Engineering topics

Dunn, H. J.

Publications and source records attributed to Dunn, H. J..

23 records · Page 2

NASA NTRS1980

Realizable optimal control for a remotely piloted research vehicle

The design of a control system using the linear-quadratic regulator (LQR) control law theory for time invariant systems in conjunction with an incremental gradient procedure is presented. The incremental gradient technique reduces the full-state feedback controller design, generated by the LQR algorithm, to a realizable design. With a realizable controller, the feedback gains are based only on the available system outputs instead of being based on the full-state outputs. The design is for a remotely piloted research vehicle (RPRV) stability augmentation system. The design includes methods for accounting for noisy measurements, discrete controls with zero-order-hold outputs, and computational delay errors. Results from simulation studies of the response of the RPRV to a step in the elevator and frequency analysis techniques are included to illustrate these abnormalities and their influence on the controller design.

Dunn, H. J.↗

NASA NTRS1980

Active flutter suppression using Linear Quadratic Gaussian theory

This paper describes the application of Linear Quadratic Gaussian (LQG) methodology to the design of active control systems for suppression of aerodynamic flutter. A full-size wind tunnel model of a supercritical wing with associated sensors and actuators comprises the system to be controlled. Results of a synthesis methodology that provide small values of rms response, insensitivity to flight condition, and robust stability are presented. Results of control surface and sensor position optimization are also presented. Both frequency response matching and residualization are used to obtain practical flutter controllers.

Mahesh, J. K.↗

NASA NTRS1979

Application of two synthesis methods for active flutter suppression on an aeroelastic wind tunnel model

Two flutter suppression control laws have been synthesized, implemented, and demonstrated on an aeroelastic wind-tunnel model of a transport-type wing. One control law was synthesized using an aerodynamic energy method and the other from using results of optimal control theory. At M = 0.95, the model was tested to a dynamic pressure 44 percent above the system-off flutter dynamic pressure. Both synthesis methods yielded control laws effective in suppressing flutter. The experimental results also indicate that wind-tunnel turbulence is an important factor in the experimental demonstration of system performance.

Abel, I.↗

NASA NTRS1977

A moving window parameter adaptive control system for the F8-DFBW aircraft

This paper describes the moving window parameter adaptive control system developed for the NASA F8-DFBW aircraft. The control system employs a parameter identification process that, iteratively, adjusts parameters of a model of the aircraft motions in a batch-processing manner so that responses generated from the model fit the outputs of sensors stored in a finite record referred to as the moving window. Tests are made on the validity of the parameter estimates before using the parameters in an on-line design process. The on-line design process is an algebraic mapping of the parameters of the model into primary control system feedback and feedforward gains. The mapping was selected to satisfy specific flying quality characteristics over the range of parameter variations expected. Results are presented from simulation studies on the identification algorithm made during the development of the system.

Dunn, H. J.↗

NASA NTRS1976

A moving-window parameter adaptive control system for the F8-DFBW aircraft

This paper describes the moving-window parameter adaptive control system developed for the NASA F8-DFBW aircraft. The control system employs a parameter identification process that, iteratively, adjusts parameters of a model of the aircraft motions in a batch processing manner so that responses generated from the model fit the outputs of sensors stored in a finite record referred to as the moving window. Tests are made on the validity of the parameter estimates before using the parameters in an on-line design process. The on-line design process is an algebraic mapping of the parameters of the model into primary control system feedback and feedforward gains. The mapping was selected to satisfy specific flying quality characteristics over the range of parameter variations expected. Results are presented from simulation studies on the identification algorithm, tests for parameter validity, and the on-line design process.

Montgomery, R. C.↗