2 Wheel Drive electric bike prototype

X

xranalli

1 W
Joined
Mar 18, 2013
Messages
52
Location
Montefano
Dear All
I'm designing and making a lightweight motorcycle prototype with following characteristics:
2 wheel drive whit one electric motor for every wheel
6kW x 2 continuos power at shaft = 12kW (I will use Plettenberg Predator 37 coupled with gears)
2 kelly controlles
3.1kWh 80V battery pack
aluminium frame with non conventional front suspension
rear suspension mono swing arm
the 2 controllers for 2 motors are controlled by Arduino to manage the correct torque to front and rear wheel.
Please give me your opinions, suggestions, questions.
Thanks in advance.

foto (1).JPG

IMGP6270-1.JPG

battery pack.JPG
 
...really love what your doing. Great to see some out of the box thinking, and some great fabrication work.

12KW is a lot of power, and a battery pack of that size is a lot of weight. The single sided swing arm and linkages may not be strong enough to cope with the forces of riding - given the weight and power.... it may want to twist the frame, which would not be good.
Love the front 'BMW' type suspension.... but would question the use of a front motor - it adds complexity, cost and weight. Keep it simple would be my suggestion.... a single motor driving the back wheel.

...looking forward to seeing this one finished.

S.
 
You're right
target for weight is 70Kg, the batteries weight about 40Kg, this is a challenge (all project is challenge)
about stiffness of components we are doing FEM analysis
first test in braking phase shows that stifness of front suspension is ok.
Front suspension is like BMW telelever but with mono-arm so you can dismount wheel in a simple way
and design is better.
About 2 wheels drive you're right that I add weight and complexity but the performances should be unique, I hope!
 
the scope of front motor (geared) is not only traction but to recovery energy during brake phase
because in motorcycle the energy that goes to front wheel is much more than rear wheel
so the idea is to recovery a good part of this energy.
The weight of front motor (as rear motor) is 4-4.5Kg.
My question is if it is usefull for performances (acceleration and regen) or not
 
Awesome design, for the battery pack you can get it down to ~20kg for 3kwh for the batteries which would make the bike alot more usable :) I am testing the batteries and they should be great for a peak load of 30kw. Let me know if you want more info.

Love the fact you have just gone ahead and built the bike! When designing it did you ever consider doing the bike with a hub center steered front swing arm? Using a chain drive on the outside of the swing arm and a CV joint to allow the wheel to turn. Doing that you could have had the motors in the middle of the frame rather then mounted on the wheel hubs. Atm i am looking to build a 2wd bike for similar reasons to you, its significantly better for regen but it also gives better control on corners if you can get the front wheel to provide even a small amount of drive when the rear wheel kicks out slightly. Meaning for idiots like me who can not ride a motorbike like a racer i can push it much harder with a much lower chance of highsiding on a track.

As a commuter bike that thing is going to rock :)
 
I've hit over 70A at 80V peak regen current on a rear wheel with no scrubbing or skipping. Regen is NOT a reason to put a motor on the front, because current batteries generally can't handle the energy possible from rear regen, much less what is possible on the front.

I do like the idea of 2wd on motorcycles though. It's been the holy grail that the motorcycle companies never have been able to pull off well. To me electrics change that. I can't wait to hear how your motors down near the hub work out.
 
About battery I'm using Lifebatt 20Ah prismatic cell, please let me know what are u using because I need to reduce the weigth, absolutely.
About front suspension I'm fan of hub steering (please see http://www.rygriffon.it) but here I choosen a sort of telelever because motorcycle is all terrain and high stearing capablity is necessary.
Unfortunatly there is no space on frame for motor because this is very compact (wheelbase 1240mm, like a small moped) and I would to avoid every type of chain for transmission to simplify all.
About front traction against high side I agree, difficult is to manage the torque that goes there...
Please share your solution when you want, I'm very curious.
Because I want to see difference with and without front motor I'll test both solutions.
 
