A sliding mode missile pitch autopilot synthesis for high angle of attack maneuvering

1998 ◽  
Vol 6 (3) ◽  
pp. 359-371 ◽  
Author(s):  
A. Thukral ◽  
M. Innocenti
Keyword(s):  
Sliding Mode ◽  
Angle Of Attack ◽  
High Angle ◽  
High Angle Of Attack

scholarly journals The choice of sliding surface for robust roll control: Better suppression of high angle of attack/sideslip perturbations

2018 ◽  
Vol 10 (4) ◽  
pp. 330-339 ◽  
Author(s):  
S Seyedtabaii ◽  
M Delavari
Keyword(s):  
Sliding Mode ◽  
Angle Of Attack ◽  
Sliding Surface ◽  
High Angle ◽  
High Angle Of Attack ◽  
Control Effort ◽  
Roll Control ◽  
Dynamic Uncertainty ◽  
Aerodynamic Parameters ◽  
And Control

The nominal aerodynamic parameters of aircraft are often approximate and aircraft may experience high value of angle of attack/sideslip perturbations during their manoeuvres. Preventing instability and air crash requires a robust controller capable of containing the dynamic uncertainty and the perturbations. In this respect, the problems of roll control in such a situation are studied and a better choice of sliding surface is proposed. Sliding mode control manages the uncertainty and adaptive fuzzy is employed to shape the transient response. As a result, a setup is formed which outperforms the basic controller both in terms of transient speed, response robustness and control effort. The strength of the method is more appreciated in case of high angle of attack/sideslip perturbed manoeuvres. This is proved theoretically and illustrated by simulations.

scholarly journals Leading Edge Blowing to Mimic and Enhance the Serration Effects for Aerofoil

2021 ◽  
Vol 11 (6) ◽  
pp. 2593
Author(s):  
Yasir Al-Okbi ◽  
Tze Pei Chong ◽  
Oksana Stalnov
Keyword(s):  
Boundary Layer ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Boundary Layer Separation ◽  
Shear Instability ◽  
Vortical Flow ◽  
High Angle ◽  
High Angle Of Attack ◽  
Layer Separation ◽  
Aerodynamic Performances

Leading edge serration is now a well-established and effective passive control device for the reduction of turbulence–leading edge interaction noise, and for the suppression of boundary layer separation at high angle of attack. It is envisaged that leading edge blowing could produce the same mechanisms as those produced by a serrated leading edge to enhance the aeroacoustics and aerodynamic performances of aerofoil. Aeroacoustically, injection of mass airflow from the leading edge (against the incoming turbulent flow) can be an effective mechanism to decrease the turbulence intensity, and/or alter the stagnation point. According to classical theory on the aerofoil leading edge noise, there is a potential for the leading edge blowing to reduce the level of turbulence–leading edge interaction noise radiation. Aerodynamically, after the mixing between the injected air and the incoming flow, a shear instability is likely to be triggered owing to the different flow directions. The resulting vortical flow will then propagate along the main flow direction across the aerofoil surface. These vortical flows generated indirectly owing to the leading edge blowing could also be effective to mitigate boundary layer separation at high angle of attack. The objectives of this paper are to validate these hypotheses, and combine the serration and blowing together on the leading edge to harvest further improvement on the aeroacoustics and aerodynamic performances. Results presented in this paper strongly indicate that leading edge blowing, which is an active flow control method, can indeed mimic and even enhance the bio-inspired leading edge serration effectively.

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