Relative navigation method for orbital objects

Now the problem of space debris is relevant, because the amount of artificial debris in near-Earth space makes further space flights dangerous. There are various programs for the destruction of such debris, but there are many scientific and technological problems for their implementation. One of such problems is tracking a passive orbital object and predicting its motion in the event of loss of contact with it from another device. The peculiarity of such a problem is that only relative measurements are possible for a passive object, and the initial model of its motion is a priori incomplete. In this regard, the article presents the results of solving the navigation problem for two orbital objects, one of which is active, the second is passive. The first object is equipped with a navigation system that includes an orientation determination system, a computer, a GPS signal receiver, and a radio-technical tracking system. The task is to develop algorithms for determining the current coordinates and speed based on available measurements from GPS for the first object and relative measurements of the distance between the objects and the direction of the line of sight to the passive object from the tracking system for the second object. In both cases, a 9-dimensional extended Kalman filter in discrete form is used. Correction is carried out according to a closed-loop scheme. An additional component of the filter state vector is assigned to the correction to the model acceleration. The choice of such a filter among other correction schemes is justified by modeling. The need for special tuning of the selected filter for specific operating conditions is identified. The algorithm for solving the problem is described and specific formulas for tuning the extended filter are given, namely for selecting the input noise dispersion matrices. Modeling the operation of filters for specific GPS error models and the tracking system demonstrates an improvement in the accuracy of determining coordinates relative to the GPS accuracy for an active object by up to 10 times, for a passive object by 3‒4 times. This property is useful in autonomous navigation mode, when certain external measurements are temporarily absent. Aspects of the practical implementation of algorithms in the onboard software are analyzed.