Abstract
In this paper, a static state observer algorithm based on the static equilibrium position is proposed, which can realize accurate control of electric vehicle height adjustment with existing road excitation. The existence of road excitation can lead to deflection variation of the electronically controlled air suspension (ECAS). The use of only dynamic deflection as the reference for the electric vehicle height adjustment will produce great errors. Therefore, this paper provides an observation algorithm, which can realize the accurate control of vehicle height. Firstly, the static equilibrium position equation of suspension is derived according to the theory of hydrodynamics and characteristics of pneumatic chamber. Secondly, a vehicle dynamics model with seven degrees of freedom (7-DOF) is established and the kinetic equations are discretized. Then, the unscented Kalman filter (UKF) algorithm is used to obtain the static equilibrium position of vehicle. According to the vehicle static equilibrium position obtained by UKF, the height of the vehicle is adjusted by using a fuzzy controller. The simulation and experimental results show that this proposed algorithm can realize the control of vehicle height with an accuracy of over 96%, which ensures the excellent driving performance of vehicles under different road conditions.
Highlights
IntroductionThe electric vehicle semi-active suspension system has attracted more and more attention [1,2,3,4]
The electric vehicle semi-active suspension system has attracted more and more attention [1,2,3,4]because it can effectively improve the ride comfort, handling stability and trafficability to ensure the comfort of passengers, the integrity of goods and the safety of driving [5,6,7]
The vehicle height sensors can only detect the changes of suspension dynamic deflections which is related to the road excitation, but it’s difficult to obtain the actual air suspension height changes caused by inflating/deflating
Summary
The electric vehicle semi-active suspension system has attracted more and more attention [1,2,3,4]. 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 On this basis, the hierarchical control method was proposed by using the VSC technique and fuzzy control theory. Established a nonlinear model of vehicle height adjustment with a variable mass inflation/deflation system based on the theory of vehicle system dynamics and thermodynamics. If the reference variables selected are inaccurate or even lacking an effective reference to judge whether the vehicle height has reached its target value, it’s difficult to reasonably control the vehicle body attitude in the process of movement and ensure normal driving In this case, the vehicle height sensors can only detect the changes of suspension dynamic deflections which is related to the road excitation, but it’s difficult to obtain the actual air suspension height changes caused by inflating/deflating.
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