Study On Key Technologies Of Complex Surfaces On Machine Measurement And Application

As one of key technology of design, manufacturing and measurement integration manufacturing for complex surfaces, multisensor integration on-machine metrology not only includes many traditional contents for single sensor such as sensors calibration, sensor planning and measurement data processing, but the metrology system global calibration, combination measurement strategy and multisensor data processing etc. This dissertation address some important problems of developing an on multisensor on-machine metrology system in NC machining process. These problems include sensors global calibration, tactile sensor sample planning and surface error distribution analysis based multisensor combination measurement. The major research works and contributions of the dissertation are introduced as follows:(1) A global calibration method for tactile-laser scanning metrology system is proposed. After analyzing merits and drawbacks of present methods, a mathematical model based on unit quaternion is constituted. To get the optimal calibration data, the mathematical morphological image processing method is involved by clustering. In this method, the calibration target is a simple hexahedral part. Because of simple geometric features, short computing time and rapid calibration speed, this method is a good choice for tactile-laser scanning calibration.(2) A tactile sample planning method for similar section surfaces based on surface mass is proposed. Firstly, curve mass and surface mass are defined. Based on this, similar section surface is discussed and expressed with surface mass coordinate system. Then surface can be flattened by averaging surface mass. The sample point position is planed by Hammersley sequence with the flattened surface. Simulation and cased study are shown that this sample method can acquire higher measurement accuracy with same sample points number.(3) Most machined surface is with nonuniform error, and surface with isotonic error need to be assigned different parameters in finish machining process, to ensure machining quality. However, as requirement of high accuracy and rapid speed, single sensor is impossible to handle this problem. A tactile-laser scanner integration metrology strategy applied to analyze surface error distribution is proposed in this dissertation. The strategy starts with scanning the whole surface using laser scanner, then profile error is derived by processing point cloud. As introducing error contour map, the zone out of tolerance is extracted, which need to be re-inspected with tactile probe. The probe path is planned by applying morphological skeleton algorithm, when point cloud is transformed to 3D binary image. Experiment is performed on blade surface grinding process and validates the method effect.At last, based on these works and the present software and hardware platforms in State Key Laboratory of Digital Manufacturing Equipment and Technology, the mutisensor-OIMS (multisensor on-machine intelligent measuring system) is basically developed. To validate performance, some experiments about global calibration, sample planning and surface error analysis are implemented.