Method and apparatus for constraining output torque in a hybrid powertrain system

Method for controlling a powertrain system including a transmission operative to transfer power between an input member and a torque machine and an output member, the transmission including an applied torque transfer clutch, the method comprising:

• determining an output torque request;
• monitoring system operation;
• determining a closed loop speed error;
• determining a motor torque command to effect driveline damping;
• determining a motor torque offset to the torque machine based upon the closed loop speed error and the motor torque command to effect driveline damping;
• determining output torque constraints based upon the motor torque offset and the system operation;
• determining an output torque command based upon the output torque request and the output torque constraints;
• determining a preferred motor torque command for the torque machine based upon the output torque command;
• reducing the preferred motor torque command for the torque machine using the motor torque offset to the torque machine;
• and
• adjusting the reduced preferred motor torque command for the torque machine based upon the closed loop speed error and the motor torque command to effect driveline damping.

Method for controlling a powertrain system including a transmission operative to transfer power between an input member and a torque machine and an output member, the transmission including an applied torque transfer clutch, the method comprising:

• determining an operator torque request;
• monitoring system operation;
• determining a closed loop speed error for the input member and a determining motor torque command to compensate for the closed loop speed error to achieve the operator torque request;
• determining a motor torque offset to the torque machine based upon the motor torque command to compensate for the closed loop speed error;
• determining output torque constraints based upon the motor torque offset;
• determining an output torque command based upon the operator torque request and achievable within the output torque constraints;
• determining a preferred motor torque command for the torque machine based upon the output torque command;
• compensating the preferred motor torque command for the torque machine using the motor torque offset to the torque machine;
• and
• adjusting the compensated preferred motor torque command for the torque machine based upon the motor torque command to compensate for the closed loop speed error.