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Scientists Discover How To Stop Luggage From Toppling On the Race Through the Airport (theguardian.com)
An anonymous reader quotes a report from The Guardian: Scientists have worked out why suitcases tend to to rock violently from one wheel to the other until they overturn on the race through the airport. This most pressing of modern mysteries was taken on by physicists in Paris, who devised a scale model of a two-wheeled suitcase rolling on a treadmill and backed up their observations with a pile of equations and references to holonomic restraints, finite perturbations and the morphing of bifurcation diagrams. Fortunately for non-physicists, the findings can be reduced to simpler terms. For the suitcase to rock it had to hit a bump or be struck in some other manner; the faster the suitcase was being pulled, the more minor the bump needed to set it off. So far, so obvious. But Sylvain Courrech du Pont wanted to know more. Why did a rocking suitcase swerve and make such violent movements that it might eventually topple over? After more treadmill tests and more equations, the answer popped up: because a suitcase's handle pulls from the middle and the wheels are at its sides, the suitcase swerves inwards whenever it tilts up on one wheel. If the rocking overcomes the dampening effect that happens when each wheel touches the ground again, the suitcase will keep on rocking or eventually flip over. In conclusion, the researchers discovered that "when a suitcase starts to rock out of control, the correct response is not to slow down but to pull it faster." The scientists have published their findings in the journal Proceedings of the Royal Society.
Or just get one that has 4 wheels and don't look like a dork
People who tow trailers have known about this for decades.
The handle is also on the same side as the wheels, so when you're pulling it along the weight is above the pivot point between the wheel still on the ground and your hand.
If the handle was on the opposite side from the wheels the weight wouldn't be as high (it would be more in line with your hand and the wheel), so the suitcase would be more stable.
As noted in the full text of one of the original articles about the wheeled suitcase research, slowing down is the worst thing you can do when towing a trailer and the trailer begins to oscillate back and forth. Slowing down will increase the probability of a "jacknife" crash, in which the trailer being towed jerks the towing vehicle out of control.
I had to do this years ago, towing a large U-Haul trailer which probably weighed as much as the car towing the trailer ( I never should have tried to tow such a heavy trailer with such a light car -- this is a BAD idea and I'd never attempt it again ).
The excitement began as I was towing the trailer at around 70mph ( too fast, again I was making a novice mistake, driving too fast ). The trailer and car began to oscillate and each swing of the trailer was larger than the last. I instinctively knew if I backed off the throttle I would lose control. So instead I downshifted one gear and gave the engine full throttle. This acted to jerk the trailer and stabilized things. I am sure if I had slowed down, it would have resulted in the sort of crash that led the local TV news that day.
The same physical principal applies to two-wheeled trailers pulled by cars with a hitch.
Have you ever seen someone driving down an interstate, two-wheeled U-Haul or similar trailer in tow behind their Honda Civic? I sure have. I back off, and watch while the driver tries various maneuvers. The trailer will start to swing side-to-side. Then it will start skipping from side-to-side. Then I get bored and pass... two lanes over. Never once has one of them simply decelerated and pulled over to the shoulder.
Because they don't have enough tech stories?
Get a suitcase with a rigid handle. Then it is impossible to rock because your hand would keep it steady. It can only rock if youre pulling it by the strap and the reason why it topples over faster when you slow down is because you are reducing the tension on the strap.
This. Already debunked.
Simple enough to design shock absorbers for the wheels. A proper shock absorber reduces harmonic effects. On vehicles these devices are remarkably affordable and effective. For luggage they could be very cost effective. A simple friction device with a compressed gas cartridge would do the trick. Feel free to design & patent- I don't need the millions it will bring.
...omphaloskepsis often...
The same principle applies when pulling a trailer behind your car/truck. If it starts swaying/swerving, speed up! It'll straighten right the fuck up. Slow down/brake and get ready to wipe out!
I would think that would get you shot, nowadays.
#DeleteChrome
Anyone who has ever driven a trailer should have been told about fishtailing. (If you have driven a trailer and haven't been told you should google it immediately.)
It's the same thing.
The only thing preventing this scientific breakthrough was the apparent inability to intersect the community of truckers and physicists despite their relative interdependencies.
Ad impressions?
This is common knowledge. Also goes for bikes and speed wobble.
