Why don't EUC's have internal brakes?

[mike_bike_kite]

It's been interesting reading the reviews about suspension. I was trying to think of simple things that could be added to new models of EUC that might still make a difference. My 16S stops pretty quick but heavier EUC's take much longer. Why can't wheels just have an internal mechanical brake that steadily gets activated once the rider leans back beyond a certain point? You'd still have the advantage of regen when descending hills. I'm not sure how you'd monitor the wear on the brakes but perhaps it could just be a serviceable item that could be replaced after so many 1000 miles. You could even slightly increase the softness of the pedals under heavy braking just to allow the rider to "dig in" better. Or is there a good reason we don't have more powerful braking?

[null]

As it is I guess mainly because it would impeach the balancing.

Maybe the algorithm could be adapted to compensate or dose mechanical breaking though.

With the current (and future) powerful wheels we might be more lacking in breaking technique (60 degree backward without wobbling) than in motor breaking power.

IDK

Edit: speaking of which I wonder how hard we could train emergency breaking without damaging the wheel.

Edited August 7, 2020 by null

[Kai Drange]

6 minutes ago, null said:

As it is I guess mainly because it would impeach the balancing.

Hmm, yes, I guess the extra braking could possibly shift the rider's weight forward again, reducing the effect? Then again, probably not if the rider has learned to deal with the extra braking. Here's hoping some DIY person tests it .

Ok, after 5 minutes of brainstorming more ideas for future EUC features:

• Removable batteries of different sizes/weight. E.g. owning a lightweight battery for daily commutes, and a big one for long trips, for instance.
• zip-on tires for winter/trails (something like these, perhaps).
• Some kind of attachable bag system to put (small) stuff in (like the bags on the back on bicycles.
• A "rumble" feature for warnings that can be felt instead of heard (like the rumbling in game controllers and cell phones, say).
• A "someone is right behind me"-sensor and warning.

 

[RockyTop]

Electric braking is not anything new. elevators have used electric braking for 100 years. while elevators do have a mechanical brake it is only used to hold the elevator still after it has stopped. (Governor and safeties are  triggered when things go wrong)

[Vellberger]

1 hour ago, Kai Drange said:

Hmm, yes, I guess the extra braking could possibly shift the rider's weight forward again, reducing the effect? Then again, probably not if the rider has learned to deal with the extra braking. Here's hoping some DIY person tests it .

Ok, after 5 minutes of brainstorming more ideas for future EUC features:

• Removable batteries of different sizes/weight. E.g. owning a lightweight battery for daily commutes, and a big one for long trips, for instance.
• zip-on tires for winter/trails (something like these, perhaps).
• Some kind of attachable bag system to put (small) stuff in (like the bags on the back on bicycles.
• A "rumble" feature for warnings that can be felt instead of heard (like the rumbling in game controllers and cell phones, say).
• A "someone is right behind me"-sensor and warning.

 

These are really great ideas. Hope some of them will come.

[mrelwood]

3 hours ago, mike_bike_kite said:

My 16S stops pretty quick but heavier EUC's take much longer.

Before inventing a solution, you have to figure out the reason for the behavior. Heavy EUCs don’t take a notably longer to stop. Larger diameter tires do. Just like acceleration on any 18” feels much more sluggish than on any 16”, regardless of wheel weight or power. Additional brakes do not affect the tire diameter, so braking distance wouldn’t change.

 You also disregard the word “balancing” in the self-balancing vehicle. For the wheel to be in balance with the rider, it can only accelerate and brake as fast as the rider’s lean requires. Accelerate more and the rider experiences a tilt-back or falls on one’s back. Brake too fast and the rider tips forward, stopping the braking event.

 If riders would fall on their back during braking, then additional braking power would be needed. But they don’t, so braking power is already sufficient.

Edited August 7, 2020 by mrelwood

[esaj]

 

2 hours ago, Kai Drange said:

Hmm, yes, I guess the extra braking could possibly shift the rider's weight forward again, reducing the effect? Then again, probably not if the rider has learned to deal with the extra braking. Here's hoping some DIY person tests it .

