Study On Accuracy Of Portable Railroad Wheel Profilometer

The train speed is highly associated with the accurency and efficiency of the measurement to the train wheel, the more it's higher, the higher the measuring requests. Although the auto-measuring equipment can realize the dynamic measure, the train wheel has to pass the given region. Obviously, the best measuring equipment is portable instrument because the train wheel is hard to move or tear down. Another, the accurency of the laser triangle sensor is influenced by the figure and color of the train wheel, environment, and the price is very high, so the contact measuring method is worthy of research. Therefor, some researches about the five-bar profilometer and how to improve the measurement accurency of the five-bar profilometer are all intruduced in the thesis.Firstly, by analyzing the composing, operation principle and measuring process, measuring mathematical model is made. Aiming at the process of the measurement, the error sources of the measuring system are analysed, and the error analytic model of the profilometer is also made by differential theroy and the accurate parameter model by MATLAB. Furthermore, the influences to the measure result about the interacion between single-factor error and mult-factor error are analysed. The results of the analysises prove that each factor is linear and unattached, the angle of the two encoders is the biggish factor of the influences to the measure result. These results provides the gist to the demarcate methord of the incertitude and the accurency.Secondly, to accomplish the affiliation of gauge, Calibration method which is from easy to hard, approximate to pinpoint, layered, and hardware test combination with software emulate is studied in the thesis. Testing instrument of the five-bar profilometer is designed and a simple and reasonable calibration method is set, the feasibility of the calibration method is validated by experiments. As a result of measuring JM3 model, error of shape below±0.02mm.Finally, according to JJF1059—1999 Estimation and Demonstration of Measuring Uncertainty and JJF 1130-2005 Guide to the Estimation of Uncertainty in Calibration of Gemetrical Measuring Equipment. The measuring uncertainty of profilometer is analysed. When the believe probability is 0.99 and cover gene is 2.58, the expand uncertainty as follows,shape parameter less than±0.03mm. The uncertainty of the diameter of wheel will expand as the increase of it. However, by increasing the geometry dimension of the profilometer, we can make the uncertainty within 0.1 mm.The study on the accurency of the five-bar profilometer indicates that it can insure the profilometer has the eligible measurement accurency by calibrating proper dimension parameters and locational parameters, compensating error and operating correctly. The measurement accurency of the five-bar profilometer can meet the requirements of the high-speed train. This study has vital pratical value.