Fig. 1. Composition of point light source turntable system. (a) Schematic of sun sensor; (b) coordinate system definition and structural diagram; (c) mirror reflectivity

Fig. 2. Fitting of calculated solar vector value and theoretical value with first group of data when μ₀, ν₀, and ω₀ are 0, and α₀ and β₀ are initial values. (a) SU

Fig. 3. Fitting of calculated solar vector value and theoretical value with the second group of data when μ₀, ν₀, and ω₀ are 0, and α₀ and β₀ are initial values. (a) SU

Fig. 4. Comparison of test results of elevation angle of turntable. (a) Angle measured by pitch encoder; (b) angle of pitch encoder calculated by calibrated model; (c) comparison of calculation and measurement values

Fig. 5. Comparison of azimuth measurement results of turntable. (a) Angle measured by azimuth encoder; (b) angle of azimuth encoder calculated by calibrated model; (c) comparison of calculation and measurement values

Fig. 6. Centroid pixels collected by camera at different sun positions and at different times. (a) Image centroid coordinates when sun observer is aligned with sun; (b) centroid coordinates of sun obtained by camera after calibration; (c) difference of pre-calibration and post-calibration pixels