Performance sensitivity of helicopter global and local optimal harmonic vibration controller.

*(English)*Zbl 1165.93308Summary: A comparison of local and global controllers is conducted for helicopter vibration reduction using actively controlled single/dual trailing-edge flaps. It is found that for high-speed flight conditions, both local and global controllers perform equally well. However, for low-speed flight, local controller gives a marginally better optimal solution compared to the global controller but at the cost of much greater computation time. An objective function containing the hub vibratory loads is minimized using the global controller. The control effort is weighted such that each flap is used to complete authority. A reduction of 73% and 75% in hub vibration is obtained at high-speed flight using single and dual flap configurations, respectively. At low-speed flight, single and dual flap configurations gave 52% and 63% reduction in vibration, respectively. Numerical studies using an aeroelastic simulation show that the vibration control system performs well up to \(\pm 5\) degrees error in flap phasing from optimal phase. The control law is insensitive to small perturbations (up to \(\pm 0.3\) deg) in the optimal flap harmonics and is fairly insensitive to stiffness and mass changes of the rotor blade as well as noise in the measured hub load data. Dual flap configuration was found to be more insensitive to errors in optimal flap control harmonics than single flap configuration.

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\textit{S. R. Viswamurthy} and \textit{R. Ganguli}, Comput. Math. Appl. 56, No. 10, 2468--2480 (2008; Zbl 1165.93308)

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