Getting the mechanical braking "right" (ie. not causing you to faceplant because it brakes too much) would be quite difficult, plus you'd have extra parts that wear down over time, possibly malfunctioning mechanical brake could lock the wheel etc. I don't think the problem with current electrical braking is the power, rather just that you need to really push down backwards to trigger more powerful braking while maintaining your balance. On a power brake I lean backwards really heavily, almost as if falling backwards (takes some practice) while slamming down with my heels. If the wheel would brake too "powerfully"  (it could do that technically), you'd end up flying off the wheel forwards, so IMO mechanical brakes wouldn't really add to the braking power (at least significantly), but would add more points of failure. Maybe with a very heavy rider and wheel and slamming on the brakes, even the current power FETs couldn't soak up the braking current without frying, but even there I'd look into dissipating the extra braking power in resistors or power LEDs (there's a circuit for "brake chopper" for 16S wheels using 100W COB LEDs floating around the forums) rather than mechanical brakes.

 

Quote

Ok, after 5 minutes of brainstorming more ideas for future EUC features:

• Removable batteries of different sizes/weight. E.g. owning a lightweight battery for daily commutes, and a big one for long trips, for instance.

Already done, KS had removable / replaceable battery cases for KS14B model (  https://www.ewheels.com/product/king-song-14b-removable-battery-pack/ ), back in 2015 or 2016. Didn't really sell well, I guess, plus the packs were fairly small in capacity (16S1P / 150Wh or so), but still physically large as removable batteries must have adequate mechanical protection around them and their own BMSs. For different sizes, the "attachment system" and case would have to be large enough to fit the largest capacity battery, which might make it unwieldy (the wheel would become pretty wide, I'd guess, or the battery would be inserted at the top of the wheel, making it pretty tall).

Contacts wearing down over time could also cause nasty surprises...

 

Quote

• zip-on tires for winter/trails (something like these, perhaps).
• Some kind of attachable bag system to put (small) stuff in (like the bags on the back on bicycles.

No idea how well those tires would work, but interesting idea. I just use a backpack while riding.

 

Quote

• A "rumble" feature for warnings that can be felt instead of heard (like the rumbling in game controllers and cell phones, say).

Firewheel F-series, 2014. Once the battery was nearly depleted, the wheel would start "rumbling", kinda like cell phone vibration but stronger. It actually worked pretty well (the wheel also had no tiltback at all), don't know if any other wheel has the same feature.

 

Quote

• A "someone is right behind me"-sensor and warning.

This might be interesting, although I don't think I'd have any use for it personally.

Edited August 7, 2020 by esaj

[RockyTop]

148wh battery packs! ..... That would give me range anxiety while traveling in my house. .... “ Do I have enough charge to get me back to the couch!? “ 

[mrelwood]

3 hours ago, RockyTop said:

148wh battery packs! ..... That would give me range anxiety while traveling in my house. .... “ Do I have enough charge to get me back to the couch!? “ 

Well, I guess a low battery “tilt-back” wouldn’t be too bad in that situation... 

Edited August 7, 2020 by mrelwood

[mike_bike_kite]

5 hours ago, RockyTop said:

148wh battery packs! ..... That would give me range anxiety while traveling in my house. .... “ Do I have enough charge to get me back to the couch!? “ 

Somehow I keep picturing this each time I read you comment

 

[mike_bike_kite]

5 hours ago, mrelwood said:

Before inventing a solution, you have to figure out the reason for the behavior. Heavy EUCs don’t take a notably longer to stop. Larger diameter tires do. Just like acceleration on any 18” feels much more sluggish than on any 16”, regardless of wheel weight or power. Additional brakes do not affect the tire diameter, so braking distance wouldn’t change.

 You also disregard the word “balancing” in the self-balancing vehicle. For the wheel to be in balance with the rider, it can only accelerate and brake as fast as the rider’s lean requires. Accelerate more and the rider experiences a tilt-back or falls on one’s back. Brake too fast and the rider tips forward, stopping the braking event.

 If riders would fall on their back during braking, then additional braking power would be needed. But they don’t, so braking power is already sufficient.

I think I understand what you're saying but many wheel reviewers seem to complain about the braking on larger wheels ie the Sherman. I can see that motor torque would be affected by the diameter of the wheel. Would that also translate into poor braking? or is it just that the reviewers aren't doing enough to brake the wheel?

[esaj]

12 hours ago, mike_bike_kite said:

I think I understand what you're saying but many wheel reviewers seem to complain about the braking on larger wheels ie the Sherman. I can see that motor torque would be affected by the diameter of the wheel. Would that also translate into poor braking? or is it just that the reviewers aren't doing enough to brake the wheel?

