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Time-varying perceived motion mismatch due to motion scaling in curve driving simulation
Abstract
In motion simulation, motion input scaling is often applied to deal with the limited motion envelopes of motion simulators. In this research, the time-varying effects of scaling the lateral specific force up or down during passive curve driving in a car driving simulation are investigated through a simulator experiment. It is concluded that lateral specific force scaling has a time-varying effect on the perceived fidelity of a curve-driving simulation. In particular, motion scaling during a curve entry is found to be less detrimental than motion scaling during a curve's sustained part and during the curve exit.
... in the same direction as the vehicle (m v > p), but either weakened or too strong. Because humans can have a range of acceptable scaling factors that they still consider as coherent, the scaling errors are only defined if the simulator is moving at less than 70% or more than 130% of the vehicle motion (Van Leeuwen, et al., 2019). • Correct cue (0): If none of the other error types are detected, the cue is considered to be correct. ...
BMW's new driving simulation center operates multiple motion-base simulators-each with a different kinematic configuration-to serve various experiment use-cases and requirements of simulator users. The selection of a simulator for each experiment should ideally be based on their relative strengths and weaknesses. To support this decision-making process, subjective and objective predictions of motion cueing quality can be used. This paper provides an example comparison of four motion-base driving simulators. The kinematic configurations of the simulators considered differed in the additional presence of a yaw-drive and/or a linear xy-drive. The comparison is made by calculating offline, optimization-based motion cueing with perfect prediction capabilities (the 'Oracle') for nine urban drives. A prediction of subjective motion incongruence ratings is made for each simulator. In addition, an error type identification method is used (identifying scaling, missing cue, false cue and false direction cue errors) and evaluated per simulator. As Oracle can fully utilize the available workspace, the employed evaluation methods provide an insight in the fundamental capabilities of each simulator. Both the modelled ratings and the error type analysis show the benefits of adding a xy-drive in urban use-cases: predicted ratings reduce by 19% (i.e., better), while scaling and missing cue errors in the yaw rate are reduced when adding a yaw-drive. The presence of both of these additional motion systems allow for practically one-to-one and therefore error-free motion cueing. The proposed methods provide a straightforward , yet insightful basis for simulator selection. The presented methods can be extended towards the analysis of multiple motion cueing algorithms and/or other use-cases for systematically selecting the best-suited motion cueing method.
... There is extensive literature on the subject [40][41][42][43], in which attempts have been made to increase the user's perception by applying scaling to the different channels that make up the washout filters. In general, it is concluded that the application of scaling to certain washout channels, always within certain limits, is usually positive [44] since it increases the user's perceptual level, but there is no consensus on how to apply them. ...
Motion platforms have been used in simulators of all types for several decades. Since it is impossible to reproduce the accelerations of a vehicle without limitations through a physically limited system (platform), it is common to use washout filters and motion cueing algorithms (MCA) to select which accelerations are reproduced and which are not. Despite the time that has passed since their development, most of these algorithms still use the classical washout algorithm. In the use of these MCAs, there is always information that is lost and, if that information is important for the purpose of the simulator (the training simulators), the result obtained by the users of that simulator will not be satisfactory. This paper shows a case study where a BMW 325Xi AUT fitted with a sensor, recorded the accelerations produced in all degrees of freedom (DOF) during several runs, and data have been introduced in mathematical simulation software (washout + kinematics + actuator simulation) of a 6DOF motion platform. The input to the system has been qualitatively compared with the output, observing that most of the simulation adequately reflects the input to the system. Still, there are three events where the accelerations are lost. These events are considered by experts to be of vital importance for the outcome of a learning process in the simulator to be adequate.
... Although efforts are made to improve upon this washout strategy (see e.g., work on Model Predictive Control [2][3][4][5][6]), the inherent limitations of a motion simulator's envelope cannot entirely prevent missing cues, false cues, and/or scaling errors. These limitations may in turn negatively affect the perceived realism and immersion in the simulation, and may even trigger motion sickness [1,[7][8][9]. ...
In dynamic driving simulators, the experience of operating a vehicle is reproduced by combining visual stimuli generated by graphical rendering with inertial stimuli generated by platform motion. Due to inherent limitations of the platform workspace, inertial stimulation is subject to shortcomings in the form of missing cues, false cues, and/or scaling errors, which negatively affect simulation fidelity. In the present study, we aim at quantifying the relative contribution of an active somatosensory stimulation to the perceived intensity of self-motion, relative to other sensory systems. Participants judged the intensity of longitudinal and lateral driving maneuvers in a dynamic driving simulator in passive driving conditions, with and without additional active somatosensory stimulation, as provided by an Active Seat (AS) and Active Belts (AB) integrated system (ASB). The results show that ASB enhances the perceived intensity of sustained decelerations, and increases the precision of acceleration perception overall. Our findings are consistent with models of perception, and indicate that active somatosensory stimulation can indeed be used to improve simulation fidelity.
