The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Mohammad Hassan Moradi - One of the best experts on this subject based on the ideXlab platform.
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Classical and fuzzy-genetic autopilot design for unmanned aerial vehicles
Applied Soft Computing, 2011Co-Authors: A. R. Babaei, Mohammad Mortazavi, Mohammad Hassan MoradiAbstract:In this paper, an efficient strategy is proposed to design the altitude hold Mode autopilot for a UAV which is non-minimum phase, and its Model includes both parametric uncertainties and unModeled nonlinear dynamics. This work has been motivated by the challenge of developing and implementing an autopilot that is robust with respect to these uncertainties. By combination of classic controller as the principal section of the autopilot and the fuzzy logic controller to increase the robustness in a single loop scheme, it is tried to exploit both methods advantages. The multi-objective genetic algorithm is used to mechanize the optimal determination of fuzzy logic controller parameters based on an efficient cost function that comprises undershoot, overshoot, rise time, settling time, steady state error and stability. Simulation results show that the proposed strategy performances are desirable in terms of the time response characteristics for both Phugoid Mode and short period Mode, the robustness, and the adaptation of itself with respect to the large commands.
J. Karimi - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Response Analysis of a High Glide Ratio Parachute System
International Journal of Engineering, 2021Co-Authors: M. A. Ghapanvary, M. Nosratollahi, J. KarimiAbstract:This paper is concerned with the dynamic stability study of a gliding parachute-payload system along its gliding path. To scrutinize the respective dynamic response characteristics after releasing from high altitude, a modified multi-body Model is developed. In the stability analysis procedure, the yawing motion of the payload is considered in system dynamics, which in turn creates a state-dependent matrix in the stability analysis and makes the linearization algorithm more cumbersome. To solve the problem, a unified Jacobian-based symbolic differentiation algorithm is implemented and the dynamics is linearized about various operating points along gliding segment of a typical planned trajectory. Based on results, the system has short period and Phugoid Modes in longitudinal channel just like an aircraft. In addition to dutch roll Mode, the system has a low frequency coupled roll-spiral Mode in lateral-directional channel which is a result of effective canopy anhedral angle. It is shown, the coupled Mode can be decomposed into two distinct roll and spiral Modes for small anhedral angles. Based on results, as the parachute descends, both the period and damping ratio for the short period Mode were increased by 18 and 30%, respectively. For the Phugoid Mode the period of oscillations is decreased by 20% and the damping ratio, almost remains constant. For the lateral-directional channel,. As the parachute descends, the dutch roll Mode is destabilized whereas the other Modes are stabilized. Furthermore, from a practical point of view, lengthening the suspension lines stabilizes the coupled roll-spiral Mode whereas destabilizes the other Modes.
Andrea Amerio - One of the best experts on this subject based on the ideXlab platform.
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1 Stability and Flying Qualities of an Unmanned Airplane using Vortex Lattice Method
2016Co-Authors: Elsa M. Cárdenas, Pedro J. Boschetti, Andrea AmerioAbstract:The purpose of the present work is to evaluate the static stability and open loop dynamic stability for unpowered condition of the Unmanned Aerial Vehicle for Ecological Conservation. Forces and moments were obtained by the vortex lattice method. These were computed for different values of angle of attack, sideslip angle, aileron, rudder and elevator deflection, and pitch, yaw and roll rates. Static stability and control derivatives were obtained and used for the analysis of airplane open loop dynamic stability and response. The longitudinal and lateral–directional derivates show that the airplane is statically stable. The short period Mode and Phugoid Mode correspond with damped Mode. Dutch roll Mode and roll Mode of the airplane matches with damped Mode and convergent Mode, respectively. However, spiral Mode response prediction corresponds to a divergent Mode. The airplane reaches flying qualities equal and better than those of Level 2 Nomenclature c = mean aerodynamic chord CD, CL, CY = drag, lift and side force coefficients CM, Cn, C = pitching, yawing and rolling moment coefficient
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Stability and Performance of a Light Unmanned Airplane in Ground Effect
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 2010Co-Authors: Pedro J. Boschetti, Andrea Amerio, Elsa M. Cárdenas, Ángela ArévaloAbstract:The objective of the present work is to understand the effect of ground proximity on the aerodynamic performance and stability of a light unmanned aerial vehicle. The flowfield around the airplane was computed by PAN AIR and Athena Vortex Lattice. The ground effect was simulated using the method of images. The stability coefficients and other aerodynamic characteristics were obtained at different heights above ground and in free flight. The results demonstrate that the airplane is lateral-directional statically stable, longitudinal statically stable in free flight and longitudinal statically unstable in ground effect. The dynamic stability characteristics of the airplane were obtained at different heights above ground. The Phugoid Mode is considerable influenced by ground effect and a divergent and non-oscillatory Mode appears when the airplane is near to the ground. This is called non-dimensional height Mode. The short-period, the Dutch roll, the roll and the spiral Modes are slightly affected by ground effect. Significant differences were obtained when the z derivatives were neglected in the dynamic analysis for longitudinal motion. The present work demonstrates that the performance and stability of the unmanned airplane are considerably influenced by ground effect.