Never had the chance to try any of the bigger wheels, but even on the "small" (16") ones, I find it's considerably easier to brake when there's more "give" on the pedals (soft riding mode). I think it comes down to physics, your umm... "force vector" (or maybe momentum vector... couldn't come up with a better term right now ) points down and forwards when braking (gravity downwards + the inertia of your body going forwards), so if the pedals angle backwards while you brake, they're more perpendicular towards the movement and you're like "standing on a floor". When the pedals stay level, it's much harder to apply force to the back of the pedal to cause strong braking and maintain your balance / not fly forwards when the wheel brakes, at least on my case it's easier to brake with soft mode. To start stronger braking, I've noticed I also sort of "throw" the wheel in front of me with my legs when starting to brake, rather than just leaning straight back.

What I mentioned in a Firewheel review a long time ago was that I'd like to see a mode where the pedals are stiff/hard when leaning forwards (no give), but allow them to dip backwards when braking, because many people don't like the softness when leaning forwards. Firewheel had a somewhat "unique" soft mode in the sense that it actually sort of did this when you rode faster (something like 20-25km/h and above), at slower speed the pedals dipped forwards all the time, but hitting the higher speed they leveled and became stiff even on the soft mode, but I'd like to see the same behavior at any speed. Other than that, the FW's soft mode was way too soft in my opinion, it felt like standing on a spring... I used to ride in the hardest mode of the KS16B & S, but found out that it's easier for me not just to brake but also to accelerate (going uphill) if the pedals have a bit of a "give", so I've been riding in the medium setting for a long time.

Edited August 8, 2020 by esaj

[mike_bike_kite]

1 hour ago, esaj said:

I also sort of "throw" the wheel in front of me with my legs when starting to brake, rather than just leaning straight back.

I do exactly the same. It must be a 16S "thing". I agree with getting the wheels to go softer under medium to heavy braking. Maybe that's what's needed on the larger wheels to allow riders to achieve better braking. Maybe our ankles (or our brains) simply don't allow us to lean back far enough otherwise. It would be interesting to see a "scientific" comparison of braking for different wheels in different ride modes. In fact it would be great to see some scientific comparisons of wheels for range, speed, acceleration, braking, regen, speed throttling, charge times, waterproofing, ride comfort etc - at the moment we either just accept manufactures numbers which are totally unrealistic or a range of reviewers who love every wheel they try or owners who've just bought their wheel and who can be just a little biased.

[Scottie888]

I find the electric braking (or more like going into reverse to brake) to be ample. Sure there's a braking distance but that's true for every motorized (land & air) vehicle out there unless an anti gravity drive is invented. But then the G forces involved in an instant stop might kill us instead.

What I really really want is a swappable wheel/tire ala bicycle tires. Instead of the hours involved in changing tires, wouldn't it be great to instant swap an offroad or rain or winter or whatever tires for the tasks of the day?

[mike_bike_kite]

1 hour ago, Scottie888 said:

I find the electric braking (or more like going into reverse to brake) to be ample.

For smaller wheels I think the braking is fine, I have a 16S and have no problem with braking, but on the larger wheels they don't seem to stop as well. Do you find emergency braking as good on  the S18 as on your 2 smaller wheels?

[Scottie888]

1 hour ago, mike_bike_kite said:

For smaller wheels I think the braking is fine, I have a 16S and have no problem with braking, but on the larger wheels they don't seem to stop as well. Do you find emergency braking as good on  the S18 as on your 2 smaller wheels?

Unfortunately I don't have the S18 as yet. I ordered mid last month so I'm assuming my order will be the 2nd batch to arrive. I've been told end of Aug🤞.

That said, all things being equal, I would assume the Tesla with the 16" tires to have the shorter stopping distance due to mechanical advantage. However the larger motor of the S18 might alleviate or even neutralize that advantage.

I find the Mten3 to brake really well too but then, I usually cruise at 1/2 the speed of the Tesla. Regardless much like using regular hydraulic disc brakes, a bit of sitware & approx dist mgmt will always be needed for accident avoidance.

[mrelwood]

On 8/7/2020 at 10:27 PM, mike_bike_kite said:

I think I understand what you're saying but many wheel reviewers seem to complain about the braking on larger wheels ie the Sherman.

That’s exactly what I was saying. The first reaction to riding the MSX/P is almost always that it requires a lot of effort to accelerate and brake. The GW firmware by being initially very hard on any mode makes the behavior even more prominent.

Quote

I can see that motor torque would be affected by the diameter of the wheel. Would that also translate into poor braking? or is it just that the reviewers aren't doing enough to brake the wheel?

The phenomena is related to geometry, not the wheel’s torque. The behavior is exactly the same even when using just 1/100 of the available torque, when the wheel has zero trouble applying all the power it takes to keep the pedals flat. It’s the geometry that requires more lean, proportionately to the wheel size increase.

