A new algorithm for determining a collision-free path for a CMM probe

Recent developments in computer integrated manufacturing (CIM) systems have made the speed and accuracy of the traditional approaches in dimensional inspection bottlenecks of the production line. To overcome these bottlenecks, computer integrated dimensional inspection was proposed with the coordinate measuring machine (CMM) being the key device. In this investigation, a framework for integrating the CMM into the computer-aided design/computer-aided manufacturing (CAD/CAM) environment is developed to automate the process of design, manufacturing and inspection. An algorithm to generate an optimum collision-free CMM probe path is proposed. This algorithm uses the ray tracing technique to locate the collision of the possible paths, between the initial probe point and the target point, with the workpiece to be inspected. If there is a collision, the algorithm works through the topological structure of the part and selects the midpoint of the edge, shared by the face with which the path collides and the adjacent face nearest to the target point, as the next probe point. This procedure is followed till the target point is reached. The first half of the proposed algorithm is implemented using Mechanical Desktop as the CAD system and AutoCAD Runtime Extension (ARX) as the application programming interface, running on a Windows NT 4.0 platform. The effectiveness of the proposed algorithm is verified by the results of the implementation demonstrating optimum collision-free dimensional inspection path generation for three prismatic parts.