Control of Contactless Profilometer for Scanning Surfaces of Complex Profile

Abstract

The research problem of a surface’s profile with an extended precision detail of irregular shape with a given accuracy is considered by the contactless scanning profilometer. The contact of the measuring block with a controlled surface needs to be excluded because of a possibility of damage of a product and, at the same time, to provide the necessary accuracy of assessment of its profile. For the solution of this task in work the double-circuit system containing two sensors is used: the distance converter on the basis of optical tunneling for the “exact” channel and the converter on the basis of a chromatic aberration for “rough” channel of scanning. It is shown that based on these measurements of the “rough” channel providing the guaranteed exception of contact of “rough” channel’s contact with a surface of the studied product. It is possible to predict situation and traverse speed of the sensor of the “exact” channel for the purpose of an exception of contact with the studied surface and ensuring necessary accuracy of measurements. The mathematical model of a dynamic system of scanning based on a prior information about entering it elements and blocks is developed. The analysis of the main dynamic properties of a system of scanning is carried out and the law of its management providing the required quality of transition processes based on mathematical modeling is constructed. The algorithm of the forecast of the subsequent position of the sensor of the “exact” channel based on these measurements of “rough” channel, which provides the required speed and accuracy of scanning depending on the predicted object’s surface profile height is developed. The flowchart of the algorithm determining the value of movement of the sensor of the “exact” channel in the vertical direction depending on the received assessment of measurements of “rough” channel is developed. The conducted researches allowed developing the block diagram of a double-circuit measuring system. Modeling of this system in the environment of MATLAB/SIMULINK, which allowed evaluating efficiency of its functioning for the different studied profiles was carried out. Results of modeling showed efficiency of the offered scheme of a profilometer’s control system.