Output tracking of a nonlinear non-minimum phase system: An application to a turbocharged diesel engine (TDE)

This paper presents a control design method based on feedback linearization applied to a turbocharged diesel engine, namely TDE. Our goal is to track desired constant values of a chosen vector output: the pressure in the intake manifold and the compressor mass flow rate instead of the air fuel ratio (AFR) and the fraction of exhaust gas recirculated (EGR) which are not accessible for measurements, see [10]. Unfortunately, the reduced-order model of TDE with these chosen outputs presents a non-minimum phase behavior. In order to solve this issue, we first make an Input-Output (IO) linearization of the nonlinear system obtained from the successive derivations of the components of the vector output with a change of coordinates, see [9]. Then, zero dynamics are linearized approximatively around a computed equilibrium point. Once this done, the I-O linearized system is extended with the approximative linearized zero dynamics. Therefore a pole placement is then applied to this linear decoupled extended system. This method presents the advantage of avoiding implicit problems of measurements, see [3],[6], [5] and [4]. Simulation results are presented to highlight the efficiency of the proposed method.