Abstract: To further improve the comprehensive vibration isolation performance of commercial vehicles equipped with air suspension under complex driving conditions, a damping control method based on a new configuration of quasi-zero stiffness air suspension is proposed. Firstly, a nonlinear model of quasi-zero stiffness air suspension system is established by combining gas thermodynamics and suspension dynamics theories, and the nonlinear restoring force expression of the suspension is expanded by Taylor series, and the semi-active control model of quasi-zero stiffness air suspension for 1/4 vehicle is reduced to a linear system considering the uncertainty of stiffness parameter. Secondly, Lyapunov stability theory is introduced to construct a multi-objective performance output index considering the acceleration of suspension sprung mass, suspension working space and tire dynamic load with constrained constraints, and the H_∞ state feedback control strategy is designed by using linear fractional transformation, meanwhile, the Luenberger state observer based on the body height sensor is designed as the input, and the control law design problem is transformed into a convex optimization problem of linear matrix inequalities. Finally, the Hardware-in-the-loop tests show that the effectiveness of the proposed semi-active control method and structure of the quasi-zero stiffness air suspension, and can significantly lower the sprung mass acceleration with not sacrificing the suspension working space and less sacrificing the dynamic tire load, which will improve the multi-objective comprehensive performance of commercial vehicles’ suspension.

Key words: quasi-zero stiffness, semi-active suspension, H_∞ control, parameter uncertainty, vibration isolation