Transmission clutch control using lumped inertia modeling

A transmission assembly for a vehicle powertrain having an engine, the transmission assembly comprising:

• an input member that receives input torque from a drive shaft of the engine;
• an output member;
• a plurality of clutches operable to execute a clutch-to-clutch shift;
• and
• a controller that includes a processor and tangible, non-transitory memory on which is recorded a plurality of lumped inertia models and instructions for executing the clutch-to-clutch shift using the lumped inertia models, wherein the lumped inertia models collectively reduce the dynamics of the vehicle powertrain to two degrees of freedom (DOF) for all fixed gear modes and three DOF for all clutch-to-clutch shifts of the transmission, and wherein the controller is programmed to:
• estimate required clutch torques for each clutch-to-clutch shift of the transmission using the lumped inertia models;
• and
• execute a designed one of the clutch-to-clutch shifts using the estimated clutch torques for the designated one shift.

A method for executing a clutch-to-clutch shift of a transmission of a vehicle powertrain having an internal combustion engine, a transmission, and a torque converter assembly, the method comprising:

• recording a plurality of lumped inertia models and instructions for executing a plurality of clutch-to-clutch shifts of the transmission using the lumped inertia models, including recording lumped inertia models which collectively reduce the dynamics of the vehicle powertrain to two degrees of freedom (DOF) for all fixed gear modes and three DOF for each of the clutch-to-clutch shifts;
• estimating, via a controller, a required clutch torque for each of a plurality of clutches of the transmission used in a corresponding one of the clutch-to-clutch shifts using the lumped inertia models;
• and
• commanding execution of the corresponding clutch-to-clutch shift via the controller using the estimated required clutch torque for each of the plurality of clutches used in the corresponding one shift.