The Fat Unicyclist Posted September 20, 2019 Share Posted September 20, 2019 On 9/18/2019 at 7:32 PM, Vik3 said: I found the video which shows that engaging from 2-3inch hight and even from half a meter is not a problem : you can see that the rider can keep selfbalansing one wheel possition ("power on") : Hide contents then jumped from half a meter hight : then seccesfully landed in two wheel position ( " power off" ) : Looks like this is a good idea to use one or two extandable self steering wheels like that (even smaller) for preventing faceplants, and also use them as parking wheels and transporting wheels in inserted (shorter) possition : I think it make sence to test this for calm plane reliable riding (no hills) from home to office and back on small light weight EUC. Sorry for my English - I am a newcomer as well . No... I still completely disagree! This Gauswheel thing is completely different - these riders are using their center of gravity to remain balanced, so the front wheel acts very differently. On an EUC we shift our center of gravity forward to accellerate (or maintain speed), so the moment the wheel slows or tilts (for the front wheel to engage) the rider tips further forward. This means that there is only one outcome... You will hit the ground! I would love to be proved wrong about this, but I don't think the rules of physics are that flexible. However it would be great to see some video that corrects me on this... 1 Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 20, 2019 Share Posted September 20, 2019 6 hours ago, The Fat Unicyclist said: No... I still completely disagree! This Gauswheel thing is completely different - these riders are using their center of gravity to remain balanced, so the front wheel acts very differently. On an EUC we shift our center of gravity forward to accellerate (or maintain speed), so the moment the wheel slows or tilts (for the front wheel to engage) the rider tips further forward. This means that there is only one outcome... You will hit the ground! I would love to be proved wrong about this, but I don't think the rules of physics are that flexible. However it would be great to see some video that corrects me on this... Yes, it is different, but far far not “completely” – almost the same. The rider 80kg or 800H moving on Gauswheel with constant speed 25kmh getting 2kg or 20H of air resistance, and leaned forward for 1.5 degree: Resultant force goes 2.5mm ahead of wheel axis. For going 25kmh on EUC with 16 inch wheel 5Nm moment is required: the 80kg rider creates needed moment on 6mm arm (5:800=6mm), so the rider center of gravity should be moved forward for 3.5mm else, and for keeping moving on EUC he should be leaned till 1.7 degree : You see – 1.5 degree and 1.7degree, the difference can hardly be seen. OK, after falling of front wheel from 3 inch height rider feet will go back for about 12mm and he will be leaned till 2.5 degree, but staying on the floor everybody can lean till 10-12 degree without falling. Need testing . I do not have EUC , just two ebikes. Quote Link to comment Share on other sites More sharing options...
Mono Posted September 20, 2019 Share Posted September 20, 2019 14 hours ago, Vik3 said: May be something wrong with my English or with my logic, but in my understanding nosediving is impossible in principle on two or more wheels vehicles. On EUC or mono wheel vehicles it possible and happens quite often just due it’s principle: Overleans happen because the design specifications are chosen such that it can happen, but they would not need to be chose like that out of principle. This is the difference to the OneWheel, where the form factor makes it virtually impossible to build a nosedive-safe version of it with current technology. 14 hours ago, Vik3 said: when speed close to idling is reached, can be prevented by tilt-back 14 hours ago, Vik3 said: low batteries, can be prevented by tilt-back limiting the speed at low batteries 14 hours ago, Vik3 said: electricity gone, True, if the device breaks you might land on your face. That's not different on a bicycle though (fork or handlebar breakages are good candidates). 14 hours ago, Vik3 said: climbing step hills, not possible to nosedive a powerful wheel if the pedals are short enough (and the rider light enough) 14 hours ago, Vik3 said: sudden restrictions to movement, I don't understand what that means. One can fall off an EUC, that's for sure, and one can fall off while trying to overlean/nosedive it. 14 hours ago, Vik3 said: heavy rider etc. yes, the (safety) specification is limited to certain rider weights. Quote Link to comment Share on other sites More sharing options...
