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The mathematical way to ride a bike
http://www.telegraph.co.uk/earth/mai.../scibike06.xml
Paper he http://tinyurl.com/2ducg9 Apologies if this is old news, Tom |
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The mathematical way to ride a bike
Thomas Hood wrote:
http://www.telegraph.co.uk/earth/mai.../scibike06.xml Paper he http://tinyurl.com/2ducg9 Apologies if this is old news, Tom Funny, really, since the control mechanism is the supercomputer between the ears of the rider. In computer speak we could just say that the brain is a heuristic learning computer. Fall down, analyze what was done wrong and try again until able to maintain upright position. Simple, huh? Bill Baka |
#3
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The mathematical way to ride a bike
On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood
wrote: http://www.telegraph.co.uk/earth/mai.../scibike06.xml Paper he http://tinyurl.com/2ducg9 Apologies if this is old news, Tom Dear Tom, This passage caused my eyebrows to rise: "Today's 'definitive review' underlines bicycles' amazing ability to balance themselves. 'You can give a bike a push and it will go 50 metres without falling. Even if it is knocked sideways, it will pop up again,' said Prof Ruina. http://www.telegraph.co.uk/earth/mai.../scibike06.xml Maybe I'm wrong, but I take this to mean a normal bicycle with no rider on an ordinary level road. A) That sounds like some push. B) I seem to recall that the bike falls over pretty quickly. Anyone who can offer an explanation adapted to a particularly mean understanding, I'd appreciate it. Maybe the bicycles that I experimented with as a little boy were different. A link to a video would be wonderful. Cheers, Carl Fogel |
#4
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The mathematical way to ride a bike
On Thu, 07 Jun 2007 13:32:52 -0600, carlfogel wrote:
On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood wrote: http://www.telegraph.co.uk/earth/mai.../scibike06.xml Paper he http://tinyurl.com/2ducg9 Apologies if this is old news, Tom Dear Tom, This passage caused my eyebrows to rise: "Today's 'definitive review' underlines bicycles' amazing ability to balance themselves. 'You can give a bike a push and it will go 50 metres without falling. Even if it is knocked sideways, it will pop up again,' said Prof Ruina. http://www.telegraph.co.uk/earth/mai.../scibike06.xml I'm not sure if this is meant to be public, but there seems to be a draft of the paper he http://ruina.tam.cornell.edu/researc...hanics/papers/ Jim Papadopoulos is one of the authors and has a discussion of bicycle stability in Chapter 8 of Wilson's Bicycling Science. Among other things, he says, "To perform steady-state riderless experiments, it is essential to have low-friction steering, a condition of initial alignment that allows the bicycle to travel straight, and a design that affords intrinsic stability at the test speed. It is then possible to engage in bicycling activities similar to a game of catch (rolling the bicycle to a partner) or kite flying (propelling and leaning the bicycle by pulling on an attached string)." Maybe I'm wrong, but I take this to mean a normal bicycle with no rider on an ordinary level road. A) That sounds like some push. My recollection is that if you release a bicycle at the top of a gentle hill, it will stay upright for a surprising distance (though it's been years since I've tried anything like that). I imagine it would take more finesse to achieve the same result on level ground because, as you say, it would require quite a push to keep the bike above the threshold speed for any length of time and a poorly executed push might start the bike out in an unstable position. Still, I don't see any reason why the same effect couldn't be achieved on level ground. What raised my eyebrow in the news story was the statement that, "Even if [the bicycle] is knocked sideways, it will pop up again." But on further thought that seems right too. An irate motorist once tried to push me off my bike. (I had dared to rap on his window when he turned into my path; he pulled ahead and darted out of his car at me as I passed.) It's possible that I subconsciously took corrective action, but what struck me as it was happening was how ineffectual the push was. There didn't seem to be any force which needed my corrections. But perhaps I'm jumping to conclusions in thinking that the bicycle (with me attached) was self-correcting. B) I seem to recall that the bike falls over pretty quickly. Anyone who can offer an explanation adapted to a particularly mean understanding, I'd appreciate it. Maybe the bicycles that I experimented with as a little boy were different. A link to a video would be wonderful. Cheers, Carl Fogel |
