Lucian Teodor Grigorie

Closed-Loop Control Validation of a Morphing Wing Using Wind Tunnel Tests

In this paper a rectangular finite aspect ratio wing, having a wing trailing edge airfoil reference airfoil cross section, was considered. The wing upper surface was made of a flexible composite material and instrumented with Kulite pressure sensors and two smart memory alloys actuators. Unsteady pressure signals were recorded and visualized in real time while the morphing wing was being deformed to reproduce various airfoil shapes by controlling the two actuators displacements. The controlling procedure was performed using two methods which are described in the paper. Several wind-tunnel test runs were performed for various angles of attack and Reynolds numbers in the 6 × 9 foot wind tunnel at the Institute for Aerospace Research at the National Research Council Canada. The Mach number was varied from 0.2 to 0.3, the Reynolds numbers varied between 2.29 and 3.36 x 10 6 , and the angle-of-attack range was within -1 to 2 degrees. Wind-tunnel measurements are presented for airflow boundary layer transition detection using high sampling rate pressure sensors.

Automatic Control of Aircraft in Longitudinal Plane During Landing

Automatic control of aircraft during landing is discussed and a new structure of automatic landing system (ALS) is designed using the dynamic inversion concept and proportional-integral-derivative (PID) controllers in conventional and fuzzy variants. Theoretical results are validated by numerical simulations in the absence or presence of wind shears and sensor errors.

Variations in Optical Sensor Pressure Measurements due to Temperature in Wind Tunnel Testing

In this paper, wind-tunnel measurements are presented for the airflow fluctuation detection using pressure optical sensors. Twenty-one wind-tunnel test runs for various Mach numbers, angles of attack, and Reynolds numbers were performed in the 6 x 9 ft 2 wind tunnel at the Institute for Aerospace Research at the National Research Council Canada. A rectangular finite aspect ratio half-wing, having a NACA 4415 cross section, was considered with its upper surface instrumented with pressure taps, pressure optical sensors, and one Kulite transducer. The Mach number was varied from 0.1 to 0.3 and the angle of attack range was within -3 to 3 deg. Unsteady pressure signals were recorded and a thorough comparison, in terms of unsteady and mean pressure coefficients, was performed between the measurements from the three sets of pressure transducers. Temperature corrections were considered in the pressure measurements by optical sensors. Comparisons were also performed against theoretical predictions using the XFoil computational fluid dynamics code, and mean errors smaller than 10% were noticed between the measured and the predicted data.

ALSs with Conventional and Fuzzy Controllers Considering Wind Shear and Gyro Errors

This paper presents the automatic control of the aircraft in the longitudinal plane during the landing process, taking into account the wind shear and sensor errors. Two automatic landing systems (ALSs) are designed. The former uses an instrument landing system (ILS), whereas the latter controls flight altitude using the state vector. Both systems have a subsystem for the control of longitudinal velocity that is based on the dynamic inversion theory. The subsystems for pitch-angle control use proportional-derivative (PD) control laws or a law based on the dynamic inversion theory and a proportional-integral-derivative (PID) controller. The slope and flare controllers are a PD controller and a PID controller, respectively. The controllers are designed in both classical and fuzzy-logic approaches. Theoretical results are validated by numerical simulations in the absence or presence of wind shear and sensor errors. Analysis of the time evolution of the main ALS parameter leads to conclusions regarding the superiority of the dynamic qualities for the ALS with fuzzy controllers.

Control strategies for an experimental morphing wing model

The paper presents the control strategies used in an experimental morphing wing model starting from the open loop architecture until a real time optimized closed loop architecture. Three control methods are exposed here, methods designed to obtain and maintain some optimized airfoils during the wind tunnel tests. Also, for all designed architectures the experimental control results are shown. First method uses a database stored in the computer memory, database which contains some optimized airfoils correlated with the airflow cases as combinations of Mach numbers and angles of attack. The method is based on a controller that takes as reference value the necessary displacement of the actuators from the database in order to obtain the morphing wing optimized airfoil shape. The second method uses a similar controller as the first method but the control loop is built around the changes of the Cp values calculated by XFoil software in two fixed positions along the chord of the wing, positions associated to two Kulite sensors linked through aerodynamic interdependence with the actuators positions. The third control method is based on the pressure information received from the sensors and on the transition point position estimation. It includes, as inner loop, the first control method of the actuation lines. The method uses an optimizer code which finds the best actuators configuration in order to maximize the position of the transition, i.e. at the end of optimization sequence the transition should be found nearest possible to the trailing edge.

An Intelligent Controller based Fuzzy Logic Techniques for a Morphing Wing Actuation System using Shape Memory Alloy

The paper presents a way to control the actuation lines of a morphing wing using an intelligent controller based on fuzzy logic techniques. The strong non-linear character of the used actuators, made from some smart materials, and the numerical simulations achieved in the design phase provides for the controller a fuzzy logic Proportional-Integral-Derivative architecture seconded by a conventional On-Off controller. The input-output mapping of the fuzzy model is designed, taking account of the system’s error and its change in error. The shapes chosen for the inputs’ membership functions are triangular, while the product fuzzy inference and the center average defuzzifier are applied (Sugeno). After the controller tuning, three validation steps are done: a numerical one, followed by other two experimentally. For the experimental validation, bench tests and wind tunnel tests are performed. The bench test experimental validation is made in laboratory conditions, in the absence of aerodynamic forces, for different actuation commands. In the wind tunnel tests, are also experimentally validated the optimized airfoils with the theoretically-determined airfoils obtained earlier. Both the transition point real time position detection and visualization are realized in wind tunnel tests.

