Closed-loop management of vehicle driveline lash

A method for controlling gear lash in a vehicle, the method comprising:

• determining a speed of a set of drive wheels and a transmission output shaft of a vehicle having a final drive unit, wherein the drive wheels are connected to a drive axle;
• calculating, via a controller, a reference output speed using the drive wheel speed;
• limiting a lash angle of meshed elements of the final drive unit, the output shaft, and the drive axle during a gear lash state of the final drive unit, the output shaft, and the drive axle by applying positive and negative limits to the lash angle;
• and
• applying a calibrated offset profile to the calculated reference output speed during a transition from the gear lash state to thereby control, via proportional-integral logic of the controller, a speed difference between the output shaft and the drive axle, including setting the calibrated offset profile to a higher relative level at an early portion of the gear lash state to speed a transition from the gear lash state, and to a lower relative level at a later portion of the lash state while freezing or maintaining the output torque of the transmission in the gear lash state to thereby reduce driveline clunk upon transition from the gear lash state.

A method for controlling gear lash in a vehicle having a transmission and a final drive unit, the method comprising:

• measuring, via a wheel speed sensor, a speed of a set of drive wheels connected to a drive axle of the vehicle;
• measuring, via a transmission output speed sensor, an actual speed of an output shaft of the transmission;
• calculating, via a controller, a reference output speed using the measured speed of the drive wheels;
• limiting a lash angle of meshed elements of the final drive unit, the output shaft, and the drive axle during a gear lash state of the final drive unit, the output shaft, and the drive axle by applying positive and negative limits to the lash angle;
• and
• applying a calibrated 2-stage offset profile to the calculated reference output speed during a transition from a gear lash state of a final drive unit, the output shaft, and the drive axle to thereby control, via proportional-integral logic of the controller, a speed difference between the output shaft and the drive axle, including:
• applying the 2-stage calibrated offset profile at a first level at an early portion of the lash state sufficient for speeding a transition from the gear lash state having the limited lash angle;
• freezing or maintaining an output torque of the transmission while in the gear lash state;
• and
• reducing the first level to a second level at a later portion of the lash state to thereby reduce driveline clunk upon transition from the gear lash state.