Integrated Flight/propulsion Control with Variable Rotor Speed Command for Rotorcraft PDF Download
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Author: Stanford University. Department of Aeronautics and Astronautics
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Book Description
Author: Stanford University. Department of Aeronautics and Astronautics
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Book Description
Author: James R. Mihaloew
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 40
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Book Description
Author: Wei Guo
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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Book Description
Flight control design issues for rotorcraft with variable rotor speed are investigated, and new design methodologies are developed to deal with the challenges of variable rotor speed. The benefits of using variable rotor speed for rotorcraft are explored with a rotor speed optimization study using a modified GENHEL model of UH-60A Blackhawk. The optimization results recommend to use the optimal rotor speed in each flight condition to improve the helicopter performance. The efforts are made to accommodate the optimal rotor speed schedule into the flight control system design and also address the stability issues due to the rotor speed variation. The rotor speed optimization results show significant performance improvements can be achieved with moderate reductions in rotor speed. The objective of the control design is to accommodate these rotor speed variations, while achieving desired flying qualities and maneuver performance. A gain scheduled model following/model inversion controller is used to control the roll, pitch, yaw, heave, and rotor speed degrees of freedom. Rotor speed is treated as a redundant control effector for the heave axis, and different control allocation schemes are investigated. The controllers are evaluated based on step responses and the ADS-33E height response requirement. Results show that dynamic variation in rotor speed can improve maximum climb rate and flying qualities for moderate to large commands in vertical speed, but that non-linear effects present significant challenges when integrating control of the aircraft and the engine. The effects of reduced rotor speeds on stability margins, torque required, and stability issues are also studied. A power command system in the vertical axis is designed to incorporate variable rotor speed while handling torque limits and other constraints. The vertical axis controller uses a fixed nonlinear mapping to find the combination of collective pitch and rotor speed to optimize performance in level flight, climbing/descending flight, and steady turns. In this scheme, the controller is open-loop, making it an inexpensive and reliable solution. The mapping is designed to produce a desired power level for a given pilot input. Thus the mapping can take into account the performance limits associated with the vertical axis such as power limits, torque limits, and maximum rate of descent. A model following controller is implemented for the pitch, roll, and yaw axes. The piloted simulation was performed to evaluate the controller. The impact of variable rotor speed on closed loop stability of rotorcraft is discussed. The model following controller can provide high bandwidth control and improve performance using variable rotor speed. However, reduction of rotor speed can result in rotor body coupling and even instability. A rotor state feedback control law can be designed independently and easily integrated into the baseline model following control architecture. Simulations were performed to verify the effectiveness of RSF control to stabilize the rotorcraft dynamics or improve the command tracking performance in the presence of reduced rotor RPM.
Author: James R. Mihaloew
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 40
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Book Description
Author: Duane Loren Mattern
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
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Book Description
Propulsion-system-specific results are presented from the application of the integrated methodology for propulsion and airframe control (IMPAC) design approach to integrated flight/propulsion control design for a 'short takeoff and vertical landing' (STOVL) aircraft in transition flight. The IMPAC method is briefly discussed and the propulsion system specifications for the integrated control design are examined. The structure of a linear engine controller that results from partitioning a linear centralized controller is discussed. The details of a nonlinear propulsion control system are presented, including a scheme to protect the engine operational limits: the fan surge margin and the acceleration/deceleration schedule that limits the fuel flow. Also, a simple but effective multivariable integrator windup protection scheme is examined. Nonlinear closed-loop simulation results are presented for two typical pilot commands for transition flight: acceleration while maintaining flightpath angle and a change in flightpath angle while maintaining airspeed. The simulation nonlinearities include the airframe/engine coupling, the actuator and sensor dynamics and limits, the protection scheme for the engine operational limits, and the integrator windup protection. Satisfactory performance of the total airframe plus engine system for transition flight, as defined by the specifications, was maintained during the limit operation of the closed-loop engine subsystem.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722748029
Category :
Languages : en
Pages : 30
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Book Description
The NASA Ames and Lewis Research Centers, in conjunction with the Army Research and Technology Laboratories have initiated and completed, in part, a joint research program focused on improving the performance, maneuverability, and operating characteristics of rotorcraft by integrating the flight and propulsion controls. The background of the program, its supporting programs, its goals and objectives, and an approach to accomplish them are discussed. Results of the modern control governor design of the T700 and the Rotorcraft Integrated Flight-Propulsion Control Study, which were key elements of the program, are also presented. Mihaloew, James R. and Ballin, Mark G. and Ruttledge, D. G. C. Ames Research Center; Glenn Research Center ...
Author: Walter C. Merrill
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Author: James F. Stewart
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
Author: James F. Stewart
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 32
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Book Description
Author: Naveen Kumar Vallabhaneni
Publisher: LAP Lambert Academic Publishing
ISBN: 9783848431472
Category :
Languages : en
Pages : 112
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Book Description
Explore the variable speed operation and shift response of a prototype of a continuously variable rotorcraft propulsion system and development of a Comprehensive Variable Speed Rotorcraft Propulsion system Modeling (CVSRPM) tool.Simulate the drive system dynamics in steady forward speed condition in an attempt to build upon previous variable speed rotorcraft propulsion studies by including, fully nonlinear first principles based transient gas-turbine engine model with shaft flexibility and incorporating a basic flight dynamics model to account for interactions with the flight control system. Explore the interactions between the various subsystems and obtain insight into the continuing development of variable speed rotorcraft propulsion systems and a study of various variable ratio transmissions that have already been explored.
