Elevator Angle Research Articles

SYSTEM IDENTIFICATION OF AIRCRAFT LONGITUDINAL MOTION BY MEANS OF FLIGHT SIMULATOR DATA

In presented article, an exemplary problem of identifying parameters of an aircraft's motion within the vertical plane of symmetry is solved. The data was collected by FlightGear simulator for a Pilatus PC-9M aircraft flight case. After submitting a sequence of commands to pitch elevator and engine thrust, the simulator records five parameters of longitudinal motion at certain frequency. The collected data are further used to build a state-space model of the flight through least-squares estimation. The obtained numerical results are compared with the experimental ones and are overlaid graphically. Charts depicting elevator angle to trim are derived in addition. A source code developed in GNU Octave is applied with the help of which the problem was solved.

Grid transformation and dynamic scattering for tail rotor radar cross section analysis

With the promotion and enhancement of stealth technology of helicopter rotor components, the research on the dynamic radar cross section (RCS) of helicopter rotor is becoming more and more important and imminent. In order to facilitate the calculation and analysis of the electromagnetic scattering characteristics during rotor rotation, a dynamic scattering calculation (DSC) method based on quasi-static principle (QSP) and grid coordinate transformation is presented. After analyzing the advantages and disadvantages of QSP, the dynamic principle is used to describe the rotation process of the rotor. Combined with the grid coordinate transformation method, the RCS of the rotor is accurately calculated by physical optics (PO) and physical theory of diffraction (PTD). Then the influence of azimuth, elevator angle and observation distance on rotor dynamic RCS is analyzed. The results show RCS of the tail rotor is indeed dynamic and periodic and its main influencing factors include azimuth and elevation angle. The proposed DSC method is efficient and effective for studying the dynamic RCS of tail rotor.

A controller comprising tail wing control of a hybrid autonomous underwater vehicle for use as an underwater glider

A controller for an underwater glider is presented. Considered underwater glider is a torpedo-shaped autonomous underwater vehicle installing adjustable buoyancy bag and movable battery in it. The controller is composed of an LQR controller to maintain zigzag vertical movement for gliding and two PD controllers to control elevator/rudder angles. The LQR controller controls the pumping speed into the buoyancy bag and the moving speed to locate the battery. One of the PD controller controls the elevator angle to assist the LQR controller, and the other controls the rudder angle to adjust the direction of the underwater glider. A reduced order Luenberger observer is adopted to estimates the center of gravity of the glider and the buoyancy mass that are essential but cannot be measured. Mathematical simulation using Matlab proved the validity of the proposed controller to obtain better performance than conventional LQR only controller under the influence of sea current.

Variance Constrained Vibration Control of Morphing Tactical Unmanned Aerial Vehicles (TUAVs)

In this study, using dynamic model of passive and active morphing featured Tactical Unmanned Aerial Vehicle (TUAV) called which is produced in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory, under the TUBITAK ARDEB 1001 program and designing Output Constrained Variance Controller for aircraft tracking the desired trajectory achieved with minimal vibration and minimum energy consumption. For this purpose, using MATLAB, in the simulation environment, studies have been performed and closed loop responses have been obtained. Longitudinal motion is in primary interest, desired output is pitching angle of TUAV, and desired input is elevator angle.

Modeling, control design, and influence analysis of catapult-assisted take-off process for carrier-based aircrafts

This paper addresses the problems of modeling, control design, and influence analysis of the steam catapult-assisted take-off process of the carrier-based aircrafts. The mathematical models of the carrier-based aircraft, steam catapult, landing gears, and the environmental factors including deck motion and bow airflow have been established to express the aircraft dynamics in the take-off process. An engineering method based automatic flight control system has been designed, which is divided into the longitudinal channel and lateral channel. The influences of the preset control surface, ship deck motion, ship bow airflow, and automatic flight control system system are tested by a series of simulations. The simulation results show that the elevator angle preset is necessary in the stage of accelerated running on the ship deck and the deck motion is the most important factor for safe take-off, while the ship bow airflow is beneficial for climbing up of the aircraft. The automatic flight control system gives the guarantee of safety and performance in the take-off process of the carrier-based aircraft.

