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At least 1,081 records · Page 60

Insensitive control technology development

THe investigation of two insensitive controller synthesis techniques was reported. The finite dimensional inverse approach produces a time varying insensitive controller and/or parameter identifier by constructing inverse functions derived from a finite number of input output pair relationships. The MD/IM concept relies on the information matrix theory that was developed in the estimation and identification field. The MD/IM synthesis technique is based on the hypothesis that minimizing the information matrix will reduce system identifiability and consequently system sensitivity to uncertain parameters. The controllers designed with both techniques were evaluated on a realistic C-5A aircraft flight control problem. Results indicate that the FDI controller is more suited to trajectory type problems because of its time varying nature. The MD/IM controller performed as well as the top-rated controllers of the initial effort and has direct application to aircraft flight control problems.

Harvey, C. A.↗

High Reynolds Number Hybrid Laminar Flow Control (HLFC) Flight Experiment: Aerodynamic Design - Report 2

This document describes the aerodynamic design of an experimental hybrid laminar flow control (HLFC) wing panel intended for use on a Boeing 757 airplane to provide a facility for flight research on high Reynolds number HLFC and to demonstrate practical HLFC operation on a full-scale commercial transport airplane. The design consists of revised wing leading edge contour designed to produce a pressure distribution favorable to laminar flow, definition of suction flow requirements to laminarize the boundary layer, provisions at the inboard end of the test panel to prevent attachment-line boundary layer transition, and a Krueger leading edge flap that serves both as a high lift device and as a shield to prevent insect accretion on the leading edge when the airplane is taking off or landing.

Source record↗

Automation of Commanding at NASA: Reducing Human Error in Space Flight

Automation has been implemented in many different industries to improve efficiency and reduce human error. Reducing or eliminating the human interaction in tasks has been proven to increase productivity in manufacturing and lessen the risk of mistakes by humans in the airline industry. Human space flight requires the flight controllers to monitor multiple systems and react quickly when failures occur so NASA is interested in implementing techniques that can assist in these tasks. Using automation to control some of these responsibilities could reduce the number of errors the flight controllers encounter due to standard human error characteristics. This paper will investigate the possibility of reducing human error in the critical area of manned space flight at NASA.

Dorn, Sarah J.↗

Wright Brothers Lectureship in Aeronautics: Experience with HiMAT remotely piloted research vehicle - An alternate flight test approach

The highly maneuverable aircraft technology (HiMAT) program explored the various and complex interactions of advanced technologies, such as aeroelastic tailoring, close-coupled canard, and relaxed static stability. A 0.44-subscale remotely piloted research vehicle (RPRV) of a hypothetical fighter airplane was designed and flight-tested to determine the effects of these interactions and to define the design techniques appropriate for advanced fighter technologies. Flexibility and high maneuverability were provided by flight control laws implemented in ground-based computers and telemetered to the vehicle control system during flight tests. The high quality of the flight-measured data and their close correlation with the analytical design modeling proved that the RPRV is a viable and cost-effective tool for developing aerodynamic, structure, and control law requirements for highly maneuverable fighter airplanes of the future.

Deets, D. A.↗

Nonlinear control of a supermaneuverable aircraft

This paper describes a technique which may be used to design the flight control system for a highly maneuverable aircraft. The control system was provided to stabilize the dynamics of the aircraft model and allow it to fly simulated, poststall 'supermaneuvers'. Although the aircraft dynamics are highly nonlinear under these conditions, the gain-scheduled, flight control system was designed using basically linear techniques. A manuever generator was implemented to pilot the mathematical model through prescribed optimal trajectories. The control system design performed well while executing maneuvers involving small angular rates where the governing dynamics could be considered linear. However, the performance deteriorated once the model was subjected to high angular rates at high angle of attack.

