Flight Mechanics, Flight Control and Aeroelasticity

Written-out Theses

Creation of trajectory optimization algorithms for energy consumption reduction (Master thesis).

Based on a given kinematic model of aircraft motion and a simplified consumption model, approaches to trajectory planning and optimization will be considered. These may include:

  • Collocation methods: Example "An Introduction to Trajectory Optimization: How to Do Your Own Direct Collocation" (Matthew Kelly).
  • Model Predictive Approaches (MPC).
  • Field-based methods
  • Graph-based methods: RRT

The paper includes a literature review and selection of an approach. A demonstration of feasibility (Matlab/Simulink/C) would be desirable.

If interested, please contact Henrik Spark.

Development of a method to determine the maximum accelerations of a UAV as a function of the flight condition (Bachelor or Master thesis, Flight Mechanics 2 required).
Based on the equations of motion of a multicopter, the maximum accelerations are to be determined (theoretically) as a function of the flight speed. The determined accelerations are to be subsequently verified using an appropriate method.

The steps include:

  • Research on the modeling and testing of multicopters.
  • Theoretical analysis of the maximum accelerations based on the equations of motion (simplified) of a multicopter.
  • Development of a method to experimentally determine the maximum accelerations.
  • Testing of the method in a nonlinear simulation (and in a flight test).

If interested, please contact Christopher Ruwisch.

 

Development and assessment of a new, distributed load alleviation system based on integrated load- and actuator control (Master thesis)

The scope of the thesis comprises development and implementation of a decentralized load control system for the inboard and outboard ailerons, which is based on the new control concept. The controller shall be validated and compared to a classical control approach using a closed-loop simulation environment comprising of an aero-servo elastic model of a generic long-range aircraft, flight control systems and actuation models.

The steps include:

  • Defining a control structure based on the new approach, which is suitable to control the roll- and plunge dynamics as well as selected aeroelastic modes
  • Implementation of the control structure using MATLAB/SIMULINK
  • Derivation of linear models from the non-linear simulation for representative reference flight states
  • Linear design of the control parameters for the selected envelope points using structured state feedback and modal control techniques
  • Assessment of the control behaviour in the non-linear simulation for selected reference flight states (using the corresponding parameter set) 
  • Analysis of the control effort and sensitivity of stability and control quality with respect to actuator performance constraints
  • Comparison of the developed controller with a centralised load alleviation approach (relying on classical, position controller actuators) based on suitable benchmark criteria

If interested, please contact Dr.-Ing. Wolfram Meyer-Brügel

Development of a control law to improve the roll dynamics of a flexible commercial aircraft by incorporating secondary control surfaces.

The roll control of modern, more flexible commercial aircraft is affected by the so-called wash-out effect. This involves the wing twisting as a result of the change in pressure distribution, which reduces the intended effect of rudder deflection. The use of secondary control surfaces (disturbance and landing flaps) to generate the roll moment is one way to reduce the influences of this effect. The purpose of this thesis is to develop a control law that incorporates the landing flaps of a modern commercial aircraft into the roll control system. This will be done using knowledge of the roll effectiveness of the various control surfaces, which will be determined for several flight conditions as part of the work. The control concept to be designed will be compared with conventional aileron roll control at different flight conditions using simulation studies.

  • Research on rudder effectiveness and roll control of commercial aircraft.
  • Investigation of the roll effectiveness of different control surfaces of a given reference aircraft
  • Development and integration of a control law for optimized roll control of the reference aircraft
  • Evaluation of the control law based on simulation calculations

For the processing of the bachelor thesis previous knowledge in FM1 and FM2 is desirable.

If you are interested, please contact Hannes Wilke.

Aeroelastic Investigation of a Composite, Smart Plate-Like Wing (Master Thesis)

The design of novel aerostructures - as for aircraft lifting surfaces or wind turbine blades - often combines the use of light ‘high-performance’ composites with the utilization of modern materials with smart capabilities, including e.g. piezoelectric materials. The major point regarding these materiall lies in the mutual dependence between their mechanical and electrical responses. This suit permits in many cases, as per in aeroelastic applications, the use of piezo patches for local actuation/sensing on the host structure. 

Therefore, in this work, a deeper look into the aeroelastic characteristics of flexible composite thin plate-like wings that account for local piezo-induced effects is intended. As a point-by-point further detailed description, this study may comprises:

  • The development of a finite element beam model, in Matlab;
  • The study and modelling of piezoelectric and composite materials;
  • The implementation of a potential flow aerodynamic method, such as the Vortex Lattice Method, in Matlab or C++;
  • Investigation of the aeroelastic characteristics of smart composite wings under several structural and piezoelectric conditions.

Prior knowledge of basic concepts in Aeroelasticity and Composite Materials is desirable, however not mandatory.

If interested, and for further information or questions, please do not hesitate to contact Gefferson Silva.

Calibration of Strain Gauges for Control Application in Flexible Aircraft (Bachelor thesis)

The Chair of Flight Mechanics, Flight Control and Aeroelasticity (FMRA) of the TU Berlin is currently developing a testbed called TU-Flex, specifically designed to study and analyze wing flexibility in new generation aircraft. TU-Flex integrates strain gauge measurement techniques with data acquisition and processing systems to provide real-time monitoring and control of wing deformation. By calibrating strain gauge measurements, TU-Flex will pave the way for reliable and accurate assessment and regulation of wing flexibility, leading to safer and more efficient flight operations. The objective of this proposed bachelor thesis is to calibrate a full strain gauge bridge thought experiments on a model of a flexible wing represented by a flat plate.

