中文摘要：

弦测法是目前常用的轨面不平顺检测方法之一,通过研究30 mm＋300 mm弦三点偏弦法的传递函数特性,给出幅频及相频关系,并利用傅立叶级数展开、合成的数学模型,实现弦测法对轨面不平顺波形的复原。单一频率下的正弦波调试验证了传递函数及傅立叶变换思路的准确性;通过比较正矢法及上海地铁波磨小车数据,分析其复原精度及可靠性,并针对弦测法中所存在的问题提出相应的改善措施,为三点偏弦法的运用及推广提供了理论依据。

英文摘要：

Chord-based method is a common method of rail irregularity detection.Through studying transfer function amplitude-frequency characteristics of 30 mm＋300 mm Asymmetrical chord offset method,relation between amplitude-frequency and phase-frequency is given.By using the mathematical model of Fourier series spreading and synthesizing,the restoration of track irregularity is realized.Single frequency sine wave debugging verifies accuracy of the transfer function and the Fourier transform.By comparing the chord versed sine method and Shanghai metro wave grinding data,the accuracy and reliability of three-point tapered chord method is analyzed.This paper also gives some problems and corresponding improving measures,which will help provide a reference for the application of asymmetrical chord offset method.