Performance Analysis of Decoupled Control of Active Chassis and Seat Suspensions

The paper presents performance analysis of passive, active and semi-active seat and chassis suspension controls based on covariance, frequency- and time-domain approaches and a half-car model. In the case of active suspensions, a linear quadratic regulator (LQR) is considered with an option of road preview control, while the semi-active suspension controller design is based on a clipped-optimal LQR approach. A practical, decoupled LQR structure is considered, which contains separate chassis and seat suspension controllers and individual cost functions accounting for conflicting criteria related to ride comfort, vehicle handling and suspension stroke limits. The decoupled LQR design is compared with an ultimate, coupled design, which simultaneously accounts for all criteria and relies on full state feedback. The analysis shows that the decoupled controller performance approaches that of the coupled controller, which is of particular interest when considering passive chassis suspension where no chassis state measurement is available.