... Some of the works reviewed in this paper fulfill most of the requirements but none is able to provide all of them. For instance, the method proposed in [91] accomplishes all these goals, except for the second goal, which is not completely fulfilled, and the first one, which is only partially accomplished; OMCT lacks these two features, lacks ease of interpretation and also lacks universality since it is designed for washout-based MCA and aircraft; MPT [99] does not comply with the last requirement and possibly with the second one since not everybody perceives motion in the same way; the Hess criterion [95] lacks, at least, applicability and acceptability; the methods proposed in [65], [88], [110] do not comply with the sortability requirement and are not used for tuning the MCA; the assessment method used in the tuning procedure utilized by Roza and de Ridder [104], [112] lacks completeness because they use a kinematic model of the motion platform and do not evaluate its dynamics (they do that to "assess only the MDA part of the FSTD"), but provide sortability upon OMCT, a remarkable contribution because OMCT does not originally provide a single value; the works of Asadi and Mohammadi [101], [102], [115] lack complete applicability since the evaluation function has many parameters that should be tuned first; the methods proposed by Cleij and van Leeuwen [55], [58], [66], [67] lack repeatability and no interference, among other problems, because they interfere in the normal use of the vehicle simulator and are, thus, only applicable for passive simulation (when the user does not operate the vehicle); the methods that use simulated motion platforms [73], [87], [88], [91], [112] provide complete availability. On the contrary, those methods using the real hardware may not be always available. ...
Motion-based simulators are used for a variety of applications, such as research, education, entertainment and training. In fact, motion cues are required to achieve the highest regulatory certifications in training vehicle simulators. Nonetheless, the reproduction of self-motion cues presents technological and economic limitations that are not present in the generation of audiovisual cues. For this reason, the generated motion does not generally match the expected one. Therefore, it is necessary to define means to assess the suitability/fidelity of the generated motion cues. After more than 50 years of motion-based vehicle simulation, no mechanism has been universally accepted as the standard solution for the evaluation of motion cues. This paper reviews the mechanisms for obtaining measures of motion fidelity, focusing on those based on objective methods. Since the design of the Objective Motion Cueing Test in 2006, researchers have shown a renewed interest in identifying objective methods to evaluate motion cueing, as the number of works following this approach in recent years reveals. Objective motion fidelity systems allow also performing automatic tuning of MCA by means of optimization techniques, which addresses one of the other main problems of these algorithms. Nevertheless, a universally accepted objective method to assess perceptual motion fidelity in vehicle simulators has not been proposed yet. For this reason, this review work frames and classifies the existing methods. In addition, the authors propose a series of features that an ideal evaluation method for assessing perceptual motion fidelity should include and provide future research guidelines for this complex topic.
Motion cueing algorithms are used in motion simulation to map the inertial vehicle motion onto the limited simulator motion space. This mapping causes mismatches between the unrestricted visual motion and the constrained inertial motion, which results in perceived motion incongruence (PMI). It is still largely unknown what exactly causes visual and inertial motion in a simulator to be perceived as incongruent. Current methods for measuring motion incongruence during motion simulation result in time-invariant measures of the overall incongruence, which makes it difficult to determine the relevance of the individual and short-duration mismatches between visual and inertial motion cues. In this paper, a novel method is presented to subjectively measure the time-varying PMI continuously throughout a simulation. The method is analyzed for reliability and validity of its measurements, as well as for its applicability in relating physical short-duration cueing errors to PMI. The analysis shows that the method is reliable and that the results can be used to obtain a deeper insight into the formation of motion incongruence during driving simulation.
This paper explains how flight simulation has made a major contribution to flight safety over the last thirty years to become critical to the operation of civil airlines and military organisations. It not only provides effective training, but for many flight training organisations has reduced the cost of flight training significantly. The paper outlines the increasing role of flight simulation covering flight training and research and development of aircraft and systems. The contribution of the flight simulation industry to the UK economy, in terms of both employment and revenue, is highlighted.
The paper focuses on advances in the underpinning technologies of flight simulation, including mathematical modelling, real-time computation, motion actuation, visual image generation systems and projection systems.
The paper also summarises the broadening roles of flight simulation; from part-task trainers to zero flight-time training in civil aviation; in military aviation, extending to combat domes and mission rehearsal; in defence procurement, where synthetic environments are used widely in evaluation studies prior to major project commitments; in aircraft development, providing powerful design tools to enable system designers to evaluate prototype systems.
As a result of the acceptance of flight simulation in flight training, the use of simulators has been standardised throughout the world, with formal programmes of simulator qualification. These regulations, drawn up with the help of the RAeS Flight Simulation Group, ensure consistency for operators, regulators and manufacturers; the status of these regulations is outlined.
The paper concludes by reviewing the lessons learnt by the flight simulation industry over the last thirty years and summaries the potential areas of growth, which will lead to simulation becoming widespread throughout many industries, in addition to the aerospace industry.
