MATLAB: Is there a discrepancy in the definition and usage of P_fric on the documentation page of Controllable Friction Clutch in SimDriveline 1.1.1 (R14SP3)

Question

In the reference page for Controllable Friction Clutch block, the definition for P_fric is not consistent with the state diagram. P_fric has been defined as

P_fric=|omega|*tau_K

and the State flow diagram indicates that P_fric>0 for Omega=0 state.

Answer 1

This is a bug in the SimDriveline documentation in the way the terms P_fric, tau_K and tau_S are defined in the table titled Clutch state variables under Friction Clutch Model section and this is fixed in R2008a version.

The correct definitions are as follows:

Pfric = max[(P - Pth), 0] (always, whether it's unlocked and kinetic or

locked and static)

tau_K = mu*(# of disks)*(moment arm)*(peak normal force)*Pfric (in the

kinetic, unlocked case)

tau_S = tau_limit = (static friction peak factor)*(kinetic friction

torque for omega -> 0) (in the static, locked case)