Wheel Torque-based Control: Transmission Input Torque Determination and Inertia Compensation
2022-01-0897
03/29/2022
- Event
- Content
- Traditionally, production vehicles have interpreted the driver pedal request as a transmission input torque demand. However, with the advent of electrified vehicles, where actuators are located at different positions in the drivetrain, and of autonomous vehicles, which are self-driving, there is a requirement to interpret the demand (either human or virtual) in the vehicle acceleration domain. To address this requirement, we develop a Wheel Torque-based longitudinal Control (WTC) framework, wherein the desired vehicle acceleration is first expressed as a wheel torque demand and then transformed into each actuator’s torque domain. For powertrains with a step-ratio transmission and a torque converter (TC), a key challenge of the WTC framework is the determination of the torque request in the transmission input domain, especially during open or slipping TC operation. This determination needs to take into account the Inertia Compensation Torque (ICT), i.e., the torque required to spin up the TC’s impeller, in order to deliver expediently the driver demand. The focus of this work is the calculation of the ICT, based on a TC model, and the evaluation of the delivered vehicle acceleration. This calculation takes into account the state of the TC (i.e., open, slipping, etc.,) and also the state of the transmission (i.e., fixed gear or shifting) in order to ensure the robust delivery of the driver demand. The developed strategy was baselined against the traditional strategy and was found to be less calibration-intensive and, at the same time, effective in delivering the vehicle acceleration targets.
- Citation
- Roy, J., Ravichandran, M., Meyer, J., and Zhao, Y., "Wheel Torque-based Control: Transmission Input Torque Determination and Inertia Compensation," SAE Technical Paper 2022-01-0897, 2022, .