Automated design of structured gain-scheduling oil pressure controllers by modern synthesis methods

This paper presents a new systematic approach for the design of a gain-scheduling-control system for the oil pressure system of internal combustion engines. Therefore, optimal linear time invariant controllers are designed at given operating points and their characteristics are interpolated by an analytical function. An optimization algorithm finds optimal parameters for a given linear controller structure with a fixed order and two degrees of freedom. To solve the optimization problem, constraints in the H ∞ -norm are given for six different transfer functions of the closed loop. The same restrictions are applied for all operating points. For the gain-scheduling-approach, no classical superimposition of the output variables of the linear controllers is selected, as it is often the case with gain-scheduling-controllers. Instead, the poles and zeros of the gain-scheduling-controller are functionally calculated from the linear control loops depending on the scheduling variable. Therefore, the resulting gain-scheduling-controller shows the set behaviour of the linear controllers independently of the original operating points. A control loop that is independent of the nonlinearity of the controlled system is more efficient than conventional oil pressure control systems that use too high target oil pressures for robustness reasons. This results in increased efficiency of the oil pressure system, which can make a significant contribution to fuel savings.