The calculation of motion drive signals for piloted flight simulators
Calculation of motion drive signals for piloted flight simulators
Conrad, B.↗
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Numerical and laboratory simulation of fault motion and earthquake occurrence
Simple linear rheologies were used with elastic forces driving the main events and viscoelastic forces being important for aftershock and creep occurrence. Friction and its dependence on velocity, stress, and displacement also plays a key role in determining how, when, and where fault motion occurs. The discussion of the qualitative behavior of the simulators focuses on the manner in which energy was stored in the system and released by the unstable and stable sliding processes. The numerical results emphasize the statistics of earthquake occurrence and the correlations among source parameters.
Cohen, S. C.↗
Motion-based carriage simulation of extra-vehicular activity (EVA) rescue
A research program was outlined for a series of Extra-Vehicular Activity (EVA) rescue studies. The general purpose is to get a better appreciation of the characteristics describing an EVA rescue scenario. Several studies have been completed in the Virtual Interactive Environment Workstation (VIEW) at NASA Ames Research Center. Similar studies are planned for a variety of simulators both to get more reliable results for the EVA rescue problem and to baseline the simulators against one another. Work is planned for a motion-based carriage to expand the validity of the previously obtained results.
Brody, Adam R.↗
Visual and motion cueing in helicopter simulation
The visual cues presented in the simulator are compared with those of flight in an attempt to identify deficiencies. For the low-amplitude maneuvering tasks normally associated with the hover mode, the unique motion capabilities of the Vertical Motion Simulator (VMS) at Ames Research Center permit nearly a full representation of vehicle motion. Especially appreciated in these tasks are the vertical-acceleration responses to collective control. For larger-amplitude maneuvering, motion fidelity must suffer diminution through direct attenuation through high-pass filtering washout of the computer cockpit accelerations or both. Experiments were conducted in an attempt to determine the effects of these distortions on pilot performance of height-control tasks.
Bray, Richard S.↗
A study of the comparative effects of various means of motion cueing during a simulated compensatory tracking task
NASA's Langley Research Center conducted a simulation experiment to ascertain the comparative effects of motion cues (combinations of platform motion and g-seat normal acceleration cues) on compensatory tracking performance. In the experiment, a full six-degree-of-freedom YF-16 model was used as the simulated pursuit aircraft. The Langley Visual Motion Simulator (with in-house developed wash-out), and a Langley developed g-seat were principal components of the simulation. The results of the experiment were examined utilizing univariate and multivariate techniques. The statistical analyses demonstrate that the platform motion and g-seat cues provide additional information to the pilot that allows substantial reduction of lateral tracking error. Also, the analyses show that the g-seat cue helps reduce vertical error.
Mckissick, B. T.↗
Simulation of rotor blade element turbulence
A piloted, motion-based simulation of Sikorsky's Black Hawk helicopter was used as a platform for the investigation of rotorcraft responses to vertical turbulence. By using an innovative temporal and geometrical distribution algorithm that preserved the statistical characteristics of the turbulence over the rotor disc, stochastic velocity components were applied at each of twenty blade-element stations. This model was implemented on NASA Ames' Vertical Motion Simulator (VMS), and ten test pilots were used to establish that the model created realistic cues. The objectives of this research included the establishment of a simulation-technology basis for future investigation into real-time turbulence modeling. This goal was achieved; our extensive additions to the rotor model added less than a 10 percent computational overhead. Using a VAX 9000 computer the entire simulation required a cycle time of less than 12 msec. Pilot opinion during this simulation was generally quite favorable. For low speed flight the consensus was that SORBET (acronym for title) was better than the conventional body-fixed model, which was used for comparison purposes, and was determined to be too violent (like a washboard). For high speed flight the pilots could not identify differences between these models. These opinions were something of a surprise because only the vertical turbulence component on the rotor system was implemented in SORBET. Because of the finite-element distribution of the inputs, induced outputs were observed in all translational and rotational axes. Extensive post-simulation spectral analyses of the SORBET model suggest that proper rotorcraft turbulence modeling requires that vertical atmospheric disturbances not be superimposed at the vehicle center of gravity but, rather, be input into the rotor system, where the rotor-to-body transfer function severely attenuates high frequency rotorcraft responses.
