The invention relates to a method for ascertaining the backlash (40) of a gear (24) which is coupled to an electric machine (12) of a vehicle which has at least one electric machine (12). According to the method, at least the following steps are carried out: a) detecting the rotational speed of the at least one electric machine (12) during a driving intervention (80) and detecting rotational speed fluctuations produced therefrom, b) evaluating a high-frequency vibration (60) which is generated as a result of the gear (24) reaching a lower stop (54) in delay phases (56) and reaching an upper stop (50) when reversing the rotational direction in acceleration phases (58), c) filtering out high-frequency components from the high-frequency vibration (60) according to step b), wherein position information (42), relating to a corresponding rotational angle, from the rotational speed signal is saved in the event said components occur, and d) evaluating the distance between the upper stop (52) and the lower stop (54) and ascertaining the backlash (40) from the difference of the position information (42) between the upper stop (52) and the lower stop (54).

A powertrain system includes a transmission, torque generating device, load coupled to a drive axle, a final drive unit in meshed gear engagement with the output shaft and the drive axle, and a controller. A requested output torque is processed using an open-loop lash state model populated with a capped output torque request table and a lash closure rate estimate table respectively providing a capped torque value and an estimated lash closure rate. Output speed is determined using a plant model, the capped torque value, and the estimated lash closure rate. The powertrain is controlled during the transition using the output speed. A lash angle may be calculated from the closure rate using an integrator logic block. A calibrated lash offset profile may be determined using the lash angle, and a reference speed may be generated using the lash offset profile.

A powertrain system includes a transmission, torque generating device, load coupled to a drive axle, a final drive unit in meshed gear engagement with the output shaft and the drive axle, and a controller. A requested output torque is processed using an open-loop lash state model populated with a capped output torque request table and a lash closure rate estimate table respectively providing a capped torque value and an estimated lash closure rate. Output speed is determined using a plant model, the capped torque value, and the estimated lash closure rate. The powertrain is controlled during the transition using the output speed. A lash angle may be calculated from the closure rate using an integrator logic block. A calibrated lash offset profile may be determined using the lash angle, and a reference speed may be generated using the lash offset profile.

A control system and method for a vehicle having a powertrain comprising a torque generating system and an automatic transmission each utilize a pedal position sensor configured to measure a position of an accelerator pedal of the vehicle and a controller configured to, based on the accelerator pedal position, detect a pedal tip-in or tip-out event and, in response to detecting the pedal tip-in or tip-out event: (i) determine a desired output torque for the torque generating system corresponding to the pedal tip-in or tip-out event and (ii) command the torque generating system to gradually transition, over a period, from its current output torque to the desired output torque to mitigate clunk caused by abrupt contact between gear teeth of the torque generating system shaft and the automatic transmission shaft.

A method of operating a drive-train (1) of a motor vehicle, which has a drive aggregate (2), a transmission (3) with a hydrodynamic torque converter (4), an engine brake device (6) and a drive output (5). The engine brake device (6) which is activated when the drive-train (1) is operating in an overdrive mode, during a coasting process, before carrying out an overdrive downshift, when the turbine rotational speed (n_tu) of the torque converter (4) is lower than the engine idling rotational speed (n_mot_LL) of the drive aggregate (2). The engine brake device (6) is deactivated at a point in time chosen such that, when the overdrive downshift is carried out, a load change in the drive-train (1) is avoided.

A control system and method for a vehicle having a powertrain comprising a torque generating system and an automatic transmission each utilize a pedal position sensor configured to measure a position of an accelerator pedal of the vehicle and a controller configured to, based on the accelerator pedal position, detect a pedal tip-in or tip-out event and, in response to detecting the pedal tip-in or tip-out event: (i) determine a desired output torque for the torque generating system corresponding to the pedal tip-in or tip-out event and (ii) command the torque generating system to gradually transition, over a period, from its current output torque to the desired output torque to mitigate clunk caused by abrupt contact between gear teeth of the torque generating system shaft and the automatic transmission shaft.