Precision measurement and evaluation of flatness error for the aero-engine rotor connection surface based on convex hull theory and an improved PSO algorithm

Abstract

The precision measurement and evaluation of the geometry form error for high-end precision components is one of the most important tasks for metrologists. In this paper, a novel hybrid flatness error evaluation method is proposed to measure and evaluate the flatness error for large-scale point cloud data. This method is based on the convex hull algorithm and the improved particle swarm optimization (IPSO) algorithm. Not only are a large number of redundant measurement data points effectively removed through the convex hull algorithm, but also this operation does not lose any valuable information for flatness error evaluation. Then an accurate mathematical model for flatness error evaluation is established based on the minimum zone criteria recommended by ISO, and then the IPSO algorithm is adopted to solve this complex non-linear optimization problem. In particular, the non-linear dynamic inertia weights w and learning factors c 1 , c 2 are introduced to improve the calculation accuracy. Finally, the proposed method is verified through an experiment measuring and evaluating the flatness error of an aero-engine rotor connection surface. The effective measurement data points are reduced from 18 000 to 856, or 4.76%, which is significant compared to the original data points. The flatness error evaluation result is 369 µm according to the IPSO method that we propose. Last but not least, we compare our method with the traditional least squares method and unmodified particle swarm optimization algorithm. The calculation results indicate that the evaluation accuracy is increased by 21 µm and 44 µm, respectively.

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Network traffic prediction method based on autoregressive integrated moving average and adaptive Volterra filter

“…Many studies have shown that the inertia weight should be larger in the global phase but smaller in the local stage of determining the exact location of the optimal solution. 34,35 However, the inertia weight of standard PSO algorithm is linear decreasing, which is simple and intuitive, but it is easy to fall into local optimum, so this paper uses nonlinear decreasing strategy instead of linear strategy. The specific implementation formula is as follows.…”

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Decoupling method for four-degree-of-freedom automatic centering and tilting worktable

“…Aero-engine assembly is the last part of the aero-engine manufacturing process, and its assembly quality will directly affect the performance, reliability, and life of the aero-engine [1][2][3][4][5], and the poor assembly may lead to serious vibration or even collision when the rotor rotates at high speed, which is related to the stable operation and safety of the aviation system [6][7][8][9]. The multi-stage rotors in aero-engines are cylindrical components of the rotary symmetry class, and there is a problem of gradual accumulation of machining errors of rotors at all levels during the assembly process [10][11][12], so the precision measurement of single-stage rotor circular contours is a prerequisite and basis for ensuring the rationality of the assembly process.…”