Mono Posted September 20, 2019 Share Posted September 20, 2019 (edited) 10 hours ago, The Fat Unicyclist said: On an EUC we shift our center of gravity forward to accellerate (or maintain speed), so the moment the wheel slows or tilts (for the front wheel to engage) the rider tips further forward. This means that there is only one outcome... You will hit the ground! There could be a safety wheel in front that prevents that the pedal can dip more than, say, 25º. That would prevent the rider from slipping off the dipping pedal or the motor disengaging (which it does when the dip exceeds 45º-or-so). Of course it cannot make sure that the rider is not already too much in front of the wheel and that he will fall off over the pedal edge. Edited September 20, 2019 by Mono Quote Link to comment Share on other sites More sharing options...
M640x Posted September 21, 2019 Share Posted September 21, 2019 (edited) Funny you show that. Many Onewheel owners have wheels on the front for that exact purpose. They're called fangs I think. Edited September 21, 2019 by Senior Coffee Quote Link to comment Share on other sites More sharing options...
The Fat Unicyclist Posted September 21, 2019 Share Posted September 21, 2019 (edited) 9 hours ago, Mono said: There could be a safety wheel in front that prevents that the pedal can dip more than, say, 25º. That would prevent the rider from slipping off the dipping pedal or the motor disengaging (which it does when the dip exceeds 45º-or-so). Of course it cannot make sure that the rider is not already too much in front of the wheel and that he will fall off over the pedal edge. That is exactly the flaw with this logic... How many of us have slipped off a wheel and watched it quite happily roll away for quite a distance before falling ove? The only reason a wheel tilts forwarrd is becuase the rider has their centre of gravity forward of the axle. So if a wheel cuts out and tilts forward 25 degress (before the "safety" wheel engages) then the rider will also be ilted forward 25 degrees. Combine that with the fact that the wheel is slowing down at the same time and there is ONLY ONE POSSIBLE OUTCOME. I am happy to be proved wrong about this - in fact I would love to be proved wrong! But until someone with an actual physics degree can explain how I won't end up hurting, I don't believe it is possible. Note: if anyone out there who doesn't have a physics degree wants to convince me, please build your solution and provide video evidence that I am wrong. Edited September 21, 2019 by The Fat Unicyclist Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 21, 2019 Share Posted September 21, 2019 4 hours ago, The Fat Unicyclist said: The only reason a wheel tilts forwarrd is becuase the rider has their centre of gravity forward of the axle. So if a wheel cuts out and tilts forward 25 degress (before the "safety" wheel engages) then the rider will also be ilted forward 25 degrees. Combine that with the fact that the wheel is slowing down at the same time and there is ONLY ONE POSSIBLE OUTCOME. I am happy to be proved wrong about this There is no any 25 degrees: the pad (pedals) will lean forward for 12 degrees, and the rider will stay pretty much at the same position 2…3 degree leaned – only his front leg or front part of feet (pedals) will dive : Hope you are happy now Quote Link to comment Share on other sites More sharing options...
The Fat Unicyclist Posted September 21, 2019 Share Posted September 21, 2019 36 minutes ago, Vik3 said: Hope you are happy now No... Not at all. Well actually, I am quite happy. But that doesn't mean I agree any more with the ridiculous ideas being presented here. Your latest post is all about a OneWheel... Aren't we talking about EUC? Also, do you have a degree in physics? Quote Link to comment Share on other sites More sharing options...
