In a fairly predictable turn of events, my development efforts pretty much ground to halt over summer. But a recent touch of autumnal chill in the air has shuffled the trainer project a couple of notches back up the todo list..
So, progress since the last post? Not much – just the addition of a micro and hall effect sensor to the prototype for some more accurate speed measurement.
This is presently just dumping a serial datastream to the PC for post-processing, while I wrestle with the maths for the un-braked roller assembly. There is obviously work to do, but the very first attempts at calculating speed & power weren’t entirely terrible.
The trainer power consists of the steady state power derived from a spindown test, plus an estimate for acceleration/deceleration (see shonky graph above).
While the steady state power is tracking pretty well already, it’s fair to say the acceleration component needs some work! I think this is primarily down to a very slack update rate from the initial firmware. I’m only sending speed updates to the PC every second, which is then averaging the acceleration over a 2 second window, so it’s this area that I’m aiming to improve on next..