Automotive coldstart emissions reduction using MIMO sliding mode control with actuator saturation

Abstract

In this study, a modified version of multi-input multi-output (MIMO) sliding mode control technique is applied to reduce the total hydrocarbon emissions of an automotive engine during the coldstart period. This specific control design technique is suitable for MIMO systems with constraints on their input signals and it allows finding a set of upper limits for the gains of sliding mode controller (SMC) with regard to the given input constraints. In this context, an optimization problem is formulated to calculate the upper bounds of SMC gains to ensure the feasibility of the calculated control commands for the considered coldstart control problem. Through simulations, it is indicated that the devised SMC can properly track the given exhaust gas temperature (Texh) and engine-out hydrocarbon emission (HCraw-c) desired profiles in the presence of external disturbances without violating the existing engine system input constraints.