In order to solve the problem of large sample demand and low computational efficiency in the current sensitivity analysis method

a global sensitivity analysis method based on polynomial chaos expansion was proposed. Firstly

a complete spatial error model was established based on the screw theory by taking the AC type double turntable five-axis CNC machine tool as the research object. Secondly

the polynomial chaos expansion model of machine tool geometric error was constructed. The orthogonal matching pursuit was used to sparse the model

and the Sobol sensitivity index based on this method was given. Furthermore

the geometric errors of five-axis CNC machine tools were analyzed. he approximate probability distribution of 41 errors are measured and count

ed

and the key geometric errors affecting he pose error components in each direction are analyzed. Compared with Monte Carlo simulation and Latin hypercube ampling

the correctness of the polynomial chaos expansion method is verified. Under the premise of not reducing the calculation accuracy

the sample size is reduced from 1×10

5

to 1×10

3

the calculation time is reduced by 96.8% and 98.1% respectively

and the calculation efficiency is significantly improved.