Methods of trajectory control of observation in air-based angle-measuring two-position radio monitoring systems. Part 2. Gradient methods
Authors: Verba V.S. , Merkulov V.I. , Chernov V.S. 
Published: November 2021

To control and monitor the electronic situation, air-based passive angle-measuring two-position systems radio monitoring can be used. A feature of the functioning of these systems is the fact that the accuracy of the estimation of the coordinates and parameters of the movement of radio emission sources (RES) depends largely on the configuration of the relative position of the receiving positions placed on the aircraft and the RES. Therefore, the problem of optimization the relative position of aircraft and AIR is relevant, and various gradient methods of trajectory control of observation have been developed to solve this problem. Usually in two-position systems one aircraft is the leader, and the second one provides information support. To implement gradient methods, the control of the information support aircraft is organized in such a way that the error of determining the position of the RES at any time is minimal. To fulfill this condition, the information support aircraft must move along a special trajectory, the parameters of which are determined by an algorithm based on gradient optimization methods. The dependence of the error in determining the position of the RES on the relative position of the aircraft and RES and the direction finding accuracy is used as an target function. The article provides information on the gradient methods of trajectory control in the angle-measuring two-position systems, which provide the fastest increase in the accuracy of estimating the coordinates and parameters of the motion of RES for various conditions of practical application in a volume sufficient to obtain a general idea of the ways to solve the problem of trajectory control of an aircraft in the angle-measuring two-position systems. For the trajectory control of the information support aircraft, the gradient method of course guidance was first developed. This method is a relatively simple iterative procedure based on information about the gradient of the quality functional. The disadvantage of this method is the low accuracy of determining the coordinates of the RES at the initial moment of time with a relatively small distance of the aircraft from each other at the beginning of the guidance, as well as in the greater fuel consumption on board the information support aircraft compared to the leading aircraft during the guidance process. To eliminate this disadvantage, trajectory control methods have been developed for two situations of practical application of anglemeasuring two-position systems. The first situation occurs when there is a two-stage procedure of target guidance. At the stage of long-range guidance, aircraft are brought to the RES detection zone by commands from the control center. At the second (short-range) stage of guidance, after the detection of the RES signals by the direction finders of the aircraft, the process of self-homing of leading aircraft to the RES begins and information support for the task solution by other aircraft. For this situation, a modified gradient method of trajectory control of information support aircraft has been developed. The second method to eliminate the disadvantage of the gradient method involves the rejection of the distribution functions of guidance and information support between the aircrafts. It can be used in a situation where the guidance of the aircraft on the RES begins from the moment it is detected on aircraft board. At the same time, the solution of the problem of minimizing the RES location errors is assigned not to one information support aircraft, but simultaneously to both aircrafts. However, mentioned methods do not take into account possible restrictions on the movement of the information support aircraft when forming the control parameters of this aircraft, associated with the presence of dangerous zones for flights, as a result, the flight safety of this aircraft is not guaranteed. For flights in the presence of dangerous zones, the method of trajectory control of the aircraft on the course and the corresponding algorithm of trajectory control of information support aircraft based on the method of gradient projection of the target function has been developed. However, this technique does not guarantee that the flight of the information support aircraft will be carried out exactly on the border of the dangerous zone. In order to eliminate this disadvantage, the method of trajectory control based on the gradient projection method was upgraded using the algorithm of the route guidance method of the aircraft.