Advanced helicopter flight control using two-degree-of-freedom H(infinity) optimization

1996 ◽  
Vol 19 (2) ◽  
pp. 461-468 ◽  
Author(s):  
D. J. Walker ◽  
I. Postlethwaite
Keyword(s):  
Flight Control ◽  
Degree Of Freedom ◽  
H Infinity ◽  
Helicopter Flight ◽  
Two Degree Of Freedom

The Two-Degree-of-Freedom Tuned-Mass Damper for Suppression of Single-Mode Vibration Under Random and Harmonic Excitation

2005 ◽  
Vol 128 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Lei Zuo ◽  
Samir A. Nayfeh
Keyword(s):  
Vibration Suppression ◽  
Single Mode ◽  
Tuned Mass Damper ◽  
Harmonic Excitation ◽  
Degree Of Freedom ◽  
Primary System ◽  
H Infinity ◽  
Mass Damper ◽  
Mode Vibration ◽  
Two Degree Of Freedom

Whenever a tuned-mass damper is attached to a primary system, motion of the absorber body in more than one degree of freedom (DOF) relative to the primary system can be used to attenuate vibration of the primary system. In this paper, we propose that more than one mode of vibration of an absorber body relative to a primary system be tuned to suppress single-mode vibration of a primary system. We cast the problem of optimization of the multi-degree-of-freedom connection between the absorber body and primary structure as a decentralized control problem and develop optimization algorithms based on the H2 and H-infinity norms to minimize the response to random and harmonic excitations, respectively. We find that a two-DOF absorber can attain better performance than the optimal SDOF absorber, even for the case where the rotary inertia of the absorber tends to zero. With properly chosen connection locations, the two-DOF absorber achieves better vibration suppression than two separate absorbers of optimized mass distribution. A two-DOF absorber with a negative damper in one of its two connections to the primary system yields significantly better performance than absorbers with only positive dampers.

Gain-scheduled flight control via two-degree-of-freedom H∞ optimization

1997 ◽  
Vol 211 (4) ◽  
pp. 263-268 ◽  
Author(s):  
D J Walker
Keyword(s):  
Flight Control ◽  
Equations Of Motion ◽  
Linear Interpolation ◽  
Gain Scheduling ◽  
Degree Of Freedom ◽  
Nonlinear Simulation ◽  
On Line ◽  
Air Speed ◽  
Gain Scheduled ◽  
Two Degree Of Freedom

The gain scheduling of a multivariable controller designed using H∞ optimization is presented. The design uses a two-degree-of-freedom H∞ optimization based on five linearizations taken from the non-linear rigid body equations of motion of a helicopter over the range 0–80 knots. The scheduled controller's parameters were computed on-line by linear interpolation with air speed of the design parameter sets. The resulting controller schedule was tested using a sophisticated and representative nonlinear simulation.

Robust Decoupled System Design of Uncertain Multivariable Feedback Systems

1999 ◽  
Vol 121 (4) ◽  
pp. 703-708
Author(s):  
Chih-Min Lin ◽  
Chen-Ling Ying
Keyword(s):  
Flight Control ◽  
Design Method ◽  
Degree Of Freedom ◽  
System Structure ◽  
Phase System ◽  
Model Matching ◽  
Feedback Systems ◽  
Design Algorithm ◽  
Multivariable Feedback ◽  
Two Degree Of Freedom

This paper presents a design algorithm of involving robust decoupled control of uncertain multivariable feedback systems. Two-degree-of-freedom system structure is adopted to handle the quantitative robustness and decoupled performance requirements. Quantitative feedback theory is applied for loop compensator design to achieve quantitative robustness. A decoupled model matching approach is employed for prefilter design to achieve input-output decoupling performance. Thus, the design method of two-degree-of-freedom compensators is proposed to achieve decoupled system control with quantitative robust performance. Since internal stability is satisfied, this design method performs appropriately for any stable or unstable, minimum or non-minimum phase system. The AFTI/F-16 flight control system is considered as the design example to illustrate the design algorithm.

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