This research includes the next goals:

  • Model the flat plate as a finite element beam.
  • Design the test sequence and all apparatus needed for this test campaign.
  • Gather the results and compare with the expected ones.
  • Conduct experiments to evaluate the impact of temperature variation on the measurements.
  • Perform a wind tunnel test to check the dynamic response of the system.
  • Propose a step by step calibration procedure to be used on the TU Flex wing.

Prior knowledge of basic concepts in Aeroelasticity, structural analysis and electrical engineering is desirable.

If interested, and for further information or questions, please do not hesitate to contact Guilherme Barbosa.

Development and validation of a flight dynamic model for an unmanned, remotely piloted aircraft (Master Thesis)

The ZOHD Talon Nano Evo is a model UAV used by the Chair of Flight Mechanics, Flight Control and Aeroelasticity to fly various test manoeuvres with the purpose of modelling and testing different control laws. This Master thesis aims to create a flight dynamics model for the Talon Nano Evo and to validate it using flight test data. The flight dynamics model should then be adapted to fit the flight test data.

This research includes the next goals:

  • Creating an initial geometry of the aircraft and calculating the aerodynamic and stability derivatives.
  • Building a flight dynamic model.
  • Evaluation of the flight dynamics characteristics of the Talon Nano Evo.
  • Performing flight tests to gather data for the validation of the flight dynamics model.
  • Flight dynamics model update based on flight test data.
  • Creating a X-Plane model for the Talon Nano Evo.

Prior knowledge of basic concepts in Flight Mechanics is desirable.

If interested, and for further information or questions, please do not hesitate to contact Sutej Singh.

Entwicklung und Implementierung einer Simulationsumgebung für eine Morphing Wing Konfiguration (Masterarbeit)
As part of the interdisciplinary research project "Morphing Technologies & Artificial Intelligence Research Group" (morphAIR) at DLR in Braunschweig, a simulation environment for an aircraft with morphing elements is to be built and validated using flight test data. This will be used for training a controller based on reinforcement learning.

The steps include:

  • Literature review on
    • simulation environments and flight mechanics simulations
    • Possibilities of aerodynamic modeling of morphing elements.
  • Development of a surrogate flight mechanics model in MATLAB/Simulink.
  • Modeling of aerodynamics
  • Analysis and validation of the model

This is an external work from DLR in Brauschweig, which is supervised by FMRA on the TU side. The task is well suited for remote work.

If you are interested, please contact Lina Dehmlow.

Validierung der unabhängigen Monitore für Flugregelungsfunktionen mit Hilfe der „Counter Optimization“ Methode (Master Thesis)

Within the EASA-Monitor project, different variants of independent monitors are developed at the Department of Flight Mechanics, Flight Control and Aeroelasticity. The monitors are validated in terms of reliability and robustness using the existing simulation environment of the VFW614 -ATD aircraft and its flight control laws. The objective of the work is to investigate the robustness of the independent monitors using the "Counter Optimization" method. Based on a given model of a VFW614-ATD fly-by-wire aircraft, different monitor functions for the flight control laws (FCL) and the Counter Optimization LIBraRY - COLIBRY, pilot inputs/flight maneuvers and wind conditions that lead to false hitting of the monitor functions are to be determined.

Specifically, the following items are to be addressed:

  1.     Familiarization with the following topics of optimization procedures using literature:
    • Global Optimization Algorithms, Optimal Control Theory, Reinforcement Learning.
    • Documentation of the flight simulation environment
  2.     Integration of COLIBRY into the flight simulation environment
  3.     Execution and evaluation of a validation campaign with different optimization methods to evaluate robustness of the independent monitors.
  4.     Documentation of all work steps

If you are interested and for further information or questions please contact Dmitry Chernetsov or Dominik Hübener.

Effects of Actuator Saturation on Active Flutter Suppression Performance for a Typical Aeroelastic Section (Master Thesis)

The interaction between the structure, dynamics, structural dynamics, and unsteady aerodynamics of the deformable moving airplane may lead to self-excited aeroelastic instabilities such as flutter (an oscillatory constant amplitude or divergent motion/deformation). This phenomenon has destructive potential and it is a function of the dynamic pressure, as well as (in some cases) load factor and other maneuver parameters.

The possibility of suppressing airplane flutter instabilities through the actively controlled closed-loop action of control surfaces and other control effectors has been known for years and became feasible with the appearance of high-bandwidth actuators and developments in control systems theory and hardware. The stabilization capability of Active Flutter Suppression (AFS) technologies, is strongly affected by actuators’ characteristics and delays in the closed-loop. Commercial aircraft are typically equipped with electro-hydraulic actuators with limited bandwidth and embedding various internal nonlinearities such as backlash or rate limits which constrain the stabilization action of the AFS controller. The objective of this Master thesis is to artificially impose typical electro-hydraulic actuator performance in terms of amplitude and rate limits, and to evaluate the performance loss of the closed-loop system employing performance measures.

The research task includes:

  1. Creating a numerical model which implements artificial actuators’ amplitude and rate saturation
  2. Quantify the closed-loop degradation of the closed-loop system with LPV/LFR state-feedback employing performance measures
  3. Verify that the closed-loop experimental response of the TS is consistent with the theoretical boundaries imposed by the artificial saturation.
  4. Documentation of all work steps.

If interested, please contact Dr. Pedro Jose Gonzalez Ramirez.