controller for torque sensing BB

Hi

I have a converted bike, that I would really like to add a torque sensor to.
I think the feel is highly superior to that of a PAS bike.

I can buy a torque sensing BB from aliexpress, it seems that they generally work by outputting a voltage between 1,5 and 4 volts depending on the torque on the crank arms.
I don't want to hook it up to the throttle on a regular controller because i don't think that's the optimal solution. So i'm looking for a controller with either a programmable throttle response curve or one specifically made for torque sensors.

Any suggestions?

- Victor

KT make a TS controller but I have only seen it for sale as part of a kit.

This Bafang TS controller is available.
https://www.aliexpress.com/item/32787065325.html?spm=a2g0s.8937460.0.0.395f2e0eisHcK6

The issues might be compatibility as they are thin on the ground.

CAv3?

the two main options for the diyer (not buying a complete oem bike with torque sensing built in) are:

--using the open source firmware (threads here on es by casainho, stancecoke, etc) on the proper version of a kt kunteng kun teng controller, to directly connect the ts bb output to, separately from the throttle.

--using the cycle analyst v3 from http://ebikes.ca as an interpreter for the throttle and ts bb and other available inputs, to output a single throttle signal that combines these per your settings in the ca menus, so that you can control the system via one or more methods.

the first method is probably cheaper, and may give the same level of user-settability that the cav3 does (but i don't know, not having used the kt or osfw yet).

the cav3 has a lot of user-settability, but it does have some limitations, and it's not a controller so you'd still need one, making this a more expensive option.

so you'd want to look at each one's details to see which is more likley to do all the things you're after, teh way you want to do them.

and there may be other options, like the ones pointed out previously.

Phase runner.

phaserunner https://www.ebikes.ca/product-info/phaserunner.html#features is *not* a controller that has an input for a torque-sensing bb.

it *only* has an input for a throttle--that is the only control input it has.

if the ts bb output goes to zero, for instance, it will activate the regen braking of the pr, unless there is a way to disable that in the pr. (regen braking in pr is activated by a throttle voltage between 0.0 and 0.8v).



if an interpreter (like the cycle analyst v3) is put between the torque sensing bb and the phaserunner, then, just like any other controller with a throttle input and no pas requirement, it would be operable from the torque sensing bb.

a torque sensing bb can't (or perhaps, rather, "shouldn't") directly be used to drive the throttle input of any controller, unless the rider wants to have assistance that varies instantly and constantly because of the changes in torque on the cranks, and doesn't mind having the assist engage anytime any pressure at all is applied to the cranks whether or not they are rotating (like when trying to mount the bike, or just resting feet on pedals sitting waiting at a light, etc).

if the rider doesn't mind this potential jerkiness of and not-always-predictable motor operation, then any torque sensing bb that has a voltage output range that matches the throttle voltage input range of the controller in question can be used.

in order for the torque sensing bb to not cause the controller to react even when just resting feet on pedals/etc., the cadence output of the ts bb must also be used, so that it requires rotation before the controler responds to the torque on the cranks.

or, the ebrake input to the controller must be used with a control the rider can hold engaged in some way, to disable the controller until assist is desired.


electronics can be designed and built, or an mcu (arduino, etc) can be programmed, to do all this for any controller...but if that's what is wanted, the ca v3 already does it, with limitations. (

How can someone who knows so little about the phaserunner write so much?

It can do torque based throttle, perfect for torque sensing bb. There are settings for ramp up and down, avoiding the oscillation you mention. The controller is intended to be used with torque sensing bbs.

The regen is programmable and can be disabled or made variable. I mean, really.

Really uncalled for, even if you were right.

Phaserunner is FOC, perfect throttle control, very smooth even with huge power levels, thanks to

accurate access to motor's per-phase amps

which is ~proportional to actual torque.

Nothing to do with PAS control via torque sensors at the pedals.

https://endless-sphere.com/forums/viewtopic.php?t=102074

flat tire said:

It can do torque based throttle, perfect for torque sensing bb.

