| Air suspension is widely used in high-end cars because of its advantages of adjustable spring rate and elastic coefficient.Therefore,the modeling and control of air suspension is a key issue in the current automotive control field.In this thesis,according to the control difficulties of air suspension system,the air suspension system is modeled and the sliding mode control method is studied,and a semi-physical simulation test is performed.The main content is as follows:(1)The nonlinear dynamic model of two-degree-of-freedom air suspension is established.The nonlinear relationship between elastic force of air spring and displacement deformation is fully considered in the model.(2)The sliding mode control method for air suspension is designed based on the established dynamic mathematical model,and MATLAB simulation analysis is performed.(3)The dSPACE real-time simulation system is used to design and develop a hardware loop simulation experiment platform for an air suspension.The experimental platform consists of oil source,actuator system,suspension hardware test bench,remote control cabinet,and console.CarSim vehicle model and suspension control algorithms can be run in real time.Based on the dSPACE real-time simulation platform mentioned above,a real-time monitoring interface and control program are developed to complete the test of the sliding mode control method of the 1/4 air suspension.The experimental and simulation results show that the nonlinear model of air suspension presented in this thesis can better reflect the nonlinear dynamic characteristics of the air suspension.At the same time,the designed air suspension sliding mode control method can obtain good control performance. |
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