This paper describes a perception-based motion cueing (PBMC) algorithm, which aims to bridge the gap between what is known about human self-motion perception and what is currently used in motion simulation. In PBMC, motion perception knowledge is explicitly incorporated by means of a perception model and a cost function. PBMC has the potential of improving the realism of the motion simulation by exploiting the limitations and ambiguities of human self-motion perception and increasing the utilization of the simulator envelope, while reducing the need for parameter tuning. The PBMC algorithm was compared to a classical filter-based approach in an experimental study. To allow for a robust and reliable comparison, an evaluation method for motion cueing algorithms (MCAs) based on psychophysical techniques was developed. Results show that the PBMC approach received significantly higher ratings than the filter-based approach. This demonstrates the potential of the PBMC approach to improve motion cueing in vehicle simulation.
The development and tuning of flight simulator motion filters relies on understanding human motion perception and its limitations. Of particular interest to flight simulation is the study of visual-inertial coherence zones. Coherence zones refer to combinations of visual and inertial cues that, although not being physically coherent, still provide the pilot with the perception of a congruent motion, indicating a realistic simulation. Coherence
zones have been measured before during passive tasks, for pre-determined stimuli. During a pilot-in-the-loop simulation, however, the type of inertial and visual cues being provided are considerably influenced by the pilot’s control strategy. For this reason, it is important to understand how the amplitude and frequency content of the stimuli affect the perception of a coherent motion. Three experiments were performed to measure the ef-
fect of cue amplitude and frequency on yaw perception coherence zones. In accordance with previous research, the measured coherence zones were generally wider for higher amplitudes of the visual motion cue. At higher amplitudes of the visual cue, subjects preferred inertial motion amplitudes that were lower than the visual cue amplitude. The stimulus frequency was shown to have an effect on the coherence zones. For a higher frequency stimulus the preferred inertial motion amplitudes were significantly lower than for a lower frequency stimulus. These results are explained using a model of the semi-circular canals dynamics.
The MPI CyberMotion Simulator provides a unique motion platform, as it features an anthropomorphic robot with a large workspace, combined with an actuated cabin and a linear track for lateral movement. This paper introduces the simulator as a tool for studying human perception, and compares its characteristics to conventional Stewart platforms. Furthermore, an experimental evaluation is presented in which multimodal human control behavior is studied by identifying the visual and vestibular responses of participants in a roll-lateral helicopter hover task. The results show that the simulator motion allows participants to increase tracking performance by changing their control strategy, shifting from reliance on visual error perception to reliance on simulator motion cues. The MPI CyberMotion Simulator has proven to be a state-of-the-art motion simulator for psychophysical research to study humans with various experimental paradigms, ranging from passive perception experiments to active control tasks, such as driving a car or flying a helicopter.
Knowledge about motion perception thresholds is essential for simulator motion cueing. Thresholds are generally measured in a passive experimental setup in which subjects do not actively influence their motion. For flight simulation applications, it is useful to also investigate thresholds during control tasks, where pilots actively influence the motion they sense. In this paper, thresholds were estimated during an active control task using a pilot model parameter identification method. A comparison with conventional passive threshold measurements was made. The threshold identification method was based on a multichannel pilot model extended with a nonlinear absolute threshold element. Two experiments were performed in a flight simulator: a passive experiment to measure the sensory pitch threshold, and an active experiment with a compensatory control task to identify the active pitch threshold. In the active experiment, the gain of the inertial motion amplitude was varied and two types of compensatory control tasks were considered. For both tasks, the pitch threshold was identifiable only for high motion gain levels. The measured passive threshold was lower than other values found in literature. The threshold identified from the active control task was higher than the measured passive threshold, but it was comparable with passive threshold values reported in other studies.
Advanced driving simulators aim at rendering the motion of a vehicle with maximum fidelity, which requires increased mechanical travel, size, and cost of the system. Motion cueing algorithms reduce the motion envelope by taking advantage of limitations in human motion perception, and the most commonly employed method is just to scale down the physical motion. However, little is known on the effects of motion scaling on motion perception and on actual driving performance. This paper presents the results of a European collaborative project, which explored different motion scale factors in a slalom driving task. Three state-of-the-art simulator systems were used, which were capable of generating displacements of several meters. The results of four comparable driving experiments, which were obtained with a total of 65 participants, indicate a preference for motion scale factors below 1, within a wide range of acceptable values (0.4-0.75). Very reduced or absent motion cues significantly degrade driving performance. Applications of this research are discussed for the design of motion systems and cueing algorithms for driving simulation.
In the field of motion-based simulation, it was found that a visual amplitude equal to the inertial amplitude does not always provide the best perceived match between visual and inertial motion. This result is thought to be caused by the "quality" of the motion cues delivered by the simulator motion and visual systems. This paper studies how different visual characteristics, like field of view (FoV) and size and depth cues, influence the scaling between visual and inertial motion in a simulation environment. Subjects were exposed to simulator visuals with different fields of view and different visual scenes and were asked to vary the visual amplitude until it matched the perceived inertial amplitude. This was done for motion profiles in surge, sway, and yaw. Results showed that the subjective visual amplitude was significantly affected by the FoV, visual scene, and degree-of-freedom. When the FoV and visual scene were closer to what one expects in the real world, the scaling between the visual and inertial cues was closer to one. For yaw motion, the subjective visual amplitudes were approximately the same as the real inertial amplitudes, whereas for sway and especially surge, the subjective visual amplitudes were higher than the inertial amplitudes. This study demonstrated that visual characteristics affect the scaling between visual and inertial motion which leads to the hypothesis that this scaling may be a good metric to quantify the effect of different visual properties in motion-based simulation.
