PID-based torque phase control of a power downshift

A vehicle comprising:

• an internal combustion engine having a drive shaft;
• a transmission having an input shaft;
• a torque converter having a pump and a turbine, wherein the pump is connected to the drive shaft and the turbine is connected to the input shaft;
• and
• a controller having a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for controlling the torque phase of a clutch-to-clutch power downshift in the vehicle;
• wherein execution of the instructions by the processor causes the controller to:
• determine, during a near sync boost (NSB) state of the power downshift, a synchronization speed of an offgoing clutch and an oncoming clutch of the transmission, wherein the NSB state is a portion of the torque phase that occurs prior to the offgoing and oncoming clutches reaching synchronous speed (sync speed);
• estimate, via a controller, a feed-forward clutch pressure that holds a turbine speed of the torque converter at the sync speed;
• ramp a clutch pressure command to the oncoming clutch to the estimated feed-forward clutch pressure;
• and
• initiate closed-loop proportional-integral-derivative (PID) control over the clutch pressure command during the NSB state in response to a predetermined PID activation event.

A system for a vehicle, comprising:

• a transmission having a first and a second clutch, and also having an input shaft that is connectable to a drive shaft of an engine;
• and
• a controller having a processor and a tangible, non-transitory memory device on which is recorded instructions for executing a method for controlling the torque phase of a clutch-to-clutch power downshift in the vehicle, wherein the first clutch acts as an offgoing clutch and the second clutch acts as an oncoming clutch during the power downshift;
• wherein execution of the instructions by the processor causes the controller to:
• determine, during a near sync boost (NSB) state of the power downshift, a synchronization speed of the offgoing and oncoming clutch of the transmission, wherein the NSB state is a portion of the torque phase that occurs prior to the offgoing and oncoming clutches reaching a synchronous speed;
• estimate, via a controller, a feed-forward clutch pressure that holds a turbine speed of the torque converter at the synchronous speed;
• ramp a clutch pressure command to the oncoming clutch to the estimated feed-forward clutch pressure;
• and
• initiate closed-loop proportional-integral-derivative (PID) control over the clutch pressure command during the NSB state in response to a predetermined PID activation event.