Clutch torque trajectory correction to provide torque hole filling during a ratio upshift

A powertrain comprising:

• a torque input shaft;
• a multiple-ratio power transmission mechanism with an oncoming friction element and an off-going torque transmitting friction element for effecting ratio upshifts during torque delivery to a torque output shaft;
• and
• a shift controller programmed to:
• increase torque input during a torque phase of a ratio upshift;
• control torque input to achieve a desired off-going friction element slip;
• measure actual friction element torque for the torque transmitting friction elements of the transmission;
• and
• correct an estimated oncoming friction element torque using the measured torque whereby a target torque for the oncoming torque transmitting friction element is achieved with minimal torque transients during the torque phase;
• determine whether a measured torque of the off-going torque transmitting friction element is less than a predetermined threshold;
• if the measured off-going torque transmitting friction element torque is less than the threshold, release the off-going torque transmitting friction element, and repeat the step to correct an estimated oncoming torque transmitting friction element torque if the measured off-going torque transmitting friction element torque is greater than the threshold.