Snell, S. Antony↗

ISPATOM: A Generic Real-Time Data Processing Tool Without Programming

Information Sharing Protocol Advanced Tool of Math (ISPATOM) is an application program allowing for the streamlined generation of comps, which subscribe to streams of incoming telemetry data, perform any necessary computations on the data, then send the data to other programs for display and/or further processing in NASA mission control centers. Heretofore, the development of comps was difficult, expensive, and time-consuming: Each comp was custom written manually, in a low-level computing language, by a programmer attempting to follow requirements of flight controllers. ISPATOM enables a flight controller who is not a programmer to write a comp by simply typing in one or more equation( s) at a command line or retrieving the equation(s) from a text file. ISPATOM then subscribes to the necessary input data, performs all of necessary computations, and sends out the results. It sends out new results whenever the input data change. The use of equations in ISPATOM is no more difficult than is entering equations in a spreadsheet. The time involved in developing a comp is thus limited to the time taken to decide on the necessary equations. Thus, ISPATOM is a real-time dynamic calculator.

Dershowitz, Adam↗

An Introduction to Rotorcraft Research at NASA Ames

NASA Ames Research Center, Moffett Field, CA is the NASA lead Center for rotorcraft research. Rotorcraft research at Ames includes system analysis and configuration optimization, aeromechanics, and flight control and cockpit integration. Research in other areas such as composite structure and material, and rotor acoustics are conducted mainly at Langley Research Center, and rotorcraft propulsion and drivetrain are conducted at Lewis Research Center. This seminar will discuss Ames' rotorcraft research goals and some sample research projects and results. The talk will also briefly describe the newly fanned Army/NASA Rotorcraft Division, which combines the resources of rotorcraft branches in NASA Ames Aeronautics Directorate with Army's Aeroflightdynamics Directorate to better achieve the missions of the two previous rotorcraft research organizations at Ames. Rotorcraft research activities at NASA Ames are funded by two main program categories: Research and Technology (RUTH Base program and the Short Haul (Civil Tiltrotor) program. Work in the R&T program is carried out by the research staff in the Army/NASA Rotorcraft Division, and the work on SH(CT) program is carried out jointly by the SH(CT) program office and the Army/NASA Rotorcraft Division. Sample research projects and results in REST base program, such as conceptual assessment of several high-speed rotorcraft, rotorcraft CFD, individual blade control for reduction of external noise and vibration, noise-abatement flight procedures, engine inoperative procedures, handling qualities, and advanced flight control laws are broadly reviewed. High-speed rotorcraft research related to SH(CT) technology development conducted at Ames in the areas of low-noise proprotor, and low-noise terminal-area operations is also discussed.

Chen, Robert T. N.↗

Decision Making Training in the Mission Operations Directorate

At JSC, we train our new flight controllers on a set of team skills that we call Space Flight Resource Management (SFRM). SFRM is akin to Crew Resource Management for the airlines and trains flight controllers to work as an effective team to reduce errors and improve safety. We have developed this training over the years with the assistance of Ames Research Center, Wyle Labs and University of Central Florida. One of the skills we teach is decision making/ problem solving (DM/PS). We teach DM/PS first in several classroom sessions, reinforce it in several part task training environments, and finally practice it in full-mission, full-team simulations. What I am proposing to talk about is this training flow: its content and how we teach it.

O'Keefe, William S.↗

An assessment of various side-stick controller/stability and control augmentation systems for night nap-of-Earth flight using piloted simulation

Several night nap-of-the-earth mission tasks were evaluated using a helmet-mounted display which provided a limited field-of-view image with superimposed flight control symbology. A wide range of stability and control augmentation designs was investigated. Variations in controller force-deflection characteristics and the number of axes controlled through an integrated side-stick controller were studied. In general, a small displacement controller is preferred over a stiffstick controller particularly for maneuvering flight. Higher levels of stability augmentation were required for IMC tasks to provide handling qualities comparable to those achieved for the same tasks conducted under simulated visual flight conditions.

