A Control Strategy for Height Adjustment in Closed-Loop Air Spring Suspension System

This study investigates the closed-loop air spring suspension system by developing comprehensive models for both the air spring and its associated pipeline. To address issues such as "overcharging," "over-discharging," and significant overshoot during vehicle height adjustment, a threshold control strategy was developed. This strategy manages the trigger conditions for height adjustment to mitigate overshoot and precision problems. Experiments demonstrated that while this control strategy reduced overshoot and improved accuracy, it introduced the risk of excessive control due to varying threshold settings across different modules. To resolve this issue, a fuzzy PID controller was designed, utilizing fuzzy rules to adapt PID parameters in real-time, thereby enhancing height adjustment control. Testing confirmed that the fuzzy PID controller effectively resolved the issues associated with threshold control and also improved the rate of height adjustment. Furthermore, to prevent excessive height differences between the front and rear axles during adjustment, a height adjustment sequencing control strategy was proposed and validated through vehicle tests. Finally, to minimize the impact of road surface irregularities on height sensors and enhance adjustment precision, Kalman filtering was employed for optimal estimation of sensor signals, demonstrating effective performance. The proposed control strategies result in smoother, more efficient, and precise height adjustments in the closed-loop air spring suspension system.