Simulation Research Based On The Wavelet Transform Of The Semi-Active Suspension Control Strategy

With the development of automobile technology, higher and higher performance requirements are for the car, in addition to the requirements of safety, people also hope to be able to improve the ride comfort and handling stability. Suspension is an important part of the connecting body with axle, the transfer function between the wheels and the vehicle body forces and torques and cushion the impact from the uneven pavement to transfer, the attenuation due to dynamic load of vibration, on vehicle ride comfort and handling and stability of have great influence. Because of its good spring and damping characteristics air suspension are more and more widely used.The air suspension as the research object, to improve vehicle ride comfort and handling stability as the goal, on the basis of a bus, designed three kinds of control strategies and was verified in two degree of freedom quarter vehicle model and the whole vehicle model. The main contents of this paper are as follows:(1) On the basis of understanding of the air suspension structure and characteristics, according to the suspension dynamics differential equations, established the two degree of freedom model of passive suspension and air suspension, researched the suspension spring characteristic parameters and damping parameters influence the suspension performance, which is concluded that the suspension parameters have a certain consistency on three indicators of the body acceleration, suspension dynamic deflection and dynamic tire load in the frequency domain. According to the national standard, constructed in accordance with the standards of the random road spectrum through the harmonic superposition method.(2) Based on the variation of the error and the rate of change of the error designed fuzzy control strategy, and established the controller model in Simulink. The validity and correctness of the control strategy are verified on the random road surface.(3) Considered the frequency domain, introduced the wavelet analysis, and according to the matching principle of vibration energy in the frequency domain distribution and spring stiffness designed a wavelet fuzzy control strategy which is a major band intermediate frequency values as input, the spring stiffness for the output, combined with the wavelet analysis, frequency control and fuzzy control. The feasibility of the control strategy is verified under the B and C two level random road surface, and the control effect is better than that of the passive suspension.(4)Because of the wavelet fuzzy control strategy of the existing shortcomings, puts forward the improved type, through continuous wavelet transform to extract the main frequency band of the instantaneous frequency and taking it as the new control strategy is designed fuzzy controller input. The ride comfort simulation test is carried out on the random road surface, the feasibility of the method is verified, and improved the deficiency of the fuzzy control strategy.(5) Established a whole bus model in the TruckSim, through the TruckSim and Simulink co-simulation, set up the simulation test conditions of ride comfort, constructed the pavement and carried out the simulation test in the software, analyzed and compared the control effects of the three control strategies.