Simulation and results on real-time positioning of ChangʹE-3 rover with the same-beam VLBI observations

The real-time and high precision positioning of the lunar rover vehicle is an important step for lunar exploration and science. SBI (same-beam interferometry) is the differential very long baseline interferometry (VLBI) technology, which can be used in lunar exploration with its high precision and stability. In this paper, the relative positioning model of the lunar rover vehicle (LRV) to lunar module (LM) based on the SBI and extended kalman filtering (EKF) is developed and presented. Using the current Chinese VLBI network and the planed ChangʹE-3, SBI observation data with an attainable precision of picoseconds and a sample interval of 4 s are simulated. The LRVʹs relative position to the LM is then estimated by the least squares adjustment, EKF and an adaptive EKF, respectively. Results show that the Adaptive EKF performs the best real-time solutions with the accuracy of 1.86 m in X direction, 0.33 m in Y direction and 0.09 m in Z direction, which can provide a good reference for real-time positioning of planed ChangʹE-3 rover.