Performance Evaluation of the Image Total Station Astrogeodetic Positioning and Orientation System

The automatic astrogeodetic survey method based on total stations has emerged as the second near-Earth astrogeodetic technology after digital zenith cameras, offering high automation, precision, portability, and cost-effectiveness. The method employs an automatic scheduling algorithm for optimal observation sequencing and integrates Global Navigation Satellite System (GNSS) receiver synchronization with a precision oscillator to ensure time accuracy. This enables high-precision surveys with flexible field deployment, effectively replacing manual observations. Using the improved Image Total Station Astrogeodetic Positioning and Orientation System (ITSAPOS) as the measurement platform, we examined its operating principle, focusing on accuracy and reliability. Between 2022 and 2024, 76 experiments were conducted at 24 observation sites across plains, plateaus, hills, and mountains given varying seasonal conditions. ITSAPOS, the entire system weighing no more than 15 kg, consistently outperformed the Astrogeodetic Surveying System Based on Electronic Theodolites (ASSET), achieving standard deviations approximately half those of ASSET, thereby doubling precision. Longitude standard deviations ranged from 0.002 to 0.009 s and latitude standard deviations from 0.003″ to 0.110″ based on multinight observations at the same points. ITSAPOS also achieved stable closure errors for the meridian triangle within shorter times, reaching 0.01 s accuracy. Longitudinal external point accuracy was high, with a maximum difference of 0.012 s, average absolute difference of 0.007 s, and root mean square error (RMSE) of 0.009 s. For latitude, the maximum difference was 0.481″, with average absolute difference of 0.253″ and RMSE of 0.301″. In comparison, ASSET showed 0.053 s and 0.532″ for maximum differences, 0.018 s and 0.300″ for average differences, and 0.025 s and 0.334″ for RMSE. Overall, the automatic astrogeodetic survey method based on total station images provides autonomous measurement, portability, cost-effectiveness, and stable high precision. The method allows rapid adjustment of observation points and cycles, offering transformative advantages for remote deployments and continuous monitoring.