aren't all that helpful to anyone.

[Kevin Hayward]

Darien,

Not sure of what the situation is that you and pat are talking about, but "one of the world's greatest race car designers" that Pat mentioned is invariably Ron Tauranac.

Designer for Brabham from 1962 to 1970, and the man behind Ralt (which he sold in 1988). Could possibly be the most successful (in terms of competition wins) designer of customer race cars ever.

He was judging at FSAE-A in 2003 and 2004. I don't know if he is still judging, but it would be good for the comp if he is. Definitely worth listening to what he has to say.

Kev

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kevin Hayward:
Darien,

Not sure of what the situation is that you and pat are talking about, but "one of the world's greatest race car designers" that Pat mentioned is invariably Ron Tauranac.

Designer for Brabham from 1962 to 1970, and the man behind Ralt (which he sold in 1988). Could possibly be the most successful (in terms of competition wins) designer of customer race cars ever.

He was judging at FSAE-A in 2003 and 2004. I don't know if he is still judging, but it would be good for the comp if he is. Definitely worth listening to what he has to say.

Kev </div></BLOCKQUOTE>

I'm sure it would, except that I have no idea what he supposedly said...

[PatClarke]

Hi Kev,
It was, of course, Ron T I was talking about and he will be judging at FSAE-A in future as long as he can.
As for what 'Darien' and I were talking about, we have discussed that on a back channel and he does know exactly what I was saying.
Pat

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
Hi Kev,
It was, of course, Ron T I was talking about and he will be judging at FSAE-A in future as long as he can.
As for what 'Darien' and I were talking about, we have discussed that on a back channel and he does know exactly what I was saying.
Pat </div></BLOCKQUOTE>

I think you're a bit confused Pat...

We've discussed nothing on any 'back channel', and I still have no idea what you're talking about. Are you sure you haven't confused me with someone else?

[PatClarke]

OOps, it sounds like it =]

Have a chat with Matthew Cherian
Pat

[Rob86]

Hey Darienphoenix...

From testing last week it looks like we wont have too many troubles getting around the tight turns this year http://fsae.com/groupee_common/emoticons/icon_smile.gif

Rob


... I thought removing one of the trailing arms wasn't too bad of an idea

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob86:
Hey Darienphoenix...

From testing last week it looks like we wont have too many troubles getting around the tight turns this year http://fsae.com/groupee_common/emoticons/icon_smile.gif

Rob


... I thought removing one of the trailing arms wasn't too bad of an idea </div></BLOCKQUOTE>

So Ron's advice was to remove one of the trailing arms? Fair enough, sounds reasonable to me. Who's Matthew Cherian?

Alec said he had plenty of lock on Thursday, and at least the steering wasn't heavy like we were worried it might be. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Oh and hi Rob.

Mark

[PatClarke]

I give up http://fsae.com/groupee_common/emoticons/icon_confused.gif
Best argument yet for putting real names to posts
Pat

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
I give up http://fsae.com/groupee_common/emoticons/icon_confused.gif
Best argument yet for putting real names to posts
Pat </div></BLOCKQUOTE>

You could have just asked, rather than assuming and confusing the crap out of everyone...

[D-Train]

Well, back on the topic of 4WS and getting around that hairpin, Darien I'd suggest looking back on the 05 DVD. You can see the Adelaide car hit full lock and still not turn tight enough. If you're still not convinced, watch the interview with Samantha Reid. She mentions the inability to negotiate the hairpin as being "a combination of not enough lock and a lack of front end grip".

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by D-Train:
Well, back on the topic of 4WS and getting around that hairpin, Darien I'd suggest looking back on the 05 DVD. You can see the Adelaide car hit full lock and still not turn tight enough. If you're still not convinced, watch the interview with Samantha Reid. She mentions the inability to negotiate the hairpin as being "a combination of not enough lock and a lack of front end grip". </div></BLOCKQUOTE>

Just to get rid of some of the confusion, my comment on 4WS being helpful to get around the hairpin was more a joke than anything else.