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The mathematical way to ride a bike
On Thu, 07 Jun 2007 13:32:52 -0600, carlfogel wrote:
On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood wrote: http://www.telegraph.co.uk/earth/mai.../scibike06.xml Paper he http://tinyurl.com/2ducg9 Apologies if this is old news, Tom Dear Tom, This passage caused my eyebrows to rise: "Today's 'definitive review' underlines bicycles' amazing ability to balance themselves. 'You can give a bike a push and it will go 50 metres without falling. Even if it is knocked sideways, it will pop up again,' said Prof Ruina. http://www.telegraph.co.uk/earth/mai.../scibike06.xml I'm not sure if this is meant to be public, but there seems to be a draft of the paper he http://ruina.tam.cornell.edu/researc...hanics/papers/ Jim Papadopoulos is one of the authors and has a discussion of bicycle stability in Chapter 8 of Wilson's Bicycling Science. Among other things, he says, "To perform steady-state riderless experiments, it is essential to have low-friction steering, a condition of initial alignment that allows the bicycle to travel straight, and a design that affords intrinsic stability at the test speed. It is then possible to engage in bicycling activities similar to a game of catch (rolling the bicycle to a partner) or kite flying (propelling and leaning the bicycle by pulling on an attached string)." Maybe I'm wrong, but I take this to mean a normal bicycle with no rider on an ordinary level road. A) That sounds like some push. My recollection is that if you release a bicycle at the top of a gentle hill, it will stay upright for a surprising distance (though it's been years since I've tried anything like that). I imagine it would take more finesse to achieve the same result on level ground because, as you say, it would require quite a push to keep the bike above the threshold speed for any length of time and a poorly executed push might start the bike out in an unstable position. Still, I don't see any reason why the same effect couldn't be achieved on level ground. What raised my eyebrow in the news story was the statement that, "Even if [the bicycle] is knocked sideways, it will pop up again." But on further thought that seems right too. An irate motorist once tried to push me off my bike. (I had dared to rap on his window when he turned into my path; he pulled ahead and darted out of his car at me as I passed.) It's possible that I subconsciously took corrective action, but what struck me as it was happening was how ineffectual the push was. There didn't seem to be any force which needed my corrections. But perhaps I'm jumping to conclusions in thinking that the bicycle (with me attached) was self-correcting. B) I seem to recall that the bike falls over pretty quickly. Anyone who can offer an explanation adapted to a particularly mean understanding, I'd appreciate it. Maybe the bicycles that I experimented with as a little boy were different. A link to a video would be wonderful. Cheers, Carl Fogel |
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The mathematical way to ride a bike
On Jun 7, 2:32 pm, wrote:
On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood wrote: http://www.telegraph.co.uk/earth/mai...2007/06/06/sci... SNIPSNIPSNIP A link to a video would be wonderful. Cheers, Carl Fogel The aforementioned Telegraph link has a video link at the top of the page. Do review it, to see a bicycle 'popping back up' after a shove. Also take a look at Arend Schwab's web page with treadmill experiments: http://audiophile.tam.cornell.edu/~a...ycle/index.htm Arend was an important contributor to the discussed paper, and so am I Jim Papadopoulos |
#7
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The mathematical way to ride a bike
On Sun, 22 Jul 2007 10:50:04 -0700, Jim Papadopoulos
wrote: On Jun 7, 2:32 pm, wrote: On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood wrote: http://www.telegraph.co.uk/earth/mai...2007/06/06/sci... SNIPSNIPSNIP A link to a video would be wonderful. Cheers, Carl Fogel The aforementioned Telegraph link has a video link at the top of the page. Do review it, to see a bicycle 'popping back up' after a shove. Also take a look at Arend Schwab's web page with treadmill experiments: http://audiophile.tam.cornell.edu/~a...ycle/index.htm Arend was an important contributor to the discussed paper, and so am I Jim Papadopoulos Dear Jim, Thanks--here's the link, which is broken in some posts: http://www.telegraph.co.uk/earth/mai.../scibike06.xml Here's the video at the top, with the sideways push in the second half: http://ruina.tam.cornell.edu/researc..._stability.mpg It looks as if the initial push was indeed more powerful than my childhood disasters. Probably it helps to be over three feet tall. Cheers, Carl Fogel |
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