Model and simulation of fringe projection measurements as part of an assistance system for multi-component fringe projection sensors

Abstract

Multi-component fringe projection sensors allow the fast, holistic, exact, robust, contact free sampling of a workpiece surface. The success of an inspection relies on the skills, diligence and experience of the inspection planner. For setting up an inspection, there is no standardized method established yet. Therefore there is a need for assistance systems to support the operator. A prototype of an such assistance system for multi-component fringe projection sensors is introduced. The assistance system supports the inspection planner in determining the ideal sighting- and positioningstrategy. As key element, the result of a planned inspection is simulated. First, the optical performance of the designated fringe projection sensor is calculated by use of raytracing software. Then the measurement result and the measurement uncertainty for specific measurement tasks and a chosen measuring pose, is simulated. Fundament for this simulation is a complete mathematical-physical model of the measurement. Building on this and on the knowledge of influences, which were previously inscribed in entry masks, the measurement uncertainty can be estimated and displayed individually for each point of a workpiece surface. Thus the inspection planner can easily evaluate the quality of the planned inspection setup. Additional optimizing algorithms were implemented. The aim of the multi-criteria optimization is to determine the best configuration for the measurement device and the ideal sighting- and positioning-strategy. As measure of quality serves hereby the reduction of the measurement uncertainty.