I know there wasn't enough lock, and yeah Sam's complained about that and the inability to get enough rear brake bias.

However, is passive or active 4WS useful in any situation on a FSAE course? I know several teams have used it, just wondering whether they saw any performance increase to justify the increase in weight and complexity.

[D-Train]

I'd have say no to a passive system (or at least one with a constant ratio front:rear steering angle). A few teams have tried it before and then scrapped it the next year.

What exactly would you want it to do? What gain would you expect to get from a 4WS system?

[repeatoffender]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by darienphoenix:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
I give up http://fsae.com/groupee_common/emoticons/icon_confused.gif
Best argument yet for putting real names to posts
Pat </div></BLOCKQUOTE>

You could have just asked, rather than assuming and confusing the crap out of everyone... </div></BLOCKQUOTE>

You know darien

You could use alittle more tact. Being rude and arogent wont get you anywhere. Id be a little more respectful of Pat. Id be willing to bet he has offered alot of support to your team in the past.

[Rob86]

repeatoffender, I quite agree.

Mark, I would hope that you wouldn't speak to Pat Clarke like that to his face (or anyone else you don't know for that matter), so don't do it over the internet. This applies especially when you're not just representing yourself but your entire team, that sort of behaviour can reflect bad on everyone. Speak to people on these forums in a polite and tactful manner and it will get you much further.

Pat, would "Matthew Cherian" actually be Cherian Thomas? He is the suspension team leader for Adelaide this year.


Rob
University of Adelaide

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by repeatoffender:
You know darien

You could use alittle more tact. Being rude and arogent wont get you anywhere. Id be a little more respectful of Pat. Id be willing to bet he has offered alot of support to your team in the past. </div></BLOCKQUOTE>

*sigh*

Alright. I apologise for coming across as rude, I should have added a smiley after that last comment to Pat. I have no idea how that comment could be seen as 'arrogant', though...

However all I asked was a simple question and then had my identity mistaken for someone else, despide already mentioning I'm a new team member , was not present at the tournament last year, and had no idea what Pat was talking about.

As for representing the team, Rob, that's why I (was) using a pseudonym - so I could ask stupid questions without too much hassle. It's not my fault I was confused for Cherian.

I think Pat is referring to Cherian Thomas, Cherian asked me about it today.

Mark

PS: http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif

[darienphoenix]

Just another note, I wasn't aware 'Pat' was Pat Clark, or I wouldn't have been so quick to put my foot in my mouth. Sorry Pat.

Anyway, back to the topic... those teams which do run active 4WS, are they using parallel steer or opposite? Or do they use both and alter it based on vehicle speed?

I can see the latter (or 4WS systems in general) being a nightmare of complexity with the effort involved probably better spent on other areas of the car. Would this be a fair comment?

[PatClarke]

I had decided to pass on this thread, but, obviously I need to clear some things up.
Yes, the Matthew Cherian thing is a slip of the finger (I shouldn't write in haste from my work...Mathew Cherian is a guy I train in my real job), and the guy I had back channel discussions with was indeed Cherian Thomas. The unusual name caused the 'finger slip'.
I had posted the initial message hoping to prompt some off forum discussion. When Cherian messaged me, I mistakenly thought I had opened that communication, as you will see in the messages. Ask Cherian to show you the correspondence we had.

Now some bald statements. Your team did make themselves look boorish at last years event, whether you were part of it or not. Despite not being supposed to help, Ron and I went to offer some advice as we could see your teams frustration. Essentially, we were 'pi**ed off' because they were busy. Ron's comment was, 'Oh well, I guess they know more than me'. Ron was the senior design judge and your team members must (or should have) known who he was.

We had observed what was going on around the track. We (mostly he) had determined what changes could help, and we went to suggest you remove one particular radius arm. The effect of that change was more than simply loosening up the DeDion location.
But it didn't happen, and you guys understeered yourselves right out of the competition!

Maybe now my earlier comments are a little less cryptic. Another suggestion is that the team should look at a better dissemination of information down through the generations, a suggestion that should be heeded by all teams!

