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  • 1
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    Design of neural network-based estimator for tool wear modeling in hard turning (2008)
    Springer
    Details
    Publication Date: 2008-01-25
    Print ISSN: 0956-5515
    Electronic ISSN: 1572-8145
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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    PAPER CURRENT
  • 2
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    Aircraft Fault Detection and Classification Using Multi-Level Immune Learning Detection (2005)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: This work is an extension of a recently developed software tool called MILD (Multi-level Immune Learning Detection), which implements a negative selection algorithm for anomaly and fault detection that is inspired by the human immune system. The immunity-based approach can detect a broad spectrum of known and unforeseen faults. We extend MILD by applying a neural network classifier to identify the pattern of fault detectors that are activated during fault detection. Consequently, MILD now performs fault detection and identification of the system under investigation. This paper describes the application of MILD to detect and classify faults of a generic transport aircraft augmented with an intelligent flight controller. The intelligent control architecture is designed to accommodate faults without the need to explicitly identify them. Adding knowledge about the existence and type of a fault will improve the handling qualities of a degraded aircraft and impact tactical and strategic maneuvering decisions. In addition, providing fault information to the pilot is important for maintaining situational awareness so that he can avoid performing an action that might lead to unexpected behavior - e.g., an action that exceeds the remaining control authority of the damaged aircraft. We discuss the detection and classification results of simulated failures of the aircraft's control system and show that MILD is effective at determining the problem with low false alarm and misclassification rates.
    Keywords: Aircraft Stability and Control
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Towards Intelligent Control for Next Generation Aircraft (2008)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: NASA Aeronautics Subsonic Fixed Wing Project is focused on mitigating the environmental and operation impacts expected as aviation operations triple by 2025. The approach is to extend technological capabilities and explore novel civil transport configurations that reduce noise, emissions, fuel consumption and field length. Two Next Generation (NextGen) aircraft have been identified to meet the Subsonic Fixed Wing Project goals - these are the Hybrid Wing-Body (HWB) and Cruise Efficient Short Take-Off and Landing (CESTOL) aircraft. The technologies and concepts developed for these aircraft complicate the vehicle s design and operation. In this paper, flight control challenges for NextGen aircraft are described. The objective of this paper is to examine the potential of state-of-the-art control architectures and algorithms to meet the challenges and needed performance metrics for NextGen flight control. A broad range of conventional and intelligent control approaches are considered, including dynamic inversion control, integrated flight-propulsion control, control allocation, adaptive dynamic inversion control, data-based predictive control and reinforcement learning control.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN121 , International Powered Lift Conference; Jul 22, 2008 - Jul 24, 2008; London; United Kingdom
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Needs-Driven (Rationalistic) Autonomy (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This presentation discusses rationalistic autonomy context, various autonomy scenarios of interest, and the technical challenges associated with autonomy.
    Keywords: Cybernetics, Artificial Intelligence and Robotics
    Type: ARC-E-DAA-TN17333 , 2014 Intelligent Systems Workshop; Aug 08, 2014; CLeveland, OH; United States
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    NASA TECHNICAL REPORTS
  • 5
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    Input and Output Performance of M-MRAC in the Presence of Bounded Disturbances (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper presents performance analysis of novel modified model reference adaptive control (M-MRAC) architecture in conjunction with different robust adaptive laws for the uncertain linear systems subject to unknown but bounded disturbances. It is shown that for any robust adaptive law the tracking error of the M-MRAC system can be arbitrarily decreased in transient and in the steady-state by increasing the adaptation rate, without generating high frequency oscillations in the control signal, which are unavoidable in conventional MRAC systems for large adaptation rates. Moreover, the generated adaptive control signal arbitrary closely tracks the ideal control signal when the error feedback gain is simultaneously increased with the adaptation rate, according to derived rule. The results are demonstrated via simulations.
