Does the drive wheel really need a separate piston?
Can't you just drive the switch directly with the connecting rod?
I've never met a finger which didn't put a small side-load on a switch...
Just thinking 'bout the setup... Maybe you want to acquire data while cycling at 5Hz...
200ms for one rotation of the drive wheel. Perhaps we can acquire at 10k samples/sec.
That would mean 2k samples for one revolution. Leaving some head room,
Maybe a 1024 count rotational encoder is the right answer for position info.
Perhaps this:
https://www.sparkfun.com/products/11102You could just post-analyze the data to identify TDC, or have a single absolute
Mark which comes off a hole on the wheel and an optical switch...
You could just spool the serial datastream to file and make a graph after.
Seems like one of the small load cells would be the hot ticket for force measurement,
Though calibration could be interesting. Resolution might be a challenge... Has anyone picked their favorite force measurement device?