Spelling suggestions: "subject:"airplanes -- 7control"" "subject:"airplanes -- bcontrol""
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Application of differential games to pursuit-evasion problems /Miller, Linn Earl January 1974 (has links)
No description available.
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Aircraft cruise performance optimization using chattering controlsBhardwaj, Pradeep 15 November 2013 (has links)
Aircraft Cruise Performance is examined by using energy-state modelling to investigate fuel-range optimal trajectories. Chattering controls are considered appropriate when the hodograph is non-convex.
Classical steady-state cruise, simple chattering-cruise and the extended chattering-cruise models are studied as constrained parameter-optimization problems. The term "extended chattering" refers to vehicle system modelling extended to maintain vertical equilibrium only on the average. Numerical solution is obtained using a variable-metric gradient-protection algorithm and computational results are presented for three different aircraft.
This study shows that simple chattering cruise for certain specific energies can result in substantial fuel savings over classical steady-state cruise. However extended chattering cruise results in only marginal fuel savings when compared to simple chattering cruise. / Master of Science
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Model-following control applications to nonlinear mechanical systemsBarlas, Mustafa Remzi 31 October 2009 (has links)
Model-following control design methodology is introduced for nonlinear plants and models. The plant equations are considered to be linear in the control input. Dynamic matching conditions are presented and the resulting error dynamics are given. The stability of error dynamics is ensured, using Liapunov's second theorem; by modifying the model state rates, which effectively introduces error feedback.
The methodology is applied to two problems. Motion control of an n-link manipulator with torque controllers on each linkage, and control of an aircraft lacking direct control of lift and side force. The former represents the systems where all of the degrees of freedom can be controlled, and the latter represents the systems where only some of the degrees of freedom can be controlled.
The aircraft control problem is analyzed in more detail. The resulting control law does not require any explicit gain scheduling, but instead, requires estimates of the stability and control derivatives. A method is proposed to compensate for actuator dynamics. The control law is then verified by simulating some maneuvers on the aircraft model provided for the AIAA Controls Design Challenge, which includes nonlinear and full-envelope aerodynamic and engine models, and rate and position limited controls. The maneuvers simulated include a level acceleration and a 3-g turn. / Master of Science
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Nonlinear adaptive control of highly maneuverable high performance aircraftCho, Sul 14 October 1993 (has links)
This thesis presents an effective control design methodology using a one-step-ahead prediction adaptive control law and an adaptive control law based on a Lyapunov function. These control law were applied to a highly maneuverable high performance aircraft, in particular, a modified F/A-18. An adaptive controller is developed to maneuver an aircraft at a high angle of attack even if the aircraft is required to fly over a highly nonlinear flight regime. The adaptive controller presented in this thesis is based on linear, bilinear, and nonlinear prediction models with input constraints. It is shown that the linear, bilinear, and nonlinear adaptive
controllers can be constructed to minimize the given cost function or Lyapunov function with respect to the control input at each step. The control is calculated such that the system follows the reference trajectory, and such that control signal remains
within its constraints. From several simulation results, the nonlinear controller is controller is better than the linear controller. A nonlinear adaptive control law based on a Lyapunov function is designed such that control inputs are smoother than for the one-step-ahead prediction adaptive controller. / Graduation date: 1994
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Sliding-mode control of the super maneuverable aircraftKoo, Chang Sul 13 July 1993 (has links)
In this thesis, A nonlinear methodology for the control of the highly
maneuverable, high performance aircraft HARV (F-18) is studied by using sliding-mode
control (SMC). This control law, which takes a continuous function when the
input constraints are not considered, satisfies the reachability condition by which
concerned states are driven to their sliding surfaces. Especially, this SMC is
generalized for the so-called (square) uncoupled multi-input multi-output (MIMO)
system by the use of error dynamics and applied directly to the nonlinear aircraft
system without linearizing the system.
For the practical application of the SMC to aircraft with input constraints, two
control schemes are used, considering that variations of pitch rate q directly affect
variations of the angle of attack. The first scheme consists of an ��-q control for the
fast response. The second scheme consists an a-control for making the output
approach its sliding surface slowly by setting boundary layers and adjusting reachable
speeds to the sliding surface.
