In Ch 3 mechanics example, can stiction be represented by c(\dot q)?

[Richard Murray]

Contributed by Jason Rolfe, Jan 2019: On page 3-2, isn't stiction zero after the relevant part begins moving? If so, then it doesn't seem like it could be represented usefully by c (\dot{q}), since this term is zero by definition when the part is stationary, and must be zero once it starts moving if it is representing stiction.

[Richard Murray]

Proper representation of stiction is more complicated, with the resistive force balancing the applied forces up to some threshold. It’s possible that it could be approximated by some sort of (strongly) nonlinear function?

Not sure if we want to reword this or just remove the word “stiction” and replace it with some other term indicating that the function can be nonlinear.

[Richard Murray]

Change to “Coulumb and viscous friction”

[Richard Murray]

Fixed in commit afae2ce.