Landis, K. H.↗

Simulator investigations of side-stick controller/stability and control augmentation systems for night nap-of-earth flight

Several night nap-of-the-earth mission tasks were evaluated using a helmet-mounted display which provided a limited field-of-view image with superimposed flight control symbology. A wide range of stability and control augmentation designs was investigated. Variations in controller force-deflection characteristics and the number of axes controlled through an integrated side-stick controller were studied. In general, a small displacement controller is preferred over a stiffstick controller particularly for maneuvering flight. Higher levels of stability augmentation were required for IMC tasks to provide handling qualities comparable to those achieved for the same tasks conducted under simulated visual flight conditions. Previously announced in STAR as N82-23216

Landis, K. H.↗

Quantitative EEG patterns of differential in-flight workload

Four test pilots were instrumented for in-flight EEG recordings using a custom portable recording system. Each flew six, two minute tracking tasks in the Calspan NT-33 experimental trainer at Edwards AFB. With the canopy blacked out, pilots used a HUD display to chase a simulated aircraft through a random flight course. Three configurations of flight controls altered the flight characteristics to achieve low, moderate, and high workload, as determined by normative Cooper-Harper ratings. The test protocol was administered by a command pilot in the back seat. Corresponding EEG and tracking data were compared off-line. Tracking performance was measured as deviation from the target aircraft and combined with control difficulty to achieve an estimate of 'cognitive workload'. Trended patterns of parietal EEG activity at 8-12 Hz were sorted according to this classification. In all cases, high workload produced a significantly greater suppression of 8-12 Hz activity than low workload. Further, a clear differentiation of EEG trend patterns was obtained in 80 percent of the cases. High workload produced a sustained suppression of 8-12 Hz activity, while moderate workload resulted in an initial suppression followed by a gradual increment. Low workload was associated with a modulated pattern lacking any periods of marked or sustained suppression. These findings suggest that quantitative analysis of appropriate EEG measures may provide an objective and reliable in-flight index of cognitive effort that could facilitate workload assessment.

Sterman, M. B.↗

Control Reallocation Strategies for Damage Adaptation in Transport Class Aircraft

This paper examines the feasibility, potential benefits and implementation issues associated with retrofitting a neural-adaptive flight control system (NFCS) to existing transport aircraft, including both cable/hydraulic and fly-by-wire configurations. NFCS uses a neural network based direct adaptive control approach for applying alternate sources of control authority in the presence of damage or failures in order to achieve desired flight control performance. Neural networks are used to provide consistent handling qualities across flight conditions, adapt to changes in aircraft dynamics and to make the controller easy to apply when implemented on different aircraft. Full-motion piloted simulation studies were performed on two different transport models: the Boeing 747-400 and the Boeing C-17. Subjects included NASA, Air Force and commercial airline pilots. Results demonstrate the potential for improving handing qualities and significantly increased survivability rates under various simulated failure conditions.

Gundy-Burlet, Karen↗

Radio astronomy Explorer-B in-flight mission control system development effort

A description is given of the development for the Mission Analysis Evaluation and Space Trajectory Operations (MAESTRO) program to be used for the in-flight decision making process during the translunar and lunar orbit adjustment phases of the flight of the Radio Astronomy Explorer-B. THe program serves two functions: performance and evaluation of preflight mission analysis, and in-flight support for the midcourse and lunar insertion command decisions that must be made by the flight director. The topics discussed include: analysis of program and midcourse guidance capabilities; methods for on-line control; printed displays of the MAESTRO program; and in-flight operational logistics and testing.

Lutsky, D. A.↗

A program to evaluate a control system based on feedback of aerodynamic pressure differentials, part 1

The use of pressure differentials in a flight control system was evaluated. The pressure profile around the test surface was determined using two techniques: (1) windtunnel data (actual); and (2) NASA/Langley Single Element Airfoil Computer Program (theoretical). The system designed to evaluate the concept of using pressure differentials is composed of a sensor drive and power amplifiers, actuator, position potentiometer, and a control surface. The characteristics (both desired and actual) of the system and each individual component were analyzed. The desired characteristics of the system as a whole are given. The flight control system developed, the testing procedures and data reduction methods used, and theoretical frequency response analysis are described.