Mono Posted September 21, 2019 Share Posted September 21, 2019 (edited) 7 hours ago, The Fat Unicyclist said: That is exactly the flaw with this logic... How many of us have slipped off a wheel and watched it quite happily roll away for quite a distance before falling ove? The only reason a wheel tilts forwarrd is becuase the rider has their centre of gravity forward of the axle. I agree it is the main reason, but it is actually not the only reason. By flexing the foot ankle joints, one can put pressure for a short time without changing the center of gravity. I don't think it is relevant for your problem though. Quote So if a wheel cuts out and tilts forward 25 degress (before the "safety" wheel engages) then the rider will also be ilted forward 25 degrees. Certainly not. Rider angle and tilt angle are positively correlated, but they are not the same, not even close. An easy way to see this is to acknowledge that there are soft and hard riding modes. EDIT: I also tend to consider the rider not anymore as tilting, but as displacing while staying upright. It's just a different way to model the change of CoG, and it's also how I tend to ride: from the knee upwards the body tilt angle remains the same (up to leaning against wind). I also realized that modeling the rider as a stick that tilts is not enough, because the point of contact with the pedal must move to have a reasonable model. Quote Combine that with the fact that the wheel is slowing down at the same time and there is ONLY ONE POSSIBLE OUTCOME. I agree, if the wheel continues to slow down under the rider there is only one possible outcome. That's why it is crucially important to release pressure by bending the knees, such that the wheel can catch up under the rider. So I guess we agree that a fang wheel won't solve the problem of the wheel slowing down. In the situations I have in mind, the CoG of the rider is always behind the front edge of the pedal. I believe this is the crucial difference between the scenarios we are considering. Then the rider does not fall off unless a) the wheel slows down and "falls" behind the rider or b) the pedals dip such that either the front edge comes behind the riders CoG or the rider slips off. The b) case is where a fang wheel can help. (If the riders CoG is in front of the front pedal edge, the rider will fall off when the wheel stops accelerating and a fang wheel can't prevent this from happening.) If one applies a constant pedal pressure to accelerate the wheel while keeping the riders CoG behind the front edge of the pedal, one ends up in case b): the wheel will stop accelerating (it will not slow down, just stop accelerating) and will not be able to sustain enough torque which is needed to counter the applied pedal pressure, hence dip. Stop accelerating does not mean that the wheel falls behind the rider, as the rider also keeps their velocity and does not accelerate on their own. Edited September 21, 2019 by Mono 1 Quote Link to comment Share on other sites More sharing options...
Chriull Posted September 21, 2019 Share Posted September 21, 2019 18 hours ago, Vik3 said: ... You see – 1.5 degree and 1.7degree, the difference can hardly be seen. ... Nice comparison! For constant speed driving (no acceleration) this not really surprising. The gaus wheel driver has to do the balancing - so his lean angle is determined by the air resistance. In the case with constant speed it's (more or less) the same with an EUC. As soon as one accelerates (or decelerates) it starts to become very different - the rider of an EUC causes an imbalance (leaning forward or backward) and the wheel balances him by accelerating or decelerating. So here the lean angles get very different from gaus wheels. If you try to lean forward on the gaus wheel one is not balacing it anymore, but driving on the front wheel - without the frontwheel one would just fall on the nose. So now as next step lets look what happens and what the boundary conditions would have to be for a front wheel in combination with an EUC: - For acceleration the rider needs to lean forward and cause some slight pedal tilt. The "weaker" the rider mode, the more forward pedal tilt will happen. But by the self balancing of the EUC (the acceleration by the motor) the pedals stay more or less straight and the higher lean angle of the rider is supported. - Do not make the front wheel dangerous (causing accidents at bumps, curbs, obstacles) it needs some "safety margin" height while normal driving and at maximum acceleration pedal forward tilt (which should be "very" low). In case of a "classical" overlean the forward leaning rider was supported by the motor acceleration, which gets less now which causes the rider to fall forward. Falling forward this something very roughly about 10° (or more) is a small eternity for the rider - and then once the front wheel touches the ground and stops the forward turning of the EUC the rider gets another toruqe forward which will increase his falling tendency! The only real chance is for the rider to accelerate into the "overlean" (wheels limit) slow enough and react fast enough (stop leaning forward) to give the EUC a chance to start self balancing again. There could be a small zone inbetween, where the rider almost manages to almost lean back enough and the _soft_ touching of the front wheel could save him. So imo such a front