Using a Cycle Analyst without a torque sensor?

[dpe743]

I had an idea, that I'd like to see in the next version of the Cycle Analyst. I've seen some bicycle computers that will estimate your power input based on current speed, cadence, rider/bike weight, and using an accelerometer to measure incline and current acceleration. If this could be added to the Cycle Analyst, then it could figure out how much torque (and power) the rider is putting in, by subtracting out battery amperage from the computed total vehicle wattage (rider + motor), combined with known characteristics of a given motor. This would eliminate the need to install a torque sensing bottom bracket (edit: in order to gain full pedal assist mode), all for the cost of an accelerometer chip and a bit of computation.

Does this sound reasonable?

 

[dogman dan]

Not to me, but coming from both motorcycles and bicycles in my past, I just don't get why you need PAS.

Throttles work good, and nothing compares to the senses in your feet, combined with the human brain, for maintaining the perfect power setting for constant cadence and effort up and down hills and in gusts of wind. Oh, yeah, you do have to think subconsciously. Bummer. I will admit, you don't learn to ride this well in 100 miles, and maybe not even in 1000 miles. Once you get there though, sweet!

But I do understand, if you want PAS, avoid cheezy PAS with nothing but hall sensors. You know what I mean, pedal two revolutions, then wham! then when you want to slow down, better have e brakes.

Sounds like what you want, could be an add on device, that simulated the signal from the Thun. Get going and invent it.

I could be wrong, but I think the hottest new mid drives will have something like this. The PAS on the Bosch was WAYYYYY better than all the other PAS bikes I rode at Interbike. You could tell that even if it just used hall sensors, it was running through some intelligent algorithims.

 

[dpe743]

Not to me, but coming from both motorcycles and bicycles in my past, I just don't get why you need PAS.

I haven't started my conversion project yet, won't until next spring, but in my thinking it is the difference between a "bicycle with power assistance" and an "electric motorcycle with a built in exercise bike" experience. Maybe I'm wrong on this, won't know til I try I guess.

Sounds like what you want, could be an add on device, that simulated the signal from the Thun. Get going and invent it.

I believe I can handle all the software side, but would need to obtain knowledge when it comes to hardware. So I was thinking of either using a Raspberry Pi or Arduino (or both) to make my own version of the Cycle Analyst. I should be able to read the throttle input, speed and cadence via the analog inputs on the Arduino, then control the throttle port on the controller using an add-on digital potentiometer chip, but not sure of the mechanics of reading the current draw (measuring the voltage across an inline shunt is how it's done? Just need to figure out which chip would do this and hook up to an Arduino).

But what would be really nice is if Grin Tech had a generic board available that converted everything to a USB data stream, that could be read on any device (such as the Raspberry Pi).