The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space

The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system

Development of a dynamic virtual reality model of the inner ear sensory system as a learning and demonstrating tool

In order to keep track of the position and motion of our body in space, nature has given us a fascinating and very ingenious organ, the inner ear. Each inner ear includes five biological sensors - three angular and two linear accelerometers - which provide the body with the ability to sense angular and linear motion of the head with respect to inertial space. The aim of this paper is to present a dynamic virtual reality model of these sensors. This model, implemented in Matlab/Simulink, simulates the rotary chair testing which is one of the tests carried out during a diagnosis of the vestibular system. High-quality 3D-animations linked to the Simulink model are created using the export of CAD models into Virtual Reality Modeling Language (VRML) files. This virtual environment shows not only the test but also the state of each sensor (excited or inhibited) in real time. Virtual reality is used as a tool of integrated learning of the dynamic behavior of the inner ear using ergonomic paradigm of user interactivity (zoom, rotation, mouse interaction,…). It can be used as a learning and demonstrating tool either in the medicine field - to understand the behavior of the sensors during any kind of motion - or in the aeronautical field to relate the inner ear functioning to some sensory illusions

Roll motion control of a dissymmetrical wingspan aircraft

The present study focuses on the design of a controller for an unmanned aircraft using a variable-span dissymmetric system. This is primarily intended to stabilize roll, although it was designed as a robust system for total control. The system in use is new in its application, being studied similar aircraft built to date. The aircraft for which the system has been designed is an experimental UAV built entirely at the University of Beira Interior. The stability derivatives and other data were obtained with the help of XFLR software. The development and simulation were done using MATLAB, where were tested two different control methods, LQR and Batz-Kleinman controller. A review of the flight dynamics equations for a standard aircraft was originally done, being then adapted this new concept. The interaction between the control surfaces and the response of a general aircraft was studied. An implementation of predetermined flying qualities in order to scale the state weight matrix in the LQR controller for optimal levels was also performed. At the end three separate simulations were performed to confirm the validity of the theoretical system in control and stabilization, for leveled flight when suffering disturbances, and for various equilibrium states described by a sinusoidal equation and a random variation.O presente estudo concentra-se no projecto de um controlador para uma aeronave não tripulada usando um sistema de asa de envergadura dissimétrica e variável. Este visa primeiramente estabilizar o rolamento, embora tenha sido projectado um sistema robusto de controlo total. O sistema em uso é pioneiro na sua aplicação, tendo sido estudadas semelhantes aeronaves construídas até à data. A aeronave para qual o sistema foi dimensionado é um UAV experimental construído totalmente na Universidade da Beira Interior. As derivadas de estabilidade e restantes dados aerodinâmicos foram obtidos com a ajuda do software XFLR. O desenvolvimento e simulação foram realizados em software MATLAB, para o qual são testados dois métodos de controlo distintos, com LQR e controlador Batz-Kleinman. Foi inicialmente feita uma revisão das equações da dinâmica de voo para uma aeronave generalizada, sendo depois adaptado o novo conceito em estudo. A interacção entre as superfícies de controlo gerais e a resposta de uma aeronave foi estudada. Uma implementação de qualidades de voo pré-determinadas com vista a dimensionar a matriz de pesos de estado no controlador LQR para níveis óptimos foi também realizada. No final foram feitas três simulações distintas para confirmar teoricamente a validade do sistema no controlo e estabilização, em voo nivelado sofrendo perturbações, e consoante pontos de equilíbrio pré-determinados segundo uma equação sinusoidal e para uma variação aleatória

Layout Analysis and Optimization of Airships with Thrust-Based Stability Augmentation

