Composed adaptive control of a bio-diesel engine with EGR & VGT

In this paper, a Third-order dimensional nonlinear model is proposed for a bio-diesel engine equipped with a Variable Geometry Turbocharger (VGT) and an Exhaust Gas Recirculation (EGR) valve. The referred model which takes into account the engine air-path dynamics and its corresponding uncertain dynamics is a non-minimum phase unstable system. The fuel flow rate W_f which is considered as input for the engine crankshaft subsystem acts as an external perturbation for the three-order dimensional non-minimum phase air-path subsystem. The global control objectives are to track desired values of exhaust manifold pressure and compressor flow mass rate which can be suitably chosen according to low emission criterions. For the considered objectives a composed adaptive robust stabilization control is proposed: an inner uncertain dynamics compensation sub-control and an outer Piecewise Continuous Hybrid Systems (PCHS) based stabilization sub-control. The inner compensation sub-control considers a unknown input observer which realizes the compensation of the uncertain system dynamics. The outer loop concerns the PCHS based EGR & VGT control. With the inner compensation sub-control, this outer stabilization loop ensures both the desired exhaust manifold pressure and the desired compressor mass flow rate trajectory tracking. The robustness and efficiency of the proposed method are demonstrated by simulation results.