Multi-rotor with suspended load: System Dynamics and Control Toolbox

There is an increasing demand for Unmanned Aerial Systems (UAS) to carry suspended loads as this can provide significant benefits to several applications in agriculture, law enforcement and construction. The load impact on the underlying system dynamics should not be neglected as significant feedback forces may be induced on the vehicle during certain flight manoeuvres. The constant variation in operating point induced by the slung load also causes conventional controllers to demand increased control effort. Much research has focused on standard multi-rotor position and attitude control with and without a slung load. However, predictive control schemes, such as Nonlinear Model Predictive Control (NMPC), have not yet been fully explored. To this end, we present a novel controller for safe and precise operation of multi-rotors with heavy slung load in three dimensions. The paper describes a System Dynamics and Control Simulation Toolbox for use with MATLAB/SIMULINK which includes a detailed simulation of the multi-rotor and slung load as well as a predictive controller to manage the nonlinear dynamics whilst accounting for system constraints. It is demonstrated that the controller simultaneously tracks specified waypoints and actively damps large slung load oscillations. A linear-quadratic regulator (LQR) is derived and control performance is compared. Results show the improved performance of the predictive controller for a larger flight envelope, including aggressive manoeuvres and large slung load displacements. The computational cost remains relatively small, amenable to practical implementations

Automatic Flight Control Systems

The history of flight control is inseparably linked to the history of aviation itself. Since the early days, the concept of automatic flight control systems has evolved from mechanical control systems to highly advanced automatic fly-by-wire flight control systems which can be found nowadays in military jets and civil airliners. Even today, many research efforts are made for the further development of these flight control systems in various aspects. Recent new developments in this field focus on a wealth of different aspects. This book focuses on a selection of key research areas, such as inertial navigation, control of unmanned aircraft and helicopters, trajectory control of an unmanned space re-entry vehicle, aeroservoelastic control, adaptive flight control, and fault tolerant flight control. This book consists of two major sections. The first section focuses on a literature review and some recent theoretical developments in flight control systems. The second section discusses some concepts of adaptive and fault-tolerant flight control systems. Each technique discussed in this book is illustrated by a relevant example

Survey on Flight Control Technology for Large-Scale Helicopter

A literature review of flight control technology is presented for large-scale helicopter. Challenges of large-scale helicopter flight control system (FCS) design are illustrated. Following this, various flight control methodologies are described with respect to their engineering implementation and theoretical developments, whose advantages and disadvantages are also analyzed. Then, the challenging research issues on flight control technology are identified, and future directions are highlighted

Nonlinear robust control of tail-sitter aircrafts in flight mode transitions

© 2018 Elsevier Masson SAS In this paper, a nonlinear robust controller is proposed to deal with the flight mode transition control problem of tail-sitter aircrafts. During the mode transitions, the control problem is challenging due to the high nonlinearities and strong couplings. The tail-sitter aircraft model can be considered as a nominal part with uncertainties including nonlinear terms, parametric uncertainties, and external disturbances. The proposed controller consists of a nominal H∞controller and a nonlinear disturbance observer. The nominal H∞controller based on the nominal model is designed to achieve the desired trajectory tracking performance. The uncertainties are regarded as equivalent disturbances to restrain their influences by the nonlinear disturbance observer. Theoretical analysis and simulation results are given to show advantages of the proposed control method, compared with the standard H∞control approach

Model Predictive Control of an Unmanned Quadrotor Helicopter: Theory and Flight Tests

Model Predictive Control (MPC) has been well established and widely used in the process control industry since years. However, due to dependability of its success on availability of high computational power to handle burden of online repetitive calculations, and existence of a precise mathematical model of the controlled plant, it has found less application in other areas of systems and control, specifically speaking when it comes to fast dynamics control systems featuring a highly elaborate plant. Preceded by previous successful efforts made in the application of MPC to other areas of systems and control rather than process control, this thesis initiates employment of MPC in the unmanned aerial systems industry. To this end, the system of the quadrotor UAV testbed in the Networked Autonomous Vehicles Laboratory of Concordia University is chosen. A three dimensional autopilot control system within the framework of MPC is developed and tested through numerous flight experiments. The overall performance of the quadrotor helicopter is evaluated under autonomous fight for three flight scenarios of trajectory tracking, payload drop, robustness to voltage/current drop, and fault-tolerant control in the presence of faults induced by reduced actuator effectiveness. This has been achieved by the proper use of a model reduction technique as well as a fast optimization algorithm to address the issues with high computation, and incorporation of the integral action control in the MPC formulation to meet the offset-free tracking requirement. Both simulation and experimental results are presented to demonstrate success of the design

