[AdamHeard]

Without knowing the exact mechanical design it's hard to give completely valid advice.

First it'd be good to test (as discussed) if looking at the velocity of the sensor is enough to determine the "edge" of the piece. If that's a no, this plan clearly won't pan out without modifications.

Could you modify the design such that the motor doesn't directly close the jaw, but rather moves and is linked to the jaw with a spring? If you got the ratio/spring figured out right this would allow you to "overclamp" substantially, and have a forgiving/flexible clamp due to the spring.

This would certainly simplify the software, as you only have one PID setpoint to call for closing, and it never changes.

You could also use some sort of limit/touch sensor on the jaw to indicate when the jaw first makes contact with the object, then set your setpoint to some value further than that (a constant which you figure out by testing of course).

It's important to take a step back and see if the overall approach needs modification, versus more advanced individual features.