Simulation and analysis of transmission shift dynamics

This paper presents a simulation model for the shift process of vehicle automatic transmissions implemented in an object-oriented software environment. All the subsystems or components in the driveline from the engine to the wheels are integrated into the overall vehicle powertrain model. Standard library models are directly used for some of the common components used in the powertrain such as gears, inertia, clutches, etc. Other components such as the engine, torque converter, shift controller are either developed independently or adopted from existing sources. A 4-speed automatic transmission is used as an example in the paper to illustrate the modelling and simulation. The dynamic behaviour of the transmission in up and down shift processes is simulated by the model under various powertrain operation conditions. The simulation data on shift transmissions such as torque hole, torque overshoot, shift time, etc., are quantitatively analysed for the assessment of shift quality. Shift control variables are adjusted interactively to calibrate the transmission for the best trade off between shift time and smoothness based on model simulation.