Nonlinear control of valves in diesel engines using the derivative-free nonlinear Kalman Filter

Abstract

The paper studies robust nonlinear control for gas exchange valves in diesel engines, with the use of the Derivative-free nonlinear Kalman Filter. Robust control of gas exchange valves is important for improving the efficiency in the operation of diesel engines. By applying differential flatness theory the initial nonlinear model of the system is transformed in the linear canonical (Brunovsky) form. For the latter model it is possible to design a state feedback controller that enables accurate tracking of the valve’s reference set-points. To estimate the nonmeasurable state variables of the model and the unknown external disturbances the Derivative-free nonlinear Kalman Filter is used as a disturbance observer. The Derivative-free nonlinear Kalman Filter consists of the standard Kalman Filter recursion on the linearized equivalent model of the valve and of computation of state and disturbance estimates using the diffeomorphism (relations about state variables transformation) provided by differential flatness theory. Evaluation tests are performed for assessing the performance of the proposed control scheme.