Comfort-enhanced vibration control for delayed active suspensions using relaxed inequalities

This paper presents a comfort-enhanced vibration control design approach for vehicle active suspensions with control delay. By introducing some novel relaxed inequalities, a less conservative bounded real lemma is derived such that the suspension system is asymptotically stable and has an enhanced vibration attenuation performance in the presence of road disturbance and control delay. In the control design, an augmented Lyapunov–Krasovskii functional is proposed to enlarge the degree of freedom of design. A suitable controller can be obtained via a sufficient condition with linear matrix inequality constraints. Compared with the previous methods based on frequently used inequalities and the traditional Lyapunov–Krasovskii functional, the proposed controller can provide better comfort performance for different control delays. Finally, the advantages of the proposed method are demonstrated using numerical examples.