Newbie question about Yamaha PW-ST motor

[tpcollins]

First post - I recently bought a Haibike with the Yamaha PW-ST. I bought it over the hunting type rear hub drive e-bikes because I liked the power even though it’s a pedelec.

I wish this bike had a throttle and I’m trying to understand how the torque sensor works on this motor. My son is an electrician at Ford’s and is a computer/electrical whiz.

I was wondering once my warranty expires if a “throttle” could be spliced into the electrical circuit to allow the motor to run via both peddling or thumb throttle. I’ve seen some electrical diagrams online of the SE model but nothing so far for my ST model.

Maybe someone here would know where to start. Here is an earlier thread I found on this forum but doesn’t show exactly what I’m looking for. Just wondering if this is doable or not? Thanks.

https://endless-sphere.com/forums/viewtopic.php?f=30&t=100440

 

[amberwolf]

With an OEM system it's unlikely that you can add any options that didn't come with it originally. Even if it has a plug (or pads on a PCB) for a throttle, it is probably not enabled in the system. Software to alter settings in such systems is typically not publicly available, either.

But you can ask Haibike if these are options.

If the torque sensor uses an analog voltage output, rather than some form of PWM or serial communication, you could add a buffer (op-amps) for both the torque sensor output (which would remain 1:1 voltage scaling) and a throttle output (which would be scaled and offset as necessary to make it match the voltage range of the torque sensor output), and tie the outputs of both opamp circuits into the torque sensor input of the system.

(some TS units output the same voltage range as a typical throttle, so you wouldn't need any complex scaling/offset stuff, just 1:1 buffering so neither throttle nor TS interferes with the other's operation/function. )

Then the throttle would simply be "faking" the signal from the TS, and the system wouldnt' even know you were doing it. You might be able to use both at teh same time, with whichever was higher voltage being the overriding one, or you might have to use only one at a time, dependign on how you setup/design the opamp buffer circuit.

The only issue would be if the system *also* requires a cadence signal (usually pulses) to enable the system to respond to the TS output. If it does, you'd also need to emulate that signal, for instance by using a 555 timer or other "astable multivibrator" that can be setup to match the waveform (might be PWM), that is enabled by moving the throttle off of zero.

 

[Robinev]

Break a radio controller from a rc toy car and steal the potentiometer then you can setup reverse shit hook up a weight with a windshield wiper motor and use that to keep it balanced, use a multiwii gyroscope board to control leveling. Hook up a trailer to sit in and taxi your self around town. Possibly endless
D


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