Adaptive control of an automatic transmission

In a vehicular automatic transmission in which a shift from a first speed ratio to a second speed ratio is carried out through concurrent disengagement of a fluid pressure operated off-going torque transmitting device associated with the first speed ratio and engagement of a fluid pressure operated on-coming torque transmitting device associated with the second speed ratio, a method of automatically shifting the transmission, comprising the steps of:

• disengaging the off-going torque transmitting device by reducing its pre-shift engagement pressure according to predetermined initial settings, and engaging the on-coming torque transmitting device by supplying it with hydraulic pressure according to predetermined initial settings, the settings being calibrated to achieve a predefined pattern of input and output speeds;
• comparing a measured speed with the predefined pattern to detect an aberration;
• so long as said aberration is detected, carrying out a fast adaptive adjustment of a stored parameter corresponding to the initial setting responsible for such aberration by calculating a change required to eliminate the aberration and altering the stored parameter in accordance therewith;
• and thereafter
• when said aberration is detected in a subsequent shift from the first speed ratio to the second speed ratio, adjusting said stored parameter by a predetermined increment to relatively slowly correct the corresponding setting.

In a vehicular automatic transmission in which a shift from a first speed ratio to a second speed ratio is carried out through concurrent disengagement of a fluid pressure operated off-going torque transmitting device associated with the first speed ratio and engagement of a fluid pressure operated on-coming torque transmitting device associated with the second speed ratio, a method of automatically shifting the transmission, comprising the steps of:

• disengaging the off-going torque transmitting device by reducing its pre-shift engagement pressure according to an off-going pressure command having a predetermined initial setting which decreases in ramp fashion to a final value;
• engaging the on-coming torque transmitting device by supplying it with hydraulic pressure according to predetermined initial settings, the settings being calibrated to achieve a predefined pattern of input and output speeds;
• sensing an event displaced in time from the predefined pattern which results from an incorrect off-going ramp pressure;
• comparing the final value of the off-going pressure command to the pressure command at a desired time of said event to derive a pressure difference;
• and
• adjusting a stored parameter corresponding to the initial setting of the off-going pressure command to change such initial setting by the pressure difference in a direction to correct the time of said event in a future shift.

In a vehicular automatic transmission in which an upshift from transmission speed ratio to another is carried out through concurrent disengagement of a fluid pressure operated off-going torque transmitting device associated with the higher of such speed ratios and engagement of a fluid pressure operated on-coming torque transmitting device associated with the lower of such speed ratios, a method of automatically shifting the transmission, comprising the steps of:

• disengaging the off-going torque transmitting device by reducing its pressure according to an off-going pressure command having a predefined initial setting, which thereafter progressively decreases to complete such disengagement;
• engaging the on-coming torque transmitting device by successively supplying it with hydraulic pressure for a predefined fill period and thereafter controlling such pressure to effect a progressive engagement of the same;
• monitoring input and output speeds of the transmission to detect an aberrant occurrence of a predefined speed event,
• adaptively adjusting a stored parameter corresponding to the predefined initial setting of the off-going torque transmitting device in a manner to increase such setting in response to the occurrence of a flare in the transmission input speed during the fill period in the on-coming torque transmitting device and indicative of low pressure in the off-going torque transmitting device;
• and
• adaptively adjusting said stored parameter in a manner to decrease such setting in response to the occurrence of an input speed change indicative of high pressure in the off-going torque transmitting device.

In a vehicular automatic transmission in which an upshift from one transmission speed ratio to another is carried out through concurrent disengagement of a fluid pressure operated off-going torque transmitting device associated with the higher of such speed ratios and engagement of a fluid pressure operated on-coming torque transmitting device associated with the lower of such speed ratios, a method of automatically shifting the transmission, comprising the steps of:

• disengaging the off-going torque transmitting device by reducing its pressure according to an off-going pressure command having a predefined initial setting, which thereafter progressively decreases to complete such disengagement;
• engaging the on-coming torque transmitting device by successively supplying it with hydraulic pressure for a predefined fill period, commanding an initial on-coming pressure and thereafter controlling such pressure to effect a progressive engagement of the same including initiating a closed-loop period in which the commanded on-coming pressure is controlled according to a difference between a detected on-coming torque transmitting device slip rate and a programmed slip rate until an input speed of the transmission reaches a target value corresponding to an output speed of the transmission at the lower ratio;
• adaptively adjusting a stored parameter corresponding to the initial pressure command following completion of the upshift in the event of a pressure increase wherein the commanded pressure when said input speed reaches said target value is greater than the commanded pressure at the initiation of the closed-loop period by a first threshold amount, and in the event of a pressure decrease wherein the commanded pressure when said input speed reaches said target value is less than the commanded pressure at the initiation of the closed-loop period by a second threshold amount, so that in future upshifts the initial pressure command will more nearly produce the programmed slip rate.

In a vehicular automatic transmission in which an upshift from one transmission speed ratio to another is carried out through concurrent disengagement of a fluid pressure operated off-going torque transmitting device associated with the higher of such speed ratios and engagement of a fluid pressure operated on-coming torque transmitting device associated with the lower of such speed ratios, a method of automatically upshifting the transmission, comprising the steps of:

• disengaging the off-going torque transmitting device by reducing its pressure according to an off-going pressure command having a predefined initial setting, which thereafter progressively decreases to complete such disengagement;
• engaging the on-coming torque transmitting device by successively supplying it with hydraulic pressure for a predefined fill period, commanding an initial on-coming pressure and thereafter controlling such pressure to effect a progressive engagement of the same including initiating a closed-loop period in which the commanded on-coming pressure is controlled to bring a detected slip of the on-coming torque transmitting device into correspondence with a predefined slip vs. time profile designed to lower an input speed of the transmission to a target value corresponding to an output speed of the transmission at the lower ratio;
• and
• adaptively increasing a stored parameter corresponding to the initial pressure command for the on-coming torque transmitting device following completion of the upshift if the input speed falls substantially below the target value during the closed-loop period so that in future upshifts the input speed will more nearly achieve the target value at the end of the closed-loop period.