Optimization of a semi-active suspension system with a variable damper for a full car model

In this study, optimization of semi-active suspension system with a variabledamper which is used in a full car model was considered. A suitable set of statevariables were defined and systems? state equations were obtained. Then aperformance index was defined using the closed loop optimal control law.Performance index is involving a weighted combination of square sprung massaccelerations for movement of sprung mass as heave, pitch and roll, meansquare suspensions deflection and mean square unsprung mass deflections withrespect to ground. Optimal values of damping coefficients of damper wereobtained by using pontryagin principles. Performances of an optimallycontrolled vehicle were calculated for step input in road elevations, as well asfor measured road profiles. For the case of measured road profile input, trade-off curves were obtained between the sprung mass accelerations andsuspension?s deflections of optimally controlled system. It is observed thatsprung mass acceleration and suspension deflection can be reducedconsiderably by controlling the damping coefficients as compared to the passivesuspension system.Key Words :semi-active suspension system, bilinear system, optimumsystem, vehicle suspension system