A blended wing body airplane with a close-coupled, tilting tail

This paper highlights a novel approach to stabilizing and controlling pitch and yaw motion via a set of horizontal tail that can act as elevator and rudder. The tail is incorporated into a new design of blended wing body (BWB) aircraft, known as Baseline-V, located just aft of the trailing edge of its inboard wing. The proposed close-coupled tail is equipped with elevators that deflect in unison, and can tilt - an unusual means of tilting where if starboard side is tilted downward at k degree, and then the portside must be tilted upward at k degree too. A wind tunnel experiment is conducted to investigate aerodynamics and static stability of Baseline-V BWB aircraft. The model is being tested at actual flight speed of 15 m/s (54 km/h) with varying angle of attack for five elevator angle cases at zero tilt angle and varying sideslip angle for four tilt angle cases at one fixed elevator angle. The result shows that the aircraft's highest lift-to-drag ratio is 32. It is also found that Baseline-V is statically stable in pitch and yaw but has no clear indication in terms of roll stability.

별도의 고정타를 갖는 수중운동체 승강타의 제어력에 미치는 받음각의 영향에 대한 실험적 연구

Conventionally, the static angle of attack and static elevator tests are carried out separately to estimate hydrodynamic stability derivatives of underwater vehicles. However, it is difficult to verify the interaction between the angle of attack and elevator angle in such cases. In this study, we perform a static elevator with angle of attack test where both the angle of attack and elevator angle are varied simultaneously. The experimental results show that the angle of attack has an influence on the elevator control force and that this tendency is dependent on the sense in which the angle of attack and elevator angle are varied. We predict level flight performance using hydrodynamic derivatives estimated through this experiment. The predictions considering the effect of angle of attack show good agreement with trials conducted in the open sea.

Active Disturbance Rejection Control for Improved Depth Model of AUV

This paper studies the implementation of an ADRC to deal with depth variations of AUV. The depth model of AUV is decoupled from the 6 DOF dynamics function at first. Then, the least square method is introduced to identify the nonlinear open-loop model of AUV offline, and a more accurate depth model that varies with the elevator angle is achieved. Finally, ADRC is applied to the improved depth model with the disturbance of inaccuracy elevator angle and the error of depth measurement. The result confirms that AUV depth model varies with the elevator angle, while the ADRC controller could reject the errors in the depth sensor and the disturbances of mechanical transmission of rudder and the nonlinear variations at different operating points. Comparing to the traditional PID controller, ADRC performs better respectively with these uncertainty. The contribution of the proposed controller would support to the future application to 3D motion control and path tracking of AUV in practice.

Oscillation Susceptibility Analysis along the Path of the Longitudinal Flight Equilibriums in ADMIRE Model

Our goal is the oscillation susceptibility analysis in the framework of a nonlinear mathematical model in the so-called ADMIRE or Aero Data Model in a Research Environment. First, we analyze the oscillation susceptibility along the path of the longitudinal flight equilibriums when the flight control system (FCS) is decoupled. After that, a similar analysis is undertaken in the case when the FCS is coupled. For decoupled FCS, it is shown that on the path of the longitudinal flight equilibriums there exists a saddle-node where stability is lost and fold bifurcation occurs. Maneuvers are simulated showing the effect of an instantaneous change of the elevator angle, and the evolution of the unstable equilibriums (due to the maneuvers) to the corresponding exponentially stable equilibriums. It is shown numerically that at the saddle-node oscillations occur when the elevator angle is less than the critical value and the start is from the saddle-node. More precisely, it is shown that if the plane state parameters coincide with the saddle-node coordinates and the elevator angle is changed instantaneously from the critical value to a value which is less than this value, then two of the state parameters (α,q) begin to oscillate with the same period and the third parameter (θ) increases, tending to infinity. Thus, the orbit of the system evolves spiraling. It is shown also, that if the elevator angle is reset, the plane returns to a stable equilibrium. Therefore, a soft or no catastrophic stability loss takes place. When the FCS is coupled, the plane for every value of the amplification factor has a unique equilibrium which is exponentially stable and attracts all the equilibriums which exist in decoupled case. In this case, there are no bifurcation points on the equilibrium path. The dependence of the equilibrium and of the relaxation period on the amplification factor value is found numerically. Finally, it is concluded that when the FCS is decoupled, then along the path of the longitudinal equilibriums oscillations can occur, but when the FCS is coupled and the pilot can modify (instantaneously) only the amplifier factor value, then the vehicle, defined by the considered numerical data, is not anymore susceptible to oscillation.

Numerical analysis of the oscillation susceptibility along the path of longitudinal flight equilibria of a reentry vehicle

In this paper, it is shown that when the automatic flight control system (AFCS) is decoupled, then on the path of longitudinal flight equilibria of the ALFLEX reentry vehicle, there exist saddle–node bifurcations resulting in oscillations: when the elevator angle exceeds the bifurcation value, the angle of attack and pitch rate oscillate with the same period, while the pitch angle increases or decreases infinitely. Hence, the orbit of the system is spiraling. It is also shown that a mild (non-catastrophic) stability loss occurs due to the bifurcations. Based on this analysis, an automatic flight control design is developed.

