Intelligent Control Agent for Autonomous UAS

A self reconfiguring autopilot system is presented, which is based on a rational agent framework that integrates decision making with abstractions of sensing and actions for next generation unmanned aerial vehicles. The objective of the new intelligent control system is to provide advanced capabilities of self-tuning control for a new UAS airframe or adaptation for an old UAS in the presence of failures in adverse flight conditions. High-level system performance is achieved through on-board dynamical monitoring and estimation associated with controller switching and tuning by the agent. The agent can handle an untuned autopilot or retune the autopilot when dynamical changes occur due to aerodynamic and on-board system changes. The system integrates dynamical modelling, hybrid adaptive control, model validation, flight condition diagnosis, control performance evaluation through software agent development. An important feature of the agent is its abstractions from real-time measurements and also its abstractions from model based on-board simulation. The agent, while tuning and supervising the autopilot, also performs real-time evaluations on the effects of its actions

Joint University Program for Air Transportation Research, 1991-1992

This report summarizes the research conducted during the academic year 1991-1992 under the FAA/NASA sponsored Joint University Program for Air Transportation Research. The year end review was held at Ohio University, Athens, Ohio, June 18-19, 1992. The Joint University Program is a coordinated set of three grants sponsored by the Federal Aviation Administration and NASA Langley Research Center, one each with the Massachusetts Institute of Technology (NGL-22-009-640), Ohio University (NGR-36-009-017), and Princeton University (NGL-31-001-252). Completed works, status reports, and annotated bibliographies are presented for research topics, which include navigation, guidance and control theory and practice, intelligent flight control, flight dynamics, human factors, and air traffic control processes. An overview of the year's activities for each university is also presented

Aircraft loss-of-control prevention via backup flight control law design and flight envelope protection

This dissertation seeks to tackle the aircraft loss-of-control problem by adaptive backup flight control law design and flight envelope protection for aircraft with physical damage. In the first part of the study, a backup lateral-directional flight control law for mid-sized transport aircraft with vertical-tail damage is proposed. In particular, the damage case scenarios considered in this work are characterized by a total loss of directional control via rudder, in addition to potential changes in the mass and aerodynamic properties of the aircraft. To compensate for the loss of rudder control, the proposed flight control law employs antisymmetric thrust and asymmetric spoiler deflection as directional control effectors. The design of the backup control law relies on a frequency-shaped approach that accounts for the slow dynamics of the aero-engines, and prevents excessive lift reduction resulting from continued large deflection of the aircraft's spoilers. In addition, the flight control law incorporates an L1 adaptive augmentation loop that is designed to restore prescribed flying qualities for a family of uncertain aircraft models with similar vertical-tail damage. Simulation results with NASA's Transport Class Model demonstrate that the developed backup flight control law is able to recover directional control authority and provide satisfactory flying and handling qualities of the impaired aircraft. In the second part of the study, command limiting control laws for flight envelope protection based on potential functions are presented. In particular, two flight envelope protection methods which are based on quadratic and exponential potential functions respectively are presented and analyzed. During the design process, first the flight envelope protection law is presented based on an n-th order linear model with stability analysis using Lyapunov stability theory. Then the methods are implemented to attitude protection of aircraft models augmented with rate control augmentation systems. Tuning parameters are introduced for better performance of the design with necessary theoretical analysis. Applications on bank-angle protection for NASA's Transport Class Model and pitch-angle protection for a high fidelity nonlinear unmanned aerial vehicle model are presented to verify the design. Simulation results indicate that the proposed methods can provide envelope protection effectively. Considering the existence of uncertainties, disturbances, and possible damages to the system, L1 adaptive augmentations for the flight envelope protection control laws are also proposed, which guarantees desired performance when uncertainties are present in the system dynamics. Finally, flight envelope protection method for two parameters is proposed based on quadratic potential functions. Protection law is designed for each parameter and then the minimum command of the two protection laws is passed to the system. Stability analysis of the closed-loop system with the envelope protection is analyzed using the circle criterion. Protection of both parameters in the steady-state is proved. Simulation examples of the proposed methods for the protection of the angle-of-attack and the pitch angle of a nonlinear unmanned aerial vehicle model are presented to justify the design

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Aeronautical engineering: A continuing bibliography with indexes (supplement 272)

This bibliography lists 719 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1991. 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 277)

This bibliography lists 467 reports, articles, and other documents introduced into the NASA scientific and technical information system in Mar. 1992. Subject coverage includes: the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines); and associated aircraft components, equipment, and systems. It also includes research and development in ground support systems, theoretical and applied aspects of aerodynamics, and general fluid dynamics

Aircraft Abnormal Conditions Detection, Identification, and Evaluation Using Innate and Adaptive Immune Systems Interaction

Abnormal flight conditions play a major role in aircraft accidents frequently causing loss of control. To ensure aircraft operation safety in all situations, intelligent system monitoring and adaptation must rely on accurately detecting the presence of abnormal conditions as soon as they take place, identifying their root cause(s), estimating their nature and severity, and predicting their impact on the flight envelope.;Due to the complexity and multidimensionality of the aircraft system under abnormal conditions, these requirements are extremely difficult to satisfy using existing analytical and/or statistical approaches. Moreover, current methodologies have addressed only isolated classes of abnormal conditions and a reduced number of aircraft dynamic parameters within a limited region of the flight envelope.;This research effort aims at developing an integrated and comprehensive framework for the aircraft abnormal conditions detection, identification, and evaluation based on the artificial immune systems paradigm, which has the capability to address the complexity and multidimensionality issues related to aircraft systems.;Within the proposed framework, a novel algorithm was developed for the abnormal conditions detection problem and extended to the abnormal conditions identification and evaluation. The algorithm and its extensions were inspired from the functionality of the biological dendritic cells (an important part of the innate immune system) and their interaction with the different components of the adaptive immune system. Immunity-based methodologies for re-assessing the flight envelope at post-failure and predicting the impact of the abnormal conditions on the performance and handling qualities are also proposed and investigated in this study.;The generality of the approach makes it applicable to any system. Data for artificial immune system development were collected from flight tests of a supersonic research aircraft within a motion-based flight simulator. The abnormal conditions considered in this work include locked actuators (stabilator, aileron, rudder, and throttle), structural damage of the wing, horizontal tail, and vertical tail, malfunctioning sensors, and reduced engine effectiveness. The results of applying the proposed approach to this wide range of abnormal conditions show its high capability in detecting the abnormal conditions with zero false alarms and very high detection rates, correctly identifying the failed subsystem and evaluating the type and severity of the failure. The results also reveal that the post-failure flight envelope can be reasonably predicted within this framework

Aeronautical engineering: A continuing bibliography with indexes (supplement 254)

This bibliography lists 538 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 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 enginnering: A cumulative index to a continuing bibliography (supplement 312)

This is a cumulative index to the abstracts contained in NASA SP-7037 (301) through NASA SP-7073 (311) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled by the Center for AeroSpace Information of the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract number, report number, and accession number indexes