Fuzzy Switching Cable Angle Feedback for Piloted Helicopter Slung Load Operations

In helicopter slung load operations, Cable Angle Feedback (CAF) is an effective, universal and cost-efficient approach of stabilizing load swing oscillation. However, CAF has the inherent conflict between command tracking performance and load swing damping, causing degraded handling quality and man-machine conflict problem. This paper presents a novel Fuzzy Switching Cable Angle Feedback (FS-CAF) approach to provide response characteristics in accord with pilot intention. A comprehensive nonlinear pilot-helicopter-slung-load system model is established and validated for CAF inherent conflict analysis, FS-CAF controller design and numerical flight simulation. The pilot intention fuzzy reasoning module is integrated in the FS-CAF controller to identify pilot intentions and change response characteristics in real-time, which is based on pilot's instant inputs, moving average inputs, and moving average load swing angle. The mechanism of FS-CAF controller is explained with a square input response example, while FS-CAF's capability is proved with a numerical piloted simulation example of lateral reposition task. Results show that FS-CAF can adjust system response characteristics between command tracking optimal and load swing damping optimal as the pilot expected. Further researches are recommended on pilot-in-the­ loop simulations for validation.