10-04-2020, 03:18 PM
Interesting setup you have there Balor, would like to know more.
The servo pulling against a spring is something that has bothered me to, must surely under some conditions result in constant current draw by the servo. Fortunately enviolo hubs use a 2 cable system so has never been a problem for me. Although they can pull a little towards underdrive under load.
You mention torque sensing which is interesting because it's exactly where I went with my automatic shifter. Got me into building homemade power meters. For me having my cadence vary based on power output is the ultimate fully automatic shifting.
“servo jitter” I was going to look into turning the PWM signal to the servo on and off. Apparently a servo only tries to maintain a position when its being fed a valid PWM signal, kind of obvious really. In my case with the 2 cables I thought it might be more efficient if the servo is only driven when it needs to make a significant movement. Can waste some energy trying to move the last fraction of a degree.
The servo pulling against a spring is something that has bothered me to, must surely under some conditions result in constant current draw by the servo. Fortunately enviolo hubs use a 2 cable system so has never been a problem for me. Although they can pull a little towards underdrive under load.
You mention torque sensing which is interesting because it's exactly where I went with my automatic shifter. Got me into building homemade power meters. For me having my cadence vary based on power output is the ultimate fully automatic shifting.
“servo jitter” I was going to look into turning the PWM signal to the servo on and off. Apparently a servo only tries to maintain a position when its being fed a valid PWM signal, kind of obvious really. In my case with the 2 cables I thought it might be more efficient if the servo is only driven when it needs to make a significant movement. Can waste some energy trying to move the last fraction of a degree.