Using learning from demonstration to enable automated flight control comparable with experienced human pilots

Modern autopilots fall under the domain of Control Theory which utilizes Proportional Integral Derivative (PID) controllers that can provide relatively simple autonomous control of an aircraft such as maintaining a certain trajectory. However, PID controllers cannot cope with uncertainties due to their non-adaptive nature. In addition, modern autopilots of airliners contributed to several air catastrophes due to their robustness issues. Therefore, the aviation industry is seeking solutions that would enhance safety. A potential solution to achieve this is to develop intelligent autopilots that can learn how to pilot aircraft in a manner comparable with experienced human pilots. This work proposes the Intelligent Autopilot System (IAS) which provides a comprehensive level of autonomy and intelligent control to the aviation industry. The IAS learns piloting skills by observing experienced teachers while they provide demonstrations in simulation. A robust Learning from Demonstration approach is proposed which uses human pilots to demonstrate the task to be learned in a flight simulator while training datasets are captured. The datasets are then used by Artificial Neural Networks (ANNs) to generate control models automatically. The control models imitate the skills of the experienced pilots when performing the different piloting tasks while handling flight uncertainties such as severe weather conditions and emergency situations. Experiments show that the IAS performs learned skills and tasks with high accuracy even after being presented with limited examples which are suitable for the proposed approach that relies on many single-hidden-layer ANNs instead of one or few large deep ANNs which produce a black-box that cannot be explained to the aviation regulators. The results demonstrate that the IAS is capable of imitating low-level sub-cognitive skills such as rapid and continuous stabilization attempts in stormy weather conditions, and high-level strategic skills such as the sequence of sub-tasks necessary to takeoff, land, and handle emergencies

Modelling and control of a twin rotor MIMO system.

In this research, a laboratory platform which has 2 degrees of freedom (DOF), the Twin Rotor MIMO System (TRMS), is investigated. Although, the TRMS does not fly, it has a striking similarity with a helicopter, such as system nonlinearities and cross-coupled modes. Therefore, the TRMS can be perceived as an unconventional and complex "air vehicle" that poses formidable challenges in modelling, control design and analysis and implementation. These issues are the subject of this work. The linear models for 1 and 2 DOFs are obtained via system identification techniques. Such a black-box modelling approach yields input-output models with neither a priori defined model structure nor specific parameter settings reflecting any physical attributes. Further, a nonlinear model using Radial Basis Function networks is obtained. Such a high fidelity nonlinear model is often required for nonlinear system simulation studies and is commonly employed in the aerospace industry. Modelling exercises were conducted that included rigid as well as flexible modes of the system. The approach presented here is shown to be suitable for modelling complex new generation air vehicles. Modelling of the TRMS revealed the presence of resonant system modes which are responsible for inducing unwanted vibrations. In this research, open-loop, closed-loop and combined open and closed-loop control strategies are investigated to address this problem. Initially, open-loop control techniques based on "input shaping control" are employed. Digital filters are then developed to shape the command signals such that the resonance modes are not overly excited. The effectiveness of this concept is then demonstrated on the TRMS rig for both 1 and 2 DOF motion, with a significant reduction in vibration. The linear model for the 1 DOF (SISO) TRMS was found to have the non-minimum phase characteristics and have 4 states with only pitch angle output. This behaviour imposes certain limitations on the type of control topologies one can ado·pt. The LQG approach, which has an elegant structure with an embedded Kalman filter to estimate the unmeasured states, is adopted in this study. The identified linear model is employed in the design of a feedback LQG compensator for the TRMS with 1 DOF. This is shown to have good tracking capability but requires. high control effort and has inadequate authority over residual vibration of the system. These problems are resolved by further augmenting the system with a command path prefilter. The combined feedforward and feedback compensator satisfies the performance objectives and obeys the constraint on the actuator. Finally, 1 DOF controller is implemented on the laboratory platform

