Management of gear lash closure rate in a powertrain system

A method for managing a lash state transition of a meshed gear engagement within a powertrain system having a torque generating device, a transmission coupled to the torque generating device and having an output shaft, a drive axle connected to a load, and a final drive unit in the meshed gear engagement with the output shaft and the drive axle, the method comprising:

• determining a requested output torque of the transmission via a controller;
• in response to the requested output torque, using an open-loop lash state model of the controller to provide a capped torque value and an estimated lash closure rate from respective lookup tables of the open-loop lash state model;
• calculating the output speed, using a driveline plant model of the controller, as a function of the capped torque value and the estimated lash closure rate;
• and
• controlling a dynamic operating state of the powertrain during the lash state transition using the output speed.

A motor vehicle comprising:

• at least one electric traction motor;
• a transmission having an output shaft, wherein the transmission is coupled to and configured to receive an input torque from the at least one electric traction motor and, in response thereto, to produce an output torque sufficient for rotating the output shaft at an output speed;
• a set of drive wheels coupled to and driven by a drive axle;
• a final drive unit in meshed gear engagement with the output shaft and the drive axle;
• and
• a controller configured to manage a lash state transition of the meshed gear engagement via execution of instructions, wherein execution of the instructions by a processor of the controller causes the processor to:
• process a requested output torque using an open-loop lash state model populated with a capped output torque request table and a lash closure rate estimate table respectively providing, in response to the requested output torque, a capped torque value and an estimated lash closure rate;
• calculate the output speed using a driveline plant model as a function of the capped torque value and the estimated lash closure rate;
• calculate a lash angle of the meshed engagement from the estimated lash closure rate using an integrator logic block;
• apply a calibrated lash offset profile using the lash angle, the calibrated lash offset profile having a magnitude that is higher at earlier stages of the lash state transition relative to later stages of the lash state transition;
• calculate a reference speed of the electric traction motor using the calibrated lash offset profile;
• use the driveline plant model to calculate the output speed as a function of the capped torque value and the reference speed;
• and
• control a dynamic operating state of the powertrain via speed or torque control of the electric traction motor during the lash state transition, using the output speed, to thereby manage the lash state transition.