Regen (only my opinion - probably not worth a cent) is over rated. If your doing regen for extended range - forget about it. Good brakes are so much nicer than the feeling of regen...and your not really going to get much back in the real world. If you want extended range, efficiency is key - this includes weight, and very importantly aerodynamics. I'm quite surprised that you have designed a 'space frame' of sorts, and then mounted the batteries outboard. ideally you want the weight as low, central and as compact as you can.
A single motor, driving through a reduction - with two or three speeds (or infinitely variable) would be the go for motor efficiency.

I've come to a conclusion of sorts - design your battery pack, then build your bike around it - rather than adding the battery at the end as a retro-fit.

I still think your doing some great prototyping work... bravo.
 
John in CR said:
I've hit over 70A at 80V peak regen current on a rear wheel with no scrubbing or skipping. Regen is NOT a reason to put a motor on the front, because current batteries generally can't handle the energy possible from rear regen, much less what is possible on the front.

I do like the idea of 2wd on motorcycles though. It's been the holy grail that the motorcycle companies never have been able to pull off well. To me electrics change that. I can't wait to hear how your motors down near the hub work out.
Click to expand...

there is a reason why 2wd motorcycles are very rare, it makes them dangerous, introduces to much complexity and weight . Its been played around with nearly every major motorcycle company at some point and electric will not really change this.

Edit:
All you need is some very clever , very fast electronics that controls the power to the rear wheel to eliminate highsides,,
 
xranalli,

As gwhy stated - there are many known issues with dual wheel drive motorcycles and they are and likely have been the holy grail for sport bike design since the first proof of feasible electric motorcycles became reality.

I spent about a year perfecting (well, for my purposes) an all wheel drive primary controller using my favorite prototype MCU board the Arduino ATmega328, I had to dump the arduino library to regain my second time for use in Interrupts - **(loss or detection of loss of front wheel traction must be accounted for immediately, hence the use of interrupts). In the end the system monitored both motors current looking for various tells such as if the front motor loads up second or so before the rear it usually means an incline and delivers proportionally more power to the rear - unless there is slip.

One other trick was in monitoring the wheel speed of each wheel using 3 hall sensors and 14 bit oversampling per analog input - dedicating a single Atmega to detection of this condition when one wheel would go faster than the other.

My use in the end of a dual Hub Motor 2004 Hard Rock Pro with normal dirt track tires was to commute dozens of times to the pharmacy 4 miles from my condo complex at roughly 40 mph in 26" of snow (yes I was wearing ski gear and a full helmet) but the miraculous parts were:

A.) I was passing snow plows through the rough by at least 10 MPH on major highways
B.) My anti lock brake warning worked (could be connected to regen) and indicates if a wheel is slipping (small LED light on bar readout)
C.) No matter how hard I pushed the bike it felt more like an AWD truck or perhaps a Quad Runner is a better analogy, it was fast to accelerate, ran through the worst of it and never complained.
D.) In the 80+ miles of errand running on this bike with Pannier packs (running 15S2P per motor) I never once lost it, went down or had a hairy experience of loosing traction or balance! The log showed my anti slip system had activated > 1000 times in that 80+ miles over 2 days.

my system wasn't perfect (I hadn't designed for some hardware failures and didn't feel like it since I had proven the concept) but it's along the lines of what I believe you will need...

If I can be of assistance in designing or implementing an embedded or RTOS style control system, feel free to PM me.

Regards,
Mike Keefer
mwkeefer@gmail.com
267-303-7050
 
two wheel drive motorbikes for offroad are not that rare..
and i wouldnt call the Christini AWD "dangerous" haha..
in fact on this day & course i bet many wish they had one.. :wink:

Christini AWD @ 2013 Erzberg Rodeo GoPro Footage:
[youtube]2E3_cN3hKeQ[/youtube]

non-Christini riders cant climb & end up in the ditch.. : :lol:
[youtube]z484SYSWaQc[/youtube]

Christini AWD also has a dual-sport street version.. 8)
someone please electrify one of these beasts!! :twisted:

gwhy! said:
John in CR said:
I've hit over 70A at 80V peak regen current on a rear wheel with no scrubbing or skipping. Regen is NOT a reason to put a motor on the front, because current batteries generally can't handle the energy possible from rear regen, much less what is possible on the front.

