Drone Arrestment System

Abstract

Autonomous fixed wing drones have the potential to significantly improve maritime search and rescue operations by providing early situational awareness before rescue vessels depart. A central challenge for such systems is the reliable and autonomous retrieval of the drone after a completed mission. This thesis addresses that challenge by investigating and developing a mechanical drone arrestment system intended as a test platform for the Swedish Sea Rescue Society’s autonomous drone program. The work focuses on conceptual design, mechanical feasibility, and preliminary dimensioning of an arrestment system inspired by existing mid air recovery solutions. A capture concept based on a fixed hook mounted on the drone and a ground based string mechanism was selected and developed through iterative prototyping. Special attention was given to compensating for the roll motion typical of flying wing aircraft, as well as to handling the high mechanical loads generated during the arrestment event. A kinematic model based on a cylindrical coordinate system was developed to describe the position of the capture string relative to the approaching drone. This model was used to guide the mechanical layout of the system and to support a proof of concept control approach. Several energy absorption concepts were evaluated, and a constant force band spring was selected as a compact and mechanically simple solution for controlled deceleration. Physical prototypes and preliminary structural analyses were used to assess geometric feasibility and to identify critical design constraints. The outcome of the project is a mechanically viable arrestment system concept supported by analytical reasoning, CAD models, and prototype testing. Although full scale validation and closed loop control were outside the scope of the work, the results demonstrate that the proposed approach is feasible and provide a clear foundation for future experimental testing and system integration.