1.2m望远镜跟踪架结构设计与分析
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摘要
为提高望远镜系统的响应速度,增加伺服系统的控制带宽,望远镜的结构刚度需要得到有效保证。首先,根据望远镜力的传递路径,选择双排角接触球轴承作为承载元件,设计了适用于1.2m望远镜的地平式结构。然后,在ANSYS中使用Matrix27单元模拟轴承结构,并建立了望远镜的详细有限元模型,以预测该系统的性能。最后,通过有限元分析、模态测试以及扫频实验获得系统的性能,并借助于流场分析,研究了风载对望远镜性能的影响。仿真结果表明,系统的一阶谐振频率可达21.3Hz,能够满足前期设计要求;模态试验结果显示,系统的一阶谐振频率约为18.5Hz;扫频实验结果显示,方位轴一阶谐振频率为20.8Hz,进而验证了前期分析的正确性。流场分析显示,风载对望远镜驱动电机的力矩输出能够产生影响,控制系统校正后扰动力矩大小约为3.4Nm RMS。仿真和实验结果证明1.2m望远镜轴系的设计方案合理,测试方法可行,能够达到预期效果。
In order to improve the response speed of the telescope system and increase the control bandwidth of the servo system,the structural rigidity of the telescope needed to be effectively ensured. Firstly,double rows of angular contact ball bearings based on the transmission path of telescope force was selected and a ground-based structure of1.2 m telescope was designed. Then the detailed finite element model of the telescope was built by using matrix 27 element of ANSYS to simulate the bearings in order to predict the performance of the system. Finally,the performance of the system was obtained through finite element analysis,modal testing and frequency sweep experiment. Moreover,the influence of wind load on telescope was still studied. The simulation results showed that the first-order resonant frequency of the system can reach 21.3 Hz,which can meet the requirements of the previous design. The modal testing showed that the first-order resonant frequency of the system is about 18.5 Hz,which verified the ANSYS analysis. The flow field analysis showed that wind load can affect the torque output of the drive motor;and the disturbance torque after correction by the control system was about 3.4 Nm rms. The simulation and experimental results showed that the design of the 1.2 m telescope shaft system was reasonable and could meet the expected effect.
In order to improve the response speed of the telescope system and increase the control bandwidth of the servo system,the structural rigidity of the telescope needed to be effectively ensured. Firstly,double rows of angular contact ball bearings based on the transmission path of telescope force was selected and a ground-based structure of1.2 m telescope was designed. Then the detailed finite element model of the telescope was built by using matrix 27 element of ANSYS to simulate the bearings in order to predict the performance of the system. Finally,the performance of the system was obtained through finite element analysis,modal testing and frequency sweep experiment. Moreover,the influence of wind load on telescope was still studied. The simulation results showed that the first-order resonant frequency of the system can reach 21.3 Hz,which can meet the requirements of the previous design. The modal testing showed that the first-order resonant frequency of the system is about 18.5 Hz,which verified the ANSYS analysis. The flow field analysis showed that wind load can affect the torque output of the drive motor;and the disturbance torque after correction by the control system was about 3.4 Nm rms. The simulation and experimental results showed that the design of the 1.2 m telescope shaft system was reasonable and could meet the expected effect.
引文
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[2] Ezaki Y,Kato A,Hattori T,et al. Overview of key technologies for TMT telescope structure[C].SPIE Astronomical Telescopes+Instrumentation. International Society for Optics and Photonics,2016.
[3] Gray P,Ciattaglia E,Dupuy C,et al. E-ELT assembly,integration,and technical commissioning plans[C].SPIE Astronomical Telescopes+Instrumentation. International Society for Optics and Photonics,2016.
[4]赵宏超,张景旭,杨飞,等.30m望远镜三镜系统运动学接口设计及分析[J].光学学报,2015,35(03):128-135.
[5]王槐,代霜,吴小霞.600mm薄镜面主动光学望远镜轴系结构设计[J].红外与激光工程,2015,44(4):1260-1266.
[6]王显军.大型望远镜测角系统误差的修正[J].光学精密工程,2015,23(9):2446-2451.
[7]苏燕芹,张景旭,陈宝刚,等.谐波分析方法在提高精密转台回转精度中的应用[J].红外与激光工程,2014,43(1):274-278.
[8] Patel N A,Nishioka H,Huang C W L. Control and monitoring software for the Greenland Telescope[C].SPIE Astronomical Telescopes+Instrumentation. International Society for Optics and Photonics,2016.
[9] Guerra J C,Brusa G,Christou J,et al. The LBT experience of adaptive secondary mirror operations for routine seeing and diffraction limited science operations[C].SPIE,2013(8860):141-149.
[10]苏燕芹,张景旭,陈宝刚,等.TMT三镜系统Rotator组件轴承设计[J].红外与激光工程,2013,42(12):3289-3294.
[11]王槐,代霜,张景旭.大型地平式望远镜的方位轴系支撑结构[J].光学精密工程,2012,20(07):1509-1516.
[12]范磊,张景旭,邵亮,等.采用液压Whiffle tree的大口径主镜轴向支撑[J].红外与激光工程,2013,42(08):2126-2131.
[13] McPherson AM,Craig SC,Sutherland W. Project VISTA:a review of its progress and overview of the current program[J].Proceeding of SPIE International Society for Optics and Photonics,2003,15(1):82-93.