In flight simulation, motion-cueing algorithms are used to transform aircraft motion into motion within the simulator limits. When looking for the best match between visual and inertial amplitude in a simulator, researchers have found that there is a range of inertial amplitudes, rather than a single inertial value, that is perceived by subjects as optimal. This zone, hereafter referred to as the optimal zone, seems to correlate to the perceptual coherence zones measured in flight simulators. However, no studies were found in which these two zones were compared. This study investigates the relation between the optimal and the coherence-zone measurements within and between different simulators. An experiment was conducted at NASA Langley Research Center, where two simulators were used to measure the optimal and the coherence zone in the sway axis. Results show that the optimal zone lies within the coherence zone. The center of the optimal zone is significantly lower than the center of the coherence zone. In addition, it was found that, whereas the width of the coherence zone depends on the visual amplitude and frequency, the width of the optimal zone remains constant. No statistical differences between the two simulators were found.
The use of a driving simulator in the development of human–machine-interfaces (HMI) such as a navigation, information or entertainment system is discussed. Such use addresses the need to study and evaluate the characteristics of a candidate HMI early in the R&D and design stage to ensure that it is likely to meet various objectives and requirements, and to revise the HMI as may be necessary. Those HMI requirements include such things as usability, driver comfort, and an acceptable level of attentional demand in dual task conditions (driving while using an HMI). Typically, such an HMI involves an information display to the driver, and a means for driver input to the HMI. Corresponding simulator requirements are discussed, along with typical simulator features and components. The latter include a cab, control feel systems, visual image generator, real time scenario control (task definitions), a motion system (if provided), and data acquisition. Both fixed and moving base systems are described, together with associated benefits and tradeoffs. Considerations in the design of the evaluation experiment are discussed, including definition of primary and secondary tasks, and number of driver subjects (experimental participants). Possible response and performance measures for the primary and secondary tasks are noted, together with subjective measures such as task difficulty and ease of using the HMI. The advantages of using a driving simulator to support R&D are summarized. Some typical and example simulator uses are noted.
In most moving-base flight simulators, the simulated aircraft motion needs to be filtered with motion washout filters to keep the simulator within its limited motion envelope. Translational motion in particular requires filtering, as the low-frequency components of the vehicle motion tend to quickly drive simulators toward their motion bounds. Commonly, linear washout filters are therefore used to attenuate the simulated motion in magnitude and in phase. It is found in many studies that the settings of these washout filters affect pilot performance and control behavior. In most of these studies, no comparison to a case with one-to-one motion cues is performed as a result of the limited motion envelope of the simulators used. In the current study, an experiment was performed in the SIMONA Research Simulator at the Delft University of Technology to investigate the effects of heave washout settings on pilot performance and control behavior in a pitch attitude control task. In addition to rotational pitch motion, heave accelerations at the pilot station that result directly from aircraft pitch were evaluated. This heave motion component could be supplied one-to-one in the simulator due to the modest size of the aircraft model, a Cessna Citation I business jet. The experiment revealed that pilot performance and control activity both increased significantly with increasing heave motion fidelity. An analysis of pilot control behavior using pilot models indicated that the enhanced performance was caused by an increase in the magnitude with which pilots responded to visual and physical motion stimuli and a decrease in the amount of visual lead that was generated by the pilots.
The number of Advanced Driving Assistance Systems (ADAS) integrated in modern cars has grown over the last few years (e.g., BAS, ACC, navigation systems). Because car manufacturers must ensure that all these systems are compatible with the driving task, evaluation using an experimental protocol is often necessary. When analyzing the data from such evaluations, the driving context must be accurately taken into account since it has an important influence on the driving task. Thus, methods for assessing "mental workload" are often considered useful tools, as they can take both the driving context (e.g., kind of road, traffic, meteorological conditions) and the use of ADAS into account. Though subjective workload assessment methods have proved quite sensitive in many studies, they are not well suited to on-line assessment. To solve this problem, we have adapted the Instantaneous Self Assessment method (ISA), initially developed for air traffic control, for use during the driving task. An experiment was conducted on the SHERPA full-size driving simulator. Fourteen subjects were asked to complete the same 30-kilometer run twice, once with an Adaptive Cruise Control (ACC; a kind of ADAS) and once without. The route comprised stretches on motorways, major roads and mountain roads, and included various traffic densities. The ISA scale was quite senstive to traffic conditions. Moreover, ISA highlighted the prevailing influence of traffic density over road profile. However, the impact of ADAS use could not be ascertained. This study constitutes a first step towards the development of a new on-line workload assessment technique based on an automatic classification system able to take several indicators into account, including vehicle indicators (e.g., speed, brake and clutch pedals) and driver indicators (e.g., eye-gaze position).
Access to current workload is regarded as crucial for new driver assistance systems that aim at optimising drivers' workload in addition to their specific functionalities (e.g. coordinate, prioritise information). As stress factors change dynamically within the driving context, workload assessment should be dynamic and continuous rather than discrete. Here, the effects of two dynamically changing stress factors (traffic density and different demands within the manoeuvre 'entering the motorway') on workload are examined. The aim of the study is to analyse whether the influence of these stress factors on workload can be measured using a continuous subjective rating method. The results demonstrate that the use of the subjective rating method allowed the assessment of detailed information on the influence of varying stress factors on subjective strain. Furthermore, t.he significant interaction between the stress factors demonstrated the importance of precise description of the relations among different dynamically changing stress factors and resulting subjective driver strain. By integrating the current findings with results from the previous studies, the wider aim of the research, the development of a qualitative and quantitative model of stress and strain, is discussed.
We report three experiments using a new form of direct subjective presence evalua- tion that was developed from the method of continuous assessment used to assess television picture quality. Observers were required to provide a continuous rating of their sense of presence using a handheld slider. The first experiment investigated the effects of manipulating stereoscopic and motion parallax cues within video sequences presented on a 20 in. stereoscopic CRT display. The results showed that the presen- tation of both stereoscopic and motion-parallax cues was associated with higher pres- ence ratings. One possible interpretation of Experiment 1 is that CRT displays that contain the spatial cues of stereoscopic disparity and motion parallax are more inter- esting or engaging. To test this, observers in Experiment 2 rated the same stimuli first for interest and then for presence. The results showed that variations in interest did not predict the presence ratings obtained in Experiment 1. However, the subsequent ratings of presence differed significantly from those obtained in Experiment 1, suggest- ing that prior experience with interest ratings affected subsequent judgments of pres- ence. To test this, Experiment 3 investigated the effects of prior experience on pres- ence ratings. Three groups of observers rated a training sequence for interest, presence, and 3-Dness before rating the same stimuli as used for Experiments 1 and 2 for presence. The results demonstrated that prior ratings sensitize observers to differ- ent features of a display resulting in different presence ratings. The implications of these results for presence evaluation are discussed, and a combination of more-re- fined subjective measures and a battery of objective measures is recommended.
Research on new automotive systems currently relies on car driving simulators, as they are a cheaper, faster, and safer alternative to tests on real tracks. However, there is increasing concern about the motion cues provided in the simulator and their influence on the validity of these studies. Especially for curve driving, providing large sustained acceleration is difficult in the limited motion space of simulators. Recently built simulators, such as Desdemona, offer a large motion space showing great potential as automotive simulators. The goal of this research is: first, to develop a motion drive algorithm for urban curve driving in the Desdemona simulator; and second, to evaluate the solution through a simulator driving experiment. The developed algorithm, the one-to-one yaw algorithm, is compared to a classical washout algorithm (adapted to the Desdemona motion space) and a control condition where only road rumble is provided. Results show that regarding lateral motion, the absence of cues in the rumble condition is preferred over the presence of false cues in the classical algorithm. No motion seems to be favored over bad motion. In terms of longitudinal motion, the one-to-one yaw and the classical algorithm are voted better than the rumble condition, showing that the addition of motion cues is beneficial to the simulation of braking. In a general way, the one-to-one yaw algorithm is classified better than the other two algorithms.
It is still an unsolved problem how to optimally simulate self-motion using motion simulators. We investigated how a forward acceleration can be simulated as believably as possible on a hexapod motion platform equipped with a projection screen. Human participants rated the believability of brief forward accelerations. These were simulated as visual forward accelerations over a ground plane with people as size cues, presented together with brief forward surge translations and backward pitches of the platform, and synchronous random up--down movements of the camera in the visual scene and the platform. The magnitudes of all of the parameters were varied independently across trials. Even though variability between participants was high, the most believable simulation occurred when visual accelerations were combined with backward pitches of the platform, which changed the gravitoinertial vector direction approximately consistent with the visual acceleration. However, a wide range of platform pitches was accepted as believable. With high visual acceleration cues most participants reported trials as realistic even when the platform tilt rate was above vestibular canal thresholds reported in other works. Other manipulated parameters had only a mild influence on the responses. These results can be used to optimize motion-cueing algorithms for simulating linear accelerations in motion simulators.
We carried out a number of subjective experiments using typical streaming content, codecs, bitrates and network conditions. In an attempt to review subjective testing procedures for video streaming applications, we used both Single Stimulus Continuous Quality Evaluation (SSCQE) and Double Stimulus Impairment Scale (DSIS) methods on the same test material. We thus compare these testing methods and present an analysis of the experimental results in view of codec performance. Finally, we use the subjective data to corroborate the prediction accuracy of a real-time non-reference quality metric.
Simulators, in particular driving simulators, are gaining importance not only for research and development purposes, but also for education, training and even recreation. Progress in computer graphics and performance allow for highly realistic simulator visuals. High-end models are becoming somewhat better at generating acceptable inertial self-motion information, sometimes even providing real (but limited) linear translation in addition to angular movements. Simpler versions do not generate inertial information at all (fixed-base simulators). Here, we present a study on a problem that often occurs with driving simulators, i.e., simulator sickness. This phenomenon closely resembles the classically experienced motion sickness and can make a user abort a simulator run within minutes. We investigated the hypothesis that simulator sickness is caused by a visual-vestibular conflict, comparing susceptibility in normals and in vestibular-loss patients. We studied the psychophysical reactions of subjects, and quantitatively recorded their neurovegetative activity, to improve understanding of the underlying causes of simulator sickness, and to develop an objective measure for monitoring purposes. We used a fixed-base simulator, with an urban circuit with many sharp turns and traffic lights. No vestibular input was received during driving simulation, thus creating numerous visual-vestibular conflict situations. Subjects were asked to indicate continuously their discomfort on a visual-analog scale. We studied 33 normals (19 became sick) and 6 bilateral vestibular-loss subjects (one became truly sick, 2 others somewhat). Sickness correlated strongly with an increase in anxiety (Spielberger STAI). The subjective discomfort readings correlated well with simultaneous neurovegetative data and with a symptom scoring test administered immediately afterwards. There was no clear indication of an age or gender dependence in the normals. The fact that a complete vestibular-loss patient became sick indicates that more parameters may be responsible for simulator sickness than just a visuo-vestibular conflict situation (anxiety, nauseating odours, etc.). - Supported by the European Union (QLK6-CT-2002-00151: EUROKINESIS).
To better understand early positive emotional expression, automated software measurements of facial action were supplemented with anatomically based manual coding. These convergent measurements were used to describe the dynamics of infant smiling and predict perceived positive emotional intensity. Over the course of infant smiles, degree of smile strength varied with degree of eye constriction (cheek raising, the Duchenne marker), which varied with degree of mouth opening. In a series of three rating studies, automated measurements of smile strength and mouth opening predicted naïve (undergraduate) observers' continuous ratings of video clips of smile sequences, as well as naïve and experienced (parent) ratings of positive emotion in still images from the sequences. An a priori measure of smile intensity combining anatomically based manual coding of both smile strength and mouth opening predicted positive emotion ratings of the still images. The findings indicate the potential of automated and fine-grained manual measurements of facial actions to describe the course of emotional expressions over time and to predict perceptions of emotional intensity.
Pilot rating scales and their use in assessing aircraft handling qualities
As virtual reality technology continues to attract significant attention in clinical psychology, especially in the treatment of phobias, physiological monitoring is increasingly considered as an objective measurement tool for studying participants. There are few studies, however, of the normal physiological response to virtual environments or reactions to different virtual environments. The goal of this study is to analyze nonphobic participants' physiological reactions to two virtual environments: driving and flying. Eleven nonphobic participants were exposed to each virtual environment for 15 min. Heart rate, skin resistance, and skin temperature were measured during physiological monitoring, and the Presence and Simulator Sickness Questionnaire scores were obtained after each exposure. This study found that skin resistance and heart rate variability can be used to show arousal of participants exposed to the virtual environment experience and that such measures generally returned to normal over time. The data suggest that skin resistance and heart rate can be used as objective measures in monitoring the reaction of non-phobic participants to virtual environments. We also noted that heart rate variability could be useful for assessing the emotional states of participants.
In driving simulation, simulator tilt is used to reproduce sustained linear acceleration. In order to feel realistic, this tilt is performed at a rate below the human tilt rate detection threshold, which is usually assumed constant. However, it is known that many factors affect the threshold, such as visual information, simulator motion in additional directions, or the driver’s active effort required for controlling the vehicle. Here we investigated the effect of these factors on the roll rate detection threshold during simulated curve driving. Ten participants reported whether they detected roll motion in multiple trials during simulated curve driving, while roll rate was varied over trials. Roll rate detection thresholds were measured under four conditions. In the first three conditions, participants were moved passively through a curve with the following: (i) roll only in darkness; (ii) combined roll/sway in darkness; (iii) combined roll/sway and visual information. In the fourth (iv) condition participants actively drove through the curve. The results showed that roll rate thresholds in simulated curve driving increase, that is, sensitivity decreases, when the roll tilt is combined with sway motion. Moreover, an active control task seemed to further increase the detection threshold, that is, impair motion sensitivity, but with large individual differences. We hypothesize that this is related to the level of immersion during the task.
