| In high-end equipment in the fields of aerospace,electronic information,and defense industry,there are a class of wave-transmitting components with specific electromagnetic properties.Such components can ensure the normal operation of the communication and guidance of the radar antenna,and generally have a complex profile.Insert Phase Delay(IPD)is a comprehensive evaluation index for evaluating whether the production of complex surface wave-transmitting components meet the requirements.At this stage,limited by the material and production process level,the most common way to correct and compensate the IPD error is adjusting the geometric thickness of wave-transmitting components by grinding the its inner wall.The precise point-by-point measurement of the wave-transmitting components IPD can not only screen out qualified products,but also is one of the effective means to determine the thickness adjustment distribution for mechanical compensation.This paper designe and develops the control system of radome IPD measuring equipment,and studies the problem of multi-axis coordinated contour control in the measurement process.First of all,in view of the particularity of the measuring equipment,workpieces and the specific conditions during the measurement process,a dual CPU numerical control system based on "IPC+GALIL controller" is adopted.The overall structure of the measurement equipment hardware system was planned,and the main circuit construction of the control system and the design and selection of the servo system were completed.Based on the modular design concept,the main interface of measuring equipment adjustment and the programming interface of microwave system were developed,and the movement program of the lower computer and the underlying PLC program were designed.And the software and hardware platform of the measurement equipment control system is completed.Then,in order to solve the contour error caused by the mismatch of the dynamic characteristics and the coupling between axis of multi-axis servo system during measurement,the nonlinear PID controller is applied to the single-axis position control and cross-coupled contour control based on the analysis of the system contour error.For any contour curve,the nonlinear PID cross-coupling control can accelerate the dynamic response of the servo axis and improve the single-axis tracking accuracy,at the same time,the contour error is estimated in real time and then the dynamic gain compensation is performed to each axis to realize the information sharing between the axis to reduce the system contour error and improve IPD measurement accuracy.Experiment results based on X-Y platform with a typical circular contour show that the contour error has decreased by 30.77%,32.65% and 30.43% in RMS,maximum and average values,which effectively accelerates the dynamic response of the servo axis and improves the contour processing accuracy of the system using nonlinear PID cross-coupling control structure compared with the variable gain CCC structure.Finally,the software and hardware debugging of the measuring equipment control system was carried out.According to the dynamic and static performance requirements of the control system,the PID parameters and the speed/acceleration feedforward parameters of the servo motors are adjusted to ensure the control accuracy of the system.In order to improve the positioning accuracy of the system,the laser interferometer is used to detect the position error of each servo axis of the measuring equipment,a compensation method based on the "error table" is designed,and the positioning error compensation experiment is carried out.Experiments show that: X,Y,Z axis positioning accuracy is less than 0.04 mm,repeat positioning accuracy is less than 0.02mm;A axis positioning accuracy is less than 1′,repeat positioning accuracy is less than 0.6′;C axis positioning accuracy is less than 2′,repeat positioning accuracy less than 1.2’;the designed control system meets the requirement of precision design index. |
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