Method and apparatus for controlling clutch deactivation in a multi-mode powertrain system

A method for controlling deactivation of a torque transfer clutch of a multi-mode transmission configured to transfer torque among an engine, torque machines, and a driveline, the method comprising:

• determining clutch torque constraints including minimum and maximum long-term desired clutch torque constraints, minimum and maximum soft clutch torque constraints, minimum and maximum short-term desired clutch torque constraints, and minimum and maximum hard clutch torque constraints;
• and
• employing a tiered priority structure to control clutch torque to deactivate an off-going clutch, wherein said clutch torque is controlled in response to the minimum and maximum long-term desired clutch torque constraints superseded by the minimum and maximum soft clutch torque constraints superseded by the minimum and maximum short-term desired clutch torque constraints superseded by the minimum and maximum hard clutch torque constraints.