Methods Of Automatic Calibration For Four-wheel Alignment Based On Superimposing Angle

The four-wheel aligner is a widely used piece of testing equipment for calibrating the positional parameters of wheels on automobile maintenance and production enterprises and related scientific research institutions.Reliable and precise four-wheel alignment is directly related to the running stability,fuel consumption,safety,and drive comfort of the vehicle.Typical positional parameters include the camber and toe angles of the wheel,and the caster and inclination angles of the kingpin.The establishment of mathematical model between the caster and inclination angles of the kingpin and horizontal angle is based on the geometric model and working mechanism of the vehicle suspension system.This mathematical model is very complex and cannot use explicit expression.So the existing four-wheel aligner is applied of a simplified model.Because different production enterprises to adopt the differently simplified method,the measurement error is inevitable.So how to ensure that the value transfer of positional parameters is the key to the test.Existing calibration devices for four-wheel alignment are based on a process of independently setting the angles of the vertical and horizontal planes of the automobile(vertical plane in the vehicle,vertical and horizontal planes perpendicular to its).Applying the principle of unequal angle displacement,based on angle subdivision,calibration devices verify several positional parameters in four-wheel alignment.Because of the complicated structure and setting adjustment mode,it is difficult for existing calibration devices to achieve automatic detection.Indeed,these devices can only achieve manual operation.This paper describes a method of using the superposition and decomposition of angles in the horizontal plane and a rotating vertical plane to verify each positional parameter.The accurate and explicit mathematical model is between superimposed on the two angles and the caster and inclination angles of the kingpin and based on geometric features.The calibration device makes full use of the characteristics of the direct drive motor and a relatively simple mechanical structure to achieve the function of automatically detecting positional parameters.We put 3D model based on Solid Works into the ANSYS Workbench for finite element analysis.We optimize the design for the geometrical dimensions of the mechanical structure.Under the premise of meeting the requirements of measurement accuracy,making it lighter inweight and smaller in size.In order to meet the needs of technical supervision departments of on-site testing,easy to carry and simple operation.Based on above,this paper also studied that how to scientifically and rationally select the measurement points to verify the parameters of four-wheel aligner.Formerly,in order to reflect the true level of the instrument being tested,there is a large number of dense uniform selection points.The test workload is huge,especially the calibration of the kingpin parameters.Combining experimental data and Blanket Technique analyze the correlation is raised in the paper firstly.Through the method to analyze the correlation between the measured value of four-wheel aligner and the set value of verification device and to analyze the trend of measurement points scientifically.Selecting the valid measurement points based on the result of Blanket Technology.Using a small amount of measurement data responses the overall bias.provide a scientific basis for the development of various standards.This can provide a scientific basis for the selection of detection points of various parameters.Meanwhile greatly reducing the amount of testing to make the development of the standard has a strong enforceability.Additionally,it also provides a reasonable basis for selecting of measurement points reasonably in the four-wheel aligner factory inspection and performance testing.