Author: Aaron J. Ostroff
Publisher:
ISBN:
Category : Feedback control systems
Languages : en
Pages : 28

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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722149260
Category :
Languages : en
Pages : 24

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This paper describes the design and evaluation of a stochastic optimal feed-forward and feedback technology (SOFFT) control architecture with emphasis on the feed-forward controller design. The SOFFT approach allows the designer to independently design the feed-forward and feedback controllers to meet separate objectives and then integrate the two controllers. The feed-forward controller has been integrated with an existing high-angle-of-attack (high-alpha) feedback controller. The feed-forward controller includes a variable command model with parameters selected to satisfy level 1 flying qualities with a high-alpha adjustment to achieve desired agility guidelines, a nonlinear interpolation approach that scales entire matrices for approximation of the plant model, and equations for calculating feed-forward gains developed for perfect plant-model tracking. The SOFFT design was applied to a nonlinear batch simulation model of an F/A-18 aircraft modified for thrust vectoring. Simulation results show that agility guidelines are met and that the SOFFT controller filters undesired pilot-induced frequencies more effectively during a tracking task than a flight controller that has the same feedback control law but does not have the SOFFT feed-forward control. Ostroff, Aaron J. and Proffitt, Melissa S. Langley Research Center RTOP 505-64-30-01...

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722909970
Category :
Languages : en
Pages : 152

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A new control design methodology is developed: Stochastic Optimal Feedforward and Feedback Technology (SOFFT). Traditional design techniques optimize a single cost function (which expresses the design objectives) to obtain both the feedforward and feedback control laws. This approach places conflicting demands on the control law such as fast tracking versus noise atttenuation/disturbance rejection. In the SOFFT approach, two cost functions are defined. The feedforward control law is designed to optimize one cost function, the feedback optimizes the other. By separating the design objectives and decoupling the feedforward and feedback design processes, both objectives can be achieved fully. A new measure of command tracking performance, Z-plots, is also developed. By analyzing these plots at off-nominal conditions, the sensitivity or robustness of the system in tracking commands can be predicted. Z-plots provide an important tool for designing robust control systems. The Variable-Gain SOFFT methodology was used to design a flight control system for the F/A-18 aircraft. It is shown that SOFFT can be used to expand the operating regime and provide greater performance (flying/handling qualities) throughout the extended flight regime. This work was performed under the NASA SBIR program. ICS plans to market the software developed as a new module in its commercial CACSD software package: ACET. Halyo, Nesim and Direskeneli, Haldun and Taylor, Deborah B. Unspecified Center AIRCRAFT CONTROL; AIRCRAFT PERFORMANCE; CONTROL SYSTEMS DESIGN; F-18 AIRCRAFT; FEEDBACK CONTROL; FEEDFORWARD CONTROL; FLIGHT CONTROL; OPTIMAL CONTROL; STOCHASTIC PROCESSES; APPLICATIONS PROGRAMS (COMPUTERS); FLIGHT CHARACTERISTICS; SENSITIVITY...

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 836

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Author:
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ISBN:
Category :
Languages : en
Pages : 392

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Author:
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ISBN:
Category : Science
Languages : en
Pages : 1302

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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723182426
Category :
Languages : en
Pages : 102

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The need for integrated/constrained control systems has become clearer as advanced aircraft introduced new coupled subsystems such as new propulsion subsystems with thrust vectoring and new aerodynamic designs. In this study, we develop an integrated control design methodology which accomodates constraints among subsystem variables while using the Stochastic Optimal Feedforward/Feedback Control Technique (SOFFT) thus maintaining all the advantages of the SOFFT approach. The Integrated SOFFT Control methodology uses a centralized feedforward control and a constrained feedback control law. The control thus takes advantage of the known coupling among the subsystems while maintaining the identity of subsystems for validation purposes and the simplicity of the feedback law to understand the system response in complicated nonlinear scenarios. The Variable-Gain Output Feedback Control methodology (including constant gain output feedback) is extended to accommodate equality constraints. A gain computation algorithm is developed. The designer can set the cross-gains between two variables or subsystems to zero or another value and optimize the remaining gains subject to the constraint. An integrated control law is designed for a modified F-15 SMTD aircraft model with coupled airframe and propulsion subsystems using the Integrated SOFFT Control methodology to produce a set of desired flying qualities. Halyo, Nesim Langley Research Center FEEDFORWARD CONTROL; FEEDBACK; OPTIMAL CONTROL; PROPULSION; THRUST VECTOR CONTROL; F-15 AIRCRAFT; CONTROL SYSTEMS DESIGN; STOCHASTIC PROCESSES; CONTROL THEORY; NONLINEARITY; COMPUTATION...

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 522

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Author: Nesim Halyo
Publisher:
ISBN:
Category :
Languages : en
Pages : 156

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Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 866

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