Steering outside the box.

[McGuyver]

Why doesn't anyone use dual steering levers with linked bellcranks inboard of the inner tierods, given the quick steering ratios used and the few degrees the wheels turn?

I see no requirement to have a steering wheel, column, or rack. The bellcranks could have a relatively linear ratio in such a narrow range of motion.

3.4.6 in the '07 rules dictates the form the steering wheel must take. It does not say a steering wheel must be installed.


The front hoops distance and height could be from vertical steering levers with the steering centered. The bike shifter can be cable actuated with a thumb rocker on the right steering lever.

No need for any emotional responses.

[McGuyver]

Why doesn't anyone use dual steering levers with linked bellcranks inboard of the inner tierods, given the quick steering ratios used and the few degrees the wheels turn?

I see no requirement to have a steering wheel, column, or rack. The bellcranks could have a relatively linear ratio in such a narrow range of motion.

3.4.6 in the '07 rules dictates the form the steering wheel must take. It does not say a steering wheel must be installed.


The front hoops distance and height could be from vertical steering levers with the steering centered. The bike shifter can be cable actuated with a thumb rocker on the right steering lever.

No need for any emotional responses.

[SNasello]

This sounds like an idea from the Queen's Solar Team. No.

[billywight]

Lever steering??? Looks like you'll have to pay royalties to this guy:

http://www.google.com/patents?vid=USPAT6709013&id=9KcQA...AJ&dq=lever+steering (http://www.google.com/patents?vid=USPAT6709013&id=9KcQAAAAEBAJ&dq=lever+steering)

or as Stefan suggested, No.

[Bill Kunst]

How about this for steering outside the box: Telekenetic steering. No steering wheel or levers would be needed. Just call me Magneto.

[McGuyver]

Royalties are paid where profit is made. If your going to do what everybody else does, what is the point? Pull left lever/push right to turn left. It's not magic as no magnets are required.

With a rack, the inner tie rod pivot point would only change position laterally. This system would complicate things as that inner pivot point moves both laterally and longitudinally. Thanks for the replies, but I want to know why "no" is the answer.

[Garlic]

"given.. the few degrees whe wheels turn"

Not sure what car you are looking at but the FSAE tracks generally require a lot of steer angle.

[billywight]

This team already did it:

http://img334.imageshack.us/img334/6774/trimaxionmicrocarday2006ky.jpg

[Steve Yao]

One of the factors that determine your placement at competition is how good your drivers are in the car. One fo the factors to how good your drivers are is how much time they are in the car and how familiar they are with it. If your drivers have to devote time to learning this new steering setup and then learn to drive it fast, you've wasted valuable learning and testing time by choosing a outside the box solution. Besides, it better damn well make the driver/car faster. If the driver/car never regains the speed lost in the initial learning period, then you've just shot yourself in the foot. You've got an out-side the box solution that has made your car slower. Thats extremely poor judgement.

Do some testing, try and setup a video game or something using "Tank Steering" and see if its faster before devoting real resources to it.

[KU_Racing]

Maybe its just me, but I thought entry period for the contest to determine angular velocity adjustment controller champion of the world ended in 1917.

The votes have been tallied, and here are the results:

Final Score:
Steering Wheel: 789,985,785,456,782,763,624,154.087

Fiddle Brakes: 1

Tiller: 0

[SNasello]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by McGuyver:
Royalties are paid where profit is made. If your going to do what everybody else does, what is the point? Pull left lever/push right to turn left. It's not magic as no magnets are required.

With a rack, the inner tie rod pivot point would only change position laterally. This system would complicate things as that inner pivot point moves both laterally and longitudinally. Thanks for the replies, but I want to know why "no" is the answer. </div></BLOCKQUOTE>
Let me expand on why this is such a bad design choice. First of all, as SEY said, it will take a long time for your drivers to figure out a) how to use it, and b) how to go fast with it. Second, and more important, i doubt that b) will ever come into play because of the horrible feedback from the road the driver will get. Its just a bad idea all around and would cost you points in both design and all of the dynamic events. Probably sales too, because it would be pretty difficult to sell a car that doesnt have a steering wheel.

[McGuyver]

Thanks for the posts Garlic, Stephan, and SEY. I did consider the drivers learning curve. The control would be like snow skiing.

