Rear Wheel Steering

[ross]

Honda and other Japanese manufacturers have offered rear-wheel steering combined with front-wheel steering in a few limited editions. But RWS has a couple of built-in problems. At speed, you'd want the rear wheels to steer in the same direction as the fronts, producing a slight "crabbing" vector that would allow you to change lanes quickly without much disturbance to the stability of the car. At low speeds, you might want to have the rears counter-steer, to cut the turning radius and make the vehicle handle more nimbly in parking lots and drive-up windows. The problem appears when trying to switch between those two modes - intuition goes out the window.

With counter-steering rear wheels, it's easier to flip the vehicle at speed, when the rear wheels increase the effective steering angle and you wind up attempting to violate that second part of Newton's First Law:
"An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force" . . . Think of it as mechanically-assisted oversteer.

There just doesn't seem to be a way to transition between the two steering modes, "crab" and counter-steer, without at some point getting dangerous. A few manufacturers have addressed this problem by making the rears steer only tiny fraction of what most of us think would be effective. My limiting the steering angle to only a degree or two, you get some benefit, but can't get in so deep as to become a threat to your own safety. Like many other automotive innovations, the legal risks probably exceed the actual customer benefit - so don't look for this to be in production soon.

Honda and other Japanese manufacturers have offered rear-wheel steering combined with front-wheel steering in a few limited editions. But RWS has a couple of built-in problems. At speed, you'd want the rear wheels to steer in the same direction as the fronts, producing a slight "crabbing" vector that would allow you to change lanes quickly without much disturbance to the stability of the car. At low speeds, you might want to have the rears counter-steer, to cut the turning radius and make the vehicle handle more nimbly in parking lots and drive-up windows. The problem appears when trying to switch between those two modes - intuition goes out the window.

With counter-steering rear wheels, it's easier to flip the vehicle at speed, when the rear wheels increase the effective steering angle and you wind up attempting to violate that second part of Newton's First Law:
"An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force" . . . Think of it as mechanically-assisted oversteer.

There just doesn't seem to be a way to transition between the two steering modes, "crab" and counter-steer, without at some point getting dangerous. A few manufacturers have addressed this problem by making the rears steer only tiny fraction of what most of us think would be effective. My limiting the steering angle to only a degree or two, you get some benefit, but can't get in so deep as to become a threat to your own safety. Like many other automotive innovations, the legal risks probably exceed the actual customer benefit - so don't look for this to be in production soon.

I think I would want the system to lock out at much over 30 mph. Just for low speed maneuvers, it shouldn't be too complicated as there's only one wheel to control, small servo motor on a vertical axis. I don't expect it in production at all, just something that gearheads like myself love to mess with.

 

[BlioKart]

I don't think its possible with the way the Elio is currently designed.

 

[BilgeRat]

I would be comfortable with this as a parking aid. It seems a really good idea for that.

 

[Jim H]

$6800, 5-star safety, 84 MPG, 90% North American parts. The guiding principle is KISS. For all of you who want to re-engineer it, wait until you get yours and you can re-engineer it to your heart's content. The rest of us will take the plain vanilla version.

 

[Rickb]

$6800, 5-star safety, 84 MPG, 90% North American parts. The guiding principle is KISS. For all of you who want to re-engineer it, wait until you get yours and you can re-engineer it to your heart's content. The rest of us will take the plain vanilla version.

I like it the way it is. I was just curious if it was even possible to single rear wheel steer, no front wheel, like the Toyota i-Road.

 

[Chris F]

It's like driving a forklift

 

[Rickb]

It's like driving a forklift

I can't remember the last time I took my Hyster out for a 70 mph spin down the lonesome road. lol

I do like and can relate to the example.......thanks.

 

[zelio]

$6800, 5-star safety, 84 MPG, 90% North American parts. The guiding principle is KISS. For all of you who want to re-engineer it, wait until you get yours and you can re-engineer it to your heart's content. The rest of us will take the plain vanilla version.

No! I want the dark chocolate version. I don't like vanilla! :-) Z

 

[Jim H]

No! I want the dark chocolate version. I don't like vanilla! Z

Z, I thought you wanted Creamsicle. Dark Chocolate isn't one of the color choices......LOL

 

[BilgeRat]

Strictly "blue sky" Jim... :-)