Development of a linear control system for a throttle of a UAV propeller-motor group

Orientation and positioning control of an unmanned aerial vehicle (UAV) vertical take-off and landing multi-rotor type in space is inextricably linked with the formation of a motion control vector, consisting of a combination of thrusts and aerodynamic moments of each propeller-motor group. The accuracy and speed of formation of the motion control vector greatly affect the positioning and orientation errors of the UAV. Most works devoted to the synthesis of UAV control systems use a motion control vector without taking into account the dynamics of the rotor-motor groups, which in some cases forces the control system to reduce its performance. The performance of the UAV control system can be increased by increasing the speed of generation of the thrust of the propeller-motor groups, for which a system for controlling the thrust of the propeller-motor group has been proposed. The propeller-motor group in its composition has a nonlinear internal connection in the aerodynamic torque and an output signal – thrust, that nonlinearly depends on the square of the propeller rotation speed. Typically, the propeller group is controlled like an electric motor – the internal coupling of the aerodynamic torque is considered an external disturbance, and the thrust is controlled by changing the speed of rotation of the propeller which is calculated based on the required motion control vector. It is proposed to consider thrust and aerodynamic torque an integral part of the propeller-engine group, for which to build a linear thrust control system. For this purpose, we carried out feedback linearization of the rotor-motor group system, connecting the voltage supplied to the motors with the motion control vector, which is the output value. The linearization process is divided into two stages: at the first stage feedback linearization is performed for an electric motor with internal nonlinear coupling by aerodynamic torque; at the second stage, linearization is performed with feedback on the output obtained at the first stage of the system with a nonlinear output signal – thrust. In accordance with the principles of subordinate control, motor control is formed for linearized feedback of the propeller group. Simulation was completed. An important issue when using feedback linearization is the preservation of the quality characteristics of the control system in the event of a mismatch between the parameters of the object and the model, the parameters of which are used to calculate the linearizing feedback. In this work, modeling was carried out with a discrepancy of some parameters up to 50%.