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Stability and Flying Qualities of an Unmanned Airplane Using the Vortex-Lattice Method
Journal of Aircraft, 2009Co-Authors: Elsa M. Cárdenas, Pedro J. Boschetti, Andrea AmerioAbstract:The purpose of the present work is to evaluat e the static stability and open loop dynamic stability for un power ed condition of the Unmanned Aerial Vehicle for Ecological Conservation. Forces and moments were obtained by the vortex lattice method. These were computed for different values of angle of a ttack, sideslip angle, aileron, rudder and elevator deflection, and pitch, yaw and roll rates. Static stability and control derivatives were obtained and used for the analysis of airplane open loop dynamic stability and response. The longitudinal and later al –directional derivates show that the airplane is statically stable. The short period Mode and Phugoid Mode correspond with damped Mode. Dutch roll Mode and roll Mode of the airplane matches with damped Mode and convergent Mode, respectively. However, spi ral Mode re spo nse prediction corresponds to a divergent Mode. The airplane reaches flying qualities equal and better than those of Level 2
Wahyu Kuntjoro Wirachman Wisnoe - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic, Stability and Flying Quality Evaluation on a Small Blended Wing-body Aircraft with Canard Foreplanes
Procedia Technology, 2014Co-Authors: Rizal Effendy M Nasir, Wahyu Kuntjoro, Wahyu Kuntjoro Wirachman WisnoeAbstract:Blended wing-body (BWB) concept promises up to 30 percent increase in aerodynamic efficiency and reduction in fuel cost by having planform geometry optimized to increase lift and to reduce drag. Many claimed to have achieved the target of increasing lift-to-drag ratio better than current conventionally-configured airplanes either large airliners or small unmanned airplane. However, achieving good balance of aerodynamic efficiency, stability and flying quality is harder then one might expect. Over years of studying small BWB aircrafts in Universiti Teknologi MARA (UiTM), it is found that unconventional behaviour of aerodynamic characteristics leads to limitations to BWB aircraft's flight envelope. In this paper, a short overview of aerodynamic, stability and flying quality of UiTM's BWB aircraft design is highlighted. Lessons learned from its unsusual lift-angle of attack curves, stability reversals, the effect of canard to flight stability and poor longitudinal flying quality (short-period Mode and Phugoid Mode) are discussed. A classical control solution to improve it flying quality has been proposed and simulated and the result shows that both short-period and Phugoid Modes are able to achieve damping ratios within 0.6 to 0.8 exceeding minimum Level 1 damping ratios of 0.35 and 0.04 respectively. Design flaws of this aircraft and recommendations to be implemented on the next evolution of aircraft design conclude this paper.
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Investigation on the Effect of Airspeed and Altitude to Phugoid Mode of a Small Unmanned Blended Wing-Body Aircraft with Canard as a Longitudinal Control Surface
Applied Mechanics and Materials, 2012Co-Authors: Rizal Effendy Mohd Nasir, Wahyu Kuntjoro, Wahyu Kuntjoro Wirachman WisnoeAbstract:Phugoid Mode is a lowly damped, low-frequency oscillatory motion representing vertical translation usually related to kinetic and potential energy interchange. MIL-F-8785C standard has ruled out qualitative specification requirements on measurement of flying and handling qualities of piloted aircraft. For Phugoid Mode, these requirements lie in the value of its damping ratio. Small aircraft is sensitive to atmospheric conditions and poor Phugoid Mode performance is observed in many unmanned aircraft. This paper discusses the effect of airspeed and altitude to Phugoid Mode of small, unmanned blended wing-body (BWB) aircraft named Baseline-II E-2. Baseline-II is a low subsonic, remotely-piloted UAV used to study the behaviour of a BWB-type aircraft. The case presented here is an E-2 version in which a specifically-designed canard is incorporated as its longitudinal control surface. Five Category B flight cases (airspeeds) per altitude-case, and three altitude cases (low, medium and high) are studied. Model-N dynamic Model is introduced here to become the basis of flight simulation. The Model is compared to Models derived by other authors and approximation equations. The mean of simulating Phugoid behaviour is using state-space representation of the aircraft using Matlab SIMULINK. The computations show that Baseline-II E-2 undamped natural frequency of Phugoid Mode is inversely-proportional to airspeed and reduces as altitude increases. These have adverse effect on its damping ratio that increases near parabolically when the aircraft flies faster, and reduces when it climbs up. The cause of these trends is looked into in detail and issues concerning Baseline-II E-2’s unsatisfactory and unstable Phugoid Mode oscillation at low speed are addressed.
A. R. Babaei - One of the best experts on this subject based on the ideXlab platform.
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Classical and fuzzy-genetic autopilot design for unmanned aerial vehicles
Applied Soft Computing, 2011Co-Authors: A. R. Babaei, Mohammad Mortazavi, Mohammad Hassan MoradiAbstract:In this paper, an efficient strategy is proposed to design the altitude hold Mode autopilot for a UAV which is non-minimum phase, and its Model includes both parametric uncertainties and unModeled nonlinear dynamics. This work has been motivated by the challenge of developing and implementing an autopilot that is robust with respect to these uncertainties. By combination of classic controller as the principal section of the autopilot and the fuzzy logic controller to increase the robustness in a single loop scheme, it is tried to exploit both methods advantages. The multi-objective genetic algorithm is used to mechanize the optimal determination of fuzzy logic controller parameters based on an efficient cost function that comprises undershoot, overshoot, rise time, settling time, steady state error and stability. Simulation results show that the proposed strategy performances are desirable in terms of the time response characteristics for both Phugoid Mode and short period Mode, the robustness, and the adaptation of itself with respect to the large commands.