And that REALLY is my last word on this thread! If you wish to discuss any more, then private message me.
Regards
Pat

Edit...
PS....Well, one really really last word, hopefully to get this thread back on track.
Remember the Rules committee have put a strict limit on the amount of rear steer permitted.
PC

[Test Driver]

DP,

Look into the 4ws system that Honda had as an option on some US market Preludes. I beleive the system was offered during the late eighties or early nineties.

As I recall, that system was completely mechanical and passive. It went from same direction on innitial steering wheel motion to neutral and then opposite steer as more steering wheel angle was added.

Pat,

Without having seen the links you guys are mentioning regarding the DeDion, people not listening regarding overly-constrained beam suspensions probably happens quite often. In my old job, they use what are commonly called traction trailers. These all have beam axles and they all locate them with five links. One link is lateral and the other four are trailing. This of course sets up a bad situation on one-wheel bump and they snap their huge 1.25" rod ends with regularity. Even after a couple of us (who spend all together too much time thinking of these things) pointed out the design flaw, the people in charge are too happy to leave things as they are.

Cheers.

Ramon Mendoza

[D-Train]

The honda 4WS system (similar to the nissan HICAS) is designed for ultra-low speed manuverability (i.e parking) and high speed stability, if i'm not mistaken. It changes from parallel steer at low steering angle to counter steer at high steering angle (there's some great articles on 4WS production cars out there). For a FSAE application, i think you'd be causing more headaches than you solve. Trying to predict vehicle behavior in low-speed corners would be very difficult, and the added stability in higher speeds may mean manuvering around the slalom cones is more difficult as the rear wheels could turn into them (counteratcing the common practice of running a shorter rear track than front).

A system that changed from counter steer to parallel steer according to speed might work better, but when cornering and accelerating/braking, you might find the rear end having a mind of it's own.

[PatClarke]

Ramon,
You got it in one!
Pat

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
Now some bald statements. Your team did make themselves look boorish at last years event, whether you were part of it or not. Despite not being supposed to help, Ron and I went to offer some advice as we could see your teams frustration. Essentially, we were 'pi**ed off' because they were busy. Ron's comment was, 'Oh well, I guess they know more than me'. Ron was the senior design judge and your team members must (or should have) known who he was.

We had observed what was going on around the track. We (mostly he) had determined what changes could help, and we went to suggest you remove one particular radius arm. The effect of that change was more than simply loosening up the DeDion location.
But it didn't happen, and you guys understeered yourselves right out of the competition! </div></BLOCKQUOTE>

Ah. when you first commented about this, I had no idea what you were referring to. Hadn't heard about what happened at the 05 comp, other than that the car had difficulty with the hairpin.

I wouldn't want to rag on last years team without knowing the other side of the story (or the guys involved, for that matter), but it would be a slight understatement to say that you and Ron would know what you are talking about. http://fsae.com/groupee_common/emoticons/icon_smile.gif Not sure why they ignored the advice, but from what I've heard the current team feels the same way you do about it.

I hope your experiences last year (and with me in this topic - I'll make sure I know who I'm talking to in future) haven't completely lessened your opinion of UARC. Rest assured the team will be making every effort to earn your respect this year.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Suddenlee:
Maybe now my earlier comments are a little less cryptic. Another suggestion is that the team should look at a better dissemination of information down through the generations, a suggestion that should be heeded by all teams! </div></BLOCKQUOTE>

I agree. One of the aims of this years team is to do exactly that.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Test Driver:
Look into the 4ws system that Honda had as an option on some US market Preludes. I beleive the system was offered during the late eighties or early nineties. </div></BLOCKQUOTE>

Yeah I know about the Preludes, I thought it was always an opposite steer system though - for parking as D-Train mentioned. Might have another look. I know the HICAS system in Nissan 180SX's and Skylines is parralel steer at higher speeds, but that's electronically controlled with hydraulic actuators, I believe.

