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New Car Can Lean Into Curves, Literally
cartechboy (2660665) writes "You know how motorcycle riders lean into the corners, sometimes even touching their knee to the ground? Mercedes-Benz has developed new technology that replicates that sensation by leaning the car into bends. It's called Dynamic Curve and it's part of the Active Body control suspension system on the new 2015 Mercedes-Benz S-Class Coupe. In turns, special plunger cylinders raise the suspension struts and lower the opposite side, depending on the direction of the bend. This has the result of tilting the car body slightly towards the inside of the corner, countering centrifugal cornering forces. Mercedes says it's not design for increasing cornering speeds, but increasing pleasure for the driver and passengers."
As long as internal car data bus allows me to tie the sound system to the suspension system so I can bounce with the music down the road.
Except the current suspension compresses on the outside of the curve. This system sounds like it compresses on the inside of the curve, redirecting the g-forces into the occupants' buttocks and not the sides.
Think. Cars naturally lean THE WRONG WAY on curves. They tilt over toward the outside. This magnifies the centrifugal force you feel by adding a gravity component to it.
We are talking about suspensions that lean THE RIGHT WAY on curves. They tilt toward the inside, like a banking airplane. This reduces the centrifugal force you feel by subtracting a gravity component from it.centrifugal
Oblig
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
It will be used for rider's comfort. Not to take corners faster. I'm amazed they don't pretend it's for safety, like all the other gadgets and improvements that, eventually, led drivers to drive faster and more risky because their gadgets allow even the worst driver to keep his car under control at higher speed.
Which doesn't mean that I think anti-lock or traction control are bad things. Quite the opposite. But someone should tell the idiots that they were NOT meant to be used as a substitute for knowing how to drive, dammit!
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Except sway bars counter that effect by lifting the inside wheel. Stiffer/bigger sway bar, you can get it to do what mercedes is doing with a lot more work. Lets not even get into torsion bar systems.
This adaptive suspension technology can be valuable for addressing poor roadway design, such as opposite-camber banking (yes, such things exist and can be very dangerous in poor weather). One of the most egregious examples of opposite-camber banking occurs in Canada between Vancouver and Burnaby, BC on Boundary Drive on which vehicles travel steeply downhill, typically in rain, and are presented with an opposite-camber dogleg turn about half the way down. So, while everyone is riding their brakes their vehicle suddenly gets crossed up. Since it is noticeably uncomfortable in a low-slung sports car, it is more than an annoyance on buses and in large trucks. Redesigning/repairing those poor roadways can take years, so any step by vehicle makers to have this kind of adaptable suspension is worthwile.
I deny that I have not avoided attaining the opposite of that which I do not want.
Drivers depend on feedback from the car to help them make necessary adjustments.
If a curve isn't banked enough, the car shouldn't fool the driver into thinking that it is banked enough.
That feeling one gets when the car leans towards the outside of the curve is telling the driver to slow down!
A sway bar, no matter how stiff, can only reduce roll, not counteract it completely. What Mercedes is doing goes much further than that: it actually makes the car lean inward, resulting in a more comfortable ride.
There is no such thing as centrifugal force... when you talk like that you basically show why dumbasses shouldn't be involved in car design.
Stock XKCD counterpoint: Centrifugal Force
Sway bars have downsides. This system shouldn't have those.
Sway bars are cheap and the bushings are the only thing that can wear out. This system probably isn't cheap and will cost a hell of a lot more than bushings do to fix it.
Mmm... lower perception of centripetal force may encourage drivers to go faster into corners. I remember reading comments supposedly from highway safety researchers that insulating drivers from road noise and vibrations, as modern cars do, reduces their perception of speed, thereby increasing the likelihood and severity of road accidents. Let's see what happens to accident rates on corners with cars fitted with this device.
A couple of others have mentioned the ~2007 work that Bose did in active suspension, but nothing really clarifies the idea like pictures or video:
http://www.youtube.com/watch?v=eSi6J-QK1lw
Leaning into a curve is one thing, but At 1:40 the car jumps a curb-size obstable. Nice.
I'm not sure it's worth the engineering complexity versus standard sway bars (for a typical diver),
http://www.youtube.com/watch?v=_liGnV3PTiQ
but Bose's system (and Mercedes') sure as hell is cool.
And while we're on the topic of making unreasonably large cars more agile than they ought to be, I'm still pretty happy with Volvo's 4C system and oversized sway bars on a 7yo S80 V8 -- switching to "advanced" it behaves like a fat WRX or that pudgy football player you didn't think could move that fast, and in "comfort" mode it hunches down *evenly* about 6-8cm in hard curves... all with just plain old leverage, a few poly bushings, and electromagnets around the ferro-oil filled shocks. Simple is good.
I think not...(*poof*)
People that drive these cars only keep them a few years, depending on the length of the lease.
You do realize the car doesn't just disappear when it's returned at the end of the lease, right?
Check the direction and magnitude of those force vectors there -- whether the car leans inward of outward in the curve the resultant force vector is the same -- the sum of the gravity and the centrifugal force at (about) right angles to the gravity; the direction of this resultant sum as felt in the car is somewhere between down and toward the outside of the curve. The difference is that if the car is leaning inward then your body is more aligned with the resultant and it feels more comfortable (just as in an aircraft turning in a perfectly coordinated turn). If the car is leaning outward, as all conventional cars do, you feel the resultant as more of a sideways force on your body which is more uncomfortable. In either case the magnitude of the resultant is the same.
