Improving the accuracy of assessing the position deviation in coordinate measurements of GTE compressor and turbine blade profiles

The paper proposes a method for increasing the accuracy of the iterative closest point (ICP) algorithm used in metrology problems in determining position deviation. The target of using the method for determining deviation profiles were compressor blades of a gas turbine engine (GTE). We propose to formulate the problem of the optimal match in the developed method as a multicriterion task including the criteria of the minimum of squared distances, differences of normal vectors and difference values of the depth of camber at the appropriate points of the superposed profiles. Different variants of reducing the problem to the use of a single integral criterion including the above-mentioned ones are considered. The problems of optimization were solved using the quasi-Newtonian methods of sequential quadratic programming. The proposed new method of improving the ICP algorithm based on geometric features showed greater accuracy in comparison with the discussed methods for optimizing the distance between the fitting points, especially in the case of a small number of measurement points on the profiles.