| The four-channel tire-coupled road simulator is a widely used equipment for fatigue testing of vehicle parts.It has a simple structure and convenient testing,which is valued by relevant practitioners in various countries.The wheel-coupled road simulator uses four vertical vibration exciters to simulate the vehicle.The control method is based on electrohydraulic servo position control,and then iterative control is used to widen the working bandwidth through identification.Due to the complexity of the road simulation system,the non-linear factors existing in certain frequency bands are likely to have a bad influence on the experimental reproduction results.In this paper,the frequency division end control is studied to make the experiment more accurate and fast.First,starting from the structure and composition of the wheel-coupled road simulation system,clarify the role of each part and the basic working principle of the overall system.Then,a dynamic analysis was carried out on the experimental object car for road simulation.Through simplification,a mathematical model of the vehicle suspension system was built in Simulink to analyze its vibration characteristics.And through the design and construction of the single-channel servo control system of the road simulation system,the position servo control of the single-channel system is realized;according to the real vehicle suspension,the test system is created in Adams and combined with the servo control system of Simulink to build a joint Simulation model.Then,study the different identification methods of the road simulation test system,analyze and compare the traditional H1 identification method and the improved H1 frequency response function identification method under the model with the influence of noise at the input and output terminals,and compare the two through the simulation test of the two methods Compared with the actual frequency response function,the identification accuracy error.;According to the coherence analysis theory,compare the coherence between the channels in the identification results,analyze the reliability of the identification results;calculate the system impedance,due to the coupling effect between the channels of the road simulation test rig and the system nonlinear factors lead to identification errors The existence of,and even the frequency response function matrix obtained by identification may have singular phenomena at certain frequency points or frequency bands.A certain singular value processing method is adopted to ensure the stability of iterative control.Finally,a road simulation waveform reproduction test is conducted.By generating the four-wheel road excitation time domain signal of the vehicle and stimulating the road simulation system to obtain the reference signal;according to the iterative control theory,the traditional RPC method can be used to reproduce the time domain waveform reproduction;for the problem of different reproduction accuracy in different frequency bands,sub-bands are used Variable step size iteration method to improve. |
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