An Autonomous Recovery System for a Rotorcraft UAV Operating in rough Seas

Heterogeneous unmanned systems consisting of unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs) have great application potential in marine environments. At present, the fully autonomous recovery of UAVs is a key problem that restricts any significant application of a heterogeneous unmanned system. This paper presents a novel fully autonomous recovery system, covering the entire process of recovery of small fixed-wing UAVs on mobile platforms at sea. We describe methods or solutions for the key problems encountered by the current system, including active modeling of the UAV–USV heterogeneous platform motion model, accurate estimation of the highly dynamic relative motion of the heterogeneous platform, dynamic analysis of the arresting cable system, and compliance control of the manipulator recovery system. Based on these methods, a physical simulation platform for the fully autonomous recovery system, including an actively adjustable arresting cable, manipulator compliance recovery system, and other subsystems, is developed and verified through experiments. The experiments show that the system proposed in this study can achieve full autonomous recovery of a small ship-based fixed-wing UAV with a high success rate in a short period. This system is the foundation for practical applications of UAV–USV heterogeneous unmanned systems in the marine environment.

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Improved pilot training via bifurcation analysis and robust control for aircraft loss of control problems

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019846434 ◽

2019 ◽

Vol 233 (14) ◽

pp. 5414-5427

Author(s):

G Rohith ◽

Nandan K Sinha

Keyword(s):

Robust Control ◽

Pilot Training ◽

Training Procedure ◽

Structural Constraints ◽

Loss Of Control ◽

Recovery System ◽

Recovery Strategies ◽

Autonomous Recovery ◽

Training Methodologies

Aircraft loss of control is one of the largest contributors to fatal accidents in the aviation environment. The unprecedented change in aircraft dynamics due to loss of control onset and the associated structural constraints make loss of control prevention and/or recovery a challenging task. State-of-the-art autopilots are generally designed for nominal aircraft operations and disengage under off-nominal conditions, hence cannot be viewed as a safety solution during loss of control onsets. Herein lies the importance of providing training to pilots so as to equip themselves to rescue aircraft from loss of control events. Current pilot training methodologies have significant limitations when it comes to loss of control prevention and recovery strategies. In this context, a simulator for improved pilot training based on bifurcation and continuation techniques is presented in the paper. Augmenting these techniques with the current pilot training procedure can significantly improve the quality of training. This methodology can help pilots to distinguish various loss of control scenarios and aid them in taking appropriate recovery decisions intuitively. Meanwhile, a robust control-based loss of control handling module is also presented for developing non-intuitive strategies for loss of control prevention and recovery. This module can simulate adequate control profiles that the pilot can follow to get in and out of various loss of control scenarios. Moreover, it can be used as pilot activated recovery system in case of pilot disorientation and as a fully autonomous recovery system for much complex scenarios. The simulator is developed in MATLAB/SIMULINK platform and is shown to realize diverse loss of control events like spiral, spin, etc., and subsequent recovery from the same.

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