I do like the idea of 2wd on motorcycles though. It's been the holy grail that the motorcycle companies never have been able to pull off well. To me electrics change that. I can't wait to hear how your motors down near the hub work out.
Click to expand...

there is a reason why 2wd motorcycles are very rare, it makes them dangerous, introduces to much complexity and weight . Its been played around with nearly every major motorcycle company at some point and electric will not really change this.

Edit:
All you need is some very clever , very fast electronics that controls the power to the rear wheel to eliminate highsides,,
Click to expand...
 
Can't be that good all manufacturers will have a awd bike, it's bout the only viable place for a awd bike can be useful on veryloose/slippery terrain but no good for hill climbing. :).
 
Wow. Nice job man. It's good to see something different finally! How did you stumble across that motor? Big old inrunner?
 
gwhy! said:
Can't be that good all manufacturers will have a awd bike, it's bout the only viable place for a awd bike can be useful on veryloose/slippery terrain but no good for hill climbing. :).
Click to expand...

great logic haha..
well electric cant be that good or all the manufacturers will have them as well.. :roll:

or maybe they have a patent on the design???
perhaps technology takes some time to develop and gain widespread adoption???
if AWD has so little utility then why do people / companies keep developing them???
seems about like saying jeep must suck at climbing mountains since its 4wd..
or subaru must suck in the snow since its AWD..
maybe they should just follow what everyone else is doing instead.. haha

"not good for hill climbing"
did you watch the video???
starting from a dead stop, climbed everything other bikes were going back down to try again..
it is true however that the Christini rider / bike did not win the race..
but they did finish and thats more than can be said for most.. 8)
 
I'm not going to get sucked in to a debate about this, I have just said it as it is. As regard electric, all The big manufacture just want to play it safe.
 
gwhy! said:
I'm not going to get sucked in to a debate about this, I have just said it as it is. As regard electric, all The big manufacture just want to play it safe.
Click to expand...

how about ride the bike first..
then plz tell me how much it sucks at climbing
otherwise it just seems like a baseless opinion.. :wink:

This is the new christini all wheel drive military model motorcycles that the Navy Seals just purchased 24 of.. the Navy Seals requested it has every available option, this bike is really cool and there is nowhere it will not go all aluminum construction and weighs in at 280lbs..

good enough for navy seals.. good enough for me :wink:

special-forces-motorcycles-7.jpg

http://www.bikebandit.com/community/articles/special-forces-motorcycles
 
Dear all
about the electric motor I would to use a small, quick motor instead hub one, because with this solution is possible to stay under 4-4.5Kg of weight when hub motors go from 6Kg to 9Kg, too much.
About AWD vehicle I think that as in the car 4WD it is better than 2WD in all conditions but the cost is higher so where it is not necessary it is not used; in race often AWD is forbidden (formula1, motoGP).
Please do not forget that often innovation cames from garage and not from big manufacturer (have you attended sometime to meetings of innovation committee inside big company? Very hard to take decisions...my experience...)
 
cool stuff,
this bike is strictly for road use (no off road), right?

interweb browsing,

lawson
http://thekneeslider.com/lawson-ktm-all-wheel-drive-conversion-in-action/
http://www.automotto.com/double-arm-awd-motorcycle-terrain.html

yamaha/ohlins
http://www.gizmag.com/go/2351/
http://www.ohlins.com/Checkpoint-Ohlins/2WD---The-Complete-Story/Exactly-how-successful-was-the-2WD-system/

ktm
http://www.gizmag.com/go/3180/

efMX Trials Electric Freeride said:
if AWD has so little utility then why would motocross suspension legend joe lawwill be working on an AWD offroad prototype???
Click to expand...

any link?
 
This prototype is for road and just simple simple outroad, but this just first rough prototype, if it will work I'll do an evolution of it.
 
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