Inspection Path Planning Based On Triangular Mesh Model And System Development

Inspection is an important part of product quality control. and the development of Inspection Technology has had a significant impact on the manufacturing process. With the development of NC and computer technologies, On-line inspection systems that monitor the geometric dimensions of machined parts in NC machines for quality control purposes has attracted the attention of increasing numbers of enterprises. On-line inspection systems can avoid the error which is inevitably caused by the process of refixturing the part for measurement. Additionally, on-line inspection systems eliminate the time required to transfer the part to another inspection system, thereby increasing production efficiency. Therefore the development of on-line inspection technology is of realistic significance to the machining industry and is the scope of this project. This paper discusses and examines the technical issues in the area of On-line inspection technology such as: inspection path planning, probe radius compensation and collision detection. Methods and algorithms are developed this work to enable an on-line inspection system to plan and perform an inspection efficiently, accurately and safely.(1) This paper presents an optimized inspection path for the inspection of a triangular mesh model. The normal direction of the inspection points is calculated by considering the mesh triangles surrounding the point and calculating curvature of the surface at the point. The probe approaches the inspection point along a path defined by the normal direction of inspection point, so that the error of probe radius can be easily calculated. To reduce the distance the probe travels during an inspection and enhance the inspection efficiency, this paper studies two different planning strategies: the greedy and local optimization algorithm and the ant algorithm to optimize the order of inspection points and reduce the time taken for the inspection. (2) The probe's model is small and spherical and the triangular mesh model, which includes many different sized triangles, is often large and irregular in shape. This paper presents a collision detection algorithm that is based on AABB bounding boxes, to deal with the collision detection problem between the model of probe and triangular mesh model. When there is a collision path, this paper presents a method to modify the dangerous path, based on the shape of the triangular mesh model between the beginning and end points of the dangerous path. This method uses the bounding space to find a proper safe height above the surface along the dangerous path. The probe is then able to travel in a straight line from point to point at a high speed, with the knowledge that it is at a safe distance from the surface.(3) Based on the above research, this paper presents a Free-form Component On-line Inspection System and introduces different function modules such as CAD interactive, emulator module and inspection NC code program.(4)This paper tests the functions of the collision detection system, the inspection efficiency of the Free-form Component On-line Inspection System and whole operation process of on-line inspection by experiment. It shows that the system is efficient, accurate, safe and easy to use for the inspection of machined parts.