Impact of UAV Hardware Options on Bridge Inspection Mission Capabilities

Uncrewed Aerial Vehicles (UAV) constitute a rapidly evolving technology field that is becoming more accessible and capable of supplementing, expanding, and even replacing some traditionally manual bridge inspections. Given the classification of the bridge inspection types as initial, routine, in-depth, damage, special, and fracture critical members, specific UAV mission requirements can be developed, and their suitability for UAV application examined. Results of a review of 23 applications of UAVs in bridge inspections indicate that mission sensor and payload needs dictate the UAV configuration and size, resulting in quadcopter configurations being most suitable for visual camera inspections (43% of visual inspections use quadcopters), and hexa- and octocopter configurations being more suitable for higher payload hyperspectral, multispectral, and Light Detection and Ranging (LiDAR) inspections (13%). In addition, the number of motors and size of the aircraft are the primary drivers in the cost of the vehicle. 75% of vehicles rely on GPS for navigation, and none of them are capable of contact inspections. Factors that limit the use of UAVs in bridge inspections include the UAV endurance, the capability of navigation in GPS deprived environments, the stability in confined spaces in close proximity to structural elements, and the cost. Current research trends in UAV technologies address some of these limitations, such as obstacle detection and avoidance methods, autonomous flight path planning and optimization, and UAV hardware optimization for specific mission requirements

Aeronautical engineering: A continuing bibliography with indexes (supplement 304)

This bibliography lists 453 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Анализа, моделирање и оптимизација беспилотне летелице за велике висине на соларни погон

High-altitude long-endurance (HALE) or High-altitude platform station (HAPS) are aircraft that can fly in the stratosphere continuously for several months and provide support to military and civilian needs. In addition, HAPS can be used as a satellite at a fraction of the cost and provide instant, persistent, and improved situational awareness. Solar energy is the primary source of energy for these types of unmanned aerial vehicles (UAVs). Solar panels mounted on the wing and empennage capture solar energy during the day for immediate consumption and conserve the remainder for use at night. The main challenges to the successful design of HAPS are finding an appropriate model to calculate airframe weight, materials for structural analysis, designing a wing and propulsion system so that they can be integrated successfully into a unique aircraft configuration and these problems need to be solved. Therefore, this thesis investigates /focuses on the concept of HAPS, optimization of the airfoil, wing design and aerodynamic analysis, experimental analysis of different materials used in the wing structure, structural analysis of the wing and design of novel optimized propeller. The topics covered in the chapters are mentioned below. The first three chapters of this thesis deal with the introduction, review of available literature and previous relevant research, and background of existing high-altitude aircraft and their configurations. Then, in Chapter 4, the initial mission requirements, mission profile, basic characteristics of solar panels, rechargeable batteries, assessment of daily power consumption and battery mass as well as methodologies for the initial estimation of aircraft structural mass and wing loads are discussed. Chapter 5 is dedicated to selecting and defining the appropriate airfoil by using potential flow model and the multi-criteria optimization process. The aerodynamic analysis of wings performed by computational fluid dynamics is shown in Chapter 6. Calculations of aerodynamic coefficients of the wing and the flow field around the wing are presented in this chapter. Chapter 7 is dedicated to the structural design of high-performance slender wings. Tensile tests of a variety of 3D printed polymers and composite materials as well as the effect of ageing and heat treatment on the tensile properties of PLA are presented to investigate their mechanical characteristics. Structural analysis of the wing is presented in Chapter 8. Two different possible solutions of the aircraft's wing structure for high altitudes are presented and their performance is compared through static and modal analyses. Chapter 9 deals entirely with the methodology for designing the optimal propeller intended for highaltitude unmanned aerial vehicles. Coupled aero-structural optimization was performed using a genetic algorithm where input and output parameters and constraints were defined from a set of geometric, aerodynamic, and structural characteristics of the propeller. Finally, main conclusions are presented in chapter 10.Беспилотне летелице за велике висине (ХАЛЕ, ХАПС) су авиони који могу да лете у стратосфери непрекидно неколико месеци и пружају подршку војним и цивилним потребама. Поред тога, ове летелице се могу користити и као економични сателити и обезбеђивати тренутни, стални и побољшани увид у дешавања на Земљи. Сунчева енергија је главни извор енергије овог типа беспилотних летелица. Соларни панели распоређени по крилу и хоризонталним стабилизаторима упијају сунчеву енергију током дана за тренутну потрошњу док се остатак чува за лет током ноћи. Основни изазови успешном пројектовању ХАПС летелица су изналажење одговарајућег модела за процену тежине летелице, материјала за структуралну анализу, пројектовање крила и погонског система који се могу успешно интегрисати у јединствену конфигурацију летелице и ови проблеми морају бити решени. Стога, ова теза истражује/је фокусирана на концепт ХАПС-а, оптимизацију аеропрофила, дизајн и аеродинамичку анализу крила, експерименталну анализу различитих материјала коришћених у структури крила, структуралну анализу крила и дизајн нове оптимизоване елисе. Теме обрађене по поглављима наведене су у наставку. Прве три главе ове тезе баве се уводом, прегледом доступне литературе и претходних релевантних истраживања, као и прегледом постојећих ХАПС летелица и њихових конфигурација. Затим, у глави 4, разматрани су полазни захтеви и мисија, основне карактеристике соларних панела и пуњивих батерија, процена дневне потрошње енергије и потребне масе батерија, као и методологије за почетну процену масе конструкције авиона и оптерећења крила. Глава 5 посвећена је одабиру и дефинисању одговарајућег аеропрофила коришћењем модела потенцијалног струјања и вишекритеријумског оптимизационог поступка. Аеродинамичка анализа крила спроведена методом прорачунске механике флуида приказана је у глави 6. Овде су такође приказани и прорачунати аеродинамички коефицијенти крила као и струјно поље око крила. Глава 7 посвећена је унутрашњој структури високоперформантних витких крила. Описана су спроведена мерења затезних карактеристика различитих 3Д штампаних полимера и композитних материјала, као и ефекти старења и термичке обраде на механичке карактеристике 3Д штампаних епрувета. Структурална анализа крила представљена је у глави 8. Приказана су два различита могућа решења структуре крила авиона за велике висине и упоређене су њихове перформансе кроз статичку и модалну анализу. Глава 9 се у целости бави методологијом пројектовања оптималне елисе намењене беспилотној летелици за велике висине. Овде је спроведена спрегнута аеро-структурална оптимизација помоћу генетског алгоритма где су улазни и излазни параметри и ограничања дефинисани из скупа геометријских, аеродинамичких и структуралних карактеристика елисе. Коначно, основни закључци дати су у глави 10

