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At least 487 records · Page 27

The characterization of facsimile camera systems for lunar and planetary surface exploration

Advantages of facsimile camera systems are reviewed for imagery of lunar and planetary surfaces from stationary or stopped remotely controlled vehicles. They include: better geometric fidelity than television systems, more picture elements per frame, ability to take single frame panoramic pictures, a very high contrast ratio within a picture, a choice of one or more narrow-band spectral responses over a wide possible range, image transmission over a low bit-rate communications channel without storage, very low power, small size, low weight, and ruggedizability to meet space flight requirements. Systems of this kind are under development for the 1975 Viking Martian lander, and have been used by the Soviets on Lunas and Lunokhod laboratory and field evaluation of a completed facsimile camera system is presented. The applicability of facsimile cameras to lunar and planetary rovers is demonstrated.

Eisenman, A.↗

Stabilizing the elastic modes of the Space Shuttle vehicle during launch.

The influence of vibration modes on the vehicle control system stabilization problem is examined with a conventional, nonadaptive, single-rate-sensor autopilot. The linear stability analyses are based upon symmetric and antisymmetric modal data generated from flexible-beam models. Primary emphasis is placed upon using only the three orbiter engines as control effectors. Principal control system variables considered are the effective autopilot rate and attitude gains, rate and attitude sensor locations, and lead/lag stability compensation. Results indicate that a multiple-sensor autopilot configuration will be necessary to achieve satisfactory vibration mode stability margins.

Greiner, H. G.↗

Some optimal considerations in attitude control systems

The conventional six-engine reaction control jet relay attitude control law with deadband is shown to be a good linear approximation to a weighted time-fuel optimal control law. Techniques for evaluating the value of the relative weighting between time and fuel for a particular relay control law is studied along with techniques to interrelate other parameters for the two control laws. Vehicle attitude control laws employing control moment gyros are then investigated. Steering laws obtained from the expression for the reaction torque of the gyro configuration are compared to a total optimal attitude control law that is derived from optimal linear regulator theory. This total optimal attitude control law has computational disadvantages in the solving of the matrix Riccati equation. Several computational algorithms for solving the matrix Riccati equation are investigated with respect to accuracy, computational storage requirements, and computational speed.

Boland, J. S., III↗

Multivariant function model generation

The development of computer programs applicable to space vehicle guidance was conducted. The subjects discussed are as follows: (1) determination of optimum reentry trajectories, (2) development of equations for performance of trajectory computation, (3) vehicle control for fuel optimization, (4) development of equations for performance trajectory computations, (5) applications and solution of Hamilton-Jacobi equation, and (6) stresses in dome shaped shells with discontinuities at the apex.

Source record↗

Low speed aerodynamic characteristics of a lifting-body hypersonic research aircraft configuration

An experimental investigation of the low-speed longitudinal, lateral, and directional stability characteristics of a lifting-body hypersonic research airplane concept was conducted in a low-speed tunnel with a 12-foot (3.66-meter) octagonal test section at the Langley Research Center. The model was tested with two sets of horizontal and vertical tip controls having different planform areas, a center vertical tail and two sets of canard controls having trapezoidal and delta planforms, and retracted and deployed engine modules and canopy. This investigation was conducted at a dynamic pressure of 239.4 Pa (5 psf) (Mach number of 0.06) and a Reynolds number of 2 million based on the fuselage length. The tests were conducted through an angle-of-attack range of 0 deg to 30 deg and through horizontal-tail deflections of 10 deg to minus 30 deg. The complete configuration exhibited excessive positive static longitudinal stability about the design center-of-gravity location. However, the configuration was unstable laterally at low angles of attack and unstable directionally throughout the angle-of-attack range. Longitudinal control was insufficient to trim at usable angles of attack. Experiments showed that a rearward shift of the center of gravity and the use of a center-located vertical tail would result in a stable and controllable vehicle.

Penland, J. A.↗

Man-systems evaluation of moving base vehicle simulation motion cues

A motion cue investigation program is reported that deals with human factor aspects of high fidelity vehicle simulation. General data on non-visual motion thresholds and specific threshold values are established for use as washout parameters in vehicle simulation. A general purpose similator is used to test the contradictory cue hypothesis that acceleration sensitivity is reduced during a vehicle control task involving visual feedback. The simulator provides varying acceleration levels. The method of forced choice is based on the theory of signal detect ability.

Kirkpatrick, M.↗

The prologue - A look at Apollo and Apollo/Soyuz

The importance of man to the success of the Apollo missions is considered, giving attention to man's capabilities to provide rapid response to emergencies, the ability to carry out self-contained operations in the absence of communication with the ground, and the ability for rapid sensing, reaction, and vehicle control. In the upcoming Shuttle era the capabilities possessed by man are to be further utilized. The concern for the safety of men in space is one of the major reasons for the flight of the Apollo/Soyuz test project. Details regarding this project are discussed, taking into account the mission profile, hardware, program organization, mission communication modes, tracking, the participating astronauts and cosmonauts, and scientific studies.

