US 12,265,407 B2
Method for correcting pointing errors of biaxial rotation system based on spherical cap function
Yi Zheng, Jiangsu (CN); ying Li, Jiangsu (CN); Zhaoxiang Wu, Jiangsu (CN); Bin Liang, Jiangsu (CN); and Lifeng Tang, Jiangsu (CN)
Assigned to NANJING INSTITUTE OF ASTRONOMICAL OPTICS & TECHNOLOGY, NATIONAL ASTRONOMICAL OBSERVATORIES, CAS, Jiangsu (CN)
Appl. No. 17/775,472
Filed by Nanjing Institute of Astronomical Optics & Technology, National Astronomical Observatories, CAS, Jiangsu (CN)
PCT Filed Sep. 14, 2020, PCT No. PCT/CN2020/115069
§ 371(c)(1), (2) Date May 9, 2022,
PCT Pub. No. WO2021/063170, PCT Pub. Date Apr. 8, 2021.
Claims priority of application No. 201910938906.0 (CN), filed on Sep. 30, 2019.
Prior Publication US 2022/0404844 A1, Dec. 22, 2022
Int. Cl. G01S 3/786 (2006.01); G05D 3/20 (2006.01); G06F 17/15 (2006.01)
CPC G05D 3/20 (2013.01) [G01S 3/7867 (2013.01); G06F 17/15 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for correcting pointing errors of a biaxial rotation system based on a spherical cap function, wherein the biaxial rotation system includes an azimuth rotation axis and a height rotation axis and a pointing control system controlling motions of the azimuth rotation axis and the pointing control system, the method comprising:
collecting errors, comprising measuring and obtaining an error distribution;
fitting an error model, comprising selecting an orthogonal spherical cap function for the obtained error distribution and performing fitting to calculate an error fitting coefficient; the orthogonal spherical cap function model comprising a hemispheric harmonic function (HSH), a Zernike spherical cap function (ZSF) and a longitudinal spherical cap function (LSF);
controlling and compensating the error, comprising putting the error model and the related fitting coefficient into the pointing control system to controlling motions of the azimuth rotation axis and the pointing control system and compensating the pointing errors of the biaxial rotation system.