| The parameters of four-wheel alignment have a great impact on the car performance,the development of the four-wheel alignment also make a higher requirement for the detection of the wheel aligner.In this paper,the.machine vision can be applied to the verification technology.A new method which is based on the analysis of laser projection images and a new mathematical model can measure the four-wheel positioning parameters of camber,toe angle,kingpin inclination and caster angle respectively.This new way has the characteristics of real-time detection and high precision.First of all,this paper establishes the corresponding space mathematical model based on the concept of the parameters,and the results of the model can establish contact between the angle value and the feature information of the laser projection image.The model can deduce a mathematical formula to calculate the four-wheel positioning parameters according to the position of the center of the laser projection line stripes.Then,since the angle analysis which is based on the point laser projection is not very stable,this paper focuses on the parameters verification algorithm which is based on line laser projection.This way uses a variety of algorithms,including:line laser image preprocessing,edge detection,geometric center method,Gaussian curve fitting algorithm.The system finally uses the comer detection algorithm to divide the cross laser image into nine sections,and calculates the intersection coordinate of two lines by using the least squares linear fitting algorithm.Finally,the above algorithms can be implemented on the ARM9 embedded system image processing platform.And the MAX485 module transmits the center point coordinates to the host computer.A large number of experiments show the system is stable,and the repeatability and the accuracy of the data reach the four-wheel alignment standard.This paper provides a new method for the four-wheel alignment verification technology. |
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