Closed-loop model order reduction and MPC for diesel engine airpath control

This paper explores MPC for an 8th order air path dynamic model for an automotive diesel engine system. The relatively high order of the system makes the MPC real-time implementation on a practical engine control unit (ECU) infeasible, thereby motivating the model order reduction effort. For the MPC problem with terminal state penalty, Riccati-balanced truncation is used to find a reduced order model for the design of MPC. The presence of a direct feedthrough term from the input to the output in the model requires special treatment and is addressed. We present the analysis of the MPC designs for different reduced order models, compare the reduced order models through open-loop and closed-loop reduction methods, and demonstrate the performance of the resulting linear MPC on a proprietary nonlinear diesel model.