Dont think thay will catch on but stil cool..

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Dont think thay will catch on but stil cool..

Postby Eviltwin » Tue Jan 10, 2012 1:25 pm


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Re: Dont think thay will catch on but stil cool..

Postby NS Jason » Sat Jan 14, 2012 11:58 pm

I wish we had a floor that good to skate on! Doubt it will work outside at all which is what he claims they are for.

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Re: Dont think thay will catch on but stil cool..

Postby Wild Phil » Sun Jan 15, 2012 12:27 am

thats a lot of money he could have spent on a pair of skates or a skateboard with some lessons

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Re: Dont think thay will catch on but stil cool..

Postby gummidge » Sun Jan 15, 2012 9:26 am

What I'd like to invent are power assisted skates. So instead of holding a remote you just skate as normal and it feels 10 times easier.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Sun Jan 15, 2012 12:37 pm

gummidge wrote:What I'd like to invent are power assisted skates. So instead of holding a remote you just skate as normal and it feels 10 times easier.

That sounds like a much better idea. Should be feasible with present day electronics and sensors. 10 times easier might need a very big battery if you want to go far though, could impose unacceptable limits on your beer carrying capacity.

Although you could also have a little electric buggy which automatically follows you and carries your beer for you. A beer caddy. You could even have sensors fitted to the cans which detect when your can is empty and an extending arm will hand you a fresh one.

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Re: Dont think thay will catch on but stil cool..

Postby Phil » Sun Jan 15, 2012 6:55 pm

Mick wrote:Although you could also have a little electric buggy which automatically follows you and carries your beer for you. A beer caddy. You could even have sensors fitted to the cans which detect when your can is empty and an extending arm will hand you a fresh one.


Why not just make a beer fridge version of the thumpers?

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Sun Jan 15, 2012 7:33 pm

Phil wrote:Why not just make a beer fridge version of the thumpers?

Because you need a hand free to hold your beer of course!

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Sun Jan 15, 2012 8:37 pm

gummidge wrote:What I'd like to invent are power assisted skates. So instead of holding a remote you just skate as normal and it feels 10 times easier.

Been thinking about this. To start with I thought it just needed stress sensors between the boot and frame to detect the magnitude and direction of the force you're exerting against your skate, and a simple processor to translate that into control signals for motors built into the wheel hubs. But it's more complicated than that because the force is always at right angles to the direction of travel of the skate so the controller wouldn't be able to tell whether you're trying to accelerate or brake or are just cornering hard.

To make it work I think you also need to track the position and angle of each skate relative to the direction of travel of the skater's centre of mass, and also track the skater's overall motion so that the controller knows whether you're cornering or travelling in a straight line. I think it's still do-able as you can buy all sorts of inertia and position sensors off the shelf these days and connect them up to an Arduino processor or whatever, but I suspect it would take a large development budget to get it working properly. If it reacted fast enough it might even be able to give you a spot of balance assistance, Segway-style, to compensate for the effects of the beers.

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Re: Dont think thay will catch on but stil cool..

Postby gummidge » Mon Jan 16, 2012 2:55 am

Mick wrote:
gummidge wrote:What I'd like to invent are power assisted skates. So instead of holding a remote you just skate as normal and it feels 10 times easier.

Been thinking about this. To start with I thought it just needed stress sensors between the boot and frame to detect the magnitude and direction of the force you're exerting against your skate, and a simple processor to translate that into control signals for motors built into the wheel hubs. But it's more complicated than that because the force is always at right angles to the direction of travel of the skate so the controller wouldn't be able to tell whether you're trying to accelerate or brake or are just cornering hard.

To make it work I think you also need to track the position and angle of each skate relative to the direction of travel of the skater's centre of mass, and also track the skater's overall motion so that the controller knows whether you're cornering or travelling in a straight line. I think it's still do-able as you can buy all sorts of inertia and position sensors off the shelf these days and connect them up to an Arduino processor or whatever, but I suspect it would take a large development budget to get it working properly. If it reacted fast enough it might even be able to give you a spot of balance assistance, Segway-style, to compensate for the effects of the beers.

Mmm. I can't figure it out, but I would have thought that because the skates do measure my intended push by accelerating it must be possible to measure. A problem I see is it also measuring the effect of it working and not being able to distinguish between me and it. I suppose it could subtract what it thinks it is putting in. How does power steering work?

Mick wrote:Although you could also have a little electric buggy which automatically follows you and carries your beer for you. A beer caddy. You could even have sensors fitted to the cans which detect when your can is empty and an extending arm will hand you a fresh one.

I have Steph for that.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Mon Jan 16, 2012 8:41 am

gummidge wrote:Mmm. I can't figure it out, but I would have thought that because the skates do measure my intended push by accelerating it must be possible to measure.

Yeah, since I wrote that it's been bugging me for the same reason. Will ponder further.

gummidge wrote:A problem I see is it also measuring the effect of it working and not being able to distinguish between me and it. I suppose it could subtract what it thinks it is putting in. How does power steering work?

Don't know how power steering works, but because you're trying to turn it against a resistance it shouldn't be hard to measure the stress in the initial part of the steering mechanism somehow, and apply the assisting force further down the train of action (after the stress measuring section). Then it just needs the assisting force to be proportional to the measured stress.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Mon Jan 16, 2012 9:08 pm

I think the reason you have to track everything and not just the forces acting on the skate is because the skate isnt accelerating when you accelerate. When you skate you're accelerating your body directly by pushing sideways against your skate, which means you've leaving it behind briefly. The skate doesn't catch up until you stop extending your leg, by which time you're no longer pushing.

