I've been investigating S-Curve motion profiles for CNC router and 3D printer applications, and haven't come across any definitive source that says an S-Curve profile is necessary in any application. And in fact, it may even slow down a print.
This simulator compares S-Curve and trapezoidal motion profiles, showing that with the same velocity and acceleration, a move will take longer to complete. Interestingly, the maximum acceleration of the S-Curve profile can be increased a small amount while keeping the maximum positional error (and force) beneath that of the trapezoidal profile. This is because the slow ramp in acceleration allows the driven object to accelerate closer to the target speed, thus reducing the overall force.
In theory, an instantaneous change in force will also excite natural vibrations in a system as well (in the same way connecting an inductor/capacitor directly to a 12v source induces ringing). Is this a problem in real-world mechanical systems? And in those systems, would using an S-Curve profile reduce the ringing?