Hrabak, R. R.↗

Robust integrated autopilot/autothrottle design using constrained parameter optimization

A multivariable control design method based on constrained parameter optimization was applied to the design of a multiloop aircraft flight control system. Specifically, the design method is applied to the following: (1) direct synthesis of a multivariable 'inner-loop' feedback control system based on total energy control principles; (2) synthesis of speed/altitude-hold designs as 'outer-loop' feedback/feedforward control systems around the above inner loop; and (3) direct synthesis of a combined 'inner-loop' and 'outer-loop' multivariable control system. The design procedure offers a direct and structured approach for the determination of a set of controller gains that meet design specifications in closed-loop stability, command tracking performance, disturbance rejection, and limits on control activities. The presented approach may be applied to a broader class of multiloop flight control systems. Direct tradeoffs between many real design goals are rendered systematic by this method following careful problem formulation of the design objectives and constraints. Performance characteristics of the optimization design were improved over the current autopilot design on the B737-100 Transport Research Vehicle (TSRV) at the landing approach and cruise flight conditions; particularly in the areas of closed-loop damping, command responses, and control activity in the presence of turbulence.

Ly, Uy-Loi↗

Applications of Payload Directed Flight

Next generation aviation flight control concepts require autonomous and intelligent control system architectures that close control loops directly around payload sensors in manner more integrated and cohesive that in traditional autopilot designs. Research into payload directed flight control at NASA Ames Research Center is investigating new and novel architectures that can satisfy the requirements for next generation control and automation concepts for aviation. Tighter integration between sensor and machine requires definition of specific sensor-directed control modes to tie the sensor data directly into a vehicle control structures throughout the entire control architecture, from low-level stability- and control loops, to higher level mission planning and scheduling reasoning systems. Payload directed flight systems can thus provide guidance, navigation, and control for vehicle platforms hosting a suite of onboard payload sensors. This paper outlines related research into the field of payload directed flight; and outlines requirements and operating concepts for payload directed flight systems based on identified needs from the scientific literature.'

Ippolito, Corey↗

Tilt-proprotor perspective

The general tilt-proprotor concept is discussed, and a more detailed look at the XV-15 aircraft is taken. The special features of the two-engine system, engine control system, and flight control system are mentioned. The main objectives of the XV-15 program are to (1) verify rotor/pylon/wing/dynamic stability and aircraft performance over a representative operational envelope, (2) assess the handling qualities and establish a safe operating envelope, and (3) investigate gust sensitivity, effects of downwash, and hover operation. With regard to rotor/pylon stability, one challenge is to be able to predict a parameter's value and then build hardware to match. The analytical program has gained some respect through aeroelastic and full-scale XV-3 demonstrations. Special concern centers around the thrust and power management system when flying at high speed when very small changes in rotor collective pitch represent large changes in thrust and power. Demonstration of the system awaits wind-tunnel and flight testing.

Few, D. D.↗

On-Board Model Based Fault Diagnosis for CubeSat Attitude Control Subsystem: Flight Data Results

Self-sufficient, robotic spacecraft require estimates of their hardware health state in order to project future system state and plan actions toward achieving mission goals. In this paper, we report on integration of a Model-Based Fault Diagnosis (MBFD) model and reasoning engine into flight software leveraging the Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) mission, including test results against captured flight data using the ASTERIA system testbed. Our effort integrated the Model-based Off-Nominal State Identification and Detection (MONSID) model-based reasoning system, developed by Okean Solutions, into ASTERIA flight software using the F Prime software framework. The MONSID engine was supplied with a model of the Blue Canyon Technologies XACT attitude control system (ACS) and tested against flight data and seeded fault tests. While we were unable to conduct an on-board experiment due to the premature loss of ASTERIA, our effort proved the feasibility of on-board model-based fault management, demonstrating reliable and accurate diagnosis using captured data, and further supporting a closed-loop spacecraft autonomy demonstration including autonomous navigation in off-nominal conditions.

Prather, Maurice↗