Research On Measurement Uncertainty And Calibration Technology Of Automobile Four-wheel Alignment Parameters

In recent years,with the continuous development of the automobile industry and the improvement of road conditions,driving at a high speed is becoming more and more frequent.Only the stability of vehicle chassis parameters can ensure the safety and performance during driving.The four-wheel alignment detection and adjustment,which as one of the daily maintenance items,has been paid more and more attention.However,due to the limited management level of the vehicle maintenance industry and the uneven technical level of the practitioners,the four-wheel positioning detection cannot be well adjusted and maintained.Improper adjustment of positioning parameters will lead to the decrease of vehicle handling performance and the aggravation of tire wear.Therefore,it is of great significance to research on the adjustable technology of four-wheel positioning detection to ensure the driving safety and reliable performance of the vehicle.This paper mainly studies the uncertainty of four-wheel positioning measurement results and the adjustment technology of four-wheel positioning parameters in the following aspects.First of all,the basic principle of four-wheel positioning detection is described,and the working principle and technical differences between the two mainstream four-wheel positioning instruments are analyzed and compared.Then the basic theory of four-wheel positioning parameters and its influence on the control stability are explained,and the anomaly of four-wheel positioning parameters is analyzed.Secondly,a mathematical model was established based on the uncertainty theory,and experiments were designed from four aspects of human factors,environmental factors,instrument factors and sample factors to analyze the uncertainty of the four-wheel locator test results.The results show that human factors and instrument factors have a great influence on the uncertainty of logarithmic test results,while environmental factors and sample factors have little influence.Thirdly,the adjustment parts and methods of common chassis suspension areintroduced.The reliability of the parameter adjustment process and result is studied by the uncertainty experiment.The sensitivity experiment is designed to analyze the relationship of mutual influence when positioning parameters are adjusted.It is concluded that the uncertainty of the affected parameters is low in the process of positioning adjustment.The change of camber angle has great influence on the alignment parameters of kingpin,the change of toe adjustment has little influence on the alignment parameters of kingpin,and the adjustment of alignment parameters of multi link suspension has great sensitivity.The results of this paper show that the performance of the vehicle can be grasped accurately by analyzing the uncertainty of the measurement of the four-wheel positioning parameters.The four-wheel positioning parameters can be kept in a reasonable range with effective measures to ensure the driving stability and safety of the vehicle.The application of the research methods in this paper can promote the improvement of the technical level for the majority of automobile maintenance workers in the aspect of four-wheel alignment parameters detection and maintenance,and has a practical application prospect.