Optical Quality Control of High-Strength Structures

Abstract

High-strength structure components can be built by the application of an advantageously designed geometry. These structures are challenging to manufacture due to their complex shape. This motivates the design of a new system for quality assurance of the geometric properties of these structures. Firstly, different measurement approaches and their usability for the measurement of high-strength structure components are discussed. Then an optimized solution is suggested. A pattern projection method is introduced, whereas the patterns adapt locally to the measured surface. The basic object of the research are methods of the optic three-dimensional measurement of structural elements with the help of adaptable pattern projection that allows to adjust the measuring process to the local geometry and reflecting characteristics of structural elements. This technique takes care of the special properties of high-strength structure components within the production process. It is described, how a measurement speed can be achieved that can catch up with a common production frequency without interrupting the flow of the parts. Furthermore, the measurement can take place in an industrial environment, because it is relatively tolerant to movements of the measured structure. Therefore, the measurement procedure is divided into two steps. Within the adaptation-step the luminescence and the resolution of the projected pattern is adapted to the measured object. The actual picture is taken and calculated in a second step in order to be robust against vibrations. The result of the measurement is an optimized point cloud of several million points. The paper concludes with a description of the data processing procedures necessary in order to evaluate the correctness of the measured structure.