So what this is telling me is that I need to install coilovers on my suitcase. This way I could adjust the dampening and spring rates to ensure the best response on uneven terrain. I could then even lower it if I wanted, but it's pretty slammed as it is.
... when a suitcase starts to rock out of control, the correct response is not to slow down but to pull it faster.
[27] Response may be different s/suitcase/penis/, but this has not been tested on a treadmill.
It must have been something you assimilated. . . .
Hey guys, how do you nominate someone for the Nobel prize?
Dampening makes something wet. Damping absorbs energy (friction). Unless you're adding moisture to slow down oscillations, you're damping rather than dampening.
dom
It's a centipede, and it's really time for you to get back on the meds.
This article just rocked me to the core. It blew my mind. Since my brain is only attached to the rest of my nervous system by a single connection and was unable to generate a significant accelleration ... it toppled over (despite traveling cautiously and at slow speed)
Design the wheels with miniature shock absorbers. ;)
After a few years you'll get boringly familiar with journalists misreporting familiar things in lurid terms. Media hacks usually know next to nothing about science - and a good headline is much more desirable than strict accuracy even when they do. Put in perspective: this was an undergraduate research project, such as just about every student who takes a degree will undertake at one point or another. Such things are about getting the students to practice and demonstrate their abilities to investigate a problem, draw useful conclusions and present the results. They MAY break new ground, but that's certainly not a requirement - that's what PhDs are for.
How about buying luggage without wheels, and carry it? I know, what a preposterous concept.
Studies (admittedly from the wheeled-luggage lobby) suggest you can buy luggage with wheels and still carry it.
Happiness in intelligent people is the rarest thing I know.
Ernest Hemingway
I seem to remember doing an analysis like this in my undergrad dynamics and control course. Hardly challenging stuff.
And... why did they need to go to the trouble of making a scale model of the suitcase? To presumably put on a teeny tiny treadmill? When ordinary sized suitcases and ordinary sized treadmills exist?
Seriously sounds like these scientists have too much time on their hands, or are playing the 'hey lets cook up some tabloid consumption research that'll get our names out there'.
How about figuring out the 'equation for $insert_emotion_here' as an encore?
Then it hits something again, you speed up again, repeating until you're moving like O.J. Simpson in the airport.
Cwm, fjord-bank glyphs vext quiz
Studies (admittedly from the wheeled-luggage lobby) suggest you can buy luggage with wheels and still carry it.
The label 'carry-on' is discriminatory and offensive to the roll-ons. Unfortunately, the deodorant lobby stopped the roll-ons from using that label. I think the carry-ons had something to do with it.
...Now figure out why we put a man on the Moon before we put wheels on luggage.
I laughed out loud reading this story. I imagine scores of people yelling "go faster" while running through the air port.
When in doubt gas it out!
"when a suitcase starts to rock out of control, the correct response is not to slow down but to pull it faster."
My buddies who race cars always maintain that braking never solved anything, you save yourself with the gas pedal.
Anyone who has stopped a trailer from fishtailing could have told you this. This is news?
Wouldn't it be better to use roller balls instead of wheels to stop this behavior?
-USR1
does the attempt to correct the problem by pushing against the roll event by the luggage puller have anything to do with it? Like how a "tank slapper" often results from too rigid of attempts by the rider to control front wheel wobble on a motorcycle where a passive damping device works wonders to settle even the twitchiest rake geometries?
No way to lock 'em on a hill. But they win on smooth level ground.
"No fear. No envy. No meanness." Liam Clancy
Sort of like those "For Your Consideration..." ads the movie studios run in trade magazines before the Academy Award voting. Granted the Ig Noble awards are much more prestigious, but this seems like an attempt at building early name recognition.
Besides, my luggage has short skis instead of wheels. Much better over a variety of challenging terrain.
Science is answering the real questions!
goddamned lazy physicists, wasting time studying rolling luggage instead of curing cancer!
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Just fyi...
It's been discovered that it is trivially easy to break into zippered luggage with a ball point pen, plunder it, and then reset the zipper (with the zipper handle) so it looks like it wasn't opened.
Any new luggage, you probably want to get without zippers. Shady baggage handlers have been quickly and easily robbing stuff from suit cases lately.
She was like chocolate when she drank... semi-sweet at first and then increasingly bitter.