Flight and multicopter algorithm in the absence of GPS signals

The problem of developing an algorithm for automatic return of the multicopter to the place of takeoff in the absence of GPS signals is considered. 
         An algorithm for controlling the flight of a multicopter based on the information of a magnetometer, air velocity sensor, barometric altimeter, which allows to perform the task in the absence of external perturbations. 
The efficiency and effectiveness of the algorithm are confirmed by the results of modeling using Mission Planner software and the results of experimental tests.