Dimensional Measurement by Projection of Locally Adapted Patterns

Abstract

High‐strength structure components can be obtained by using an advantageously designed geometry. Examples are bar frame structures or organically shaped parts. Such components are challenging to manufacture due to their complex shape. This motivates the design of a new system for the 100% quality control of the geometric properties of such 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 where the patterns adapt locally to the measured surface. This technique takes care of the special properties of high‐strength structure components within the production process. The paper presents a method how to obtain a measuring speed that can cope with a high production frequency without breaking the flow of the parts. Furthermore, measuring can take place in an industrial environment because it is relatively tolerant to movements of a component being measured. Therefore, the measuring procedure is divided into two steps. Within the adaptation‐step the luminescence and the resolution of the projected pattern is adapted to the object to be measured. The actual picture is taken and calculated in a second step in order to be robust to vibrations. The result of this measuring procedure 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.