Method and control unit for operating a drivetrain of a motor vehicle comprising a power take-off

A control unit for operating a drivetrain of a motor vehicle, wherein the control unit, for a determination of a torque taken up by a power take-off:

• first shifts a transmission by control means into a condition in which, relative to an input of the transmission, a mass moment of inertia of the transmission is as large as possible and in which, relative to an output thereof, the transmission is torque-interrupted,
• then calls for a defined torque from a drive aggregate, when the power take-off is coupled to the drive aggregate, and
• at defined time-points during this the control unit receives rotational speeds of a shaft driven by the drive aggregate and, from the rotational speeds of the shaft driven, determines an angular acceleration of the shaft,
• the control unit determines, from the angular acceleration with the power take-off coupled to the drive aggregate, a first torque of the shaft, and
• the control unit determines, as a function of the first torque of the shaft, the torque taken up by the power take-off.

A method for operating a motor vehicle drivetrain having a drive aggregate, a transmission connected between the drive aggregate and a drive output, a power take-off that is coupleable to the drive aggregate on the drive aggregate side in order to take up drive torque delivered by the drive aggregate, the method comprising:

• first shifting the transmission to a condition in which, relative to an input of the transmission, a mass moment of inertia of the transmission is as large as possible and in which, relative to a transmission output, the transmission is torque-interrupted,
• then delivering a defined torque by the drive aggregate at least when the power take-off is coupled to the drive aggregate, and during this, at defined points in time, determining rotational speeds of a shaft driven by the drive aggregate, and determining an angular acceleration of the shaft from the determined rotational speeds,
• determining a first torque of the shaft from the angular acceleration with the power take-off coupled to the drive aggregate, and
• determining a torque taken up by the power take-off as a function of the first torque.