Research And Develop Of Non_Contact Measurement System Of Wheel Alignment

The parameters of four wheel alignment, which are some angles and distances betweenthe wheels and suspension parts in static installation of the wheels, include camber angle,Toe-in Distance between the wheels, kingpin caster angle and kingpin inclination angle. Theappropriate selection of the parameters of wheel alignment has a great influence on theoperating stability, driving security, tire wearing and fuel consumption. Nowadayscontact-type methods are widely used in wheel alignment equipments. Because of thelimitation of measurement principle, the inspection process of the contact wheel alignmentsystem is very complex. For the low inspection efficiency, small measurement range andinflexibility, the contact wheel alignment is difficult to widely use in modern automanufactory and inspection line.This paper presents a measurement method for wheelalignment parameters with computer vision inspection technology. The proposed method is anon-contact alignment system with advantages of high-speed inspection, operatingconvenience and moderate precision.The main research work in this paper includes:(1)The advantage and disadvantage of the existent wheel alignment methods areanalyzed, the math model of the new non-contact wheel alignment system based on the lasersensors are constructed.(2)Zhang’s method is used to calibrate camera, the camera structure parameters andcoordinates unification parameters of multi-sensors are calibrated by the method ofsuspension fiber with two theodolites. According to the characteristic of the wheel and image,the curves of the rim and the laser strip can be gained by image processing techniques. Thewheel rim and laser strip alignment is presented by Steger method. The tangent plane and thelocation parameters of the wheel are obtained by the ellipse fitting in2D and the searchingalgorithm in3D(3)Software of system calibration and alignment parameters inspection is developedusing VS2008and OpenCV.