Wind-Tunnel Testing and Modeling of a Micro Air Vehicle with Flexible Wings

The field of micro air vehicles is relatively immature; consequently, high-fidelity simulations do not yet exist for a generic aircraft. The fidelity of flight dynamic simulations is closely correlated to the reliability of models representing the vehicle's aerodynamic and propulsion characteristics in the entire flight envelope, including the nonlinear region. This paper discusses wind-tunnel experiments performed to investigate the aerodynamic and mechanical characteristics of micro air vehicles with flexible wings in different conditions of propeller type, motor power, and elevator deflections. Visual image correlation was used to measure the deformation of the flexible wings to quantify general features such as variations in aerodynamic and geometric twist angle. Aerodynamic and propulsion results were used to formulate empirical models of the relevant coefficients in the form of multiple linear regressions and to estimate the effectors' functional dependencies and interactions. High-order nonlinear interactions were confirmed between the coefficients of lift, drag, and pitching moment with the independent variables. The rates of the dependencies with elevator deflections and angle of attack were found, to some extent, to be motor voltage and dynamic pressure dependent, evincing a strong coupling with the propeller speed.

Experimental Study of a Micro Air Vehicle with a Rotatable Tail

An experimental study of a rotatable tail mechanism applied to a small unmanned aerial vehicle was performed using a six-component wind-tunnel balance in the U.S. Air Force Institute of Technology low-speed wind tunnel. Attributes of the control and stability characteristics of the original vehicle, which were documented in an earlier study, are compared with those of a unique control methodology, a tail consisting of a single surface, with controllable elevation and rotation. An advantage of this change is a reduction in the storage length of the vehicle. Because there are similarities in the rotatable tail mechanism and the tail of many birds, the rotatable tail reflects a biomimetric feature. Measured force and moment coefficient measurements for the actual vehicle at a typical flight speed indicated that a rotatable tail provides a sufficient yaw moment for turning. For example, yaw moment coefficients C n , ranging from -0.02 to +0.02, which is typical for a rudder, were achievable as long as the absolute value of the tail elevation angle was large. The dependence of the yaw moment coefficient on the elevator angle and angle of attack, in addition to the tail rotation angle, indicates that there would be significant challenges in applying a robust flight control scheme with the current actuator configuration. An additional feature of the tail design is that by deflecting the tail upward, it could also function effectively as an air brake. A more than twofold increase in drag coefficient for constant angle of attack was measured when the tail elevation angle was increased to nearly 70 deg.

스마트 무인기 TR-S2 형상의 정적 풍동시험

To evaluate the aerodynamic efficiency of TR-S2 configuration designed by SUDC, wind tunnel tests of 40% scaled model were done in KARl LSWT. The aerodynamic characteristics of plain and Semi-Slotted Flaperon were compared, and vortex generators were installed to improve flow pattern along the wing surface. Effects of the control surface such as elevator, rudder, aileron, and incidence angle of horizontal tail are measured for various testing conditions. Test results showed that Semi-Slotted Flaperon produced more favorable lift, lift/drag, and stall margins and application of vortex generator would be best choice to enhance wing performance. Longitudinal, lateral and directional characteristics of TR-S2 were found to be stable for the pitch and yaw motions.

비행 시험을 통한 비행선의 운동 특성 해석 및 시험 결과 분석

For decades, airships have being developed in Europe (especially German) and America. Airships are planning to be used for advertisements and airliners as well. In Korea, KARI (Korea Aerospace Research Institute) is developing stratospheric communication airship and the similar research is carried out in Japan. Among them, Zeppelin of German has the cutting-edge airship technology with Zeppelin NT. In this paper, the flight performance and stability were evaluated by comparing mathematical theory and the real test. The stability was examined through dynamic modeling and assured by designing controllers at each flight mode. Elevator angle, rudder angle, magnitude of thrust and tilting angle of thrust vector were used as control inputs. Moreover, after measuring the airship velocity, flight direction, magnitude and direction of the wind, attitude angles and trajectories of the airship at each flight mode, the results were compared with the simulation. To get the reasonable data, low-pass filter and band-stop filter were designed to get rid of the sensor noise and engine vibration. The test was accomplished at cruise mode, turning mode, and deceleration. To conclude, with comparing the simulation data and flight test data, it could be known that the dynamic model used in this paper was reasonable.

