System and method for managing accumulator effects during engagement of a lockup clutch in a torque converter

In a torque converter having a pump that is rotatably driven by an internal combustion engine and that is fluidly coupled to a turbine, and a lockup clutch connected between pump and the turbine, a method for managing accumulator effects during engagement of the lockup clutch, the method comprising:

• continually solving a dynamic model that is configured to produce a lockup clutch command as a function of a plurality of torque converter operating parameters, the plurality of torque converter operating parameters comprising a pump speed,
• asserting the lockup clutch command to control engagement of the lockup clutch,
• selecting a profile of one of the plurality of torque converter operating parameters that is configured, when inserted into the model in place of an actual value thereof, to result in an intersection of rotational speeds of the pump and the turbine over time,
• monitoring deceleration of the pump after asserting the lockup clutch command,
• determining, from monitored values of the deceleration of the pump, a maximum deceleration of the pump, and
• temporarily holding constant the selected profile if the monitored deceleration of the pump rises at least a threshold value above the maximum deceleration of the pump.