How to control 2 DD motors independently on a 2AWD bike?

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thunderstorm80
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How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Aug 30, 2017 4:33 am

Hi,
I know it's possible to split one throttle signal output from a single CA and send it to two motors, but the problem is that not all situations were meant to apply equal torque both at the front and the rear wheels.
For example: At uphill takeoffs, you would want to have more torque on the rear and control how much you apply on the front, separately.
On downhills, you would do the reverse while you regen and brake yourself. (and especially if it's raining you would apply much less braking torque on the rear)
I love Grin's approach where you use the same throttle also for regen by holding with the other hand the E-brake lever, but then you are unable to manually, and fully, control 2 different motors. (both for acceleration and deceleration)
It would require 3 hands for regen: One activating the E-brake lever, and the two others controlling independently the braking torque with the respective throttle.

I thought to use one of the legs/pedals to close a circuit, like a microswitch, that will enable regen mode, so the two hands can control the two throttles.
Has anyone done something like that before? It would be nice to see.
Or, do someone have an idea how such application can be approached when you have two throttles, two CA's, and two (but not interconnected) E-brake levers. (and only two hands)

The solution can be electrically. I can give you example: On one bike where I have a front DD and a rear non-regen geared motor, I have the left E-brake to signal the CA + using the throttle, or, I can press the right E-brake only and this one shorts the throttle CA output so I get maximum regen instantly. This is for emergency braking situations where you need to press both mechanical levers, and so you have the advantage of having the motor helping out as well. (and no need to hold the throttle)

I was already advised to to remap the throttle voltage->torque output on each of the controllers (Phaserunners), but this is an automatic approach which doesn't fit all scenarios, and will seriously hinder your accelerating/braking abilities when you do want to use both motors equally.

And last, I know there are bi-directional throttles but I have never experienced one, and they seem awfully inconvenient for your wrists if you do lots of motor-braking. Has anyone tried those and can share the experience?

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by Hillhater » Aug 30, 2017 5:19 pm

What you need is traction control for each motor, then use a single throttle.
No idea if that can be done however, but it shouldnt be impossible . :wink:
Or to "McGuiver" it you could just use a throttle for the front and Pedalec control for the rear ?
Regen control of individual motors from the brake levers
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spinningmagnets
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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by spinningmagnets » Aug 30, 2017 6:00 pm

Teklektik covers this in his build thread:

https://endless-sphere.com/forums/viewt ... =6&t=36959

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Aug 31, 2017 9:39 am

spinningmagnets wrote:Teklektik covers this in his build thread:

https://endless-sphere.com/forums/viewt ... =6&t=36959
Cool build!
He used a switch to control which is the primary motor at a given time, but, I don't want to have any preset switches: You may forget which state it was on a critical moment and find yourself skidding on a wet road on a steep downhill due to the wrong configuration.
It should be a temporary button, like regen E-brake lever which lasts as long as you intentionally hold it.
For example, you start to pedal using a PAS and the motor strongly pushes you way too hard on a gravel terrain so you find yourself skidding a bit. This can happen because PAS power is defined as a preset configuration and not a temporary button - You can dial it on the fly with the CA, but it stays on that dialling position.
Grin sold twist throttles with e-brakes, which can help you to do 3 actions with 2 hands: I bought one and it feels quite uncomfortable to press that green button while you also twist a throttle. Maybe it's just a matter of getting used to it? Has anyone got some experience with using it?

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by Hwy89 » Aug 31, 2017 10:06 am

I have had good results with the two throttle setup posted by motomech. A thumb throttle with a half twist throttle next to it. You can operate the half twist with your palm and two fingers and still modulate the thumb throttle. It is easy to control and adjust the power to two motors with one hand. I was quite surprised at how quickly I got used to it.

