Stability and Control of Helicopters in Steep Approaches. Volume 4. Derivatives and Transfer Functions for the AH-56A Compound Helicopter and Data on Low-Altitude Turbulence Representation

1971 ◽  
Author(s):  
Julian Wolkovitch ◽  
John A. Hoffman
Keyword(s):  
Transfer Functions ◽  
Stability And Control ◽  
Low Altitude ◽  
Compound Helicopter ◽  
And Control

Quantitative Analysis of Singularities for Fractional Order Systems

2015 ◽  
Author(s):  
Yan Li ◽  
YangQuan Chen
Keyword(s):  
Fractional Order ◽  
Transfer Functions ◽  
Intrinsic Property ◽  
Time Domain Analysis ◽  
Order System ◽  
Fractional Order Systems ◽  
Stability And Control ◽  
Practical Strategy ◽  
The Time Domain ◽  
And Control

The singularity is an intrinsic property for various fractional order systems. This paper focuses on the time domain analysis of typical “non-proper” fractional order transfer functions, which plays the crucial role in the implementation, stability and control of fractional order systems. To this end, the fractional order system is converted into a weak singularity integro-differential equation, where the non-proper property can be clearly presented. A practical strategy is shown to find out the poles in the first Riemann plane, which is especially applicable to small commensurate order problems. The distributed order and order sensitivity problems are discussed as well. A number of examples are illustrated by using some reliable fractional order numerical methods.

Aircraft flight characteristics in conditions of windshear and icing

2007 ◽  
Vol 111 (1115) ◽  
pp. 41-49 ◽  
Author(s):  
Yihua Cao ◽  
Kungang Yuan
Keyword(s):  
Flight Control ◽  
Inverse Dynamics ◽  
Weather Conditions ◽  
Ice Accretion ◽  
Control Logic ◽  
Stability And Control ◽  
Aircraft Flight ◽  
Low Altitude ◽  
Flight Dynamics Model ◽  
And Control

Abstract Complex weather conditions, especially windshear and icing encounter, have severe effects on aircraft flight safety. The effect of low-altitude windshear and ice accretion on aircraft performance and control has been studied in this paper. With the employment of a windshear model and nonlinear inverse dynamics (NID) method, a low-altitude windshear penetration flight control law is designed. The effect of ice accretion was modeled on the stability and control of an aircraft. Several icing parameters are imported to the small disturbance flight dynamics model to calculate the change of performance, stability and control derivatives between clean and iced aircraft. These derivatives were used to calculate the elevator, the aileron and the rudder step responses to investigate the icing effect. The simulation results indicate that the NID control logic works effectively in the trajectory control of the aircraft during the penetration of windshear. The method used to study the effect of ice accretion on aircraft is valid and it can provide data for real-time calculation for icing encounter.

Nonlinear analysis of stability and control for an F-16 configuration

1997 ◽  
Author(s):  
Zhongjun Wang ◽  
Zhidai He ◽  
C. Lan ◽  
Zhongjun Wang ◽  
Zhidai He ◽  
...  
Keyword(s):  
Nonlinear Analysis ◽  
Stability And Control ◽  
Analysis Of Stability ◽  
And Control

Designing Stability and Control Augmentation Systems Using Genetic Algorithms

2009 ◽  
Author(s):  
Ashraf Omran ◽  
Mohamed Elshabasy ◽  
Wael Mokhtar ◽  
Brett Newman ◽  
Mohamed Gharib
Keyword(s):  
Genetic Algorithms ◽  
Stability And Control ◽  
And Control

scholarly journals Method for designing multi-input system identification signals using a compact time-frequency representation

2021 ◽  
Author(s):  
Mathias Stefan Roeser ◽  
Nicolas Fezans
Keyword(s):  
System Identification ◽  
Design Method ◽  
Flight Test ◽  
Compact Representation ◽  
Time Frequency ◽  
Stability And Control ◽  
Frequency Representation ◽  
Aerodynamic Parameters ◽  
Definition Of ◽  
And Control

AbstractA flight test campaign for system identification is a costly and time-consuming task. Models derived from wind tunnel experiments and CFD calculations must be validated and/or updated with flight data to match the real aircraft stability and control characteristics. Classical maneuvers for system identification are mostly one-surface-at-a-time inputs and need to be performed several times at each flight condition. Various methods for defining very rich multi-axis maneuvers, for instance based on multisine/sum of sines signals, already exist. A new design method based on the wavelet transform allowing the definition of multi-axis inputs in the time-frequency domain has been developed. The compact representation chosen allows the user to define fairly complex maneuvers with very few parameters. This method is demonstrated using simulated flight test data from a high-quality Airbus A320 dynamic model. System identification is then performed with this data, and the results show that aerodynamic parameters can still be accurately estimated from these fairly simple multi-axis maneuvers.

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