Michael R. Elgersma

PARAMETER IDENTIFICATION FOR SYSTEMS WITH REDUNDANT ACTUATORS

Many current and future aircraft axe open-loop unstable, and have many control surfaces. When some of these control surfaces are damaged, the remaining control surfaces may still be capable of controlling the aircraft, if the controller is reconfigured quickly enough.

Piloted Simulation of Fault, Detection, Isolation, and Reconfiguration Algorithms for a Civil Transport Aircraft

Honeywell Labs has been researching and developing together with NASA Langley Research Center (LaRC) algorithms for aircraft failure management and recovery. The algorithms have been integrated into a Control Upset Prevention and Recovery System (CUPRSys) that provides control law reconflguration, fault detection, fault isolation and pilot cueing. This paper describes the capabilities of CUPRSys and the results from an evaluation of CUPRSys by an experimental test pilot in the Integration Flight Deck (IFD) at LaRC. Also included in the paper are details about the IFD and the MATLAB simulation environment used for design. The piloted evaluation was performed at three ∞ight conditions and the results for one representative maneuver are presented. Pilot ratings were obtained for maneuvers for the un-failed aircraft, for the failed aircraft without reconflguration and for the failed aircraft with reconflguration. Only reduction of surface efiectiveness faults were considered. The piloted simulation results suggest that CUPRSys provides a robust control law with promising fault detection, isolation and reconflguration capability.

Reconfigurable control for active management of aircraft system failures

In this paper, we describe development of a distributed failure detection and isolation system for commuter and business aircraft. In particular, we examine a nonlinear continuous/discrete system with mechanical components that can experience abrupt, partial, or full faults. The faults are discrete events, which lead to a simple hybrid model. We construct an aircraft model, suitable for simulation studies, allowing for several candidate failure scenarios (e.g., aircraft icing, failures of control surface actuators, stuck or floating control surfaces, etc.) that are amenable to improved control solutions. The failure detection, isolation and recovery technique identifies both discrete mode changes and continuous parameter values.

Statistical verification of two non-linear real-time UAV controllers

We present a versatile statistical verification methodology and we illustrate different uses of this methodology on two examples of nonlinear real-time UAV controllers. The first example applies our statistical methodology to the verification of a computation time property for a software implementation of a high-performance controller as a function of controller state variable values. The second example illustrates our statistical verification methodology applied to finding verifiably safe flight envelopes for a class of maneuvers, again as a function of controller state variable values. We compare our approach to verification with other statistical techniques used for estimating execution times and controller performance. We close with candidate topics for future work.

Failure accommodating aircraft control

Describes development and performance analysis of a failure accommodation system for the commuter and business aircraft control recovery. First, system failures are detected and isolated using a hierarchy of techniques that is chosen to ensure minimal disruption of operations and to minimize the number of false alarms. Successive layers in the diagnostics hierarchy are increasingly invasive. Once a failure has been detected and identified, the failure can be accommodated in several ways, from passive pilot cueing to active autopilot reconfiguration. An autopilot reconfiguration algorithm to accommodate failures wherever possible is developed. Some preliminary pilot cueing strategies and displays to alert pilots to true failures, provide guidance on recommended responses, and inform the pilot of any reconfigurations are also introduced.

Active Failure Management for Aircraft Control Recovery

This paper describes development and performance analysis of an active failure management system for the commuter and business aircraft control recovery. System failures are detected and isolated using a hierarchy of techniques that is chosen to ensure minimal disruption of operations and to minimize the number of false alarms. Successive layers in the diagnostics hierarchy are increasingly invasive. Higher layers will be invoked only when lower layers indicate a potential problem. Once a failure has been detected and identi ed, the failure can be accommodated in several ways, from passive pilot cueing to active autopilot recon guration. This paper also describes some preliminary pilot cueing strategies and displays to alert pilots to true failures, provide guidance on recommended responses, and inform the pilot of any recon gurations. 1

A new computational algorithm for 7R spatial mechanisms

Abstract This paper describes a new computational technique for the analysis of general 1-DOF, 7R spatial-mechanisms. The problem is first formulated in standard notation, using 4 × 4-matrices to represent Euclidean motions. A different mathematical notation is then introduced by which Euclidean motions are represented by pairs of quaternions. Basic quaternion facts are reviewed, and the fundamental system of equations is defined. Special techniques required to solve the fundamental system are then presented and applied to an example.

Model-based failure management for aircraft control recovery

Abstract This paper describes the development and the performance analysis of an active failure management system for aircraft control upset prevention and recovery. The development of failure detection and system parameter identification algorithms that can reliably detect and isolate system failures with minimal disruption of normal operations constitutes the heart of the paper.