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by Alan B » Aug 31, 2017 3:11 pm

I have a 2WD with a pair of PhaseRunners on the Bonanza linked in my sig. It works quite well. They are torque control, so almost everything you read that others have done won't apply to your situation. Don't overthink it, it is fun to consider all the different possibilities, but it gets very complicated with minimal benefit.

Two throttles works quite well (eg left front and right rear), and since they are torque they just automatically add up, unlike the regular speed throttles that most controllers have. Synchronization issues are essentially self solving with torque throttles.

So far I've sent the same signal to both controllers and used the programmability of the PR to adjust the torque/power of each motor.

I generally program the front motor to have lower torque than the rear. The weight transfer causes the front to have less traction under hard acceleration anyway, and I don't want it to slip. But it has proven to be fairly non-critical. With 2 motors acceleration happens so quickly there isn't much drama.

Good luck with your project,

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by amberwolf » Sep 01, 2017 2:25 am

I just use separate throttles, one on right and one on left of handlebars.

On SB Cruiser (trike), since the motor wheels are on left and right, the throttles also control left and right (helps with turns, among other things). The ebrakes (regen left, active braking right, because the controllers are different) are on just one ebrake handle, though I've considered making them independent for more turn control, etc, but with one ebrake handle the braking is more even (less brake steer).


On CrazyBike2, since the motor wheels are front and rear, the left side stuff controls the rear motor and brakes, and the right controls the front motor and brakes. This gives me independent control of braking and steering, and has saved me from a skid or loss of control on wet roads in turns more than once, because I can apply power to one motor and braking to the other, and vice-versa. I've had it setup with independent throttles but ganged brakes, but it works better with both independent.


On both SBC and CB2 the physical brakes are on separate levers from the ebrakes, which might seem clumsy but it is easy to get used to. If I weren't generally lazy I'd've built an extra layer to the physical brake handle similar to the inner release lever on vise-grips, but on the outer side of the levers, shorter than the levers, so I could use just the ebrake, or pull just the phsyical brake, or both.

I could use just a button on there (did that once with DayGlo Avenger) but a lever is easier to just grab in a quick stop situation.

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Sep 02, 2017 2:46 pm

amberwolf wrote:I just use separate throttles, one on right and one on left of handlebars.

On SB Cruiser (trike), since the motor wheels are on left and right, the throttles also control left and right (helps with turns, among other things). The ebrakes (regen left, active braking right, because the controllers are different) are on just one ebrake handle, though I've considered making them independent for more turn control, etc, but with one ebrake handle the braking is more even (less brake steer).


On CrazyBike2, since the motor wheels are front and rear, the left side stuff controls the rear motor and brakes, and the right controls the front motor and brakes. This gives me independent control of braking and steering, and has saved me from a skid or loss of control on wet roads in turns more than once, because I can apply power to one motor and braking to the other, and vice-versa. I've had it setup with independent throttles but ganged brakes, but it works better with both independent.


On both SBC and CB2 the physical brakes are on separate levers from the ebrakes, which might seem clumsy but it is easy to get used to. If I weren't generally lazy I'd've built an extra layer to the physical brake handle similar to the inner release lever on vise-grips, but on the outer side of the levers, shorter than the levers, so I could use just the ebrake, or pull just the phsyical brake, or both.

I could use just a button on there (did that once with DayGlo Avenger) but a lever is easier to just grab in a quick stop situation.
Can you attach some pictures? It's hard to imagine all this without visualization :D
On the CB2, how can you use two hands to have all the braking/accelerating possibilities with the 2 motors?

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Sep 02, 2017 2:59 pm

Alan B wrote:I have a 2WD with a pair of PhaseRunners on the Bonanza linked in my sig. It works quite well. They are torque control, so almost everything you read that others have done won't apply to your situation. Don't overthink it, it is fun to consider all the different possibilities, but it gets very complicated with minimal benefit.

Two throttles works quite well (eg left front and right rear), and since they are torque they just automatically add up, unlike the regular speed throttles that most controllers have. Synchronization issues are essentially self solving with torque throttles.