Mcfarland, R. E.↗
Visually induced motion in flight simulation
Visually induced yaw (circularvection) resulting from a moving wide field presentation, and its interaction with vestibular yaw cues generated by base motion is discussed. A model is presented for the interaction between visual and motion cues in yaw which rationalizes the high frequency utilization of vestibular cues and the low frequency use of visual cues to support sustained angular velocity. The implications for fixed and moving base flight simulator design are discussed. Similar considerations apply to visually induced linear velocity (linearvection) and interesting asymmetries in the fore-aft direction are noted. Visually induced pitch and roll are discussed and modelled in terms of conflict between the visually induced motion and the information regarding attitude based upon graviceptor signals.
Young, L. R.↗
The Influence of Motion Cues on Driver-Vehicle Performance in a Simulator
Four different motion base configurations were studied on driving simulator. Differently responding vehicles were simulated on each motion configurations and the effects of the vehicle characteristics on driver vehicle system performance, driver control activity, and driver opinion ratings of vehicle performance during driving are compared for different motion configurations. Data show that: (1)) the effects of changes in vehicle characteristics on the different objective and subjective measures of driver vehicle performance are not disguised by the lack of physical motion; (2) fixed base simulator can be used to draw inferences despite the lack of motion; (3) the presence of motion tends to reduce path keeping errors and driver control activity; (4) roll and yaw motions are recommended because of their marked influence on driver vehicle performance (5) the importance of motion increases as the driving maneuvers become more extreme.
Repa, B. S.↗
Integration of visual and motion cues for flight simulator requirements and ride quality investigation
Investigations for the improvement of flight simulators are reported. Topics include: visual cues in landing, comparison of linear and nonlinear washout filters using a model of the vestibular system, and visual vestibular interactions (yaw axis). An abstract is given for a thesis on the applications of human dynamic orientation models to motion simulation.
Young, L. R.↗
A Study of the Characteristics of Human-Pilot Control Response to Simulated Aircraft Lateral Motions
Report presents the results of studies made in an attempt to provide information on the control operations of the human pilot. These studies included an investigation of the ability of pilots to control simulated unstable yawing oscillations, a study of the basic characteristics of human-pilot control response, and a study to determine whether and to what extent pilot control response can be represented in an analytical form.
Cheatham, Donald C↗
Translation and Rotation Trade Off in Human Visual Heading Estimation
We have previously shown that, during simulated curvilinear motion, humans can make reasonably accurate and precise heading judgments from optic flow without either oculomotor or static-depth cues about rotation. We now systematically investigate the effect of varying the parameters of self-motion. We visually simulated 400 ms of self-motion along curved paths (constant rotation and translation rates, fixed retinocentric heading) towards two planes of random dots at 10.3 m and 22.3 m at mid-trial. Retinocentric heading judgments of 4 observers (2 naive) were measured for 12 different combinations of translation (T between 4 and 16 m/s) and rotation (R either 8 or 16 deg/s). In the range tested, heading bias and uncertainty decrease quasilinearly with T/R, but the bias also appears to depend on R. If depth is held constant, the ratio T/R can account for much of the variation in the accuracy and precision of human visual heading estimation, although further experiments are needed to resolve whether absolute rotation rate, total flow rate, or some other factor can account for the observed -2 deg shift between the bias curves.
Stone, Leland S.↗
Visually guided control of movement in the context of multimodal stimulation
Flight simulation has been almost exclusively concerned with simulating the motions of the aircraft. Physically distinct subsystems are often combined to simulate the varieties of aircraft motion. Visual display systems simulate the motion of the aircraft relative to remote objects and surfaces (e.g., other aircraft and the terrain). 'Motion platform' simulators recreate aircraft motion relative to the gravitoinertial vector (i.e., correlated rotation and tilt as opposed to the 'coordinated turn' in flight). 'Control loaders' attempt to simulate the resistance of the aerodynamic medium to aircraft motion. However, there are few operational systems that attempt to simulate the motion of the pilot relative to the aircraft and the gravitoinertial vector. The design and use of all simulators is limited by poor understanding of postural control in the aircraft and its effect on the perception and control of flight. Analysis of the perception and control of flight (real or simulated) must consider that: (1) the pilot is not rigidly attached to the aircraft; and (2) the pilot actively monitors and adjusts body orientation and configuration in the aircraft. It is argued that this more complete approach to flight simulation requires that multimodal perception be considered as the rule rather than the exception. Moreover, the necessity of multimodal perception is revealed by emphasizing the complementarity rather than the redundancy among perceptual systems. Finally, an outline is presented for an experiment to be conducted at NASA ARC. The experiment explicitly considers possible consequences of coordination between postural and vehicular control.
