Eigenvalue/eigenvector assignment using output feedback

The problem of eigenvalue assignment in a linear time-invariant system using output feedback is considered. New sufficient conditions are derived to assign an almost arbitrary set of minimum (n,m + r - 1) distinct eigenvalues where n, m, and r are the number of states, inputs, and outputs, respectively. These conditions precisely identify the class of systems where such an assignment is impossible. The synthesis technique also highlights the freedom in selection of closed-loop eigenvectors under output feedback. The utility of eigenvalue/eigenvector assignment in transient response shaping is illustrated by the design of a controller for the lateral dynamics of an aircraft

Flutter suppression for the active flexible wing: Control system design and experimental validation AIAA-92-2097

The synthesis and experimental validation of a control law for13; an actiqe flutter suppression system for the Active Flexible13; Wing wind-tunnel model is presenied. The design was13; accomplished with traditional root locus and Nyquist methods13; using interactive computer graphics tools and with extensive use13; of simulation-based analysis. The design approach relied on a13; fundamental understanding of the flutter mechanism to13; formulate a simple control law structure. Experimentally, the13; flutter suppression controller succeeded in simultaneous13; suppression of two flutter modes, significantly increasing the13; flutter dynamic pressure despite errors in the design model. The13; flutter suppression controller was also successfully operated in13; combination with a rolling maneuver controller to perform13; flutter suppression during rapid rolling maneuvers

Modal control theory and application to aircraft lateral handling qualities design

A multivariable synthesis procedure based on eigenvalue/eigenvector assignment is reviewed and is employed to develop a systematic design procedure to meet the lateral handling qualities design objectives of a fighter aircraft over a wide range of flight conditions. The closed loop modal characterization developed provides significant insight into the design process and plays a pivotal role in the synthesis of robust feedback systems. The simplicity of the synthesis algorithm yields an efficient computer aided interactive design tool for flight control system synthesis

Spectral Characterization of Multi-input Dynamic Systems

Electrical Engineerin

Design, test, and evaluation of three active flutter suppression controllers

Three control law design techniques for flutter suppression are presented. Each technique uses multiple control surfaces and/or sensors. The first method uses traditional tools (such as pole/zero loci and Nyquist diagrams) for producing a controller that has minimal complexity and which is sufficiently robust to handle plant uncertainty. The second procedure uses linear combinations of several accelerometer signals and dynamic compensation to synthesize the model rate of the critical mode for feedback to the distributed control surfaces. The third technique starts with a minimum-energy linear quadratic Gaussian controller, iteratively modifies intensity matrices corresponding to input and output noise, and applies controller order reduction to achieve a low-order, robust controller. The resulting designs were implemented digitally and tested subsonically on the active flexible wing wind-tunnel model in the Langley Transonic Dynamics Tunnel. Only the traditional pole/zero loci design was sufficiently robust to errors in the nominal plant to successfully suppress flutter during the test. The traditional pole/zero loci design provided simultaneous suppression of symmetric and antisymmetric flutter with a 24-percent increase in attainable dynamic pressure. Posttest analyses are shown which illustrate the problems encountered with the other laws

Aeroservoelastic wind-tunnel investigations using the Active Flexible Wing Model: Status and recent accomplishments

The status of the joint NASA/Rockwell Active Flexible Wing Wind-Tunnel Test Program is described. The objectives are to develop and validate the analysis, design, and test methodologies required to apply multifunction active control technology for improving aircraft performance and stability. Major tasks include designing digital multi-input/multi-output flutter-suppression and rolling-maneuver-load alleviation concepts for a flexible full-span wind-tunnel model, obtaining an experimental data base for the basic model and each control concept and providing comparisons between experimental and analytical results to validate the methodologies. The opportunity is provided to improve real-time simulation techniques and to gain practical experience with digital control law implementation procedures

Eigenstructure Control: A flight vehicle handling qualities design tool

With the development of high reliability sensors, computers and actuators, it is now possible to build flight vehicle control systems with extraordinary performance. Indeed full authority fly-by-wire flight vehicles using feedback controllers can substantially mask the basic airframe dynamic characteristics and consequently its performance limitations. These technology developments in turn have brought into focus the role of multivariable control system design methods to evolve complex multi-loop systems using multiple sensors and control effectors. Multivariable control techniques are now being demonstrated in experimental flight research programs. It is thus reasonable to expect that these methods will be used in flight vehicle control design of production aircraft as increased sophistication in airframe design and performance is sought. Among the many control techniques available for such design, Eigenstructure Control techniques offer some unique advantages since the flight vehicle handling qualities requirements originate in the modal control framework. The present study explores methods to adapt this method for deriving practical flight control laws

Aircraft parameter estimation control and simulation (APES) computer: an Evaluation of quotations

Proposal of APES Computer system from the vendors are presented in this repor

Estimation of teh longitudinal stability characteristics of MiG-21BIS aircraft from flight data

This report presents the parameter estimation results derived from flight test data of a MIG-21BIS aircraft. The flight test program was executed by Aircraft & Systems Testing Establishment (ASTE) and the flight data analysis was carried out at NAL. The aircraft was tested in four configurations to evaluate the effect of i) a vortex plate attached to the leading edge of the wing to improve the drag characteristics and ii) a larger saddle tank to improve the range

Estimation of neutral and maneuver points of aircraft by dynamic maneuvers AIAA-93-3620

A new flight test technique, based on13; aircraft parameter estimation methods, is13; proposed to simultaneously determine the neutral13; and maneuver point of aircraft. The new13; procedure is derived by relating the neutral point13; and maneuver point of an aircraft to key short13; period parameters Ma and short period natural13; frequency w,' respectively. The new flight test13; method results in substantial savings in flight test13; time compared to conventional methods. The13; method is more accurate since only inertial sensor13; data (pitch rate and normal acceleration) is used13; in the estimation procedure