Nonlinear Ride Height Control of Active Air Suspension System with Output Constraints and Time-Varying Disturbances

Abstract

This paper addresses the problem of nonlinear height tracking control of an automobile active air suspension with the output state constraints and time-varying disturbances. The proposed control strategy guarantees that the ride height stays within a predefined range, and converges closely to an arbitrarily small neighborhood of the desired height, ensuring uniform ultimate boundedness. The designed nonlinear observer is able to compensate for the time-varying disturbances caused by external random road excitation and perturbations, achieving robust performance. Simulation results obtained from the co-simulation (AMESim-Matlab/Simulink) are given and analyzed, demonstrating the efficiency of the proposed control methodology.

Keywords: active air suspension; disturbance observer design; nonlinear height control; output constraints; random road excitation.

Figure 1

Schematic diagram of quarter vehicle with active air suspension (AAS).

Figure 2

Co-simulation block diagram.

Figure 3

Height tracking performance of quarter vehicle with AAS in co-simulation.

Figure 4

Height tracking error of quarter vehicle with AAS in co-simulation, where $|z_1|$ always stays within its corresponding bound.

Figure 5

Height comparison of quarter vehicle with AAS in co-simulation.

Figure 6

Error comparison of quarter vehicle with AAS in co-simulation, where $|z_1|$ exceeds its allowable maximum value.

Figure 7

Disturbance estimation of quarter vehicle with AAS in co-simulation.

Figure 8

Tracking height and error of quarter vehicle with measurement noise in co-simulation.

Figure 9

Height comparison of quarter vehicle with AAS in co-simulation.

Figure 10

Error comparison of quarter vehicle with AAS in co-simulation.

Figure 11

Tracking performance comparison of quarter vehicle with hybrid model predictive controller (HMPC) presented in [7].