Automatic Generation Of Continuous Scanning Path And Application For Porous Free-form Surface

As a new contact surface inspection technology,five-axis continuous scanning technology has been widely used in industrial production because of its higher inspection efficiency than the traditional three-axis point-by-point inspection technology.However,for the precise parts with porous surfaces used in some special fields,the most efficient measurement method in practical application is to plan the five-axis measuring trajectory as a whole,and then to avoid these holes by lifting and dropping the measuring needle.The continuity of measurement process is seriously disturbed,and the overall measurement efficiency is greatly reduced.Motivated by these deficiencies,a trajectory planning algorithm for continuous scanning measurement of porous free-form surfaces is proposed,which improves the continuity of the whole measurement process and the measurement efficiency.In this paper,the following methods are used to improve the continuity of the measurement process of porous free-form surface: Firstly,skeleton extraction operation is carried out according to the boundary characteristics of the measured surface,and the skeleton line obtained is used as the guiding curve in the five-axis inspection trajectory planning process.In the process of skeleton extraction,the whole porous surface is partitioned,that is,each skeleton line corresponds to a region.Secondly,the characteristics of the skeleton line are abstracted to make it a weighted undirected graph,and the transformation from undirected graph to Euler graph is realized.Finally,the Euler tour of the Euler graph is obtained,and the continuous traversal order of all skeleton lines is obtained,that is,the scanning order of the guiding curve.The algorithm of continuous scanning trajectory planning for porous free-form surface presented in this paper is as follows: Firstly,the trajectory curve of the probe’s center point is generated from the guiding curve;secondly,the nominal scanning trajectory curve and the scanning trajectory curve of the probe in each area are generated;finally,the continuous scanning trajectory of the whole porous surface are generated by connecting the five-axis measuring trajectory in series with the scanning order obtained before.For the two trajectory curves of the center point of the probe corresponding to the two adjacent guiding curves,this paper adopts the method of linear interpolation of tilt angle to solve the problem of connection between the two adjacent trajectory curves.Finally,this paper designs a corresponding experiment to verify the proposed generation method of the five-axis continuous scanning measurement trajectory of the porous free-form surface,and uses the existing industrial five-axis continuous scanning measurement trajectory solution as a control.By comparing the experimental results with the measurement efficiency,it is proved that the proposed method for generating continuous curved scanning trajectories of porous free-form surface improves the measurement efficiency.