An iterative coordinate setup algorithm for airfoil blades inspection

The six-point principle was widely used in blade design to provide a reference coordinate for dimensioning. The coordinate setup for CMM inspection was conventionally done manually. It was not only time-consuming, but also inaccurate. We proposed an algorithm for the coordinate setup of airfoil blades inspection. The datum points were divided into five types based on their locations. A specific algorithm was applied to measure each type of the datum points. A procedure based on 3-2-1 method was developed to establish the coordinate system. The coordinate setup process was formulated as an iterative procedure where an error function was derived to evaluate the convergence of the iteration. Experimental results and practical applications were also provided to demonstrate the feasibility of the proposed algorithm.