Research On Straightness Measurement System Of Long Rails Based On2D-PSD

Straightness error which is one of the main form and position errors of guide rails, is the most important factor in determining the quality of rails and affects its work performance directly. The inspection of straightness error has the characteristics of many sampling data, long measuring distance, real-time, high reliability, field test needed and so on, such as the traditional ruler, steel wire, etc. These methods are simple, but have the disadvantage of low precision and low efficiency. Although the new type of measuring instruments have high precision, they are expensive and difficult to popularize. In view of this, the straightness error of guide rails is chosen as the research object with accuracy and economic requirements. A new measuring method is proposed based on double two-dimensional position sensitive detector (PSD) and laser spatial bias correction.First of all, according to the requirements of straightness inspection, the measurement principle of the solution to the abstract analysis is determined. The laser space angle correction and the mathematical model of guide rail straightness and machinery are established. Based on the established mathematical model, the overall design of the system is designed. The two-dimensional PSD is chosen as the sensor. BP artificial neural network optimization algorithm is used in the PI micro displacement worktable to reduce the pincushion distortion. The cross-correlation study is done to overcome the influence of background light. The data acquisition program of a two-dimensional PSD is written by the LabVIEW software. The straightness error assessment program is written by the MATLAB software, which has the powerful data processing ability. The nonlinear correction of the two-dimensional PSD is achieved with the aid of PI micro displacement worktable and BP neural network optimization algorithm. The feasibly of the system is verified by the original rational experiment, field experiment and contrast experiment. The laser device which is made of reshaper, beam expander and collimating system has good stability and laymen in the scope of the10m, and the spot size is within the allowable range. The system can effectively solve the problem between the precise long rail straightness detection and high precision measurement. The measurement accuracy can reach to0.002mm in10meters of the effective measurement range. As a result, a new method of detection is provided for wide range of long rails straightness measurement.