Operational Safety Control for Unmanned Aerial Vehicles Using Modular Barrier Functions

Keep-in operational envelopes are essential to maintain the safety of autonomous systems such as unmanned aerial vehicles (UAVs). System constraints, including actuator saturation, dramatically affect the maneuverability of the system inside the operational envelope. Moreover, sate-of-the-art safety control depends heavily on the specifications of the operational envelope. Thus, this paper presents a modular technique to transform safety envelopes into low and high barriers along position and velocity axes. The proposed safety envelope guarantees safety and asymptotic stability simultaneously. The closed-form solution of the safety rule is obtained in the form of allowable high and low control limits, which are calculated adaptively. Thus, the design scalability is improved, and control tuning effort is minimized. Furthermore, it is shown that the proposed safety design seamlessly integrates with an existing motion control algorithm with minimum modification. Numerical simulations are conducted to verify the effectiveness of the proposed algorithm on a quadrotor drone.