Power assistance would be easier (from a control point of view) if you wore an exoskeleton on each leg with powered joints, it would simply be a matter of measuring the force you exert with your leg as it straightens and amplify it with the powered joints. But if you're trying to simulate the effect of a stronger leg push by using motorised wheels then the controller needs to understand the dynamics of the whole system.

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Re: Dont think thay will catch on but stil cool..

Postby lurch » Tue Jan 17, 2012 11:31 am

Certainly wouldn't want it accelerating when I'm doing that duck-walk-stopping thing.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Tue Jan 17, 2012 2:36 pm

Ah yes, "antiskating". I think that's a good example of why a power-assistance controller needs to know more than just the forces acting on the skate.

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Re: Dont think thay will catch on but stil cool..

Postby gummidge » Tue Jan 17, 2012 2:55 pm

Mick wrote:I think the reason you have to track everything and not just the forces acting on the skate is because the skate isnt accelerating when you accelerate. When you skate you're accelerating your body directly by pushing sideways against your skate, which means you've leaving it behind briefly. The skate doesn't catch up until you stop extending your leg, by which time you're no longer pushing.

I'm not sure I agree with that. If your skate only accelerated when you weren't pushing then wouldn't that mean that all of your acceleration came from pushing off from the skate rather than from pushing sideways? Maybe I don't understand how acceleration actually works on a skate. On a related note, if the push is just maintaining speed then an acceleration enhancer wouldn't work after all.

Power assistance would be easier (from a control point of view) if you wore an exoskeleton on each leg with powered joints, it would simply be a matter of measuring the force you exert with your leg as it straightens and amplify it with the powered joints. But if you're trying to simulate the effect of a stronger leg push by using motorised wheels then the controller needs to understand the dynamics of the whole system.

I still feel there must be some fundamental way to measure your push based on the physics of how the push actually accelerates the skate. How about, given your weight, the current weight on the skate combined with the direction of the weight relative to the skate and/or gravity?

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Re: Dont think thay will catch on but stil cool..

Postby gummidge » Tue Jan 17, 2012 2:58 pm

Mick wrote:Ah yes, "antiskating". I think that's a good example of why a power-assistance controller needs to know more than just the forces acting on the skate.

A simple "don't accelerate in the opposite direction to the wheel spin" would sort that out*. But I suspect a push detection system that did measure the force you were producing would necessarily have to know the direction anyway.

* EDIT: unless you both meant that you don't want it accelerating as a result of you decelerating rather than not wanting enhanced deceleration as well - which is what you probably meant now that I think about it.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Tue Jan 17, 2012 3:40 pm

Yes, the controller has to know whether you intend to accelerate or decelerate when you're pushing against the skate. Enhanced deceleration would be nice, and should be automatic anyway if the controller is doing it's job properly.

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Re: Dont think thay will catch on but stil cool..

Postby Mick » Tue Jan 17, 2012 5:18 pm

gummidge wrote:I'm not sure I agree with that. If your skate only accelerated when you weren't pushing then wouldn't that mean that all of your acceleration came from pushing off from the skate rather than from pushing sideways?

Well, there are two ways of looking at the acceleration of the skater, either as the actual acceleration of the skater's centre of mass during a single stroke, or else as the average acceleration in the overall direction of travel. The actual acceleration will always be very close to 90 degrees to the fore/aft axis of the skate, so there can be no acceleration of the skate in the same direction as the momentary acceleration of the skaters centre of mass.

However it is possible to accelerate the skate in the average direction of travel by using a purely sideways stroke, but it's not necessary and it will vary depending on how far you let your foot fall behind you during a stroke. Because it's variable I don't think it's a useful measure of how much power assistance to supply.

If you did use just that acceleration to decide how much power assistance to provide then it might be possible to learn to control it, but you would no longer just be skating normally but more powerfully, you would need to learn a special technique. And I have a suspicion that it might be unstable. If you accidentally let a skate shoot out a bit too much the power assistance would try to accelerate it even more.

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Re: Dont think thay will catch on but stil cool..

Postby Phil » Tue Jan 17, 2012 5:36 pm

I really don't understand why you'd want assisted acceleration whilst skating, I think simplicity is the key and really you'd only want acceleration whilst cruising. Therefore just have a system which detects when both skates have been on the floor for say 2 seconds and have been accelerating (so that you can still cruise to a stop) and then kick in the acceleration, if the skater picks a foot off the floor then stop the motors immediately.

This way you could go from a standing start, accelerating under your own pace for a few strides then roll a little bit and the motor kicks in and takes you up to 20mph

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Re: Dont think thay will catch on but stil cool..

Postby Stoo » Tue Jan 17, 2012 8:43 pm

Perhaps a Bluetooth or xbee small controller in your pocket/hand, or perhaps integrated into some gloves (Lilypad arduino?) might be a better bet?

Squeeze to go faster and some sort of failsafe to disengage it - so you don't shoot off when you grab someone/a beer/something else etc..

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Re: Dont think thay will catch on but stil cool..

Postby gummidge » Tue Jan 17, 2012 9:36 pm

Nah, I'd only like it if it works like we're discussing, like your skating on ABEC 10,000s (i.e. it just makes it feel like you have more strength and energy while skating completely naturally).


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