scholarly journals Distributed Modeling and Control of Large-Scale Highly Flexible Solar-Powered UAV

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Rui Wang ◽  
Zhou Zhou ◽  
Xiaoping Zhu ◽  
Xiaoping Xu
Keyword(s):  
Large Scale ◽  
Flight Dynamics ◽  
Beam Model ◽  
Modeling And Control ◽  
Distributed Modeling ◽  
Stability And Control ◽  
Short Period ◽  
Solar Powered ◽  
And Control ◽  
Flexible Model

The modeling, stability, and control characteristics of a large scale highly flexible solar-powered UAV with distributed all-span multielevons were presented. A geometrically nonlinear intrinsic beam model was introduced to establish the structural/flight dynamics coupled equation of motion (EOM); based on it, the explicit decoupled linear flight dynamics and structural dynamics EOM were derived through mean axis theory. Undeformed, deformed, and flexible models were compared through trimming and modal analysis. Since the deformation of wing has increased the UAV’s moment of inertia about the pitch axis, the frequency of short period mode has obviously decreased for the deformed model. The serious coupling between short period mode and 1st bending mode also significantly influences the roots of short period mode of flexible model. So flexible model was the only one which is able to accurately estimate the flight dynamics behaviors and was selected as the later control model. Forty distributed elevons and LQG/LTR controller were employed to control the attitude and suppress the aeroelastic deformation of the UAV simultaneously. The dynamics performance, robustness, and simulation results show that they were suitable for large scale highly flexible solar-powered UAV.

scholarly journals Heterogeneity and effectiveness analysis of COVID-19 prevention and control in major cities in China through time-varying reproduction number estimation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qing Cheng ◽  
Zeyi Liu ◽  
Guangquan Cheng ◽  
Jincai Huang
Keyword(s):  
Prevention And Control ◽  
Large Scale ◽  
Reproduction Number ◽  
Correlation Method ◽  
Control Measures ◽  
Time Varying ◽  
Short Period ◽  
Significant Difference ◽  
Prevention And Control Measures ◽  
And Control

AbstractBeginning on December 31, 2019, the large-scale novel coronavirus disease 2019 (COVID-19) emerged in China. Tracking and analysing the heterogeneity and effectiveness of cities’ prevention and control of the COVID-19 epidemic is essential to design and adjust epidemic prevention and control measures. The number of newly confirmed cases in 25 of China’s most-affected cities for the COVID-19 epidemic from January 11 to February 10 was collected. The heterogeneity and effectiveness of these 25 cities’ prevention and control measures for COVID-19 were analysed by using an estimated time-varying reproduction number method and a serial correlation method. The results showed that the effective reproduction number (R) in 25 cities showed a downward trend overall, but there was a significant difference in the R change trends among cities, indicating that there was heterogeneity in the spread and control of COVID-19 in cities. Moreover, the COVID-19 control in 21 of 25 cities was effective, and the risk of infection decreased because their R had dropped below 1 by February 10, 2020. In contrast, the cities of Wuhan, Tianmen, Ezhou and Enshi still had difficulty effectively controlling the COVID-19 epidemic in a short period of time because their R was greater than 1.

Modelling the flight dynamics of the hang glider

2005 ◽  
Vol 109 (1102) ◽  
pp. I-XX ◽  
Author(s):  
M. V. Cook ◽  
M. Spottiswoode
Keyword(s):  
Complex Geometry ◽  
Equations Of Motion ◽  
Linear Equations ◽  
Flight Dynamics ◽  
Control Analysis ◽  
Stability Margins ◽  
Stability And Control ◽  
Centre Of Gravity ◽  
Weight Shift ◽  
And Control

AbstractThe development of the non-linear equations of motion for the hang glider from first principles is described, including the complex geometry of control by pilot ‘weight shift’. By making appropriate assumptions the linearised small perturbation equations are derived for the purposes of stability and control analysis. The mathematical development shows that control is effected not by pilot weight shift, but by centre of gravity shift and that lateral-directional control by this means is weak, and is accompanied by significant instantaneous adverse response.The development of a comprehensive semi-empirical mathematical model of the flexible wing aerodynamics is described. In particular, the modelling attempts to quantify camber and twist dependencies. The performance of the model is shown to compare satisfactorily with measured hang glider wing data obtained in earlier full scale experiments. The mathematical aerodynamic model is then used to estimate the hang glider stability and control derivatives over the speed envelope for substitution into the linearised equations of motion.Solution of the equations of motion is illustrated and the flight dynamics of the typical hang glider are described. In particular, the dynamic stability properties are very similar to those of a conventional aeroplane, but the predicted lateral directional stability margins are significantly larger. The depth of mathematical modelling employed enables the differences to be explained satisfactorily. The unique control properties of the hang glider are described in some detail. Pitch and roll control of the hang glider is an aerodynamic phenomenon and results from the pilot adjusting his position relative to the wing in order to generate out of trim aerodynamic control moments about the centre of gravity. Maximum control moments are limited by hang glider geometry which is dependent on the length of the pilot‘s arm. The pilot does not generate control moments directly by shifting his weight relative to the wing. The modelling thus described would seem to give a plausible description of the flight dynamics of the hang glider.

Modeling and Control of a Cable-Driven Robot for Inspection of Wide-Area Horizontal Workspaces

2016 ◽  
Author(s):  
Forrest Montgomery ◽  
Joshua Vaughan
Keyword(s):  
Parallel Manipulator ◽  
Large Scale ◽  
Parallel Manipulators ◽  
End Effector ◽  
Modeling And Control ◽  
Oscillatory Dynamics ◽  
Flexible Wire ◽  
Length Changes ◽  
Stiffness And Damping ◽  
And Control

Cable Driven Parallel Manipulators (CDPMs) utilize flexible wire to actuate an end-effector, allowing rapid accelerations across large workspaces. CDPMs are predominantly modeled with rigid cables, greatly simplifying the analysis. This model is satisfactory for small, fixed masses traveling short distances. However, as cable length increases, the flexibility of the cables, including the variation in stiffness and damping as length changes, cannot be ignored. In addition, the end-effector, which may be modeled as a pendulum, will rotate and contribute to the motion. This paper presents the modeling and control of a large-scale, cable-driven parallel manipulator, with application to inspection of large workspaces. The multi-degree-of-freedom model developed takes into account flexibility of cables and the oscillatory dynamics of the end effector. The dominant dynamics are identified and used to design a control system to limit vibration.

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