Robustness to parameter uncertainties and disturbances is also studied for the
SMC. Especially, when the effect of parameter uncertainties is severe, then multiple
boundary layers are set in the neighborhood of sliding surface, in which different
reachable speeds to the sliding surface are used to sustain the concerned state within
the boundary layer and to reduce the effect of chattering. / Graduation date: 1994
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An adaptive pitch axis autopilot design for an unstable nonminimum phase pitch axis modelChen, Long Ren 14 June 1990 (has links)
An adaptive pitch axis autopilot design procedure is presented. The
design procedure is applicable to both stable and unstable pitch axis models
and to those having nonminimum phase. The design approach assumes
the adaptive autopilot is activated after achieving level flight. It is shown a
rate-feedback compensator can be designed to ensure stable level flight
pitch axis operation for the entire desired flight regime. The adaptive
control loop design utilizes a pole-placement algorithm. The closed-loop
characteristic polynomial is designed to have dominant poles of that of an
ideal second order system to obtain the desired transient response. The
identification of the system uses a modified least-squares algorithm with a
variable forgetting factor. The nonlinear pitch axis model is used in
simulations to evaluate the design. Command response tests include the
step response and the ramp command response.
Simulation results indicate that the adaptive pitch axis autopilot is
capable of tracking altitude commands after activation. The closed-loop
system response is close to that of the ideal second order system having the
dominant poles. / Graduation date: 1991
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Adaptive limit margin detection and limit avoidanceYavrucuk, Ilkay 08 1900 (has links)
No description available.
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Control authority assessment in aircraft conceptual designKay, Jacob 24 March 2009 (has links)
All aircraft must meet controllability requirements to be certified for commercial use or adopted by the mi1itary. Aircraft maneuverability is often 1imited by control authority. Thus, it is essential for designers to evaluate a candidate concept's control authority early in the conceptual design phase. In this thesis, a methodology for rapid control power evaluation of preliminary design configurations against requirements at the key flight conditions is established.
First, a collection of critical flight conditions to be considered using this methodology is identified. To examine a variety of aircraft configurations and accelerate the process of estimating stability and control derivatives, a FORTRAN program using the Vortex-Lattice Method was written to estimate subsonic, low angle-of-attack aerodynamics. Then, a spreadsheet processes the aerodynamic data to check whether the design configuration possesses adequate control power to satisfy the requirements of the critical flight conditions. / Master of Science
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Digital model reference aircraft controlTauke, Glen John January 1974 (has links)
A digital model reference scheme is presented for the control of the longitudinal modes of an EBF-STOL aircraft. The method used is based on Liapunov's direct method and is used to update feedback and feedthrough matrices. An equilibrium point of the EBF-STOL is chosen about which to constrain performance to follow that of a linearized decoupled DC-9 model. The change of control matrix elements is controlled by
(1) an error vector equal to the difference between state variables of the model and those of the STOL,
(2) the present values of the pilot inputs and STOL state variables,
(3) a P matrix obtained from the equation
A<sub>m</sub>ᵀPA<sub>m</sub> - P = - I
where
z(k + 1) = A<sub>m</sub> z(k) + B<sub>m</sub> u<sub>p</sub>
is the equation of motion for the model,
(4) selected gains, and
(5) a matrix B₋ᵤʳ⁻¹ whose elements are determined by the inverse of an n x n partition of the linearized input matrix B₋ᵤ of the STOL.
A method for smoothing control action is discussed. / Master of Science
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The longitudinal dynamics of a rigid aircraft including unsteady aerodynamic effectsChen, Ta Kang January 1977 (has links)
The main object of this thesis is to give a introductory study of the longitudinal motion of an aircraft, including some effects of nonuniform motion. Because this subject is connected with practical problems of importance in the domain of applied aerodynamics and control, a great effort has been given to setting up the physics of unsteady aerodynamics and its effects on the aircraft longitudinal modes. Numerical examples are given for both the two-dimensional and three-dimensional rigid wing, subsonic case. In this research, from the unsteady aerodynamic theory, through the frequency response calculation, system identification and the augmentation of the aircraft dynamic system, a carefully derived theory and a computer algorithm have been presented and used.
It is our main purpose that a suitable unsteady aerodynamic transfer function be obtained and be coupled to the aircraft quasi-steady dynamic system. A new modified model which includes the unsteady aerodynamic effects has been constructed and been compared with the conventional model and the differences between them have been discussed. / Master of Science
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