 

Quote

easier to brake when there's more "give" on the pedals (soft riding mode).

I’m usually a medium mode rider as well, but on the MSX I have to stay in soft mode to achieve tolerable braking distances. I do ride the tiny spare 16S in hard mode though, since I’ve gotten used to throwing the behemoth of an MSX around with my 210+ lbs off mass...

This was actually being theorized just a while before KS came out with the 2.0 fw that takes use of the exact behavior you mention. It lets the rider “fall” for a very short moment (in soft mode) before switching into a hard mode. Sort of a very steep progressive hardness. That way it takes less effort for the rider to get into the lean.

 

Quote

I agree with getting the wheels to go softer under medium to heavy braking. Maybe that's what's needed on the larger wheels to allow riders to achieve better braking.

I think the Z10 “brake assist” does exactly that. But based on the many negative comments it isn’t implemented very well. The KS fw 2.0 on the 18XL does it quite well.

 

Quote

it would be great to see some scientific comparisons of wheels for range, speed, acceleration, braking, regen, speed throttling, charge times, waterproofing, ride comfort etc

Absolutely. If only it made financial sense to make such comparisons. Until it does, I think it will take way too much work to do as a hobby. And since KS changes the riding modes almost fire every update, the work would be continuous.

Quote

- at the moment we either just accept manufactures numbers which are totally unrealistic or a range of reviewers who love every wheel they try or owners who've just bought their wheel and who can be just a little biased.

👍 It is crucial to only compare wheels based on reviewers who have ample experience on each. Chooch’s comments on the MSX have zero relevance with Marty’s comments on the Z10 for example, which, while sounding simple, is not.

[Finn Bjerke]

Why donmt rollerskies have brakes ? 

ppl like their legs too much.

[mike_bike_kite]

5 minutes ago, Finn Bjerke said:

Why donmt rollerskies have brakes ? 

ppl like their legs too much.

Obviously the brakes don't activate when you're standing upright. I'd have to be pretty stupid to propose that. Try rereading the proposal.

[GothamMike]

On 8/7/2020 at 5:51 AM, mike_bike_kite said:

It's been interesting reading the reviews about suspension. I was trying to think of simple things that could be added to new models of EUC that might still make a difference. My 16S stops pretty quick but heavier EUC's take much longer. Why can't wheels just have an internal mechanical brake that steadily gets activated once the rider leans back beyond a certain point? You'd still have the advantage of regen when descending hills. I'm not sure how you'd monitor the wear on the brakes but perhaps it could just be a serviceable item that could be replaced after so many 1000 miles. You could even slightly increase the softness of the pedals under heavy braking just to allow the rider to "dig in" better. Or is there a good reason we don't have more powerful braking?

I think you’d be thrown off like a cut out.

[mike_bike_kite]

On 8/10/2020 at 2:49 AM, GothamMike said:

I think you’d be thrown off like a cut out.

The brakes, rather than just throwing a stick through the spokes, would be applied quite gradually as in other vehicles. They'd also only be used when leaning far enough back that regen has finished and the wheel would otherwise be using electrical power to get the motor to try and slow you down. Currently I suspect the braking is limited by some formula combining the motor power, the diameter of the wheel, the riders weight and the softness of the ride - I'm not at all sure on this though. Apart from allowing more braking power and using less electrical power, it might avoid the loophole in some countries laws that state vehicles must have brakes. It would also possibly allow you to start a ride on a full battery down a steep descent.

Edited August 18, 2020 by mike_bike_kite

[RockyTop]

We do not go anywhere near the limits of electric braking. We are limited by balance and grip. If we really need to add more braking a few resistors and bigger MOSFETs would easily do the trick. We have had mechanical brakes for over 1,000 years. Only the introduction of light powerful batteries and electrical control of the motor allow us to Develop the EUC. 
When I built my first electric mini bike as a kid, my speed control was very limited. I had to use A series of limit switches and resistors to control the field voltage of the motor. ( I could have used a large potentiometer, I could not find one) Now we have motor controllers for just about anything. From windshield wipers to lathes. We can get more power and torque out of the motor than ever before. The only advantage the mechanical brake has is that it is immune to electrical failure. Mechanical brakes are bigger, heavier, less controllable, wear out, fail quicker and require lots of maintenance. In a perfect world cars would have electric brakes backed up by emergency mechanical brakes. 

[mike_bike_kite]

1 hour ago, RockyTop said:

We do not go anywhere near the limits of electric braking. We are limited by balance and grip.

