Backstepping synthesis of the height control system of an unmanned aerial vehicle

Synthesis of the height control system for an unmanned aerial vehicle (UAV) with a soft wing, like a paraglider or a powered parachute, is considered in the article. An UAV is described, its scheme is shown, the forces and moments acting on it in the longitudinal plane are examined. A mathematical model of UAV motion is described in a body-axis coordinate system. Direct control is provided by the thrust motor. The thrust motor is mounted on the UAV so that the thrust is directed along the OX axis in the OXY plane. It is proposed to form the height control law on the basis of the thrust moment, which gives the advantage of stabilizing the angular velocity and the pitch angle. To synthesize the control and stabilization systems, the backstepping method is applied. According to this method, the task of developing a control law for the entire system is divided into a sequence of respective subtasks to lower-order subsystems. The algorithm of backstepping consists in making each integrator of the object stable by adding the feedback computed from this algorithm. The resulting control takes into account the nonlinearity of the object and depends on the entire state vector. The main advantages of the regulator obtained are: the system is stable within a broad range of input values; by varying the regulator coefficients, you can easily select the desired characteristics of control quality. The results of numerical simulation of UAV motion with the regulator obtained in the MATLAB environment are presented in the article.