Evaluation of geometry error based on deviation vector of geometry feature

For evaluation geometry error problem with discrete sampling points, a evaluation method was proposed based on deviation vector of geometric features. The reference coordinate system was constructed according to the feature type of geometry errors. By using geometry tolerance definition, the actual deviation vectors of functional geometry was achieved, and the mathematical model of deviation area was constructed by combining with reference coordinate system. 3D convex hull of discrete sampling points was set up with convex hull theory, an incremental algorithm in computational geometry theory. The evaluation mathematical model of geometry error was established by using constrained freedom and convex hull. The software modules were developed based on above model. The experiment result proved that the proposed algorithm could ensure the accuracy of datum plane and meet the engineering requirement compared with the least square method.