Trajectory Planning Of Geometric Parameter Precision Measuring For Thin-wall Revolving Body

Thin-wall revolving body is a key part of high-speed aerocraft. High-performance and high-speed aerocraft has strict requirements on the manufacturing precision of thin-wall revolving body. The measurement on outer shape and thickness of the thin-wall revolving body is an effective method to verify the manufacture precision of the high-speed aerocraft. Thin-wall revolving body is the thin-wall part with three-dimension complicated surface. Its diameter in the cone bottom is about a third of its length, its measuring precision on geometric parameter is as high as micron-grade. The measuring instrument and measuring technique in being can not satisfy an accurate and fast measurement for the geometric parameter of the thin-wall revolving body. As a result, it is necessary to develop automatic geometric parameter measuring equipment with high precision and high efficiency for thin-wall revolving body.This paper does research on several aspects as follows: measuring path planning, mathematical methods of trajectory planning, the compensation of measuring precision and calibration methods, software development research on the measuring trajectory planning, and soon.This paper provides path planning for measuring the outer shape and thickness of thin-wall revolving body. According to sampling and time of measurement, an optimal measuring path is selected from several path plannings, so as to achieve the orderly, rapid and highly efficient measurements on the coordinates of the practical point of outer surface and the thickness.The model equations of outer contour generatrix are constructed by the use of third-order curve interpolation algorithm. The hinged point of the jaw-like measuring arm moves along a locus formed by a series of points that are on a series of lines tangent to the outer contour with identical distance from the tangent points. This method educes the trajectory generation algorithms, and the fixing positions change from two positions to one position. Such improvement reduces position error by the changes of position, simplifies the process and improves the precision.In the aspect of data processing, the elimination of bizarre point in measuring data, data truncation and expansion, and the congruous disposal of measuring data are developed; these methods could solve the problems, such as there's noise in measuring date, measuring data is asymmetric and the boundary of measuring data is untidy.According to the precision of measurement system, the precision calibration and compensation methods of a measurement system are brought forward. It includes the orientation precision of servo axes, the precision evaluation of reduplicate orientation, the two-dimensional precision compensation of beeline axes, and the influence of the accuracy of wall thickness on the position error of hinged point. The calibration methods of geometric parameter precision measuring equipment include the calibration method of the thickness and outer contour measurement.The trajectory planning software system is developed with VC++. It's composed by data preprocessing, the congruous disposal of measuring data, modeling of outer contour, the trajectory generation of geometric thickness, code generation, and so on. Geometric parameter measuring machine of thin-wall revolving body has been successfully applied in practice yet, and solves the geometric parameter precision measuring problems of thin-wall revolving body.