wheel only cause troubles and the scarce possibilities it could maybe help just disqualifies it. It look compelling to use some sort of such safety devices - but the great, marvellous, astonishing thing about EUCs is that the drive with just _one_ wheel. Introducing a second wheel is a big step back, makes it more dangerous and destroys the fun! And it is very easy to prevent overleans with an EUC: - don't accelerate hard (show off) at high speeds - there is no(t enough) torque available! - don't try to reach the top speed with EUCs with disabled Tiltback - look out for bumps/curbs/obstacles/potholes! Your're driving on one wheel and not in a tank! - Supress the urge to "take the speed with you" going up an incline or even worse accelerate before going up an incline. - If one is still uncomfortable with risking an overlean, drive/accelerate slower and(/or) get a stronger wheel. - if one still needs a second wheel for safety, there are ebikes, scooters, etc.... 1 Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 21, 2019 Share Posted September 21, 2019 6 hours ago, Mono said: So I guess we agree that a fang wheel won't solve the problem of the wheel slowing down. Just a reminder, as I said before this idea is for city condition: moving with safe 25kmh and regular city clopes are 4-12% or 2….7 degree only, for going from home to office. Moving with constant speed 25kmh on EUC it will get thrust about 2.5kg or 25H : The worst case is power off (not just nosedive), I made calculations: the EUC will slow down with negative acceleration -0.25m/c^2, the resultant force will move 35mm ahead, but still will go through pedal area – no fall. Nosedive or cut off during starting even with moderate acceleration requires addition thrust, I think using of existing handle and making extendable one o two parking self steering wheels can solve this problem: In transporting position it will have the same overall dimensions. Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 21, 2019 Share Posted September 21, 2019 6 hours ago, Chriull said: Nice comparison! For constant speed driving (no acceleration) this not really surprising. The gaus wheel driver has to do the balancing - so his lean angle is determined by the air resistance. In the case with constant speed it's (more or less) the same with an EUC. As soon as one accelerates (or decelerates) it starts to become very different - the rider of an EUC causes an imbalance (leaning forward or backward) and the wheel balances him by accelerating or decelerating. So here the lean angles get very different from gaus wheels. If you try to lean forward on the gaus wheel one is not balacing it anymore, but driving on the front wheel - without the frontwheel one would just fall on the nose. So now as next step lets look what happens and what the boundary conditions would have to be for a front wheel in combination with an EUC: - For acceleration the rider needs to lean forward and cause some slight pedal tilt. The "weaker" the rider mode, the more forward pedal tilt will happen. But by the self balancing of the EUC (the acceleration by the motor) the pedals stay more or less straight and the higher lean angle of the rider is supported. - Do not make the front wheel dangerous (causing accidents at bumps, curbs, obstacles) it needs some "safety margin" height while normal driving and at maximum acceleration pedal forward tilt (which should be "very" low). In case of a "classical" overlean the forward leaning rider was supported by the motor acceleration, which gets less now which causes the rider to fall forward. Falling forward this something very roughly about 10° (or more) is a small eternity for the rider - and then once the front wheel touches the ground and stops the forward turning of the EUC the rider gets another toruqe forward which will increase his falling tendency! The only real chance is for the rider to accelerate into the "overlean" (wheels limit) slow enough and react fast enough (stop leaning forward) to give the EUC a chance to start self balancing again. There could be a small zone inbetween, where the rider almost manages to almost lean back enough and the _soft_ touching of the front wheel could save him. So imo such a front wheel only cause troubles and the scarce possibilities it could maybe help just disqualifies it. It look compelling to use some sort of such safety devices - but the great, marvellous, astonishing thing about EUCs is that the drive with just _one_ wheel. Introducing a second wheel is a big step back, makes it more dangerous and destroys the fun! And it is very easy to prevent overleans with an EUC: - don't accelerate hard (show off) at high speeds - there is no(t enough) torque available! - don't try to reach the top speed with EUCs with disabled Tiltback - look out for bumps/curbs/obstacles/potholes! Your're driving on one wheel and not in a tank! - Supress the urge to "take the speed with you" going up an incline or even worse accelerate before going up an incline. - If one is still uncomfortable with risking an overlean, drive/accelerate slower and(/or) get a stronger wheel. - if one still needs a second wheel for safety, there are ebikes, scooters, etc.... 95% agree with you, but in works on OneWheel even with fixed small wheels. Need testing on EUC. Quote Link to comment Share on other sites More sharing options...
