Closed-loop torque phase control for shifting automatic transmission gear ratios based on friction element load estimation

A method for controlling gear ratio shifts in a multiple-ratio automatic transmission for an automotive vehicle powertrain including an engine, an input shaft, a transmission output shaft, a set of drive wheels, gearing defining multiple torque flow paths from the input shaft to the torque output member, and first and second pressure actuated torque establishing elements for shifting from at least a first gear configuration with a low speed ratio to a second gear configuration with a higher speed ratio during a ratio upshift event having a preparatory phase, a torque phase and an inertia phase, the method comprising:

• maintaining torque capacity of the first torque establishing element against slippage during the preparatory phase;
• calculating an estimated amount of torque transmitted through the second torque establishing element by using measured and estimated torque signals;
• and
• increasing torque capacity of the second torque establishing element during the torque phase at a desired rate based on the estimated amount of torque so as to effect a closed loop control of the amount of torque transmitted through the second torque establishing element for at least a portion of the torque phase.