Patent ID: 8630777

Claim:
A vehicle comprising: an engine; a torque converter having a turbine; an automatic transmission having an input shaft connected to the turbine which receives input torque from the engine, and which includes a neutral idle (NI) state providing a hydraulic neutral state when the transmission is in a drive detent position, and which also includes a designated NI clutch which is configured to be selectively slipped in the NI state; and a controller operable to execute an NI shift event of the transmission to shift the transmission out of the NI state and into a drive state; wherein the controller includes a slip model describing slip across the designated NI clutch and is configured to: determine a calibrated time (T) to complete the NI shift event; generate a calibrated clutch slip profile for the designated NI clutch as a differentiable time function during the NI shift event, wherein the differentiable time function is at least a third order or cubic equation which approaches zero and ultimately reaches zero not before the calibrated time (T); calculate a slip derivative of the calibrated slip profile; calculate an initial torque command as a function of the calibrated slip profile, the calculated slip derivative, a calibrated inertia value quantifying the inertia of at least the turbine, and a turbine torque of the turbine; convert the initial torque command into a clutch pressure command; and control the designated NI clutch during the NI shift event using the clutch pressure command 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.