Aerial Vehicles

This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space

Fault detection and isolation in a networked multi-vehicle unmanned system

Recent years have witnessed a strong interest and intensive research activities in the area of networks of autonomous unmanned vehicles such as spacecraft formation flight, unmanned aerial vehicles, autonomous underwater vehicles, automated highway systems and multiple mobile robots. The envisaged networked architecture can provide surpassing performance capabilities and enhanced reliability; however, it requires extending the traditional theories of control, estimation and Fault Detection and Isolation (FDI). One of the many challenges for these systems is development of autonomous cooperative control which can maintain the group behavior and mission performance in the presence of undesirable events such as failures in the vehicles. In order to achieve this goal, the team should have the capability to detect and isolate vehicles faults and reconfigure the cooperative control algorithms to compensate for them. This dissertation deals with the design and development of fault detection and isolation algorithms for a network of unmanned vehicles. Addressing this problem is the main step towards the design of autonomous fault tolerant cooperative control of network of unmanned systems. We first formulate the FDI problem by considering ideal communication channels among the vehicles and solve this problem corresponding to three different architectures, namely centralized, decentralized, and semi-decentralized. The necessary and sufficient solvability conditions for each architecture are also derived based on geometric FDI approach. The effects of large environmental disturbances are subsequently taken into account in the design of FDI algorithms and robust hybrid FDI schemes for both linear and nonlinear systems are developed. Our proposed robust FDI algorithms are applied to a network of unmanned vehicles as well as Almost-Lighter-Than-Air-Vehicle (ALTAV). The effects of communication channels on fault detection and isolation performance are then investigated. A packet erasure channel model is considered for incorporating stochastic packet dropout of communication channels. Combining vehicle dynamics and communication links yields a discrete-time Markovian Jump System (MJS) mathematical model representation. This motivates development of a geometric FDI framework for both discrete-time and continuous-time Markovian jump systems. Our proposed FDI algorithm is then applied to a formation flight of satellites and a Vertical Take-Off and Landing (VTOL) helicopter problem. Finally, we investigate the problem of fault detection and isolation for time-delay systems as well as linear impulsive systems. The main motivation behind considering these two problems is that our developed geometric framework for Markovian jump systems can readily be applied to other class of systems. Broad classes of time-delay systems, namely, retarded, neutral, distributed and stochastic time-delay systems are investigated in this dissertation and a robust FDI algorithm is developed for each class of these systems. Moreover, it is shown that our proposed FDI algorithms for retarded and stochastic time-delay systems can potentially be applied in an integrated design of FDI/controller for a network of unmanned vehicles. Necessary and sufficient conditions for solvability of the fundamental problem of residual generation for linear impulsive systems are derived to conclude this dissertation

Aeronautical engineering: A continuing bibliography with indexes (supplement 301)

This bibliography lists 1291 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical engineering: A continuing bibliography with indexes (supplement 257)

This bibliography lists 560 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1990. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical engineering: A continuing bibliography with indexes (supplement 318)

This bibliography lists 217 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics