In the Turbo PAS Specialized uses in its mid-drives, the primary control on motor power is rider power Pr measured at the crank with a dedicated power sensor.
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A torque sensor only knows how hard you are pushing the crank but has no idea how much power you are actually inputting with your legs. To reduce the thing to absurdity, you provide the maximum torque when you are riding out-of-saddle (actually stomping on the pedals) but you rotate the crank at a very slow rate (cadence). Such way of pedalling is called "grinding" and is usually bad to your knees. The same leg power (or even higher) can be provided by the rider by pedalling lightly but at a high rate (high cadence); this technique is called "spinning".
a motor is most efficient at its highest rpms. keeping track of it lets the system know how much power the motor can handle.
Totally agree in the case of my 70 lb torque-sensing hub-drive. Adding a progressive on-demand throttle to that PAS makes for a very versatile power delivery system and significantly improves bike handling, traffic safety, and knee-friendliness in the process. Even for riders like me who always pedal with effort.
Rarely miss, but you're still without on occasion for what? Ideology?
Amen
No ideology, just a very good trade-off. Wanted a very light, agile mid-drive climber with gravel bike leanings to complement my hub-drive, and you just can't get an ebike like that with a throttle. Big win despite the few times I miss a throttle on it.
It's called a brake cut off... Been around since eBikes became a thing.
I can definitely appreciate the light bike want..but I'm not a 2 bike guy and though I have a much lighter build in the end I always ride the heavier SUV.
Yrs, Im sure you find it easy, but some 80yr old on the pavement, takes off in high power mode, stops pedalling and the bike carries on surging, panics and finds themselves on top of a pram.
Yeah, really hate landing on prams. Some of those babies bite!
Here we aim to land on the mommy
Thanks for sharing this info.
It is a way more sophisticated than you might think. Several sensors together detect what happens to the e-bike. At the beginning of pedalling, torque on the pedal is detected. There is an extremely short delay from the pedal push to the motor activation (as short as the rider cannot even notice that). When the sensors detect the e-bike movement (which happens very fast), the full power amplification logic is applied.
Giant e-MTB with Yamaha motors advertise the "Zero Cadence" feature. That is, the motor is activated on a stationary e-bike as soon as the rider sets the foot on the pedal (you can actually feel the motor "cooking" under you when you do it). A similar feature is available in Specialized mountain e-bikes; you can control the motor activation delay between zero and some very short value with an app. The reason is the following: The rider might remain stationary uphill, and needs to initiate a climb onto, say, a rock. There mustn't be any delay between the pedal push and the motor action in this situation. It is why only e-MTBs are programmed for "zero cadence". Any other e-bike type with a mid-drive motor must have a delay of (say) 100 ms to protect the motor against frying and the rider against an unexpected e-bike forward movement.
Yes, precisely. Mid-drive motors feel lively above the cadence value of 70 rpm. Grinding makes the motor providing less power than expected and leads to the excessive battery use. Proper use of the derailleur is necessary (usually, I downshift three gears before a planned stop, for instance at an intersection).
Interesting approach! Constants a and b are positive, correct?
No one needs that. Unless you are on a technical trail, you just set your foot on the pedal to ride, not to support your foot
Yes, they are positive.
