justin_le wrote: ↑
Mar 05, 2018 6:43 am
The answer to this is that we tried
to get this feature in on the 3.1 release but found that there is more than meets the eye for it to be well behaved. Our plan was to provide PAS power from torque alone just for a certain time window. One that was long enough to allow the rider to get up to a speed where the crank RPM signal is coming in steady, and then it would switch to the normal torque+PAS signal operation. However, on as sensor like the THUN with just one side torque sensing, there's a huge period in the rotation where the torque is zero or even negative. This is handled well in our normal mode which does the average torque over the last full crank revolution, but when you just amplify torque alone you get no power during the right stroke. If you start pedaling with the left side, you'll get an initial boost that will then cut out once the right crank starts to take over.
Since I'm using a TDCM on the SB Cruiser trike, then it doesn't have the same issue as the THUN, as it senses both sides.
So I'd guess I wouldn't likely have a problem, before the rotation is sufficient to kick in and get the system running in dual-sensor mode.
Which beta versions (if any) have that feature? I'd be willing to try them out to see if they'll do what I need.
Heck, I'd even use an alpha version to test it out, and if anything else is broken that I don't require, I'd be perfectly happy with that.
The main issue I'd have other than that is that when I stop moving the cranks, the CA needs to stop outputting throttle instantly (as instantly as possible for however many poles the rotation sensor has). I have a few kW on tap and if I'm in a parking lot or in close slow-and-go traffic and something happens in front of me that doesn't require braking (and would be actively bad to brake cuz I'd get hit from behind) but does require cessation of power input. If it keeps outputting power for a half second, I'd probably hit whatever it was in front of me.
Pedalling backwards even a teensy fraction of a rotation does this powercut, but I might not have time to do that part--might only have time to stop pedalling.
I'm going to try the 24-pole external magnet ring and see what happens. It should be easy enough to make my own ring, I have plenty of magnets and at least a couple of generic PAS sensors from 5- and 6-magnet units that I can install in the plastic cover next to my cranks, and stick the magnets either directly to the granny gear or to a plastic sheet I can fasten to the granny gear.
IIRC we tried adding arbitrary time delays for the power to sustain through this but then if you start applying pedal force for a bit and change your mind there's a period where the motor wants to lurch you forwards. It's hard from the limited signals coming in to always properly infer what the rider is intending to do.
I definitely understand, and especially on a regular bike there are a lot of things the average person does that they have to unlearn for certain types of setups, or else figure out settings on teh CA (or add other external hardware) that will deal with the behaviors they don't want to change.
I wouldn't want any delays at all--I only want the assist exactly as I am applying torque, and as I back off teh torque it backs off the assist, as I strengthen the torque it increases teh assist.
(because for me, it's not assist--at startup the motor has to do all the work and has to do it *right now*, especially with a few hundred pounds of load and traffic waiting behind me as the light turns green).
Anyways we have some other ideas that should help get more responsiveness from the low pole sensors like the THUN that I hope we we can roll into a 3.11 or 3.12 release.
You can always add a note that goes something like this: "In order to get the proper responsiveness if using a THUN (or similar low-pole-count torque sensor), you have to add a 24-pole (or whatever) PAS magnet ring sensor in addition to the THUN, and disconnect wires X Y Z from teh PAS sensor cable on teh CA/THUN cable, and connect the CA side of those wires to the PAS magnet-wheel sensor output instead."
It's not exactly ideal in that it complicates setup and wiring, and adds the cost of the extra sensor, but if it enables functionality that can't be properly had otherwise, I'm not going to be the only one that would be willing to do that to get it.
I can relate to being averse to throttle usage once you have PAS otherwise up and running, we get spoiled with a bike that seems to know what we want.
It's not really being averse to it--I still actually will require the throttles to work, too, for using the rear side motors to help steer sharper around corners with, so they'll still be used.
See this thread:
https://endless-sphere.com/forums/viewt ... 3#p1362521
for the details of how the system is going to have to work and what I've figured out so far for it, and the electronics modules I'll have to design and build to work around the CA's present limitations.
However, the PAS needs to also be able to stand alone and control the motors as a pair. Sometimes one or both of my hands go numb, randomly, and I can still do things but not feel what I'm doing, and this gets worse as I get older. It's safer if I can have a PAS control that operates the trike without my hands' input, should I have both hands go numb at the same time but be in traffic and needing to continue on.
It's also in case they ever do pass ebike law changes here in AZ, so that if they make a mode where no throttle is allowed for either some type of bikes or to be able to use certain paths, I can qualify for that, switching to that mode on the CA, and using just PAS, etc.
But it does have to work the same way the throttle does, from a complete stop without my own power input making the trike move, to be useful. At present I'm still strong enough and my joints work well enough to be able to push hard enough in the lowest gear to get the trike moving unloaded, without a lot of pain--but this isn't always true, and as I get older it's going to worsen, and eventually I expect to be unable to do it at all.
The newer sensors like Sempu with their 24 pole cadence signal helps a lot, and your idea of tagging on one of the 24pole mini PAS sensors from King Meter to your 8 Pole Thun is certainly an interesting option too.
It's actually the 12 pole TDCM now (my original CAv3 is still dead from the speedsensor/battery+ short at the molded shunt's wire exit), and the THUN is still on CrazyBike2); I traded Cvin work on her bikes & stuff for the TDCM/CAv3 we'd setup on her Cemoto she's now selling off, as she now has other PAS bikes like Radrover, Haibike, etc. that do what she wants without the complication/expense of the CA/etc. (though there are features the CA has those don't, she doesn't need them).