Is King Song the safest / best electric unicycle available? References collected here.

[EricGhost]

We as user shall ask for reliable and safer wheels at 25-30kmh and not wheels running at 40-50kmh, there are easier and less painful ways to suicide

 

EDIT:

 

[Max Winderbaum]

On 9/12/2015 at 0:26 AM, KaleOsaurusRex said:

c. High-voltage tiltback stops user from riding downhill when battery is too fully charged. (at high voltage, beeps and tilts back at 69v) - information from direct communication with King Song

Hey @KaleOsaurusRex,

Do you know the reason for this behavior? Does the King Song charge while going downhill?

[Reivax]

13 hours ago, Max Winderbaum said:

Do you know the reason for this behavior? Does the King Song charge while going downhill?

What it needs to do is dissipate the power generated by slowing you down when you go downhill.

This electric current will go to the battery through the electronic circuit. Heat will be dissipated by both, and a little current will charge the battery.

But it's not good at that, so do not count on getting miles out of it. You don't charge a battery efficiently with a wavy current.

Anyway, when the battery is fully loaded it becomes risky to overload and overheat it (and the electronics), hence the tilt back alarm.

I've experienced it a few times with a KS14C, it's rather well handled, it does not throw you out of balance and you have time to stop before burning anything. But I wasn't going fast at that moment.

[Addwyn]

On 27/07/2016 at 5:37 PM, EUCMania said:

EricGhost suggested to give less torque or acceleration than the rider pushes for, such as if the rider wants 2g of forward force, the machine only gives 1g.

[...] Once the rider sense this softening, he may want to reduce his body's forward leaning. However, to do this, he has to push more force on the toe, the front part of the feet. This further pushes the pedal forward, asking the machine to provide more forward force. Once you get into this vicious cycle, you have to jump off or faceplant or both. [...]

I think this reasoning is flawed because if this was true, it would also apply in reverse in the opposite situation : To accelerate... It means that, from the wheel stopped, the rider who would like to increase his's body forward leaning would have to push more force on the rear part of the feet, which would slow down the wheel (or rather go back). But, this is not what happens ! When starting, we increase our body forward leaning while also pressing the front part of our feet (to accelerate) ! So, it sould also be possible to decrease the rider's body's forward leaning without pushing more force to the front of the feet...

The movements of the rider's body are a complex active part of the "system", which is much more than a simple inverted pendulum. That's why I think that the @EricGhost's reasoning is not uninteresting...

 

(Thank you to forgive my low level in English)

[EricGhost]

http://forum.electricunicycle.org/profile/2972-addwyn/  my proposal came on the fly like a brainstorming because I was surprised to discover that there were limited safety protocols applied to a control loop system and that there was a resignation in accepting the "status quo" instead of pushing for solutions.

My main idea is that the system is controlled and can react quickly if nearing dangerous parameters (which does not mean only speed, but i.e. power look like KS latest FW1.22 is taking care of it) so other than beeping it can tiltback or it can do other things, like change it's behaviour (KS has 3 cycling modes learning,bicycle and play) so the user can feel the change or better many changes (beep, tiltback, wheel behaviour) and clearly understand that he is riding in a dangerous zone.

I was not properly understood and got some answer not adeguate to the "safety issue" I was following and that I believe shall be fougth against all hope  

[Frode]

On 30.8.2016 at 1:14 AM, Addwyn said:

When starting, we increase our body forward leaning while also pressing the front part of our feet

Stand upright on a floor and bend forward in your heaps. You will definitely move your center of gravity forward and have to put pressure on your toes not to fall.

On 30.8.2016 at 1:14 AM, Addwyn said:

also be possible to decrease the rider's body's forward leaning without pushing more force to the front of the feet.

Bend in your knees and your center of gravity will move backwards.

It is however not pressure on toes and heels that is important. It is the torque you generate around the wheel axle (pressure on toes and heels will of course generate a torque tough). It is important to recognize that it is this torque that is the input to the wheel. The wheel will always - and I mean _always_ have to counter this torque with an _equally_ large counter torque. Otherwise the body of the EUC will start rotating in the direction of the largest of the two torques. The wheel will not any longer balance.

The only way the wheel can make this counter torque is to activate the motor. The motor will try to rotate the wheel in the opposite direction of the needed counter torque. If the wheel is spinning in thin air, it won't be able to generate much torque (unless it is _very_ heavy). But since it touches ground it can generate all the needed torque. The ground will hold the wheel back so to speak. This in turn will make the whole system to move since the wheel will start rolling on the ground (unless it is nailed down to the ground, sitting in a pot hole or something). It will actually have to increase its speed as long as the counter torque is needed (as long as the rider leans forward) with an acceleration that is proportional to the needed counter torque.

If now the wheel electronics decides to not accelerate the wheel that much, but just a portion of it, the counter torque will be less than the torque the rider has put on the wheel. This will inevitably lead to the body of the wheel starting to rotate in the direction of the largest torque, which means in the direction the rider is leaning. The rider will fall forward if he do not lean back again (he will probably have to bend his knees, and he will have to do it immediately to avoid falling).

Sometimes a wheel does exactly this, i.e. put only a portion of the demanded power to the motor. That is when you reach the system inherent maximum speed of the wheel (system includes rider). This happens when the battery cannot give all the current to the motor that is needed. Her is one describing how this felt:

 

[Addwyn]

@Frode, I totally agree with everything you said.

I think that the wheel+rider system is in permanent interraction. The wheel reacts instantly to the rider's solicitations but, at the same time, the rider reacts instantly and adapts to the reactions of the wheel. For example, when climbing a hill, the wheel go slower than on level ground. It's like if the wheel forces the rider to slow down. But we do not fall (at least, if we are a minimum careful). This permanent interraction takes place in both directions between the rider and his wheel. This is a sign that the balance is therefore possible even when the wheel reacts (slightly) differently to a same solicitation from the rider. That's why I think that there is possibilities for further improvements in security algorithms ...

 

[MaxLinux]

On 7/31/2016 at 6:19 AM, EricGhost said:

We as user shall ask for reliable and safer wheels at 25-30kmh and not wheels running at 40-50kmh, there are easier and less painful ways to suicide

Right, it seems lately EUC makers are competing against each other to have the fastest wheel. I wish they would start competing on torque. I hope more videos like this one start to appear:

 

[UKJ]

Interesting off road dress?

Bravo though for STEEP climb.

Thongs? glad he stayed on!

Never catch me dressed like that on any terrain any time!

ukj

[Smoother]

On 30 August 2016 at 1:14 AM, Addwyn said:

Thank you to forgive my low level in English)

No forgiveness necessary for your English it was very good. Your comprehension may need forgiveness, however.  I read the box you quoted as having flawed logic, three times, and the logic of the statement is sound., to wit, in order to reduce his forward lean, in the scenario described, he WOULD have to apply more pressure on his toes, to force his body to lean more backwards than it is currently, in order to not get ahead of the wheel that just refused to give him the torque he requested.

However, as others have stated here, if the motor does not apply enough torque to keep the wheel under the rider, it's a one way ticket to FPC (face plant city) anyway, so the scenario is abstract at best. But I'm no rocket surgeon, I could be wrong.

[Frode]

On 28.11.2016 at 4:33 AM, MaxLinux said:

I wish they would start competing on torque. I hope more videos like this one start to appear:

Really impressing

Which version of the KS-18 is that?

And I agree with you. Torque, not speed

[One]

I'm interested in the weight of the rider. Let me guess: 60kg?

What will happen on the same track if a super sized 190cm guy starts to "ride"?