Autonomous Take-off Control System with Stall Prevention for Fixed-Wing UAVs Utilizing LQR Method

During the launch sequence of a Fixed-wing Unmanned Aerial Vehicle (UAV), the process encompasses several phases: taxiing on the ground, ascending, and transitioning to steady flight. The initiation of take-off is contingent upon a control mechanism's ability to regulate the UAV's operations. The control system must keep the Angle of Attack (AoA) within specific limits during ascent to avert a reduction in lift, known as a stall. This study's autonomous take-off methodology incorporates the Linear Quadratic Regulator (LQR) approach and fuzzy logic principles. The LQR's calculated gain serves as the foundational input for the UAV's system, subsequently translated into Pulse Width Modulation (PWM) signals. These signals are responsible for adjusting the brushless motor's rotation speed and the servo's angle of deflection. The UAV is programmed to sustain the AoA at a pivotal threshold when operating autonomously. The desired pitch angle is determined through the interplay between the lift generated and the UAV's critical AoA. Findings from this study demonstrate the UAV's capability to preserve the AoA at this essential threshold.