ROBUSTNESS ANALYSIS OF UAVS’ CONTROL SYSTEMS IN CASE OF MOTORS’ PARTIAL EFFICIENCY DEGRADATION

Abstract

Multirotor unmanned aerial vehicles (UAVs) are widely used in military tasks, as well as in various civilian areas such as agriculture, search and rescue operations, detection of fires in forests, traffic monitoring, etc. In real flights of the UAVs some unexpected situations may occur bringing to failures of various elements or devices of the UAV’s control system. This, in turn, can lead to the crush and complete collapse of the entire vehicle. First of all, it concerns the DC motors and propellers, which, as opposed to electronic devises and sensors, cannot be duplicated. A method of analysis of robustness of UAV’s control systems with respect to possible partial efficiency degradation of motors is proposed in the paper. The ultimately allowable efficiency degradation is determined by a simple graphical procedure on the complex plane of the Nyquist hodographs of the system’s separate channels. A numerical example illustrating the proposed method of analysis of the UAV’s control system robustness is given.