Arresting-Cable System For Robust Terminal Landing Of Reusable Rockets

Recent successful recovery techniques for rockets require that rockets maintain a vertical configuration with zero vertical and lateral velocities; otherwise, landings may fail. To relax this requirement, a new active-arresting system (inspired by the arresting gears used on aircraft carriers) is proposed herein to achieve a robust landing, even if the rocket deviates from the target position or has notable residual velocities and inclinations. The system consists of four deployable onboard hooks above the rocket's center of mass, an on-ground apparatus containing four arresting cables forming a square capture frame, and four buffer devices to actively catch and passively decelerate the landing rocket. To catch the rocket, the capture frame was controlled by servo motors via a simple proportional-derivative controller. After catching, the buffer devices generate decelerating forces to stop its motion. A flexible multibody model of the proposed system was built to evaluate its robust performance under various combinations of multiple uncertainties, such as noise measurement, time delay in the motor, initial conditions, and wind excitation. Using a quasi-Monte Carlo method, hundreds of deviated landing cases were generated and simulated. The results confirmed the robustness of the proposed system for achieving successful terminal landings.