Handling Qualities Assessment of a Pilot Cueing System for Autorotation Maneuvers

This paper details the design and limited flight testing of a preliminary system for visual pilot cueing during autorotation maneuvers. The cueing system is based on a fully-autonomous, multi-phase autorotation control law that has been shown to successfully achieve autonomous autorotation landing in unmanned helicopters. To transition this control law to manned systems, it is employed within a cockpit display to drive visual markers which indicate desired collective pitch and longitudinal cyclic positions throughout the entire maneuver, from autorotation entry to touchdown. A series of simulator flight experiments performed at University of Liverpool’s HELIFLIGHT-R simulator are documented, in which pilots attempt autorotation with and without the pilot cueing system in both good and degraded visual environments. Performance of the pilot cueing system is evaluated based on both subjective pilot feedback and objective measurements of landing survivability metrics, demonstrating suitable preliminary performance of the system

Optimisation d'un hélicoptère tandem pour la surveillance maritime avec des rotors à vitesse variable

L'utilisation d'avions non-pilotés est une solution éprouvée dans le domaine de la surveillance maritime. Toutefois, l'utilisation d'hélicoptères non-pilotés est maintenant une alternative convoitée grâce aux bénéfices du décollage et de l'atterrissage vertical. Ces bénéfices permettent d'intégrer l'opération de l'aéronef au navire lui-même, permettant ainsi un déploiement immédiat. Le critère de performance le plus critique lors d'une mission de surveillance maritime est l'endurance, c'est-à-dire le temps de vol maximal de l'aéronef. De façon intrinsèque à leur principe de fonctionnement, les hélicoptères offrent une moins grande endurance que les avions. Il y a donc un intérêt majeur à améliorer l'autonomie de vol d'un hélicoptère lors d'une opération de surveillance maritime. Un concept prometteur pour augmenter l'endurance d'un hélicoptère est de diminuer la vitesse d'opération du rotor en plein vol. Ce mémoire présente les bénéfices potentiels de coupler le concept de rotor à vitesse variable avec un moteur à allumage commandé (gasoline) ou par compression (diesel). Jusqu'à maintenant, cette combinaison n'a pas été étudiée dans la littérature. Les études se sont plutôt limitées aux turbines à gaz, ce qui résulte en des effets conflictuels liés à la chute d'efficacité lors de la diminution de la vitesse d'opération. L'efficacité quasi-constante des moteurs à pistons permettrait donc de profiter du plein potentiel du concept de rotor à vitesse variable. Pour ce faire, un modèle de performance d'hélicoptère tandem est développé et validé expérimentalement avec le LX300 de Laflamme Aéro. Deux configurations du LX300 sont étudiées, soit l'une équipée d'un moteur à allumage par étincelle et l'autre par compression, et sont comparées. Il est démontré que la configuration du LX300 incorporant un moteur à allumage par compression bénéficie de gains plus importants que la configuration avec moteur à allumage par étincelle. Les bénéfices sont particulièrement intéressants pour des vols à grande capacité de carburant où jusqu'à 25% et 19% d'augmentation en autonomie et en rayon d'action sont réalisables respectivement pour la configuration diesel. La configuration équipée d'un moteur gasoline quant à elle offre des gains de 15% et 6% en autonomie et rayon d'action respectivement. La combinaison du concept de rotor à vitesse variable et d'un moteur à allumage par étincelle ou compression est donc une avenue prometteuse pour améliorer la performance d'hélicoptères non-pilotés pour accomplir des missions de surveillance maritime. Ces gains de performances se transfèrent aussi pour des missions de transport de charge lourde sur de longues distances