The goal of vehicle motion simulation is the realistic reproduction of the
perception a human observer would have inside the moving vehicle by providing
realistic motion cues inside a motion simulator. Motion cueing algorithms play a
central role in this process by converting the desired vehicle motion into simulator
input commands with maximal perceptual fidelity, while remaining within the
limited workspace of the motion simulator. By understanding how the one’s own
body motion through the environment is transduced into neural information by the
visual, vestibular and somatosensory systems and how this information is processed
in order to create a whole percept of self-motion we can qualify the perceptual
fidelity of the simulation. In this chapter, we address how a deep understanding
of the functional principles underlying self-motion perception can be exploited
to develop new motion cueing algorithms and, in turn, how motion simulation
can increase our understanding of the brain’s perceptual processes. We propose a
perception-based motion cueing algorithm that relies on knowledge about human
self-motion perception and uses it to calculate the vehicle motion percept, i.e. how
themotion of a vehicle is perceived by a human observer. The calculation is possible
through the use of a self-motion perception model, which simulate the brain’s
motion perception processes. The goal of the perception-based algorithm is then to
reproduce the simulator motion that minimizes the difference between the vehicle’s
desired percept and the actual simulator percept, i.e. the “perceptual error”. Finally,
we describe the first experimental validation of the newmotion cueing algorithmand
shown that an improvement in the current standards of motion cueing is possible.
Motion cueing algorithms (MCA) are used in motion simulation to map the inertial vehicle motions onto the simulator motion space. To increase fidelity of the motion simulation, these MCAs are tuned to minimize the perceived incoherence between the visual and inertial motion cues. Despite time-invariant MCA dynamics the incoherence is not constant, but changes over time. Currently used methods to measure the quality of an MCA focus on the overall differences between MCAs, but lack the ability to detect how quality varies over time and how this influences the overall quality judgement. This paper describes a continuous subjective rating method with which perceived motion incoherence can be detected over time. An experiment was performed to show the suitability of this method for measuring motion incoherence. The experiment results were used to validate the continuous rating method and showed it provides important additional information on the perceived motion incoherence during a simulation compared to an offline rating method.
Generally, motion simulators present motion and visual cues different from each other due to the physical limitations of the motion platform. Nonetheless, high fidelity motion platforms are capable of simulating some maneuvers one-to-one, i.e., motion cues equal to visual cues. However, one-to-one simulation is normally not preferred by subjects and the simulator motion is reported as too strong. In this study we investigated whether this overestimation depends on the frequency and amplitude of inertial motion. The stimuli in this study consisted of translations in the lateral direction. The Desdemona research simulator was used to generate the motion profiles. Six sinusoidal profiles with different combinations of amplitude and frequency were used as reference stimuli. For every experimental condition, the visual and inertial information had equal frequency but different amplitude. Subjects had to change the inertial motion amplitude until they obtained the best relation between the two sources of motion information. Our results showed that stimuli with high amplitude were associated with smaller motion gains than stimuli with lower amplitude. The same occurred for stimuli with higher frequency when compared to stimuli with lower frequency. The findings in this study suggest that a dynamic scaling algorithm for inertial motion could improve the perceived realism of motion simulation.
A new actuator state based adaptive motion drive algorithm that takes into account the parallel architecture of the traditional Stewart platform was developed. As opposed to traditional inertial cartesian adaptive algorithms, the proposed actuator state based adaptive algorithm cost function directly employs the simulator actuator states and therefore it implicitly accounts for the coupling between degrees-of-freedom in the workspace that exist when the motion is expressed in Cartesian coordinates. The use of the actuator states in the cost function, leads to a more robust algorithm that requires less tuning than the current UTIAS adaptive algorithm. The new algorithm also has the potential to improve the motion cues when the flight maneuvers excite multiple degrees-of-freedom unexpectedly. The new adaptive algorithm also employs a variable step size gain in the steepest descent algorithm. Adaptation is based on the position, velocity and acceleration of the simulator motion system. This adaptive gain prevents previously documented oscillations in the response of the simulator.
In January 2014, the new ITU-T P.913 recommendation for measuring subjective video, audio and multimedia quality in any environment has been published. This document does not contain any time-continuous subjective method. However, environmental parameter values are changing continuously in a majority of outdoor and also most indoor environments. To be aware of their impact on the perceived quality, a time-continuous quality assessment methodology is necessary. In previous standards, targeting laboratory-based test settings, a desk-mounted slider of substantial size is recommended. Unfortunately, there are many environments where such a device cannot be used.
In this paper, new feedback tools for mobile time-continuous rating are presented and analysed. We developed several alternatives to the generally adopted desk-mounted slider as a rating device. In order to compare the tools, we defined a number of performance measures than can be used in further studies. The suitability and efficacy of the rating scheme based on measurable parameters as well as user opinions is compared. One method, the finger count, seems to outperform the others from all points of view. It was been judged to be easy to use with low potential for distractions. Furthermore, it reaches a similar precision level as the slider, while requiring lower user reaction and scoring times. Low reaction times are particularly important for time-continuous quality assessment, where the reliability of a mapping between impairments and user ratings plays an essential role.
