Analysis Of Suspension Kinematics And Compliance Characteristics And Research On Key Technology Of Test Equipment

Suspension ’’Kinematics & Compliance(K&C)’’ characteristics not only determine vehicle handling and stability,but also have an important influence on vehicle ride comfort and active safety.The existing K&C test method based on decoupling theory is difficult to accurately reflect the vehicle actual running state,the accuracy of the suspension assembly characteristic model obtained by simply superimposing K&C characteristics in the nonlinear region needs to be improved,the widely used suspension multi-body model is usually difficult to reflect the K&C hysteresis characteristics.In this paper,the modeling theory,test method and test equipment development of suspension K&C characteristics are systematically and deeply studied.The main research contents are as follows:1)The relationship between the suspension K&C characteristics and the suspension actual motion state is studied,and a suspension assembly characteristic model based on the multi-directional coupling K&C test is established.The relationship between suspension K&C characteristics and actual motion state is revealed by vehicle multi-body simulation and K&C multi-directional coupling test.The errors of the K&C test method based on decoupling theory in the construction of suspension assembly characteristic model are analyzed,a high order Legendre polynomial based on multi-directional coupling K&C test is established to characterize the suspension assembly characteristic model,which realized accurate prediction of vehicle model motion state in complex scenes.2)A multi-body model of double wishbone air spring suspension with elastic element friction and joint clearance is established.The elastic force model of air spring is derived based on the thermodynamic equation and the modified Berg friction model.The joint clearance contact force model is derived based on the Lankarani-Nikravesh nonlinear spring damping model and modified Coulomb friction model.The identification methods of air spring nonlinear parameters are studied.A double wishbone air spring suspension model is established to analyze the suspension K&C hysteresis characteristics,the effects of elastic element friction and joint clearance on the suspension K&C hysteresis characteristics are revealed,and the accurate simulation of suspension K&C nonlinear hysteresis characteristics is realized.3)A step sequence identification method for bushing nonlinear parameters based on the suspension K&C test is studied.The mapping relationship between suspension working interval and bushing working interval is analyzed,and the bushing nonlinear parameters are decomposed into several sub-problems for parameter identification according to the mapping relationship.Based on Chebyshev polynomial theory,the Chebyshev Metamodel of suspension K&C characteristics considering the variation of the K&C test loading node is derived.A step sequence identification method of bushing parameters is studied,which reduced the identification scale of bushing parameters,and realized the efficient identification of bushing parameters based on the K&C test.4)A suspension K&C characteristics multi-directional coupling test scheme based on the non-contact measurement is studied,and a suspension K&C characteristics high-precision test equipment is developed.The overall scheme,mechanical structure,measurement control system,upper computer software and data processing system of suspension K&C characteristic test equipment are designed.The coupling suspension multi-body model and K&C test equipment is established,the accuracy difference of K&C test equipment under different loading and measuring methods is analyzed.Aiming at the suspension coupling characteristics in the K&C test,a decoupling control strategy based on real-time compensation of a six-component force sensor is studied.Aiming at the non-contact binocular vision measurement method,a K&C characteristic parameter calculation method based on the position of the optical target is studied.