System and method for model-based neutral idle clutch control

A controller comprising:

• a host machine having a tangible, non-transitory memory device, wherein the host machine is in communication with a vehicle having a torque converter with a turbine connected to an input shaft of a transmission, wherein the transmission has a neutral idle (NI) state entered while the transmission is in a drive detent position and a designated NI clutch applied for exiting the NI state during a predetermined NI shift event;
• and
• a set of instructions recorded on the memory device;
• wherein the host machine is configured for executing the instructions from the memory device to actuate the designated NI clutch during the NI shift event, including:
• determining a calibrated time (T) to complete the NI shift event;
• executing a slip model which generates a calibrated clutch slip profile of the designated NI clutch as a differentiable time function that approaches zero and ultimately reaches zero not before the calibrated time (T), wherein the calibrated clutch slip profile is at least a third order or cubic equation;
• calculating a slip derivative of the calibrated slip profile;
• calculating an initial torque command for the designated NI clutch as a function of the calibrated slip profile, the calculated slip derivative, a calibrated inertia value quantifying the inertia of the turbine, and a turbine torque of the turbine;
• converting the initial torque command to a clutch pressure command;
• and
• controlling the designated NI clutch, via the host machine, using the clutch pressure command during the NI shift event to thereby control an amount of slip across the designated NI clutch through the calibrated time (T) of the NI shift event according to the calibrated shift profile.

A method comprising:

• determining a calibrated time (T) to complete a predetermined neutral idle (NI) shift event out of an NI state in a vehicle, wherein the NI state is a hydraulic neutral state of a vehicle transmission entered when the transmission is in a drive detent position;
• executing a slip model via a controller to thereby generate a calibrated clutch slip profile of a designated NI clutch of the transmission as a differentiable time function during the predetermined NI shift event, wherein the differentiable time function is at least a third order or cubic equation which reaches zero not before the calibrated time (T);
• calculating a slip derivative of the calibrated slip profile, wherein the calculated slip derivative reaches zero at the calibrated time (T);
• calculating a clutch pressure command for the designated NI clutch of the transmission as a function of the calibrated slip profile, a turbine torque of the turbine;
• and the calculated slip derivative;
• and
• controlling the designated NI clutch during the predetermined NI shift event, via the controller, using the calculated clutch pressure command to thereby exit the NI state to thereby control an amount of slip across the designated NI clutch through the calibrated time (T) of the NI shift event according to the calibrated shift profile.