And for the other repliers who can't seem to get out of the inertial frame, centrifugal force is a perfectly fine concept in the moving reference frame of the car going around the curve. That's what an accelerometer would feel (measure) in the car -- an (apparent) force pointing outward perpendicular to the curved motion of the car.
The car going around the curve can be seen to be in a rotating reference frame from the point of view of an observer in the car with the center of rotation at the point inside the curve which the car is maintaining a constant distance from. And the car itself is rotating in inertial space by the fact that the direction it is pointing is changing going through the curve (unless it is understeering very badly).
Actually, the force that is pushing you against the seat is centripetal force, not centrifugal force.
Depends on your reference frame.
The only real force is the angular one
Centrifugal force is quite real. So is the Coriolis force and the Euler force . All three occur when the reference frame used to describe the force accelerates relative to another reference frame and in fact you cannot accurately solve many classical mechanics problems without them. For example the surface of the Earth is a rotating reference frame. Don't confuse the meaning of the term "fictitious force" to mean that it doesn't exist. A fictitious force is one that simple doesn't exist in an inertial reference frame. There still are non-inertial reference frames.
ABS is dangerous to people who learned to drive without it.
Only if they are not competent drivers to begin with. ABS was not on the vast majority of cars when I learned to drive and we seem to have somehow survived the transition. ABS demonstrably makes drivers safer and there is plenty of data to prove it.
The normal technique of locking and releasing the brakes by pumping the pedal doesn't work, because the brakes never lock in the first place, so all you end up doing is repeatedly letting go of the brake for no reason.
Manual pump braking works exactly the same way with or without ABS. ABS does exactly the same thing as manual pump braking but ABS does the braking and releasing but much faster than any human could possible do it and therefore it works better.
The only time I have ever slid though a stop sign in the snow was in an ABS vehicle.
Oh, well, one anecdote should convince us all... [/sarcasm] You can still slide in an ABS equipped vehicle if the road is sufficiently slippery. If the surface is truly close to frictionless it doesn't matter what kind of brake system you use. You are along for the ride. For example my driveway is fairly steep and after an ice storm you are going to slide down a portion of it. It does not matter what you do with the brakes because there is basically no friction between you and the road. You didn't slide through the intersection because of ABS. You slid because you were going too fast.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
All cars lean. The design of the suspension just decides how much it leans.
Think. Cars naturally lean THE WRONG WAY on curves. They tilt over toward the outside.
There's no "right way" or "wrong way" for a car to lean on a level surface with all four wheels on the ground. The motorcycle metaphor doesn't work well here because part of turning a two-wheeler involves moving the center of mass off the centerline and letting gravity pull you through the turn. To paraphrase Douglas Adams, turning a two-wheeler involves throwing yourself at the ground and missing.
This magnifies the centrifugal force you feel by adding a gravity component to it.
On the contrary: being thrown towards the outside of the turn means the turn radius increases, which results in a decrease in centrifugal force.
They tilt toward the inside, like a banking airplane.
Another poor comparison. Airplanes roll while turning because their wings are their largest working surface areas and need to be tilted off of horizontal to get the lift vector pointing "that way." The comparison here would be in banking the road surface itself (the working surface for a ground vehicle) rather than any shifting done by the suspension on a level road surface.
All Formula 1 cars had active suspensions in the early 90's. They were computer managed to keep the car flat in the curves and maximize aerodynamically generated downforce and also to absorb impact with kerbs in chicanes with almost no rebounds (more traction). Actually they were introduced by Lotus in the early '80s but didn't get mainstream because of weight and limitations in the electronics. Williams had a better version of them in their 1991 car (electronics got much better by then) and eventually all the team followed suit until FIA banned the technology starting from 1994 because of safety concerns (Zanardi barely survived a heavy crash due to an active suspensions failure). More details on F1 active suspensions here.
Production cars used them since the 80's.
What Mercedes is doing now is reminiscent of the early Italian high speed train Pendolino. "By tilting, the train could go around curves designed for slower trains at higher speeds without causing undue discomfort to passengers." See one of those trains tilting in a curve in the UK in 2012.
Force requires energy and the only energy being put into the system is rotational, and everything else that appears to be a force is simply some aspect of momentum
Congratulations, you just described movement in a non-inertial reference frame but you flunk vectors 101. Force requires mass and acceleration and nothing else - energy is merely a derived result in this case. The acceleration can be straight line or rotational. Acceleration occurs any time you have a change in velocity which is a vector. Change the magnitude (speed) or the direction (heading) and you have accelerated. So-called "fictitious forces" occur in the later case due to Newton's second law. The effects are real - they are only fictitious in the same sense that imaginary numbers are different from "real" numbers. You need both "real" and "fictitious" forces to accurately describe certain phenomena and the force (or force-like depending on reference frame) effects are demonstrably very real. In curved spacetime, ALL reference frames are non-inertial and in the real world spacetime is curved as far as we can tell. So saying "fictitious forces don't exist" is equivalent to saying we live in flat spacetime. This does not match our observations.
I've ridden on trains that do this and I found the leaning in to be very gimicky and arbitrary. It would have been just as effective and mechanically more reliable to tile the rails instead.
This is what should be done anyway. If a car is going around a curve at the designed for speed of the curve, the road is already going to be appropriately banked for the corner. If the car induces additional bank, it won't feel right. If the corner is a flat corner, the speeds involved will be so low that the bank of the care won't feel right. The only time when this will feel right is when the car is going around the corner at a speed which the corner is not designed for. At that time, the driver and passenger will feel that they are comfortably going around a gentle curve. Meanwhile their car will fly off the road and crash.
If you are not allowed to question your government then the government has answered your question.
The hands on the clock as I'm waiting for Monday to end...
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