Click to expand...

torque-based throttle is not the same as a torque-sensing bb; the one has nothing directly to do with the other, though the first may make the second easier / smoother to implement.



(this paragraph is not a reply to flat tire, but is for those reading that don't realize the difference: torque-based throttle is simply a way of responding to the control input that modulates motor current, rather than modulating motor voltage (greatly oversimplified statement for brevity). torque-sensing bb is an input method of *detecting* the torque of pedalling and converting that to a signal to be processed into a throttle control.)

There are settings for ramp up and down, avoiding the oscillation you mention. The controller is intended to be used with torque sensing bbs.

Click to expand...

i said it doesn't have an input for a torque sensing bb.

it only has a throttle input, so to use at least some of the ts bb's out there it will require other electronics to support or translate the ts bb's output, or to power the ts bb, etc. they may not all be able to connect directly to the throttle input, by itself, with nothing besides the phaserunner to operate / power them (thun, tdcm, require 10v for instance).

additionally, the exact voltage for a specific torque varies over time with the ts bb's i've had, and from what little i've read of others like the sempu, it's true of them as well. so there has to be an easy, quick, on-bike way to "zero" the input (to recalibrate it so the drift of the sensor doesn't result in undesired active throttle input). that will require external electronics of some type, even if it is a button going to an mcu that is running "programming software" for the pr to tell it the present input value of the throttle is the zero point, where the mcu is directly reprogramming the settings of the pr via the serial interface of the pr during the button push. without some functionality like this, if the sensor were to drift in output voltage for "zero torque" upwards enough, it would cause the pr to see a positive throttle input, and the pr would activate the motor system even if no rider was on the bike at all, just by being powered on. that's usually undesirable.

the cycle analyst already does the above stuff, but i can't find anything about the pr that does these things natively.



so the pr may be *adaptable* to be used with a torque sensing bb, but it isn't "intended" (designed) for it. if it was, it's info page would discuss this, and would show how to connect and set one up for it; it does not. the manual does not cover this either, nor does the phaserunner dev/sale thread by justin_le. if there is a thread here on es or a page on the ebikes.ca site that covers it, i couldn't find that, either. it doesn't mean no one has done it, but there are no examples i could locate.



if you would like to help people like the op with this, please post your working example of this (or if someone else has already done this, please link to their setup); it's an interesting idea that should be explored further if it is possible to do.

if it's just an untested idea, please post your theoretical wiring and settings, so that someone can experiment with it and find out if it can be made to work as desired with torque sensing bb's in general (or if you know it will require a specific type to do so, please note which one(s)).




regarding braking, i hadn't realized it before, but it does have a separate ebrake wire that can be used for direct proportional regen control as well, which could be used with a user-engaged switch or other control to prevent motor operation without using the cadence sensor of a ts bb when just resting feet on the cranks. the wire is not on it's own connector pin, but it is there in the cable if a user wishes to open up the harness a bit to use it. (documented in the manual)




for reference, below is the info page for the phaserunner (previously linked in another post), with headings/etc and unrelated links or troubleshooting/etc removed, but all feature/usage info left intact:

The Phaserunner is a compact state-of-the-art field oriented motor controller (FOC) from Grin Technologies based around the sophisticated control electronics from Accelerated Systems Inc. of Toronto. It is ideally suited for running brushless motors for electric vehicles in the 500-2000 watt power range, and once you have experienced the smooth response of a FOC with a torque throttle it's hard to go back to a the setup you had before.

This controller was designed as a universal device that can fit on almost any bicycle frame and handle almost any motor system. You can power it from a 24V battery or a 72V battery, and run your phase current to peaks of over 90 amps, though the continuous current capability without additional heatsinking is typically 45-50A. The wiring is pared down to the bare basics for a nice clutter-free installation; including a throttle plug, a Cycle Analyst plug, cable to your motor, and a cable to your battery pack.