Lee, C. M.↗

Timeline Analysis Program (TLA-1)

The Timeline Analysis Program (TLA-1) was described. This program is a crew workload analysis computer program that was developed and expanded from previous workload analysis programs, and is designed to be used on the NASA terminal controlled vehicle program. The following information is described: derivation of the input data, processing of the data, and form of the output data. Eight scenarios that were created, programmed, and analyzed as verification of this model were also described.

Miller, K. H.↗

Space Shuttle flight control system

The Space Shuttle is a control stabilized vehicle with control provided by an all digital, fly-by-wire flight control system. This paper gives a description of the several modes of flight control which correspond to the Shuttle mission phases. These modes are ascent flight control (including open loop first stage steering, the use of four computers operating in parallel and inertial guidance sensors), on-orbit flight control (with a discussion of reaction control, phase plane switching logic, jet selection logic, state estimator logic and OMS thrust vector control), entry flight control and TAEM (terminal area energy management to landing). Also discussed are redundancy management and backup flight control.

Klinar, W. J.↗

Design and test experience with a triply redundant digital fly-by-wire control system

A triplex digital fly-by-wire flight control system was developed and then installed in a NASA F-8C aircraft to provide fail-operative, full authority control. Hardware and software redundancy management techniques were designed to detect and identify failures in the system. Control functions typical of those projected for future actively controlled vehicles were implemented. This paper describes the principal design features of the system, the implementation of computer, sensor, and actuator redundancy management, and the ground test results. An automated test program to verify sensor redundancy management software is also described.

Szalai, K. J.↗

Lunar rover vehicle - an implication for rehabilitation

The feasibility of adapting the lunar roving vehicle control concept to automobiles and vans for quadriplegics was investigated. Topics discussed include the current state of automobile handicapped controls, a description of the affected population, and a design for interfacing the control system into a passenger vehice.

Mcfarland, S. R.↗

NASA TLA workload analysis support. Volume 1: Detailed task scenarios for general aviation and metering and spacing studies

The techniques required to produce and validate six detailed task timeline scenarios for crew workload studies are described. Specific emphasis is given to: general aviation single pilot instrument flight rules operations in a high density traffic area; fixed path metering and spacing operations; and comparative workload operation between the forward and aft-flight decks of the NASA terminal control vehicle. The validation efforts also provide a cursory examination of the resultant demand workload based on the operating procedures depicted in the detailed task scenarios.

Sundstrom, J. L.↗

Ground and flight test experience with a triple redundant digital fly by wire control system

A triplex digital fly by wire flight control system was developed and installed in an F-8C aircraft to provide fail operative, full authority control. Hardware and software redundancy management techniques were designed to detect and identify failures in the system. Control functions typical of those projected for future actively controlled vehicles were implemented.

Jarvis, C. R.↗

The 15th Aerospace Mechanisms Symposium

The purpose of the symposium was to provide a forum for the interchange of information among those active in the field of mechanism technology. To that end, 27 papers were presented on aeronautics and space flight, with special emphasis on actuators and aerospace applications for pointing systems, latches, connectors, and other mechanisms for large space structures. The papers were authored by engineers from a broad aerospace spectrum including the U. S. aerospace industry, NASA, and several European participants. Technological areas covered include: aerospace propulsion; aerodynamic devices; crew safety; space vehicle control; spacecraft deployment, positioning, and pointing; deployable antennas/reflectors; and large space structures. Devices for payload deployment, payload retention, and crew extravehicular activities on the space shuttle orbiter are also described.

Actuators↗

Optimal use of electrophysiological indicators of muscular effort and fatigue

Electromyograms (EMG) from working muscles convey information on effort and fatigue. Their application, e.g., to assess the demands of vehicle control tasks, is complicated by the cooperative action of sets of muscles, by both intrinsic and imposed filtering, and by numerous other sources of variation. Fourier analyses of these noise like signals offer one approach to interpretation; downward spectral shifts accompany fatigue. Techniques are being sought (in both time and frequency domains) for further condensing the wideband EMG signals, while retaining essential information, into a concise 'state vector' usable in comparing control system designs.

Updike, O. L.↗

Space Shuttle Orbiter auxiliary power unit

The Space Shuttle Orbiter auxiliary power units (APUs) provide hydraulic power for the Orbiter vehicle control surfaces (rudder/speed brake, body flap, and elevon actuation systems), main engine gimbaling during ascent, landing gear deployment and steering and braking during landing. Operation occurs during launch/ascent, in-space exercise, reentry/descent, and landing/rollout. Operational effectiveness of the APU is predicated on reliable, failure-free operation during each flight, mission life (reusability) and serviceability between flights (turnaround). Along with the accumulating flight data base, the status and results of efforts to achieve these long-run objectives is presented.

Mckenna, R.↗