Development of Orthros, an Evaluation System for Free Curved Plate Thickness with a Robot - Generation of the Path Considering Collision

Abstract

While it is important that evaluation of thickness of a product made with press working to evaluate a mold, currently, there is not an appropriate system which can measure thickness of a free curved plate. The study deals with a development of an automatic measurement and evaluation system for thickness of free curved plates, called Orthros. The system measures thickness of a plate with laser displacement gauges and an industrial robot. While the system has been capable for measurement of a relatively simple shaped workpiece, it had collisions between laser-path and workpiece for that of a complicated shape, owing to a geometrical limit about measuring posture of the gauges. In this article, a new method to detect collision and to avoid collision by changing measuring posture on the basis of CAD data is proposed. In the method, not only the geometrical characteristic of the laser-path but also the measuring error characteristic of the gauges depending on the measuring posture are considered and continuous measuring path having change in posture to avoid collision is devised. From the experiment result, it is confirmed that the proposed method has an ability to measure a thickness of a workpiece with complicated shape.