Features

Remote on/off switch compatible
Direct plug for both V2 and V3 Cycle Analysts
Proportional regen available through throttle signal or stand alone wire
Works both Sensored and Sensorless, and even with very high eRPMs
Waterproof, 100% potted electronics
Fully programmable parameters (regen voltage, max phase and battery currents etc.)
Field Weakening allows you to run motors faster than normal back-emf limit
Higher motor efficiency at low speeds / high torques
Torque based throttle command (no twitchy throttle with powerful system)
Operating voltage range from 20V to 90V (21S Li-Ion, 24s LiFe)
Automatic thermal rollback to prevent controller overheating

Click to expand...

Should be coined
Torque $en$ing cuz you paying for it!


https://www.ebikes.ca/shop/electric-bicycle-parts/torque-sensors.html
vs
Torque Simulation Sine Wave Controller https://bmsbattery.com/home/1033-s06sc-250watts-torque-simulation-sine-wave-controller-for-central-motor-.html

that isn't a controller for a torque sensing bb either.

direct quote from the site:

Of course, there is no real torque sensor,

Click to expand...

Yes with the "vs"

they were contrasting, how much cheaper to do without.

but pointless, because the op asked specifically for controllers that *do* and/or *can* use a torque sensing bb.


if someone is not posting answers that help the op find the solution asked for, they're not helping the op, and are off topic. i'm trying to help get people to help the op with the actually asked question, instead of posting non-solutions.

Hi

I am running a 13s battery on an old slow wind bafang SWXK motor in a 20" wheel on my e-cargo bike. That setup gives me a top-speed of around 26 km/h when the battery is fully charged, which is adequate. At the moment this setup is run by a cheap 6-fet chinesium controller, which works just fine.

I would like to add a torque sensor to this setup. I have found one on aliexpress that will take battery voltage and output 1-4 volts, depending on the torque applied to the sensor.
I would like to buy a controller which has current limiting in stead of voltage limiting in response to the throttle input signal and the ability to program the throttle curve.

I have looked at the VESC 4.20, but it seems to run really unstable on a 13s battery, which I am using, so I don't want to go down that road. Is there another way, I can go?

- Victor

Thanks for the great replies, especially Amberwolf!

I always find it funny to see the difference between european and american ebike enthusiasts when it comes to ebike power and torque sensing.

I am european and would like my bike to put down the power in the same way that I do, so I don't mind the force oscilating with my pedal strokes! Also, I want to have to work for the motor to draw current, otherwise I will get completely out of shape.

I don't want the cycle analyst because I don't like the idea of it and I think it's ugly.
But the suggestion to use the KT controller with the custom firmware seems like a really good way to go - I am definitely looking more into that!

Vbruun said:

I don't want the cycle analyst because I don't like the idea of it and I think it's ugly.

Click to expand...

if for some reason you do find you have to use a cycle analyst to do something you can't do with available controller hardware, just remember that you don't ahve to use it in a place you can see it. it can be mounted anywhere, if you do'nt need the data on the screen.

you don't even have to use the whole thing; you can use just the mcu board inside, minus the whole display and casing, though you will need to use the serial/usb connection to a computer to set it all up or modify settings later, and you'll need to have remote controls on the aux port / etc to change presets/etc if you want to do that on the fly.

That is true and maybe I was a little harsh on the thing. IT does not appeal to me but even so it can still be a good thing for some

fwiw, there are projects that add a bluetooth adapter to the serial output of the ca, to display it's information on android devices. never used any of them so don't know how well they work, but
https://endless-sphere.com/forums/search.php?keywords=android+cycle&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

so if the main objection is just the oldstyle text display, one of those probably fixes that.

unfortunatley there's no project that can *control* the ca from an external device, as the serial port on the ca is one-way during normal operation (sending data to it requires a different mode and then flashing and rebooting). grin tech would have to change the way the ca works for that to happen, so you would still have to use remote handlebar / etc controls to change presets or values, etc.



the main thing about the ca regarding torque sensing bb / etc., is that it can add control / limiting functions to a controller that otherwise can't do those things. so if you required a specific controller for some other feature it has, the ca can add the torque sensing / etc.

That is true.

I think kt controller + custom firmware is perfect for what I want to do. That route is also way cheaper