Analytical Design and Experimental Verification of Geofencing Control for Aerial Applications

Keep-in operational envelopes are essential to maintain the safety of unmanned aerial vehicles (UAVs). System properties and constraints, including underactuated dynamics and actuator saturation, dramatically affect the system's maneuverability inside the operational envelope. Moreover, sate-of-the-art safety control depends heavily on the specifications of the operational envelope. Thus, this work focuses on creating a scalable technique to transform safety envelopes into input-constrained barriers along each axis of motion. Then, it is shown that the proposed class of operational envelopes simultaneously guarantees safety and asymptotic stability. The closed-form solution for the safety rule is derived as allowable low and high bounds of the control command, which are calculated in real-time. Furthermore, it is shown that the proposed safety design seamlessly integrates with an existing motion control algorithm with minimum modification. The super-twisting control (STC) is used to handle the nonlinear complexity of the UAV and parametric uncertainties and achieve a desirable robust behavior for trajectory and attitude control. The control calibration and tuning are carried out on a state-of-the-art experimental system. The experimental results verify the effectiveness of the proposed safety control.