Flying in Harsh Environments: Anti-Rain Quantification System and Control Strategy

This article presents an anti-rain quantification system and control strategy for unmanned aerial vehicles (UAVs). Rain disturbance effect on a platform is quantitatively analyzed first based on the characteristics of raindrops, contributing to the establishment of rain disturbance model. Thereafter, a refined UAV dynamics considering rain disturbance is provided for design of the control strategy. Subsequently, a rain speed observer (RSO) within the translational loop and a fixed-time sliding mode observer (SMO) within the rotational loop are developed to deal with force and torque disturbances caused by raindrops, respectively. Further, a quantification system containing a rainmaker is designed to mimic the natural rain like moderate rain, heavy rain, and violent rain at a specific rainfall rate. Based on the quantification system and a designed waterproof UAV, real flight experiments are carried out to demonstrate the effectiveness of the proposed system and control strategy under rain disturbance.