Comment on 'Integrated development of the equations of motion for elastic hypersonic flight vehicles'

1996 ◽  
Vol 19 (5) ◽  
pp. 1198-1199
Author(s):  
Nivritti Vithoba Kadam
Keyword(s):  
Equations Of Motion ◽  
Integrated Development ◽  
Hypersonic Flight ◽  
Flight Vehicles

scholarly journals Disturbance observer-based control for nonlinear systems subject to mismatched disturbances with application to hypersonic flight vehicles

2017 ◽  
Vol 14 (2) ◽  
pp. 172988141769914 ◽  
Author(s):  
Yunling Li ◽  
Ming Zeng ◽  
Hao An ◽  
Changhong Wang
Keyword(s):  
Nonlinear Systems ◽  
Disturbance Observer ◽  
State Of The Art ◽  
Output Channel ◽  
Tracking Problem ◽  
Gain Matrix ◽  
Hypersonic Flight ◽  
Flight Vehicles ◽  
Nominal Performance ◽  
Mismatched Disturbances

For a class of multi-input multi-output nonlinear systems, a disturbance observer-based control is proposed to solve the tracking problem in the presence of mismatched disturbances. By designing a novel compensation gain matrix, the disturbances can be removed from the output channel completely as well as retaining the nominal performance. Compared with the state of the art, the gain matrix reduces to be constant; therefore, the complexity of the controller is simplified greatly. This method is applied to the control of hypersonic flight vehicles to demonstrate its effectiveness.

scholarly journals Stability Characteristics of Wing Span and Sweep Morphing for Small Unmanned Air Vehicle: A Mathematical Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Hafiz Muhammad Umer ◽  
Adnan Maqsood ◽  
Rizwan Riaz ◽  
Shuaib Salamat
Keyword(s):  
Equations Of Motion ◽  
Small Scale ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Flight Stability ◽  
Longitudinal Modes ◽  
Flight Vehicles ◽  
Stability Derivatives ◽  
Wing Sweep ◽  
Wing Morphing

Morphing aircraft are the flight vehicles that can reconfigure their shape during the flight in order to achieve superior flight performance. However, this promising technology poses cross-disciplinary challenges that encourage widespread design possibilities. This research aims to investigate the flight dynamic characteristics of various morphed wing configurations that can be incorporated in small-scale UAVs. The objective of this study was to analyze the effects of in-flight wing sweep and wingspan morphing on aerodynamic and flight stability characteristics. Longitudinal, lateral, and directional characteristics were evaluated using linearized equations of motion. An open-source code based on Vortex Lattice Method (VLM) assuming quasi-steady flow was used for this purpose. Trim points were identified for a range of angles of attack in prestall regime. The aerodynamic coefficients and flight stability derivatives were compared for the aforementioned morphing schemes with a fixed-wing counterpart. The results indicated that wingspan morphing is better than wing sweep morphing to harness better aerodynamic advantages with favorable flight stability characteristics. However, extension in wingspan beyond certain limits jeopardizes the advantages. Dynamically, wingspan and sweep morphing schemes behave in an exactly opposite way for longitudinal modes, whereas lateral-directional dynamics act in the same fashion for both morphing schemes. The current study provided a baseline to explore the advanced flight dynamic aspects of employed wing morphing schemes.

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