Controller optimization in real time for a morphing wing in a Wind Tunnel

Wind Tunnel Test results of a real time optimization of a morphing wing in wind tunnel for delaying the transition towards the trailing edge are presented. A morphing rectangular finite aspect ratio wing, having a reference airfoil cross-section, was considered with its upper surface made of a flexible composite material and instrumented with Kulite pressure sensors, and two smart memory alloys actuators. Several wind tunnel tests runs for various Mach numbers, angles of attack and Reynolds numbers were performed in the 6′×9′ wind tunnel at the Institute for Aerospace Research at the National Research Council Canada (IAR/NRC). Unsteady pressure signals were recorded and used as feed back in real time control while the morphing wing was requested to reproduce various optimized airfoils by changing automatically the two actuators strokes. The new optimization method was implemented into the control software code that allowed the morphing wing to adjust its shape to an optimum configuration under the wind tunnel airflow conditions.

Design and wind tunnel experimental validation of a controlled new rotary actuation system for a morphing wing application

The paper presents the design and the experimental validation of a position controller for a morphing wing application. The actuation mechanism uses two DC motors to rotate two eccentric shafts which morph a flexible skin along two parallel actuation lines. In this way, the developed controller aim is to control the shape of a wing airfoil under different flow conditions. In order to control the actuators positions, a proportional–derivative control algorithm is used. The morphing wing system description, its actuation system structure, the control design, and its validation are highlighted in this paper. The results, obtained both by numerical simulation and experimental validation, are obtained following the control design and its validation. An analysis of the wind flow characteristics is included as a supplementary validation; the pressure coefficients obtained through numerical simulation for several desired airfoil shapes are compared with those obtained through measurements for the experimentally obtained airfoil shapes under different flow conditions.

Design, numerical simulation and experimental testing of a controlled electrical actuation system in a real aircraft morphing wing model

The paper focuses on the modelling, simulation and control of an electrical miniature actuator integrated in the actuation mechanism of a new morphing wing application. The morphed wing is a portion of an existing regional aircraft wing, its interior consisting of spars, stringers, and ribs, and having a structural rigidity similar to the rigidity of a real aircraft. The upper surface of the wing is a flexible skin, made of composite materials, and optimised in order to fulfill the morphing wing project requirements. In addition, a controllable rigid aileron is attached on the wing. The established architecture of the actuation mechanism uses four similar miniature actuators fixed inside the wing and actuating directly the flexible upper surface of the wing. The actuator was designed in-house, as there is no actuator on the market that could fit directly inside our morphing wing model. It consists of a brushless direct current (BLDC) motor with a gearbox and a screw for pushing and pulling the flexible upper surface of the wing. The electrical motor and the screw are coupled through a gearing system. Before proceeding with the modelling, the actuator is tested experimentally (stand alone configuration) to ensure that the entire range of the requirements (rated or nominal torque, nominal current, nominal speed, static force, size) would be fulfilled. In order to validate the theoretical, simulation and standalone configuration experimental studies, a bench testing and a wind-tunnel testing of four similar actuators integrated on the real morphing wing model are performed.

Self-adaptive morphing wing model, smart actuated and controlled by using a multiloop controller based on a laminar flow real time optimizer

The modeling, the design, the numerical simulation and the experimental testing of the control system for a self-adaptive morphing wing model are here exposed. The study was performed during a multidisciplinary research project, involving industrial partners, a research institute and three academic entities. The developed control system is a multiloop one, being designed, simulated and tested in two major steps, correlated with the validation phases of the aerodynamic gains provided by the morphed wing model in terms of the laminar flow improvement over its upper surface. The two validation phases were suggestively called open loop, respectively closed loop; in the first phase the aerodynamic validation was made just by comparing the experimentally obtained results with the numerical optimization obtained ones, while in the second phase the morphing wing model was left free, to adapt itself based on the information related to the transition point position provided by some pressure sensors installed on its upper surface. The used wing model was a rectangular one, equipped with a composite made flexible upper surface, morphed along of two lines by using some shape memory alloy actuators. For the open loop phase a database with some optimized airfoils was generated and a smart controller based fuzzy logic was designed to control the position of the actuators in real time so that the desired optimized skin corresponding to the desired displacements to be obtained and maintained during the flight tests. The closed loop architecture was realized by using a real-time optimization algorithm, which included the actuators controller as inner loop. The algorithm was developed in order to generate real-time optimized airfoils starting from the information received from the pressure sensors and targeting the morphing wing main goal: the improvement of the laminar flow over the wing upper surface.