| Due to the advantages of large load capacity and high transportation efficiency,combination vehicle has been applied in the transportation industry in recent years.However,the combination vehicle has long body and high center of mass,which makes it easy to roll and instability,and rollover accidents occur in serious cases.In order to prevent the combination vehicle from rolling over,the study on the roll control is particularly important,and improving the suspension performance is the most direct and effective way to enhance the rolling stability of the vehicle.At present,most combination vehicle adopt the spring suspension to absorb vibration,which has a general effect and a large weight.The air spring suspension reduces its weight,but it has a limited improvement in stiffness.Two types of suspension cannot meet the needs of comfort and handling stability at the same time.In recent years,the emerging hydraulic interconnected suspension has been widely studied and applied in the field of single vehicle.It can basically provide the same damping performance as air suspension,and it can also provide larger roll stiffness at the same time,which has incomparable advantages over traditional plate spring and air suspension.In this paper,based on the national key research project " Test and Evaluation of Active Prevention and Control Technology for Dangerous Goods Road Transport Accident ",fully studying anti-rolling stability of combination vehicle and research status of hydraulic interconnected suspension at home and abroad,a six-axle combination vehicle and anti-roll hydraulic interconnected suspension are chosen as the research object.A coupling model of vehicle fitted with HIS was established.The matching scheme technology and fuzzy control method of vehicle were proposed,the rollover state parameters were optimized and identified,and the road test of steady-state circle of vehicle in real world was carried out.The main research contents and conclusions of this paper are as follows:1)Dynamics modeling and simulation of suspension and vehicle based on hydraulic interconnection systemBased on Newton's second law,the dynamics model of the semi-trailer mechanical suspension with four degrees of freedom was established.The transfer matrix of hydraulic interconnection system is derived by using hydraulic impedance method.Via the boundary conditions of the mechanical system and the hydraulic system,the mechanical-hydraulic coupling model of the HIS was established and verified.The dynamic equation of combination vehicle is established and the vehicle model of coupled HIS was derived by the equivalent roll stiffness method.The state space representation of the model is soloved eventually.By changing roll stiffness,torsional stiffness and the distance between the traction point and the center of mass of the semi-trailer on saddle,the anti-roll performance of the vehicle was simulated and analyzed.2)Simulation by modeling and scheme optimization of semi-trailer/tractor fitted with hydraulic interconnected suspensionThe co-simulation platform of AMESim,Trucksim and Matlab/ Simulink was built and the matching scheme of semi-trailer fitted with HIS is designed.The vehicle model in Truck Sim and the HIS model in AMESim were built.The HIS models of single axle,two axles and three axles were designed and verified in Matlab/simulink.The optimal matching strategy of semi-trailer is analyzed by simulation and the arrangement of the tractor with HIS system is simulated and analyzed.3)Research on parallel/series fuzzy control of hydraulic interconnected suspension vehicleAiming at insufficient roll stiffness of the first and the third axle of semi-trailer with HIS,a parallel fuzzy controller was designed on the second axis and the simulation of double lane change and step steering condition is carried out.And then a series fuzzy controller is respectively designed on the first axis and the third axis and the simulation under the same working condition was also made.The results show that the two types of fuzzy control strategies can both improve the anti-roll stability of vehicle with HIS,and the effect of the parallel fuzzy control strategy is more significant than that of the series control strategy.4)Optimization and identification of rollover parameters of vehicle equipped with hydraulic interconnected suspensionStep steering and fishhook rollover conditions were respectively established,and the risk axe of tractors and semi-trailers was identified as the evaluation criteria for the time of rollover.The turning conditions with variable speed and radius were simulated,and the dynamic responses of tractor and semi-trailer were analyzed respectively,and the rollover characterization parameters and rollover threshold were identified.By changing the parameters of HIS system,the influence of HIS on vehicle rollover threshold was studied in the dangerous moment of rollover and the time of complete rollover.5)Road test verification and rollover threshold prediction of vehicle fitted with hydraulic interconnected suspensionTaking three axles with HIS of the semi-trailer as the test object,the test scheme is designed and the anti-roll performance of steady-state circle with low vehicle speed was tested.Aiming at the test data with outliers noise,the robust Kalman algorithm is studied.Compared with standard Kalman filter,infinite Kalman filter and particle Kalman filter,the effectiveness of the robust algorithm is verified.And then test results after filtering were analyzed in terms of anti-roll performance.BP neural network optimized by genetic algorithm was constructed and rollover threshold of vehicle in turning condition under high-speed is predicted.The research results of this paper provide a theoretical basis for the optimal design of combination vehicle fitted with hydraulic interconnected suspension,expand the application of hydraulically interconnected suspension technology,and have important significance for predicting the change of vehicle performance. |
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