Integrated computer-aided verification of turbine blade

ABSTRACT: Computer-aided verification plays an important role in turbine blade quality control as it provides a valid means to quantify the blade geometry and thereby governs the engine performance. However, this dependency on measurement accuracy could raise significant problems and present a major drawback if the computer-aided verification results were inaccurate. Since the complex blade shape poses challenge in data acquisition, measurements have to be taken from multi viewpoints to achieve the total coverage. Registration is an important step for merging multi-view data but complex for freeform blades as which do not possess distinctive intrinsic topology to guide the registration. Many researchers made efforts to solve the registration problem by hardware or software solutions. In current industry practice, the 3-2-1 approach is commonly used to determine a reference coordinate system. However, the shortcomings are that the parts are required to have plane surfaces, and very sensitive to errors. And the alignment quality cannot be guaranteed. The Iterative Closed Point (ICP) algorithms are also popular for data alignment but high computational cost. In practice, error still exists when using the ICP algorithm. Therefore, a new system is proposed by integrating inexpensive opto-mechatronic hardware as well as intelligent algorithms to simplify the turbine blade reverse engineering for downstream quality evaluation. Alignments are computed using mechanical based transformation. A k-d tree structure is used to facilitate the data matching.