Despite offering often significant advantages with respect to other flying machines, especially in terms of flight endurance, airships are typically harder to control. Technological solutions borrowed from the realm of shipbuilding, such as bow thrusters, have been largely experimented with to the extent of increasing maneuverability. More recently, also thrust vectoring has appeared as an effective solution to ameliorate maneuverability. However, with an increasing interest for high-altitude airships (HAAs) and autonomous flight and the ensuing need to reduce weight and lifting performance, design simplicity is a desirable goal. Besides saving weight, it would reduce complexity and increase time between overhauls, in turn enabling longer missions. In this perspective, an airship layout based on a set of non-tilting thrusters, optimally placed to be employed for both propulsion and attitude control, appears particularly interesting. If sufficiently effective, such configurations would reduce the need for control surfaces on aerodynamic empennages and the corresponding actuators. Clearly, from an airship design perspective, the adoption of many smaller thrusters instead of a few larger ones allows a potentially significant departure from more classical airship layouts. Where on one side attractive, this solution unlocks a number of design variables-for instance, the number of thrusters, as well as their positioning in the general layout, mutual tilt angles, etc.-to be set according simultaneously to propulsion and attitude control goals. In this paper, we explore the effect of a set of configuration parameters defining three-thrusters and four-thrusters layout, trying to capture their impact on an aggregated measure of control performance. To this aim, at first a stability augmentation system (SAS) is designed so as to stabilize the airship making use of thrusters instead of aerodynamic surfaces. Then a non-linear model of the airship is employed to test the airship in a set of virtual simulation scenarios. The analysis is carried out in a parameterized fashion, changing the values of configuration parameters pertaining to the thrusters layout so as to understand their respective effects. In a later stage, the choice of the optimal design values (i.e., the optimal layout) related to the thrusters is demanded to an optimizer. The paper is concluded by showing the results on a complete numerical test case, drawing conclusions on the relevance of certain design parameters on the considered performance, and commenting the features of an optimal configuration

COORDINATION OF LEADER-FOLLOWER MULTI-AGENT SYSTEM WITH TIME-VARYING OBJECTIVE FUNCTION

This thesis aims to introduce a new framework for the distributed control of multi-agent systems with adjustable swarm control objectives. Our goal is twofold: 1) to provide an overview to how time-varying objectives in the control of autonomous systems may be applied to the distributed control of multi-agent systems with variable autonomy level, and 2) to introduce a framework to incorporate the proposed concept to fundamental swarm behaviors such as aggregation and leader tracking. Leader-follower multi-agent systems are considered in this study, and a general form of time-dependent artificial potential function is proposed to describe the varying objectives of the system in the case of complete information exchange. Using Lyapunov methods, the stability and boundedness of the agents\u27 trajectories under single order and higher order dynamics are analyzed. Illustrative numerical simulations are presented to demonstrate the validity of our results. Then, we extend these results for multi-agent systems with limited information exchange and switching communication topology. The first steps of the realization of an experimental framework have been made with the ultimate goal of verifying the simulation results in practice

Attitude and Position Control of a Flapping Micro Aerial Vehicle

International audienc

Unscented Kalman Filter for State and Parameter Estimation in Vehicle Dynamics

Automotive research and development passed through a vast evolution during past decades. Many passive and active driver assistance systems were developed, increasing the passengers’ safety and comfort. This ongoing process is a main focus in current research and offers great potential for further systems, especially focusing on the task of autonomous and cooperative driving in the future. For that reason, information about the current stability in terms of dynamic behavior and vehicle environment are necessary for the systems to perform properly. Thus, model-based online state and parameter estimation have become important throughout the last years using a detailed vehicle model and standard sensors, gathering this information. In this chapter, state and parameter estimation in vehicle dynamics utilizing the unscented Kalman filter is presented. The estimation runs in real time based on a detailed vehicle model and standard measurements taken within the car. The results are validated using a Volkswagen Golf GTE Plug-In Hybrid for various dynamic test maneuvers and a Genesys Automotive Dynamic Motion Analyzer (ADMA) measurement unit for high-precision measurements of the vehicle’s states. Online parameter estimation is shown for friction coefficient estimation performing maneuvers on different road surfaces