Dynamic angle of attack measurement system and method therefor

Abstract

A method measures the angle of attack for the leading and trailing sets of wheels in trucks of rail vehicles traveling over track in a wayside system. At a first point on the outside rail of a track vertical force is measured with a first vertical strain gage, lateral force is measured with a first lateral strain gage and an outside angle of attack timing signal is measured with a first angle of attack strain gage. This process is repeated on the inside track so that a raw angle of attack for each set of wheels can be determined based upon speed and time difference. Ratios between the lateral force and the vertical force for the wheels of each are used to select raw angle of attack values for properly steering trucks that are averaged together to obtain an average angular offset value related to any misalignment of the strain gages. A dynamic angle of attack for each set of wheels is obtained by subtracting the average angular offset value from each raw angle of attack value to obtain a dynamic angle of attack value for each set of wheels. Greater accuracy in measuring angle of attack values occurs by taking a derivative of the data and using a polynomial fit to find the derivative's peak.