Chriull Posted September 21, 2019 Share Posted September 21, 2019 1 hour ago, Vik3 said: ... but in works on OneWheel even with fixed small wheels. I fully understand the system with OneWheels - there one digs with the board into the ground once one overleans. There any wheel attached to the front can and will be a big advantage! 1 hour ago, Vik3 said: Need testing on EUC. Be careful and good luck! 1 Quote Link to comment Share on other sites More sharing options...
Mono Posted September 21, 2019 Share Posted September 21, 2019 (edited) 1 hour ago, Vik3 said: The worst case is power off (not just nosedive), Probably we have a different understanding what nosedive means. To my understanding it means that the nose hits the ground which usually leads to strong deceleration. Quote I made calculations: the EUC will slow down with negative acceleration -0.25m/c^2, the resultant force will move 35mm ahead, but still will go through pedal area – no fall. I have no idea what you are talking about A standing rider without handlebar who is not prepared for a deceleration will just be thrown off to the front unless they can make a step to the front. That is independent of whether the device has one, two, three, four, or how many wheels. Easy to test in a bus or underground. Edited September 21, 2019 by Mono 2 Quote Link to comment Share on other sites More sharing options...
Chriull Posted September 21, 2019 Share Posted September 21, 2019 1 hour ago, Vik3 said: ... ... Seeing one drive with the handle extended ... makes me shiver with anticipation ... of something very bad to happen... 2 Quote Link to comment Share on other sites More sharing options...
Mono Posted September 21, 2019 Share Posted September 21, 2019 1 minute ago, Chriull said: Seeing one drive with the handle extended ... makes me shiver with anticipation ... of something very bad to happen... I don't think it's a huge added risk. The handle is fragile, it will break before bones do. It just becomes "a little" more difficult to run off. On the possibly positive side one might even be able to steer the wheel out of the way using the handle bar. Quote Link to comment Share on other sites More sharing options...
Chriull Posted September 21, 2019 Share Posted September 21, 2019 Just now, Mono said: I don't think it's a huge added risk. The handle is fragile, it will break before bones do. Yes. But then one hase metal tubes going around... Just now, Mono said: It just becomes "a little" more difficult to run off. On the possibly positive side one might even be able to steer the wheel out of the way using the handle bar. My post was mainly because it made me shiver once i saw it - and reminded me on the one line of the rocky horror picture show - but with the absolutely opposite emotion... But, yes - could be nice if one drives at slow speeds. Then such a frontwheel could be maybe nice, too - but there are no overleans with EUCs at low speeds. And if (high burden incline situation) it won't really matter... Seeing such a wheel in front of an EUC and imagining of driving with this 35 km/h makes me just shiver again... 1 Quote Link to comment Share on other sites More sharing options...
Mono Posted September 21, 2019 Share Posted September 21, 2019 (edited) I surely agree, that EUCs have one and only one wheel and no handle bar is in my world view considered beautiful features rather than a bug. Edited September 21, 2019 by Mono 1 Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 22, 2019 Share Posted September 22, 2019 15 hours ago, Chriull said: I fully understand the system with OneWheels - there one digs with the board into the ground once one overleans. There any wheel attached to the front can and will be a big advantage! Yes, just one wheel will decrease deceleration for 10 times due to difference in friction coefficients 0.03 and 0.3 . Quote Link to comment Share on other sites More sharing options...
Vik3 Posted September 22, 2019 Share Posted September 22, 2019 15 hours ago, Chriull said: Seeing one drive with the handle extended ... makes me shiver with anticipation ... of something very bad to happen... This EUC with handle made of solid crossed bars looks more scary : but I guess it gives some advantages comparing with that nice EUC with same size wheel: Actually I do not like that big solid handle with heavy batteries inside, I would prefer to keep batteries in box above its wheel, and to have extendable very strong handle. In pare with extendable front safety wheels it looks pretty safe for calm city riding at 18-22kmh speed Quote Link to comment Share on other sites More sharing options...