    Keywords: Mathematical and Computer Sciences (General)
    Type: ARC-E-DAA-TN1961 , AIAA Guidance, Navigation and Control Conference; Aug 02, 2010 - Aug 05, 2010; TOronto, Ontario; Canada
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Predicting Loss-of-Control Boundaries Toward a Piloting Aid (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This work presents an approach to predicting loss-of-control with the goal of providing the pilot a decision aid focused on maintaining the pilot's control action within predicted loss-of-control boundaries. The predictive architecture combines quantitative loss-of-control boundaries, a data-based predictive control boundary estimation algorithm and an adaptive prediction method to estimate Markov model parameters in real-time. The data-based loss-of-control boundary estimation algorithm estimates the boundary of a safe set of control inputs that will keep the aircraft within the loss-of-control boundaries for a specified time horizon. The adaptive prediction model generates estimates of the system Markov Parameters, which are used by the data-based loss-of-control boundary estimation algorithm. The combined algorithm is applied to a nonlinear generic transport aircraft to illustrate the features of the architecture.
    Keywords: Avionics and Aircraft Instrumentation
    Type: ARC-E-DAA-TN5393 , AIAA Infotech@Aerospace 2012; Jun 19, 2012 - Jun 21, 2012; Garden Grove, CA; United States
    Format: application/pdf
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  • 7
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    M-MRAC for Nonlinear Systems with Bounded Disturbances (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper presents design and performance analysis of a modified reference model MRAC (M-MRAC) architecture for a class of multi-input multi-output uncertain nonlinear systems in the presence of bounded disturbances. M-MRAC incorporates an error feedback in the reference model definition, which allows for fast adaptation without generating high frequency oscillations in the control signal, which closely follows the certainty equivalent control signal. The benefits of the method are demonstrated via a simulation example of an aircraft's wing rock motion.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN4164 , 50th IEEE Conference on Decision and Control; Dec 12, 2012; Orlando, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Adaptive Control with Reference Model Modification (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This paper presents a modification of the conventional model reference adaptive control (MRAC) architecture in order to improve transient performance of the input and output signals of uncertain systems. A simple modification of the reference model is proposed by feeding back the tracking error signal. It is shown that the proposed approach guarantees tracking of the given reference command and the reference control signal (one that would be designed if the system were known) not only asymptotically but also in transient. Moreover, it prevents generation of high frequency oscillations, which are unavoidable in conventional MRAC systems for large adaptation rates. The provided design guideline makes it possible to track a reference commands of any magnitude from any initial position without re-tuning. The benefits of the method are demonstrated with a simulation example
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN4734
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Coordinated Turn Trajectory Generation and Tracking Control for Multi-rotors Operating in Urban Environment (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The paper presents an efficient trajectory generation and tracking approach for multi-rotor air vehicles operating in urban environment, which takes into account uncertainties in the urban wind field and in the vehicle's parameters. Generated trajectories are sufficiently smooth, based on the differential flatness of the vehicle's dynamics and optimal in the sense of minimum agility and time. They pass through given set of way points, guarantee flight without a side-slip, and satisfy vehicle's dynamics and actuator constraints. In addition, an algorithm is presented to compute the required power to traverse the generated trajectory. Presented algorithms are implementable in real time using on-board computers. They do not take into account the vehicle's existing flight controller, hence there is no guarantee that the controller will be able to provide acceptable tracking of the generated trajectory, especially in the presence of atmospheric disturbances. To this end, we propose an adaptive augmentation algorithm to improve vehicle's performance by taking into account the effects of disturbances and on-line estimates of vehicle's existing flight controller's gains. The algorithms have been verified by simulations using DJI S1000 octocopter's model.
    Keywords: Air Transportation and Safety
    Type: ARC-E-DAA-TN64488 , AIAA Science and Technology Forum and Exposition; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 10
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    M-MRAC With Normalization (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: This paper presents a normalization based modified reference model adaptive control method for multi-input multi-output (MIMO) uncertain systems in the presence of bounded external disturbances. It has been shown that desired tracking performance can be achieved for the system's output and input signals with the proper choice of design parameters. The resulting adaptive control signal satisfies a second order linear time invariant (LTI) system, which is the effect of the normalization term in the adaptive laws. This LTI system provides the guideline for the design parameter selection. The theoretical findings are confirmed via a simulation example.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN17809 , IEEE Conference on Decision and Control (CDC); Dec 15, 2014 - Dec 17, 2014; Los Angeles, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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