Mixed GL2/H2/GH2 control with pole placement and its application to vehicle suspension systems

This paper presents a multi-channel multi-objective synthesis framework, in which generalized L-2 (GL(2)), H-2, and generalized H-2 (GH(2)) criteria are specified for appropriate channels, and the poles of the closed-loop system are constrained within a subregion S(a, r, theta) of the left-half s-plane. The multi-objective framework is successfully applied to a seven degrees-of-freedom decoupled vehicle suspension system. The suspension control system has three channels: channel T-1, relating to ride comfort, is from road disturbances to vehicle body accelerations, the suspension travel channel, T-2, is from manoeuvre disturbances to suspension deflections, and channel T-0 is used to address system uncertainty. The control objective is to minimize a mixture of parallel toT(1)parallel to (H2) and parallel toT(2)parallel to (GH2) while guaranteeing that the closed-loop system is robustly stable, with poles located within a specified subregion S(a, r, theta). The simulation results demonstrate that this multi-objective control can improve vehicle ride comfort and decrease suspension travel simultaneously. In addition, the multi-objective synthesis framework provides a simple but effective trade-off between vehicle ride comfort and suspension travel.