Research On High-precision Drive Control System Of Aerospace Scanning Antenna Turntable Based On FPGA

As an important load on the satellite,the aerospace scanning antenna turntable is used for scanning imaging of the clouds or the ground,and its control precision directly affects the effect of scanning imaging.During scanning,large velocity fluctuation will cause blurred images,and large position tracking error will cause overlapping images.In order to improve the velocity accuracy,stationarity and position tracking accuracy during scanning,a high-precision driving control system for aerospace scanning antenna turntable is developed based on Field Programmable Gate Array(FPGA).The main work of this paper is as follows:Firstly,a mathematical model is built according to the structure of the aerospace scanning antenna turntable,and a traditional multi-closed-loop series compound control strategy is given.The classical frequency domain design method is used to correct the parameters of each loop and analyze the frequency response characteristics of each loop,which lays a theoretical foundation for high-precision control of the aerospace scanning antenna turntable.Secondly,the velocity measurement method for absolute encoder is studied,the least square method is applied to the velocity measurement,and a mechanism for dynamically adjusting the polynomial curve fitting order is proposed,which improves the speed measurement accuracy and realtime performance,and lays a foundation for high-accuracy control of velocity;the factors that cause periodic torque ripple in the aerospace scanning antenna turntable system are analyzed,and iterative learning control algorithm is used to suppress the torque ripple,reduce the velocity fluctuation at steady state,and design a transient state which improves the problem of larger velocity fluctuations caused by the iterative learning control algorithm when the velocity is abruptly changed or the load torque is disturbed;the feed-forward compensation algorithm based on the Stribeck model is used to compensate the friction torque disturbance to improve the accuracy of position tracking during the scanning startup stage.Then,the requirements analysis of the software system was performed,and the software architecture design,module division and design were completed.The key factors affecting the system bandwidth in the software system are analyzed,the two methods of serial-parallel timing planning between modules and dual PWM duty cycle update are used to increase the bandwidth of the control system to ensure the effectiveness of the compensation algorithm based on the advantages of FPGA parallel operation.Finally,an experimental platform is built to experimentally verify the system.The experimental results show that using the high-precision drive control system developed in this paper,the velocity fluctuation of the aerospace scanning antenna turntable is reduced to 1.2%,and the position tracking error is reduced to-0.05 ° ～ 0.175 °.