Results of Attempts to Prevent Departure And/or Pilot-Induced Oscillations (PIO) Due to Actuator Rate Limiting in Highly-Augmented Fighter Flight Control Systems (HAVE FILTER).
Results of Attempts to Prevent Departure And/or Pilot-Induced Oscillations (PIO) Due to Actuator Rate Limiting in Highly-Augmented Fighter Flight Control Systems (HAVE FILTER).

Author: Michael Chapa

Publisher:

Published: 1999

Total Pages: 76

ISBN-13:

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The objective of this effort was to evaluate the effects of software rate limiting the pilot command with and without a software pre-filter on a highly-augmented fighter aircraft flight control system. The software rate limiter and software pre-filter were designed to provide protection from departure and/or pilot-induced oscillation (PIO). In statically unstable aircraft stabilized with feedback, elevator/stabilator actuator rate limiting may lead to PIOs and/or departure during aggressive maneuvers. This project examined the use of a software rate limiter (SWRL) on the pilot command and compared the results with those for the unprotected airframe. Additionally, a nonlinear rate limiter pre-filter (RLPF) was used in conjunction with the SWRL. Previous attempts to suppress PIO and/or departure tendencies using similar technologies have encountered difficulty with noise-in-the-loop and out-of-trim bias development during filter operation. This project attempted to improve previous designs using a different algorithm for the RLPF. The SWRL was found to help prevent PIO and/or departure. The RLPF plus SWRL was generally found to be more helpful than the SWRL alone at preventing PIO and/or departure. However, handling qualities deficiencies arose when using low SWRL settings and worsened with low SWRL settings used in conjunction with the RLPF.

A Comparison of Nonlinear Algorithms to Prevent Pilot-Induced Oscillations Caused by Actuator Rate Limiting
A Comparison of Nonlinear Algorithms to Prevent Pilot-Induced Oscillations Caused by Actuator Rate Limiting

Author: James G. Hanley

Publisher:

Published: 2003-03

Total Pages: 107

ISBN-13: 9781423504085

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The objective of this study was to compare the ability of the Feedback-with-Bypass (FWB) and the Derivative-Switching (DS) flight control system filters to prevent PIO during actuator rate limiting, and the filters' effects on aircraft handling qualities. This comparison was conducted in three steps: computer simulation, ground simulation in the Large Amplitude Multimode Aerospace Research Simulator (LAMARS), and flight tests conducted in the Variable Stability In-flight Simulator Test Aircraft (VISTA). During computer simulation, the FWB filter better reduced the phase lag and prevented sustained or divergent oscillations during the closed-loop analysis. During both ground simulation and flight tests, the FWB filter was more effective at preventing divergent PIO and improving handling qualities. Overall the FWB filter performed better during all tests.

A Comparison of Nonlinear Algorithms in the Prevention of Pilot-Induced Oscillations Caused by Actuator Rate Limiting (Project HAVE PREVENT).
A Comparison of Nonlinear Algorithms in the Prevention of Pilot-Induced Oscillations Caused by Actuator Rate Limiting (Project HAVE PREVENT).

Author:

Publisher:

Published: 2002

Total Pages: 58

ISBN-13:

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This report presents the results of Project HAVE PREVENT, a comparison of nonlinear algorithms in the prevention of pilot-induced oscillations (PlO) caused by actuator rate limiting. The overall test objective was to compare the ability of two flight control system filters in the prevention of PlO during actuator rate limiting. The Air Force Institute of Technology, Engineering Department (AFIT/ENY) requested this testing. The USAF Test Pilot School (TPS), Class O2A, conducted 13 flight tests totaling 21.0 hours at Edwards AFB, California, from 16 to 23 October 2002.

Aviation Safety and Pilot Control
Aviation Safety and Pilot Control

Author: National Research Council

Publisher: National Academies Press

Published: 1997-03-28

Total Pages: 221

ISBN-13: 0309056888

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Adverse aircraft-pilot coupling (APC) events include a broad set of undesirable and sometimes hazardous phenomena that originate in anomalous interactions between pilots and aircraft. As civil and military aircraft technologies advance, interactions between pilots and aircraft are becoming more complex. Recent accidents and other incidents have been attributed to adverse APC in military aircraft. In addition, APC has been implicated in some civilian incidents. This book evaluates the current state of knowledge about adverse APC and processes that may be used to eliminate it from military and commercial aircraft. It was written for technical, government, and administrative decisionmakers and their technical and administrative support staffs; key technical managers in the aircraft manufacturing and operational industries; stability and control engineers; aircraft flight control system designers; research specialists in flight control, flying qualities, human factors; and technically knowledgeable lay readers.

An Investigation Relating Longitudinal Pilot-Induced Oscillation Tendency Ratings to Describing Function Predictions for Rate-Limited Actuators (Project MAX GAP).
An Investigation Relating Longitudinal Pilot-Induced Oscillation Tendency Ratings to Describing Function Predictions for Rate-Limited Actuators (Project MAX GAP).

Author:

Publisher:

Published: 2003

Total Pages: 135

ISBN-13:

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This report presents the results of Project MAX QAP, a method of predicting pilot induced oscillations (PIO) caused by actuator rate limiting. The overall test objective was to correlate, if possible, Pilot-induced Oscillation Tendency Ratings with a new preflight calculation called the Gap Criterion. The Air Force Institute of Technology, Engineering Department (AFIT/ENY) requested this testing. The USAF Test Pilot School (TPS), Class 03A, conducted 8 flight test totaling 10.8 hours at Edwards AFB, California, from 16 to 22 October 2003.

A Limited Flight Test Investigation of Pilot-Induced Oscillation Due to Elevator Rate Limiting (HAVE LIMITS).
A Limited Flight Test Investigation of Pilot-Induced Oscillation Due to Elevator Rate Limiting (HAVE LIMITS).

Author:

Publisher:

Published: 1997

Total Pages: 0

ISBN-13:

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The report presents the results of a limited flight test investigation of pilot-induced oscillation (PIO) due to elevator rate limiting. The objective of this effort was to gather in-flight and ground-based simulation data on longitudinal PIO tendecies due to elevator rate limiting. Preliminary, ground-based simulation was conducted at the USAF Test Pilot School (TPS) from 1 March to 9 April 1997. Nine sorties, totaling 12.8 flight hours, were flown in the NT-33A aircraft. Additional ground-based simulation was conducted at the Flight Dynamics Directorate, Wright-Patterson AFB, Ohio, on 25 April 1997. The USAF TPS was the responsible test organization.