I don't understand how feedback is lessened with a rack when the overall ratio is the same.

Anyway, I have found that the potential advantages of this system cannot be exploited due to other rules (which were not in place in 1917). It is much better to know why it isn't being done.

Garlic, I was looking at 40-50 degrees total at the wheels. It is interesting to me and judging from the number of posts I have received, I am not alone, even if it only brings a silly grin. Oh yes, I WILL be remembered.

KU, "We have always done it this way" is not what I would expect from an engineer. There is more to engineering than seeing how light a part can be before it breaks.

Nice car Billy. You must be very proud http://fsae.com/groupee_common/emoticons/icon_wink.gif.

[Biggy72]

But you could practice on one of these bad boys until you get your car done... I'm sure the lawn maintenance crew wouldn't mind helping out an FSAE team.

http://www.kicpics.com/cspi/images/main/HV968999301

I don't know how good of an idea it is, but they are fun to drive.

[Brendon D]

So... how would you clutch and shift this bad boy with each hand controlling a front wheel at all times? Steering wheels work extremely well in terms of ergonomics, functionality, and performance. Plus our solar car team uses that and I sure as hell will not follow them.

[Wesley]

Actually, clutching would be pretty easy. You could rotate the handle motorcycle-throttle style for clutch and put a lever bike-brake style on each one for shifts. Or thumb-buttons for a pneumatic system, and levers for clutching.

But who would want to drive it? Not to mention the added wideness necessary to fit the handles in the car.

Sure, it is outside the box, but you could also say "why not ditch these silly wheels and go to an octagon? given sufficient track preparation, they'd work fine!"

[Brendon D]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:
Actually, clutching would be pretty easy. You could rotate the handle motorcycle-throttle style for clutch and put a lever bike-brake style on each one for shifts. Or thumb-buttons for a pneumatic system, and levers for clutching.

But who would want to drive it? Not to mention the added wideness necessary to fit the handles in the car.

Sure, it is outside the box, but you could also say "why not ditch these silly wheels and go to an octagon? given sufficient track preparation, they'd work fine!" </div></BLOCKQUOTE>

This is true, and we are thinking of integrating the shifter and clutch on one handle to keep as much stuff between the wheels as possible, but thats a hell of a lot to do with your hands, I'd consider myself pretty coordinated, but I wouldn't want to race a setup like that.

[McGuyver]

The clutch and throttle could handled as they normally are. Everything could be controlled by the hands for a driver paralyzed from the waist down, although the driver probably could not get out of the car and away from it in a reasonable amount of time on his/her own.

The left and right front wheels are linked. Two levers are used to reduce driver effort. There is no reason to release either lever during the cars operation.

Lever steering force is transferred from handle to handle through the upper torso by the biceps and triceps. Steering wheel force is transferred into the harness and seat, with the major muscles being the deltoids, tricep, and upper back. With levers, driver fatigue and wrist motion should be reduced.

Since the lever moves a few degrees compared to the rotation of the steering wheel, the levers can accept hydraulic, pneumatic, and/or cable controls without binding.

[JHarshbarger]

The main problem I see with this is high speed cornering (or what you will be using the car for 99% of the time.) When you turn in to a corner, what's the chance that both of your hands will move to the optimum distances in order to make both wheels turn with, for starters, the same angle, and for further refinement, the best akerman angles?

My experience with this type of setup has been limited to lawn mowers, but that setup is far different than what you're talking about. The lawn mowers that I've driven with this setup use varying power to each rear wheel to "steer" it. It's very convenient because you can turn on a dime. Still, this is almost the opposite of what you are talking about doing and it is a very different application.

Consistency seems to be my biggest draw-back on this idea. Cornering, once you've figured out how to drive it, would be very difficult at high speeds and would not see the same refinement as a single-input steering system would. I would work on refining the linearity of a steering wheel system with adjustability. Take the "learning curve" time away and use it toward refining the akerman in your steering.

[JHarshbarger]

If the wheels are linked, then you won't have the problems that I mentioned above. Apparently you've already thought that through. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Superfast Matt McCoy]

I bet it would be a blast to drive. That's not to say it would be fast. You could tie two strings from the gas pedal to just above and below the pivot on one of the levers to control your corner exit throttle. Like hillbilly traction control.

I would love to see this steering at competition. I'm not going to do it, but if you do, find me in Detroit and I'll buy you lunch.

