Comparison of linear and nonlinear active disturbance rejection control method for hypersonic vehicle

Near space hypersonic vehicles have features of strong coupling, nonlinearity and acute changes in aerodynamic parameters, which are challenging for the controller design. Active disturbance rejection control (ADRC) method does not depend on the accurate system model and has strong robustness against disturbances. This paper discusses the differences between the fractional-order PID (FOPIλDμ) ADRC method and the FOPIλDμ LADRC method for hypersonic vehicles. The FOPIλDμ ADRC controller in this paper consists of a tracking-differentiator (TD), a FOPIλDμ controller and an extended state observer (ESO).The FOPIλDμ LADRC controller consists of the same TD and FOPIλDμ controller with the FOPIλDμ ADRC controller and a linear extended state observer (LESO) instead of ESO. The stability of LESO and the FOPIλDμ LADRC method is detailed analyzed. Simulation results show that the FOPIλDμ ADRC method can make the hypersonic vehicle nonlinear model track desired nominal signals faster and has stronger robustness against external environmental disturbances than the FOPIλDμ LADRC method

Nonlinear Adaptive Dynamic Inversion Control for Hypersonic Vehicles

Because of the widely varying flight conditions in which hypersonic vehicles operate and certain aspects unique to hypersonic flight, the development of control architectures for these vehicles presents a challenge. Previous work on control design for hypersonic vehicles often has involved linearized or simplified nonlinear dynamical models of the aircraft. This dissertation retains the nonlinear dynamics in the design of the controller for a generic hypersonic vehicle model and develops nonlinear adaptive dynamic inversion control architecture with a control allocation scheme. A robustness analysis is performed on the initial controller design, which shows that the controller is able to handle time delays, perturbations in stability derivatives, and reduced control surface effectiveness while maintaining tracking performance. One particular safety concern in hypersonic flight is inlet unstarts, which not only produce a significant decrease in the thrust but also can lead to loss of control and possibly the loss of the vehicle. This dissertation focuses on the prevention of inlet unstarts that are triggered by an altered flow that fails to pass through the throat of the engine because the aircraft has exceeded limits on angle-of-attack and sideslip angle. To prevent undesirable inlet unstart events, the nonlinear adaptive dynamic inversion control architecture is given the ability to enforce state constraints. Because several phenomena can cause inlet unstarts, the control architecture also is tested to determine if the controller is able to maintain reference trajectory tracking and to prevent the loss of the vehicle should an inlet unstart occur. Additionally, a fault- tolerant control capability is added to the control architecture so that the vehicle can handle the failure of one or more control surfaces. The tracking performance of the nonlinear adaptive dynamic inversion control architecture is analyzed for the cases of enforcement of state constraints, control surface failures, and inlet unstarts. In all three cases, the control architecture is able to track reference trajectories with minimal to no degradation in performance. Limitations were discovered in the case of the controller that enforces state constraints in terms of the trajectories that can be tracked when combined with fault-tolerant control. However, the results indicate that the nonlinear adaptive dynamic inversion controller is able to achieve tracking performance in the presence of the uncertainties and inlet unstarts conditions studied in this dissertation

Ten-year space launch technology plan

This document is the response to the National Space Policy Directive-4 (NSPD-4), signed by the President on 10 Jul. 1991. Directive NSPD-4 calls upon the Department of Defense (DoD), the Department of Energy (DOE), and the National Aeronautics and Space Administration (NASA) to coordinate national space launch technology efforts and to jointly prepare a 10-year space launch technology plan. The nation's future in space rests on the strength of its national launch technology program. This plan documents our current launch technology efforts, plans for future initiatives in this arena, and the overarching philosophy that links these activities into an integrated national technology program

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 274)

This publication is a cumulative index to the abstracts contained in supplements 262 through 273 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

The Design of Fixed-Time Observer and Finite-Time Fault-Tolerant Control for Hypersonic Gliding Vehicles

This paper proposes a fault-tolerant control scheme for a hypersonic gliding vehicle to counteract actuator faults and model uncertainties. Starting from the kinematic and aerodynamic models of the hypersonic vehicle, the control-oriented model subject to actuator faults is built. The observers are designed to estimate the information of actuator faults and model uncertainties, and to guarantee the estimation errors for converging to zero in fixed settling time. Subsequently, the finite-time multivariable terminal sliding mode control and composite-loop design are pursued to enable integration into the faulttolerant control, which can ensure the safety of the postfault vehicle in a timely manner. Simulation studies of a six degree-of-freedom nonlinear model of the hypersonic gliding vehicle are carried out to manifest the effectiveness of the investigated fault-tolerant control system

Adaptive Multivariable Integral TSMC of a Hypersonic Gliding Vehicle with Actuator Faults and Model Uncertainties

This paper presents a fault-tolerant control (FTC) strategy for a hypersonic gliding vehicle (HGV) subject to actuator malfunctions and model uncertainties. The control-oriented model of the HGV is estabilished according to the HGV kinematic and aerodynamic models. A single-loop design for HGV FTC under actuator faults is subsequently developed, where newly developed multivariable integral terminal sliding mode control (TSMC) and adaptive techniques are integrated. The multivariable integral TSMC is capable of ensuring the finite-time stability of the closed-loop system in the presence of actuator malfunctions and model uncertainties, while the adaptive laws are employed to tune the control parameters in response to the HGV status. Simulation studies based on a six degree-of-freedom (DOF) nonlinear model of the HGV are illustrated to highlight the effectiveness of the developed FTC scheme

Langley aerospace test highlights, 1985

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Significant tests which were performed during calendar year 1985 in Langley test facilities, are highlighted. Both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research, are illustrated. Other highlights of Langley research and technology for 1985 are described in Research and Technology-1985 Annual Report of the Langley Research Center

2020 NASA Technology Taxonomy

This document is an update (new photos used) of the PDF version of the 2020 NASA Technology Taxonomy that will be available to download on the OCT Public Website. The updated 2020 NASA Technology Taxonomy, or "technology dictionary", uses a technology discipline based approach that realigns like-technologies independent of their application within the NASA mission portfolio. This tool is meant to serve as a common technology discipline-based communication tool across the agency and with its partners in other government agencies, academia, industry, and across the world

Aeronautical Engineering: A Continuing Bibliography with Indexes (supplement 194)

This bibliography lists 369 reports, articles and other documents introduced into the NASA scientific and technical information system in November 1985

Aeronautical engineering: A continuing bibliography with indexes (supplement 247)

This bibliography lists 437 reports, articles, and other documents introduced into the NASA scientific and technical information system in December, 1989. 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