Vik3 Posted October 8, 2019 Share Posted October 8, 2019 On 9/19/2019 at 9:49 PM, Vik3 said: Problem with nosedive and cut off is solved on Onewheels without increasing of weight and dimensions: https://www.youtube.com/watch?v=ZPxztvTKNnQ I have to admit that I was mistaken - using of fangs or safety wheels on OneWheel do not prevent crash when high speed nosedive happens. The video above it is just an imitation of nosedive by hitting of front board end by leg and keeping body vertical. When actual high speed nosedive happens the body dives with board for at least 8-10 degrees down and to keep standing is impossible: I do not see the way how to prevent it on OneWheel units, but I still sure that it is quite possible on EUC units. Now sitting riding on EUC is becoming very popular, and riders are having fun of riding seated units using accessory seats and homemade seats. I think that if seated EUC provide with Gauswheel self steering wheel and cross bar for feet on it, this could prevent EUC crash when nosedive happens: Quote Link to comment Share on other sites More sharing options...
Mono Posted October 8, 2019 Share Posted October 8, 2019 4 hours ago, Vik3 said: I have to admit that I was mistaken - using of fangs or safety wheels on OneWheel do not prevent crash when high speed nosedive happens. It all depends on the rider. 4 hours ago, Vik3 said: The video above it is just an imitation of nosedive by hitting of front board end by leg and keeping body vertical. When actual high speed nosedive happens the body dives with board for at least 8-10 degrees down and to keep standing is impossible The rider can't stop moving, but can try to bring the board back and more upright under the body. This is virtually impossible if the nose is stuck in the tar while there is a much, much better chance with fangs. How so? By releasing weight off the board by bending the knees (a lot). 1 Quote Link to comment Share on other sites More sharing options...
Vik3 Posted October 12, 2019 Share Posted October 12, 2019 On 10/8/2019 at 3:25 PM, Vik3 said: Now sitting riding on EUC is becoming very popular, and riders are having fun of riding seated units using accessory seats and homemade seats. I think that if seated EUC provide with Gauswheel self steering wheel and cross bar for feet on it, this could prevent EUC crash when nosedive happens: I found one more video: Just to add a couple of safety wheels and a light foldable seat then it could be the safest portable vehicle : Quote Link to comment Share on other sites More sharing options...
Vik3 Posted October 19, 2019 Share Posted October 19, 2019 On 10/12/2019 at 12:35 PM, Vik3 said: Just to add a couple of safety wheels and a light foldable seat then it could be the safest portable vehicle : I found one more video proving my concept : You see, the guy attached the seat to LOW POWER EUC, made one minute safe trip, did four turns and couples of times had nosedive, but did not fall !!! Why? Because he used touching of his feet to the road : but if he used roller skates he could do this at higher speeds: and if he used safety wheels on balancing cross bar attached to another foldable bar extended in front of EUC he could do this up to 20-25km/h : Actually I used such balancing safety wheels on my ebike in winter time for two years already, and very happy with them : Quote Link to comment Share on other sites More sharing options...
milesteg27 Posted October 23, 2019 Share Posted October 23, 2019 On 7/3/2017 at 4:33 AM, Chris Westland said: Interesting discussion, but IMO misguided, resulting in potentially over-engineered (expensive, failure-prone) solutions. I think you need first to identify the "why". Riders who have had failures and done post-mortems (@esaj , @Marty Backe, @Jason McNeil@Rehab1,etc... forgive me if I've forgotten anyone) provide a list of insights on what needs fixing. In general, it seems, sudden fluctuations or loss of power to the motor (FET failure, wiring melt, brown-out, etc) are behind most crashes. EUC wheels would benefit from {power reserve (think super-capacitor) + low-pass filter + graceful degradation} systems before other engineering. Segways use multiple redundant systems (expensive) to achieve safety. I'm assuming the manufacturers mostly understand this, though maybe they aren't separately engineering such subsystems, and they have to engineer to a price point. I think this guy is right. if an extra is added it looks ugly and inperfect. there is no need for that. as this guy said the only thing you need is a super capacitor. if a high peek of power is needed the capacitor is used to prevent a instant cut off. in the next step a futher acceleration must be prevented to give the capacitor the time to reload. that can be archived if the wheel slowes down automaticly. if the user wants to lean forward in this situation, the pedals dip in but nothing happens Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.