Positioning and Accuracy Analysis of Tianwen-1 Mars Rover Based on Same-Beam VLBI Measurement

  Objectives  Aiming at the problem of rover positioning in Chinese Mars exploration mission Tianwen-1, the related research and accuracy analysis have been carried out.

  Methods  According to the existing measurement and control system and considering that the rover has no ground ranging data, we proposed a method to locate the rover using same-beam very long baseline interferometry (SBI) data of the orbiter and rover. Since it is not possible to determine the ambiguity using SBI and ranging data while determining the orbit and positioning the rover at the same time, the proposed method which only uses SBI data for the rover positioning under the fixed orbital situation is analyzed.

  Results  The results show that the rover positioning error decreases with the increase of orbital accuracy. If the orbital accuracy is increased from 1 km to 100 m or 10 m, the rover positioning error using 6-hour SBI data can be reduced to hundreds of meters.

  Conclusions  More data can further reduce the positioning error and the positioning accuracy can be improved obviously with an elevation constraint.