Riccio, Gary E.↗
Kinematic domain decomposition for boundary-motion-induced flow simulations
A method is developed to solve the unsteady Navier-Stokes equations on a composite grid, which consists of subdomain grids moving with respect to each other. These subdomains are structured grids with different topologies. This method eliminates assuming the moving components to be instantaneously stationary, where deciding on the particular frozen instants is difficult and affects the solution adversely. Moreover, this method captures the boundary-motion-induced flow component. The method is demonstrated through a transonic flow past an airfoil, which experiences a combined motion of pitching and plunging. An O-grid around the airfoil is overlapped on a fine Cartesian grid, which is zonally embedded in a coarse Cartesian grid. The coarse grid is stationary but the other two grids are plunging. Only the O-grid is also sinusoidally pitching. The results are compared successfully with the experimental data.
Baysal, Oktay↗
Platform motion for fighter simulations
The reported investigation is concerned with aspects of 'realistic' cue generation and evaluation. 'Realistic' cues are defined to mean cues that are representative of an aircraft, that are of sufficient magnitude to be sensed, that are in the proper direction arriving at the proper time, and yet that are within the presentation capabilities of the washout/synergistic platform system. Attention is given to the aircraft mathematical model, computer implementation, cockpit hardware, visual display, the motion system, vertical acceleration, longitudinal acceleration and pitch rate, and lateral acceleration and roll rate. The motion cues for fighter aircraft produced by Langley nonlinear adaptive washout/synergistic motion base system are found to be unacceptable in the roll axis representation. However, a method for producing potentially realistic roll cues is identified.
Parrish, R. V.↗
Pilot differences and motion cuing effects on simulated helicopter hover
The effects that cues of aircraft motion, delays in visual scene, and movement of a ship model have on pilots' ability to hover a simulated helicopter near a destroyer-class ship were examined. Twelve pilots were tested in a within-subject factorial combination of fixed-base, moving-base, and G-seat conditions in which delays of 66 or 128 ms existed in the simulator's visual display and the pilots had to hover near a moving or stationary ship. Best control performance was seen under the moving-base conditions, whereas poorest control was associated with the fixed-base simulation. An intermediate level of performance was produced by the G-seat. In addition, visual delay affected control of the roll axis of the simulation, and interactions between pilots and motion cuing and visual delay were seen. Movement of the ship model had little effect.
Ricard, G. L.↗
Visual and motion cueing in helicopter simulation
Early experience in fixed-cockpit simulators, with limited field of view, demonstrated the basic difficulties of simulating helicopter flight at the level of subjective fidelity required for confident evaluation of vehicle characteristics. More recent programs, utilizing large-amplitude cockpit motion and a multiwindow visual-simulation system have received a much higher degree of pilot acceptance. However, none of these simulations has presented critical visual-flight tasks that have been accepted by the pilots as the full equivalent of flight. In this paper, the visual cues presented in the simulator are compared with those of flight in an attempt to identify deficiencies that contribute significantly to these assessments. For the low-amplitude maneuvering tasks normally associated with the hover mode, the unique motion capabilities of the Vertical Motion Simulator (VMS) at Ames Research Center permit nearly a full representation of vehicle motion. Especially appreciated in these tasks are the vertical-acceleration responses to collective control. For larger-amplitude maneuvering, motion fidelity must suffer diminution through direct attenuation through high-pass filtering washout of the computer cockpit accelerations or both. Experiments were conducted in an attempt to determine the effects of these distortions on pilot performance of height-control tasks.
Bray, R. S.↗
Integration of visual and motion cues for simulator requirements and ride quality investigation
Preliminary tests and evaluation are presented of pilot performance during landing (flight paths) using computer generated images (video tapes). Psychophysiological factors affecting pilot visual perception were measured. A turning flight maneuver (pitch and roll) was specifically studied using a training device, and the scaling laws involved were determined. Also presented are medical studies (abstracts) on human response to gravity variations without visual cues, acceleration stimuli effects on the semicircular canals, and neurons affecting eye movements, and vestibular tests.
Young, L. R.↗
Computer simulation of the motion of a straight dislocation line in concentrated solid solutions. II
An investigation was undertaken to determine if the size and modulus interaction of a solute atom with a screw dislocation and the modulus interaction with an edge dislocation contributed to strengthening, in addition to the size interaction with an edge dislocation. The results indicate that the size interaction between solute atom and an edge dislocation accounts for most of the solid solution strengthening in f.c.c. alloys. The contribution to the yield stress from the modulus interaction with an edge dislocation is less than 15%. The interaction between a solute atom and a screw dislocation is much less than that between a solute atom and an edge dislocation.
Kuo, C. T. K.↗