Thanks for the help. I never was seriously considering putting a 4WS system on a FSAE car, but I like to cover all bases. Plus I find them interesting.

[TG]

Ok, I've been way, way too busy to comment on this thread over the past couple days, but I'll try and squeeze in something on steering the rear wheels. A few years back, it was being considered to use a hydraulic unit linking the steering to a rack in the rear on this up coming car. I had seen the graph of the preludes mechanical system (it's somewhere out there on the internet) and if I remember correctly had about 5 degrees maximum lock opposite to the front at some determined front angle and went back to a degree or two of lock in the same direction. The rules were then changed to (I forget if it was either mechanical or electrical) RWS systems having to have a lock at no more than 3 degrees steering, so we promptly decided on going with the other system to get around that rule. However, recently, the rules are now very general about RWS systems and include both mechanical and electrical systems at a maximum of 3 degrees.

Now, this wasn't a blind decision. There was a guy around here transferring from UT Austin and one of the years he was on their team, they did implement a 4WS car. If I'm not mistaken, they had a hydraulic system, but it only turned the wheels opposite or with the front steering, depending on a valve they used to flip it manually. Our design was to be a one -up on it and make it customizable to where it would be similar to the prelude's. What the guy said about the car with 4WS at competition it that they beasted the skidpad where it handled like a champ. They had set the system to opposite lock for the tight cornering. However, for the rest of the dynamic competition, it sucked a big one. The had to keep the rear steering going in the same direction as the front steering because the transients were just out of control in opposite steer. So we knew we could improve on the system at the time and end up with a system that could very well prove to be advantageous.

Since the rules change dashed a mechanical and electrical system that pretty much forced us to scrap this idea. I do know of a way around it (and be even more beneficial with the vehicle dynamics) but its way too complicated to start now. So that's my little story on 4WS systems.

[darienphoenix]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I do know of a way around it (and be even more beneficial with the vehicle dynamics) but its way too complicated to start now. So that's my little story on 4WS systems. </div></BLOCKQUOTE>

I don't suppose you'd be willing to share your idea for younger generations? http://fsae.com/groupee_common/emoticons/icon_smile.gif

[TG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by darienphoenix:
I don't suppose you'd be willing to share your idea for younger generations? http://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

I know I'd probably want a law student with me even though I know I'd be right. Damn spirit of the competition, that's the thing that kills me because it's so vague.

But, use your imagination. Look at vehicle dynamics from it's basis and how different things affect others. But in all honesty, I'd worry about getting the rear suspension geometry down and set before you start worrying about something like I have in mind. You need traction and grip first.

[Travis R]

Hey TG, click on the link in the very first reply. It'll help clear up some misinformation.
Here I'll even save you the effort of having to click "back". http://fsae.com/groupee_common/emoticons/icon_wink.gif
http://fsae.com/eve/forums/a/tpc/f/125607348/m/7056005743
Be sure to read my comments on the 2nd page.

[TG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Travis R:
Hey TG, click on the link in the very first reply. It'll help clear up some misinformation.
Here I'll even save you the effort of having to click "back". http://fsae.com/groupee_common/emoticons/icon_wink.gif
http://fsae.com/eve/forums/a/tpc/f/125607348/m/7056005743
Be sure to read my comments on the 2nd page. </div></BLOCKQUOTE>

Right, forgot about that thread. I remember reading a while back. Anyways, I seem to remember Everett saying you guys weren't having the best of times in the transient behavior of the car. He was probably referring to powering out of the turns. Yeah, the system we were looking at had a non-linear relation between the front and rear steering angle that addressed some of these problems, where at the lower steering angles coming out of the turn, the wheels would be straight or even a little bit towards parallel, helping with reducing the yaw moment coming out of the turn.

[Travis R]

I don't remember any problems like that. As long as you unwind the wheel as you roll on the throttle, then there shouldn't be any problems.
The only things I remember are that it ate slaloms for breakfast, and was a hassle to bleed. http://fsae.com/groupee_common/emoticons/icon_smile.gif
Good luck!