Remember, if it's stupid and it works, it's not stupid. Of course if it doesn't work...

[billywight]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Nice car Billy. You must be very proud </div></BLOCKQUOTE>

Did you notice the bitchin stereo?

[KU_Racing]

You are right on the front that 'we do it a certain way already' is not a good reason for making an engineering decision.

The other side of the coin is that the whole point of engineering is problem solving- the point is not to come up with something new whenever possible, the point is to optimize a system for the given set of conditions/requirements/constraints.

In my opinion, the steering system of a racecar must do 4 things:
(listed in order of my opinion of their relative importance)

A)provide the driver with reliable and simple method of controlling of the direction of the vehicle and still operate all other vehicle controls, i.e. shifting, clutching, accelerator, brake, and reading any pertinent information from the dashboard

B)Be as familiar and comfortable for the driver to use as possible

C)Provide significant feedback regarding the grip levels and weight transfer reactions of the tires to the drivers hands (without causing injury)

D) Allow the driver to operate the system for the entire race distance before fatigue sets in, while sacrificing as little as possible in the feedback department.... it seems to me that feedback and comfort seem to be enemies, i.e. manual steering (excellent feedback) vs. power steering (very low effort)

Now it seems to me that a simple, proven steering wheel is superior to a lever-style steering system in all of the above categories. Here is my reasoning:

(feel free to chime in)

A)A steering rack is a simple device with very few moving parts, and can be built to be very strong and reliable with no maintenance. I dare you to find a team that has been disqualified or had a steering rack failure. If there are any out there, I would venture to guess that the numbers are very small, even amongst teams that build their own steering systems. As far as reliability is concerned, I would be very worried about trusting the steering of a vehicle to any hydraulic/pneumatic/servo controlled system without another complete independant backup like you see in modern road going OEM steering systems. This would come with a severe weight/space/parts count/cost/complication penalty.

B) This one is easy: 99.99999% of everyone in the world that has ever driven a car has used a steering wheel. Comfort applies for the same reason, as well as the fact that I think a steering wheel makes sense to the human brain: rotate the control, and the thing under control rotates, as opposed to pushing/pulling something to make something else rotate. From a strictly logical standpoint, like for someone who has never been in a driver's seat before, the concept of a steering wheel seems much simpler and more linear to my brain, and I suspect to the brains of almost everyone else.

C)I dont see anyone designing a mechanical/hydraulic/pneaumatic/whateveratic control system that can beat the good ol' rack and pinion for pure driver feedback. The feedback through a steering rack, even one with a very high ratio of turns to travel, is direct, easy to read even for an entry level driver, and rarely (hitting curbs or other objects aside) has enough force to cause injury to the driver. It seems to me that there would be severe feedback problems with a lever-syle system in a racecar. the normal vibrations and movements of the car cause the driver to be bounced fore and aft in the car, as well as side to side. The fore and aft motion, being along the same axis which the driver would operate the levers through, would cause involuntary steering adjustments to be made, however small. The side-to-side motion of the driver would impart severe bending loads into the mounting points of the levers, meaning they would have to be very very strong (i.e. heavy) to withstand the forces that the driver would use to hold him or herself in place. The other possible movement of the car, in rotation, causes similar problems. The steering wheel, however, is very easy to mount in a location that is light but still very stiff in all three translation axes and the two constrainted rotation axes. This means that the driver can use the steering wheel to maintain some control over his or her position relative to the rest of the car, without affecting the actual input that is relayed to the steering system, and without imparting forces into the wheel that would damage it, its linkage to the rack, or its mounting points to the frame.

D) Fatigue is the final test of a steering system. While you seem to have confidence that a driver would be able to use the muscles of the arms to lever-steer the vehicle without significant fatigue, I would have a different opinion. In order to provide for enough steering angle without needing a herculean amount of effort to operate the system, a lever setup would need very large amounts of travel relative to the change in steering angle. This means that the designer of a lever system is stuck with two options: low travel, high effort, or high travel, with lower effort. The packaging and safety constraints of the cockpit (everything has to be below those rollhoops...) seem to point in the direction of high effort, low travel for the lever setup. This style of system would prevent the driver from making small, precise, and quick changes to steering angle in response to the car's movements. The situation could be remedied with a power assist system, but that comes at a large weight, cost, and complication penalty as mentioned above. The steering wheel allows for the use of not only the large muscles of the shoulders and back for large force inputs, but also of the smaller and more sensitive muscles in the forearms and hands when delicate and precise input is needed.

