Optimal path planning for helical gear profile inspection with point laser triangulation probes

New commercial Point Laser Triangulation (PLT) probes enable Coordinate Measuring Machines (CMMs) to take faster noncontact, accurate measurements. In this paper, we address how to apply this technology to inspect helical gears. Traditionally, gears are inspected with slow, costly, and dedicated machines. The proposed flexible inspection system with a fast measuring probe can significantly reduce capital equipment costs and inspection times. Integrating PLT probes on CMMs has been limited partly because of the difficulty in generating optimal inspection paths, and partly because of the highly reflective gear surfaces. Complex sensor-to-surface orientation and obstacle-avoidance requirements of these unique probes are the main cause of the difficulty. This paper presents a geometrical approach for obtaining an optimal path plan for helical gear profile inspection with PLT probes. Models for the orientation parameters and the allowable operating regions for the PLT probe are developed. A collision avoidance strategy is also presented. Although this new method was developed and demonstrated while creating an optimal path plan for inspecting helical gears, the developed models and principles can also be applied to optimal inspection plan generation for other parts.