How do we actually know the limit of the braking available to us? Can the wheel easily tell us what percentage of the available braking has been used? and what happens if we try to use more? When braking hard it's the motor acting against the rotating wheel that's providing the braking. We see plenty of riders overpowering their motors when accelerating and then face planting. Is the limit for deceleration somehow much stronger than the limit of acceleration?

I don't think grip is an issue, at least on larger wheels, as they probably have a larger contact patch with the road than most sports bikes.  It would be a very interesting video to see the braking distances for different EUC's from say 20mph and 30mph then compare that with the braking distance for a car, motorbike and bicycle at the same speeds. It would be interesting to see in the wet as well.

1 hour ago, RockyTop said:

If we really need to add more braking a few resistors and bigger MOSFETs would easily do the trick. We have had mechanical brakes for over 1,000 years. Only the introduction of light powerful batteries and electrical control of the motor allow us to Develop the EUC. 

Most vehicles brake roughly twice as fast as they can accelerate. You'd need circuits to handle twice the power if EUC's were to offer similar safety. You seem to suggest that not having braking is an advantage - it's certainly simpler and cheaper to build but it certainly doesn't offer better braking. Even most modern bicycles can stop faster that an EUC. 

1 hour ago, RockyTop said:

The only advantage the mechanical brake has is that it is immune to electrical failure. Mechanical brakes are bigger, heavier, less controllable, wear out, fail quicker and require lots of maintenance. 

I don't think bicycle disk brakes are heavy though you'd have to have to add an electronically controlled actuator. They'd only be used in extreme braking so they'd be unlikely to wear out. They'd also be used at the same time as motor braking so you're not really losing any of your existing braking, you'd just be getting more available braking.

1 hour ago, RockyTop said:

In a perfect world cars would have electric brakes backed up by emergency mechanical brakes. 

Tesla's and most other electric cars do use their motors to regenerate electricity when slowing down (just like on an EUC) but they also have disk brakes for harder braking. Even esk8's have brakes alongside regenerative braking.

PS I'm not arguing with you because I think you're wrong, I'm just curious why brakes aren't used especially if the vehicle can do 40mph+ and costs over $3K. 

[RockyTop]

1) Correction, from an engineering stand point. We have not come close to the limit. If we need more brakes, add bigger MOSFETs and resistors. No need for mechanical brakes.
Grip and balance. Not road grip but you gripping the wheel and balancing.  It could stop in less than 6 inches electrically with improved electronics. 

2) Again your limits, just add bigger MOSFETs and a few resistors. Less regen and all out resistance and you could stop in 6 inches. Although the physics of an EUC will not allow this. The wheel would just flip over. Side note, I agree, we should have stronger brakes. At this point we need more than regen. We need braking resistors. 
3) The disk brakes on a bicycle are not heavy but they would be compared to electrical braking when you already have 99% needed for the electric braking system. 
4) Tesla-  1)  You need to stop the car. Electric braking could do that yet you need about twice what regen will do. 2)  You need to stop the car without electric power. You need full mechanical braking system. 
You could add a resistor bank and stop the car 100% electrically. You would still need an emergency braking system that could do the same. This would require two full braking systems. Instead the Mechanical emergency braking becomes the main system with electric regen assist. An emergency brake on an EUC would not do anything. If you don’t have power you are down for the count. 
 

Back to elevators. Elevators usually use either regen that puts power back into the power grid or resistors that burn off energy and put out a lot of heat. If an elevator has a lifting capacity of 5,000 pounds and runs empty in the up direction it is stopping A combined total of 8,500 pounds and lifting/holding about 2,500 pounds of off balanced weight when it slows and levels into the floor. This is done with a 30hp motor. The slow down/ braking Can be set to slam you to the ground or throw you against the ceiling. Again that is 8,500 pounds of moving steel. 

[mike_bike_kite]

So can we tell what percentage of the available braking from a wheel we're using?

Are you saying that manufacturers only need to add larger MOSFETs and resistors to drastically improve braking? Is there a reason manufacturers aren't doing this? Is it because these resistors need to be quite large and heavy in order to dissipate the heat? 

Sorry about misunderstanding what type of grip you meant but Kuji pads seem an obvious answer. The 6" stopping distances you mention may be possible but I think it's important the rider stays on the wheel otherwise, technically, it's a crash. The braking distances I'd like to see are just those of other vehicles on the road. 

I'm afraid I know nothing about elevators but I do have the book "The Intuitionist" somewhere in my reading pile (which I think is about elevators) so I might know slightly more after I've read that.