四轮定位仪主销倾角检定模型及可靠性分析

Verification Model and Reliability Analysis of Kingpin Inclination Angle of Four Wheel Positioner

针对目前汽车四轮定位仪检定装置在检定过程中无法准确检定主销倾角的问题,基于空间几何分析,建立了四轮定位仪主销倾角检定数学模型。通过对模型空间几何关系的分析推导,验证了检定主销倾角的原理,并研制了基于多自由度空间正切机构的新型全自动四轮定位仪主销倾角检定装置。该装置采用了球铰底座和杆端关节轴承,能够独立完成主销后倾和主销内倾的调整,从原理上消除了主销合成运动所造成的运动误差。考虑运动副间隙,对检定装置进行了运动可靠性分析研究,建立了检定机构的非连续接触可靠性分析模型,分析并推算出了考虑倾角输出偏差的检定机构倾角输出偏差的方差公式。对装置进行了主销后倾角和主销内倾角检测,结果符合国标要求的精度。该设计为后续的四轮定位仪检定装置的设计提供了一定的借鉴。

At present, in verification process of the calibration device for automotive four wheel alignment, it is impossible to precisely detect the inclination of kingpin. Aiming at this situation, and based on spatial geometric analysis, the mathematical model of calibration is established. Through analysis and derivation of the spatial geometrical relationship of model, the calibration principle of inclination of kingpin is verified and a new automatic four wheel alignment inclination verification device is developed based on multiple - degree - of - freedom spatial tangent mechanism. In this device, the spherical hinge base and rod end bearing are used, thus the adjustments of caster angle and introversion angle can be accomplished independently, to theoretically eliminate the motion error caused by the kingpin resultant movement. The reliability analysis for the verification device is conducted in consideration of the clearance of kinematic pair, and the discontinuous contact reliability analysis model of the verification device is setup, the variance formula of the output deviation of the verification mechanism considering output deviation of the angle values is analyzed and calculated. The detection of caster angle and introversion angle are conducted by the device, and the results meet the precision requirements of the national standard. The design provides certain references for the design of the follow - up verification devices of four wheel alignment system.