ニューラルネットワークを用いたパイロットの着陸操縦の解析 第２報 ＧＡによるニューラルネットワーク構造の構築

A Neural Network (NN) model of a human operation is tried to construct to analyze pilot behavior. The flight data obtained by simulator operation are utilized to teach the NN model. The input data to the model are visual cues from the cockpit and the pilot column deflection history, and the output is the elevator angle. The Genetic Algorithms (GA) optimizes the NN model in order to obtain the appropriate structure and its parameters. It can be seen that the sensitivity analysis and the threshold analysis of the obtained NN model reveal the human pilot behavior.

ニューラルネットワークを用いたパイロットの着陸操縦の解析

The purpose of this study is to analyze human pilot behavior at landing operation. The pilot model is constructed using neural network from the results of the simulator tests. The inputs to this model are observation cues such as the horizon and the runway, and pilot control inputs. The output is the elevator angle. The data on two cases (with wind, or with no wind) are used for learning. The constructed pilot models are simulated in various cases and their validity and generalization are investigated. Finally, the importance of each input is evaluated using factor analysis of the Neural Network model.

2103 ニューラルネットワークを用いたパイロットの着陸操作の解析(OS.5 人間/機械/環境システム)

The purpose of this study is to analyze human pilot behavior in Landing Operation. At first, the pilot model is automatically constrtucted using neural network from the results of the simulator tests. The main inputs to this model are observation cues such as the horizon and the runway, and the output is the elevator angle. The data on two cases (with wind, or with no wind) are used for learning. Next, the constructed pilot models are simulated in various initial conditions to check their varidity and generalization. Finaly, models are evaluated with factor analysis.

Reference Management for Control Systems Under Constraints

A supervision scheme, denoted hereafter to as a Command Governor (CG), is presented for on-line handling the reference signal to be applied to a compensated control system in order to enforce pointwise-in-time input and/or staterelated constraints. A CG is basically a memoryless nonlinear device which, on the base of current plant state and reference signal, produces its action by modifying the reference signal in order to avoid potential constraint violations. An application to a bank-to-turn autopilot design is presented where the CG is used for governing the demanded pitch acceleration in order to avoid violation of physical constraints on the elevator angle.

Flexible vehicle control using quantitative feedback theory

The design of a longitudinal pitch-axis flight control system for a flexible aircraft with uncertainty in the vehicle model is presented. This uncertainty includes the characteristics of the vehicle elastic mode. Quantitative feedback theory is used in the control system design. A level 1 handling qualities requirement is included in the control systems design specifications. This requirement is generated through pilot-vehicle analysis using a structural model of the human pilot and handling qualities sensitivity functions. Although two aerodynamic controls were available (elevator and forward vane), it is shown that elevator control alone can be used to meet the command-following, disturbance rejection, and handling qualities requirements. Nomenclature [d®/dx]cp = slope of body bending mode shape evaluated at pilot's station q = dO/dt, rad/s u = perturbation of x body axis component of vehicle velocity, ft/s a = angle of attack, rad 8C = canard angle (positive trailing edge down), deg 8e = elevator angle (positive trailing edge down), deg rj = generalized modal coordinate for symmetric body bending mode 9 = pitch attitude of rigid body, rad

A Study on Altitude Control of an Autonomous Vehicle (First Report)

A guidance and control system for an autonomous vehicle of a cruising type with a rudder and elevator is studied, which is intended to investigate the surface of ocean ground continuously. In order to collect underwater information continuously taking pictures or measuring chemical characteristics, it is required to keep low altitude from the surface on the condition that it keeps the safety distance.In the paper, a simplified altitude control system to keep predetermined height is investigated observing the distances to the surface by several narrow ultra sonic fan beams in different directions. The control system is consist of two hierarchical control blocks, i. e. a guidance block to give attitude reference angle calculated from the observed distances to keep desirable altitude, and a local attitude control block to realize the reference angle keeping the stability of the vehicle. As the attitude control system, a linear feedback elevator angle control system with velocity saturation is adopted, taking account of the system dynamics.In the guidance block, pitch correction angle is calculated from the observed distances. Three different algorithms, linear, polynomial filtering, and mixed type, are proposed. And the system performance of each is evaluated from various surface conditions by simulation study using simplified two dimensional model in vertical (pitch) plane. Non-symmetric smoothing of the correction angle is also introduced to keep the safety distance for rough surfaces. From the study, it is assured that the proposed control system can control the vehicle to keep the predetermined altitude for most cases within 20% margin, and basic feasibility of the system is verified.