[McGuyver]

That is a bitchin stereo. I wonder how much it hurts the guys range? It appears to be a pure electric. That has to be one of those "more fun to build than drive" vehicles.

KU, thank you for the reply. I appreciate your opinion.

There is no question that the rack and pinion is the right tool for higher ratios of production cars. When the required ratio gets down around 3 or 4:1, other options can be considered.

The levers are bellcranks and linkages, as robust as your spherical bearing suspension.

Hyd/pneu/elec refer to other systems, not the steering.

The steering wheel is not there to position the driver and neither are steering levers.

You bring up a very good point. Broken thumbs from steering wheel spokes are common. With levers, the same force would be absorbed through the arms, hands, and wrists. Collapsable lateral links to the levers or annealed lever tubing (softer than the other steering tubes) could absorb this peak force yet allow the vehicle to still have steering control. If the hit is not enough to damage the control arms, total steering angle lock-to-lock should be approximately 90% after the hit, enough to pull over or pit. The spindles should have travel stops.

The greater the lever travel is, the finer the steering input can be.

I think the ratio can be adequate and lever travel can be reasonable. I have enjoyed the conversation and appreciate all the input.

I didn't see anything in the rules preventing a leaning car either but thats a discussion for another time.

[Marshall Grice]

using a lever for differential braking would be way cooler...

[KU_Racing]

I agree, Marshall.

A steering wheel is not designed to position the driver in the seat, but I think you would be hard pressed to find a driver who at one time or another does not use their arms and hands on the steering wheel to counteract the g forces on their body.

[Gyro]

I keep picturing that jackass from the old gazelle workout commercials.

You know, this guy: http://www.youtube.com/watch?v...iDVE&feature=related (http://www.youtube.com/watch?v=mbDe9WuiDVE&feature=related)

[Dr Tron]

this seems like complicated for the sake of complicated. if your convinced that this fore aft displacement through the linkages (im guessing similar to the patent shown) why not just run a standard steering rack with the rack facing front to back instead of left to right, at least you would have a wheel. Also you could use a steering box in place of a rack however in the end we are coming up with a way to fit a square peg in a round hole like some kind of retarted space chimp

[Whis]

I have a story on the commentary going on about 'new' ideas for the sake of being new vs new ideas that are actually better.

Every year, ISU's HPV (Human Power'd Vehicle) builds a tandem trike. Usually, they have regressive steering, 20 feet of chain and the least rigid frame possible. Especially in the pedal area. And every year, they go to competition and compete against 4-12 other teams and usually come in around half way to 2nd. And, again, every year we ask them how they did and they go "Well.... we were doing great except for this one team that beat everyone else's time by half.." Usually, it turns out that team (that won) had pretty much copied a 6000 dollar trek tandem bike, put the best bike components they could find and gotten a drive efficiency of 98%. The ISU team always speculates on how something so simple could beat their awesome super dupper bike.

My point to this is thus: If something has been around for 100 years, usually there are damn good reasons for it to be there. The design of a bike is pretty well accepted now. This is why a standard road bike blows the doors off a recumbent. There is a reason wheels are used vs levers. It's just a better user interface.

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Whis:
Usually, it turns out that team (that won) had pretty much copied a 6000 dollar trek tandem bike, put the best bike components they could find and gotten a drive efficiency of 98%. The ISU team always speculates on how something so simple could beat their awesome super dupper bike.

My point to this is thus: If something has been around for 100 years, usually there are damn good reasons for it to be there. The design of a bike is pretty well accepted now. This is why a standard road bike blows the doors off a recumbent. There is a reason wheels are used vs levers. It's just a better user interface. </div></BLOCKQUOTE>

I've been talking about this for a while, but next time HPV comes in the shop I just want to race their last year's vehicle against my 1997 Giant Upland, which was like a $150 mountain bike when it was new. I'm pretty sure I could still beat two people on their HPV by myself.

Too many engineers, especially young engineers, are too distracted by the potential spoils of "thinking outside the box" to think about the bottom line...even when the bottom line is performance, not money.