Behavioral modeling and optimal control of a vehicle mechanical drive system

This paper investigates the optimal power management of a vehicle powertrain that includes a diesel engine connected to a continuously variable transmission (CVT). A control-oriented, supervisory level powertrain model is developed using the interconnection of component dynamical/algebraic models applicable to power flow management. Of note, we perform a CVT power flow analysis and construct the corresponding power-flow-based model. Further, we introduce the use of Lyapunov energy functions into our modeling approach to mitigate solution singularities. Given the powertrain model, the paper sets forth power management based upon model predictive control that seeks to minimize vehicle velocity tracking error, fuel usage, and frictional braking, except during commanded deceleration, to avoid its use during positive engine power output. To demonstrate the validity of the approach, the controlled vehicle is simulated for a trapezoidal drive profile of 35 s. Results show that engine efficiency is greater than or equal to 30% for about 36% of the drive profile and velocity tracking 2-norm normalized error is about 1.5%.