Investigation on vehicle height control algorithm based on UKF observer

An unscented Kalman filter (UKF) observer with the ability of predicting steady height was proposed aiming at the problem that the precision of height control on the rough road decreases seriously. According to the vehicle system dynamics and variable mass inflating and deflating system thermodynamic theory, mathematical model of a quarter vehicle height adjustment for electronically controlled air suspension was established. After deducing the steady height, which characterizing the static equilibrium position of the suspension, to one of the state variables in the nonlinear state equation according to the polytropic process equation, a state observer based on unscented Kalman filter algorithm was designed. Then the steady height was fed back to the sliding mode controller. The simulation of vehicle height adjustment on rough road was conducted in the Simulink/AMESim simulation environment. The experimental results showed that the state observer designed could effectively predict the steady height, and significantly improve the accuracy and quality of the vehicle height adjustment on rough road.