Arm Angle Adjustment Mechanism for Avoiding Vortex Ring State (VRS) in Descent Maneuver of Quadrotor

In recent years, the rapid evolution of multirotor technology has driven innovation in aerial platforms tailored for diverse applications, ranging from imaging and agriculture to search and rescue missions. This article introduces a heuristic quadrotor design capable of shape-shifting through adjustable arm angles, thereby modulating its flight dynamics to improve maneuverability and facilitate safe, fast descent maneuvers. Additionally, a sophisticated control strategy termed the adaptive gain-scheduled Proportional-Integral-Derivative (PID) controller is proposed, meticulously engineered to enhance the stability and command-following of the quadrotor. This methodology integrates traditional PID control principles with dynamic parameter tuning tailored to various tilt arm configurations. The capability of rotating the motor axis highlights how utilizing a tilt arm quadrotor can expedite descent while mitigating the risk of entering the Vortex Ring State (VRS), ensuring safer and more efficient operation. Through extensive simulations and validation, we demonstrate the efficacy of our approach in achieving stability, responsiveness, and control precision in tilt arm quadrotor systems. This research signifies a significant advancement in descending maneuvers by designing an algorithm to control descent speed through adjustments to the arm angle.