Engineering topics

Eterno, J. S.

Publications and source records attributed to Eterno, J. S..

7 records

NASA NTRS1986

Initial design and evaluation of automatic restructurable flight control system concepts

Results of efforts to develop automatic control design procedures for restructurable aircraft control systems is presented. The restructurable aircraft control problem involves designing a fault tolerance control system which can accommodate a wide variety of unanticipated aircraft failure. Under NASA sponsorship, many of the technologies which make such a system possible were developed and tested. Future work will focus on developing a methodology for integrating these technologies and demonstration of a complete system.

Weiss, J. L.↗

NASA NTRS1986

Simulation results of automatic restructurable flight control system concepts

The restructurable flight control system (RFCS) described by Weiss et al. (1986) is reviewed, and several results of an extensive six degrees of freedom nonlinear simulation of several aspects of this system are reported. It is concluded that the nontraditional use of standard control surfaces in a nominal feedback control system to spread control authority among many redundant control elements provides a significant amount of fault tolerance without any use of restructuring techniques. The use of new feedback gains alone following a failure can provide significantly improved recovery as long as the control elements remain within their travel limits and as long as uncertainty about the failure identity is properly handled. The use of the feed-forward trim solution in conjunction with redesigned feedback gains allows recovery to take place even when significant control saturation occurs.

Weiss, J. L.↗

NASA NTRS1986

Evaluation of detectability and distinguishability of aircraft control element failures using flight test data

This paper examines the detectability and distinguishability of control element failures on the B-737 aircraft. The results of Weiss (1985) are used to define decentralized residuals from analytic redundancy relationships, and the results of Weiss et al. (1984) are used to define the probabilistic distance measures which provide bounds on the minimum achievable probabilities or error. The residual signals are then generated using data which were recorded during a landing approach of the NASA-Langley Advanced Transport Operations (ATOPS) transportation systems research vehicle (TSRV). The distance measures are computed using estimates of the statistics of these residual signals.

Weiss, J. L.↗

NASA NTRS1985

Robust detection-isolation-accommodation for sensor failures

The results of a one year study to: (1) develop a theory for Robust Failure Detection and Identification (FDI) in the presence of model uncertainty, (2) develop a design methodology which utilizes the robust FDI ththeory, (3) apply the methodology to a sensor FDI problem for the F-100 jet engine, and (4) demonstrate the application of the theory to the evaluation of alternative FDI schemes are presented. Theoretical results in statistical discrimination are used to evaluate the robustness of residual signals (or parity relations) in terms of their usefulness for FDI. Furthermore, optimally robust parity relations are derived through the optimization of robustness metrics. The result is viewed as decentralization of the FDI process. A general structure for decentralized FDI is proposed and robustness metrics are used for determining various parameters of the algorithm.

Weiss, J. L.↗

NASA NTRS1985

An automatic redesign approach for restructurable control systems

This paper presents an approach to the automatic redesign of flight control systems for aircraft that have suffered one or more control element failures. The procedure is based on Linear Quadratic design techniques, and produces a control system that maximizes a measure of feedback system performance subject to a bandwidth constraint.

Looze, D. P.↗

NASA NTRS1985

Application of FDI metrics to detection and isolation of sensor failures in turbine engines

This paper develops a framework for the design of failure detection and isolation (FDI) algorithms. Rather than trying to apply 'optimal' techniques in a top-down manner, the system redundancies are evaluated with respect to their ability to provide reliable FDI information. Previous work of Pattipati et al. (1984) and Weiss et al. (1984) defined a useful context and several useful analytical results, which provide a basis for the FDI design methodology developed here. A general decision structure which can take advantage of redundancy evaluation is presented, and examples of typical design considerations are discussed. The operation of the decision structure is then demonstrated for a sensor FDI application involving the F-100 jet engine.

Weiss, J. L.↗

NASA NTRS1984

A design methodology for robust failure detection and isolation

A decentralized failure detection and isolation (FDI) methodology, which is robust with respect to model uncertainties and noise, is presented Redundancy metrics are developed, and optimization problems are posed for the choices of robust parity relations. Closed-form solutions for some special failure cases are given. Connections are drawn with other disciplines, and the use of the metrics to evaluate alternative FDI schemes is discussed.

Pattipati, K. R.↗