Torque Weighting Vibration Dose Value to Aid Powertrain Calibration Process for Transient Torque Maneuvers 2021-01-1034

This paper investigates the application of torque weighting to vibration dose value. This is done as a means to enhance correlation of perceived drive comfort directly to driver pedal commands while rejecting uncorrelated inputs. Current industry standards for vehicle comfort are formulated and described by ISO2631, which is a culmination of research with single or multi-axis vibration of narrow or broadband excitation. The standard is capable of estimating passenger comfort to vibrations, however, it only accounts for reaction vibrations to controlled inputs and not perceived vibration request vs. response vibration. Metrics that account for torque inputs and the vibration response create actionable estimates of dosage due to driver torque requests without uncorrelated inputs. This reduces the need for additional accelerometers and special compensating algorithms when road or track testing. The use case for the proposed modified metric is during the powertrain calibration process. Specifically, it can be used to evaluate driver commanded torque transients that cause torque reversal(s) of the drivertrain, e.g., coast to drive or drive to coast, through pedal tip-in or tip-out, respectively. Two body on frame, solid rear axle, full-size trucks featuring a twin turbocharged gasoline direct injected engines each paired with a ten-speed automatic transmission and four-wheel drive selectable transfer case each were utilized in the investigation to collect test data. Road testing was performed on both vehicles instrumented with accelerometers, telemetry torque meters and CAN signal data. Vehicle NVH data in combination with standard and modified dose metrics acquired in various gear states, powertrain calibration configurations and vehicle loading states is presented. The utilization of transient event based torque weighting will be shown to improve correlation of subjective driver related NVH measurements to an objective quantity of dose value for the purposes of adjusting powertrain calibration.