Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracer...Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine tools.This method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement method.We consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic chain.The four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization iteration.The experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser tracer.For a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed algorithm.This research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.展开更多
Reliable connection of turbine generators in complex main wiring structures to the power grid through a plurality of switches is a new key problem,referred to as multipoint automatic synchronization(MPAS),in automatic...Reliable connection of turbine generators in complex main wiring structures to the power grid through a plurality of switches is a new key problem,referred to as multipoint automatic synchronization(MPAS),in automatic control systems(ACS).In this paper,different methods of voltage-frequency and phase-difference control are analyzed,and a control methodology based on active frequency tracking(AFT)is presented.Through the establishment of the multi-point automatic synchronization model and the analysis of the governor transfer function with this control method,the important control parameters and automatic process control sequence are summarized.The correctness and effectiveness of the designed methodology are inspected through on-site testing,and the importance of the function and selection of parameters are also explored.展开更多
基金Supported by Natural Science Foundation of Shaanxi Province of China(Grant No.2021JM010)Suzhou Municipal Natural Science Foundation of China(Grant Nos.SYG202018,SYG202134).
文摘Laser tracers are a three-dimensional coordinate measurement system that are widely used in industrial measurement.We propose a geometric error identification method based on multi-station synchronization laser tracers to enable the rapid and high-precision measurement of geometric errors for gantry-type computer numerical control(CNC)machine tools.This method also improves on the existing measurement efficiency issues in the single-base station measurement method and multi-base station time-sharing measurement method.We consider a three-axis gantry-type CNC machine tool,and the geometric error mathematical model is derived and established based on the combination of screw theory and a topological analysis of the machine kinematic chain.The four-station laser tracers position and measurement points are realized based on the multi-point positioning principle.A self-calibration algorithm is proposed for the coordinate calibration process of a laser tracer using the Levenberg-Marquardt nonlinear least squares method,and the geometric error is solved using Taylor’s first-order linearization iteration.The experimental results show that the geometric error calculated based on this modeling method is comparable to the results from the Etalon laser tracer.For a volume of 800 mm×1000 mm×350 mm,the maximum differences of the linear,angular,and spatial position errors were 2.0μm,2.7μrad,and 12.0μm,respectively,which verifies the accuracy of the proposed algorithm.This research proposes a modeling method for the precise measurement of errors in machine tools,and the applied nature of this study also makes it relevant both to researchers and those in the industrial sector.
文摘Reliable connection of turbine generators in complex main wiring structures to the power grid through a plurality of switches is a new key problem,referred to as multipoint automatic synchronization(MPAS),in automatic control systems(ACS).In this paper,different methods of voltage-frequency and phase-difference control are analyzed,and a control methodology based on active frequency tracking(AFT)is presented.Through the establishment of the multi-point automatic synchronization model and the analysis of the governor transfer function with this control method,the important control parameters and automatic process control sequence are summarized.The correctness and effectiveness of the designed methodology are inspected through on-site testing,and the importance of the function and selection of parameters are also explored.