So far I've sent the same signal to both controllers and used the programmability of the PR to adjust the torque/power of each motor.

I generally program the front motor to have lower torque than the rear. The weight transfer causes the front to have less traction under hard acceleration anyway, and I don't want it to slip. But it has proven to be fairly non-critical. With 2 motors acceleration happens so quickly there isn't much drama.

Good luck with your project,
Hmm... so you say I can do this:
I have a front H3525 and a rear ezee250rc at the moment. If I will go for the dual braking approach I will change the rear to be also H3525.
Those motors are built like a glove to the Phaserunner with their very low demand of phase current. (but a higher voltage is required - I use 82.5V battery)
For example, I can program the rear one to have a max phase current of 80A and a max regen phase current of 50A, and vise-versa for the front.
The problem is, I live in a very hilly city, and if I happen to start taking off at traffic light on a +12% slope grade with a wet road, I can't apply almost any torque to the front (or not at all). If I use the above fixed ratios (or any given fixed ratios), I will find myself unable to start as I won't be able to apply the necessary torque on the rear as well.
It can be solved by using the AuxPot on the CA which controls the front, but as I wrote above - I don't want to do any preset-changing values while I ride as it can be dangerous. That's why brake-levers and throttles which are momentary-press inputs are safe user interfaces.

I still got one of those but never tried it:
http://www.ebikes.ca/shop/electric-bicy ... ist-b.html
Do you have an experience with twisting a throttle and pressing a button for regen at the same time?
If it doesn't causes thumb strain, then with this one I don't need a third hand - When I press the e-brake button, both throttles become proportional regen throttles.

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by Alan B » Sep 04, 2017 12:40 am

I use a gearmotor in the front, so no regen there.

I use a brake lever to control rear regen so it is totally natural.

I don't expect to apply full throttle in the rain. Use less throttle. Test things out, they don't always work the way one expects. If you really want independent control, use a throttle on each hand, one for front, the other for rear. This works well with a torque controller, each one requests the desired torque, and the motors sync speed automatically. With a speed controller you have to sync the throttles to the same speed, but not with PhaseRunners. How much have you operated this system configured this way?

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Sep 04, 2017 6:49 am

Alan B wrote:I use a gearmotor in the front, so no regen there.

I use a brake lever to control rear regen so it is totally natural.

I don't expect to apply full throttle in the rain. Use less throttle. Test things out, they don't always work the way one expects. If you really want independent control, use a throttle on each hand, one for front, the other for rear. This works well with a torque controller, each one requests the desired torque, and the motors sync speed automatically. With a speed controller you have to sync the throttles to the same speed, but not with PhaseRunners. How much have you operated this system configured this way?
This is the setup I have currently - a torque throttle for each hand (and motor). I use Phaserunners of course!
It works very well, and since there is only one motor which is capable of regen the system works fine - Instead of gripping both throttles, I only grip the DD's throttle, and with the other hand I squeeze the E-brake lever. This is where the problem to independent-regen for two DD motors (which capable of regen), starts....

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by Alan B » Sep 06, 2017 8:44 am

In that case I would set up a secondary lever on each mechanical brake lever for the ebraking, and circuits to override the throttle voltage when the braking levers were used. In e vehicles they often use paddles on the steering wheel for e braking.

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by thunderstorm80 » Sep 15, 2017 3:36 am

Alan B wrote:In that case I would set up a secondary lever on each mechanical brake lever for the ebraking, and circuits to override the throttle voltage when the braking levers were used. In e vehicles they often use paddles on the steering wheel for e braking.
Can you show a diagram/picture of what you mean? (if you did something like this before)

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Re: How to control 2 DD motors independently on a 2AWD bike?

Post by atarijedi » Sep 16, 2017 5:05 pm

Adaptto controllers have been designed to be able to daisy chain them so you can run 2WD.

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