Dynamic Ride Height Adjusting Controller of ECAS Vehicle with Random Road Disturbances

Abstract

The ride height control system is greatly affected by the random road excitation during the ride height adjusting of the driving condition. The structure of ride height adjusting system is first analyzed, and then the mathematical model of the ride height adjusting system with the random disturbance is established as a stochastic nonlinear system. This system is decoupled using the differential geometry theory and stabilized using the Variable Structure Control (VSC) technique. The designed ride height control system converges in probability to be asymptotically stable in the sliding motion band, and the desired control law is solved to ensure the stable adjustment of the ride height system. Simulation results show that the proposed stochastic VSC method is effective for the dynamic adjusting of the ride height. Finally, the semiphysical rig test illustrates the applicability of the proposed scheme.

Height Adjustment of Vehicles Based on a Static Equilibrium Position State Observation Algorithm

“…According to Figure 12, the height changes of the vehicle centroid based on suspension deflection and the static equilibrium position are -0.03006 m and -0.03002 m, respectively. In the process of vehicle height lowering, the adjustment accuracy is over 99.6% and error is less than the error given in [22]. It can be seen from Figure 9, the height changes of the front left and rear left suspension adjusted by deflection are 0.02996 and 0.02995 m, respectively, and the control accuracy is above 99%.…”

“…According to Figure 10, the vehicle height changes based on suspension deflection and the static equilibrium position are 0.0305 and 0.0301 m, respectively, and the adjustment accuracy is over 99%. The error is less than the error given error in [22]. As the static equilibrium position is related to the on-off state of solenoid valve, maximum pitch angle is 0.08 • , which is smaller than the 0.095 • adjusted by the suspension deflection.…”

“…In the process of vehicle height lowering, the adjustment accuracy is over 99.6% and error is less than the error given in [22]. It's known from the process of vehicle height lifting and lowering that the error of pitch angle is not more than 0.1° and this control algorithm can effectively ensure the stability of the vehicle attitude.…”

“…It has been widely used in commercial vehicles [8], railway vehicles [9], passenger vehicles [10] and agricultural machines [11,12] because of its advantages of adjustable stiffness and height. In the past few years, the research on air suspension systems has mainly focused on three aspects: air suspension analysis modeling [13][14][15][16][17], electronic control system [18][19][20][21][22] and vehicle height control algorithms [23][24][25][26][27][28][29][30].…”

“…Xu et al established a mathematical model of a vehicle height adjustment system with random disturbance which was regarded as a nonlinear system. This system was decoupled by using the theory of differential geometry and the variable structure control (VSC) method was used to stabilize the system [22]. Then, Xu et al used three height sensors to establish a three points measuring system so as to establish a mathematical model of vehicle height adjustment.…”