I don't see how the second sensor would improve accuracy (or rather precision). iiuc, the second sensor allows for improved speed. Backlash of the motor (and

I don't see how the second sensor would improve accuracy (or rather precision). iiuc, the second sensor allows for improved speed. Backlash of the motor (and gears and linkage) could be accounted for using a PID controller, no? Said that, I'm impressed how precise this rather flimsy looking robot actually is.