This paper describes an effort to objectively evaluate the effects of variations in simulator motion cueing fidelity on pilot manual control behavior. An experiment is described in which pilot roll attitude tracking behavior is measured both in real flight and, for varying motion cueing settings, in a moving-base flight simulator. Four different roll motion cueing conditions are considered in the simulator part of the experiment: no roll motion feedback, 1-to-1 roll motion feedback, and simulator roll motion resulting from the use of two different settings of a first-order high-pass roll motion filter. By fitting a multimodal pilot model that explicitly accounts for pilot's responses to visual and (simulator) motion cues to these collected measurements of pilot roll tracking behavior, the changes in pilots' control dynamics that are induced by these different simulator motion cueing settings can be quantified and compared to real flight data. In line with the results of previous investigations, clear differences in pilot control behavior were observed over the different roll motion cueing settings evaluated in the simulator part of the experiment. With increasing roll motion fidelity, pilots' were seen to increasingly rely on the presented physical motion feedback. The most notable variations in pilot control dynamics were a decrease in the visual lead time constant and an increase in the pilot visual response gain with increasing fidelity of the presented roll motion cues. Even though extreme care was taken to minimize differences in the experimental setups used for collecting the measurements in the aircraft and the simulator, consistent discrepancies in pilot tracking behavior between the collected in-flight and simulator measurements were still observed, which could not be attributed to differences in the supplied physical motion cues.
Pure feedback and pure open-loop feedforward helicopter pilot models are currently applied for predicting the performance of pilot-helicopter systems. We argue that feedback models are likely to underestimate performance in many realistic helicopter maneuvers, whereas inverse simulation models, which have an open-loop feedforward structure, are likely to overestimate performance as they neglect typical human-in-the-loop characteristics. True verification of feedback and feedforward elements in helicopter pilot control behavior was never performed, however. This paper proposes a pilot model containing a feedback and feedforward controller acting simultaneously and presents a method to identify the hypothesized feedforward action from human-in-the-loop data collected in a simulator experiment. The results of the human-in-the-loop experiment show that actual human performance is better than predicted by a pure feedback model and worse than predicted by an (inverse dynamics) feedforward model. The identification results suggest that the human pilot indeed utilizes feedforward strategies, but it was not possible to either confirm or refute the model by means of the collected data and the developed analysis method. © 2013 by the American Helicopter Society International, Inc. All rights reserved.
In a flight simulator, the calculated aircraft motions are scaled down and filtered to fit within the envelope of the simulator motion system. A number of recent flight and ground simulation studies have reported that the simulator motion was too strong, when in fact, the motion was scaled down and filtered. This paper puts forth the hypothesis that this could be due in part to the motion drive algorithm and vehicle model exaggerating the jerk. To test the plausibility of this hypothesis a paired-comparison experiment was run to determine if the subjective impression of motion strength is a function of both the acceleration and jerk of the motion. The experiment found that the level of jerk and acceleration contributed to the perceived strength of motion, with larger jerks and accelerations leading to increased motion strength. In addition, the duration of the acceleration had a significant effect on the perceived motion strength, with longer durations leading to increased motion strength. Although the relationship between jerk and motion strength suggests that exaggerated jerk in the simulator could lead to the preference for scale factors less than one, the strength of the relationship strongly suggests that it does not entirely account for the preference.
The range of motion stimuli that produce realistic sensations of longitudinal acceleration during a simulated takeoff run in a research simulator are presented. In all conditions, the visually simulated motion profile consisted of a step acceleration of 0.35 g. The gain of the translational (surge) and tilt-coordination channel (pitch) were systematically varied. The linear travel of the motion platform was kept constant by covarying the bandwidth with the gain of the high-pass surge filter. Rate and acceleration limit of tilt coordination were fixed at 0.052 rad/s and 0.052 rad/s2, respectively. Using a two-alternative-forced-choice paradigm, seven experienced pilots judged their motion perception as pilots non-flying. Based on their subjective response, psychometric curves were constructed. Pilots' judgments were negatively influenced by any perceived discontinuity between the initial surge stimulus and the sustained pitch stimulus. The range of realistic motion parameters was centered around a gain of 0.2 and natural frequency of 0.73 rad/s for the surge filter and a gain of 0.6 for the low-pass pitch filter. Remarkably, unity gains were rejected as too powerful. Therefore it is concluded that, for the typical hexapod platform, the takeoff maneuver can be more effectively simulated by providing less than the full mathematical model acceleration.
Current motion-drive algorithms have a number of coefficients that are selected to tune the motion of the simulator, Little attention has been given to the process of selecting the most appropriate coefficient values, Final tuning is best accomplished using experienced evaluation pilots to provide feedback to a washout filter expert who adjusts the coefficients in an attempt to satisfy the pilot, This paper presents the development of a tuning paradigm and the capturing of such within an expert system, The focus of this development is the University of Toronto classical algorithm, but the results are relevant to alternative classical and similarly structured adaptive algorithms, This paper provides the groundwork required to develop the tuning paradigm. The necessity of this subjective tuning process is defended, Motion cueing error sources within the classical algorithm are revealed, and coefficient adjustments that reduce the errors are presented.
Digitally coded television pictures exhibit transient picture impairments that can vary in intensity and duration. It is an important practical question to determine the extent to which these transient impairments affect the overall quality of a television sequence, as a function of their location within the sequence, their duration and their magnitude. Five experiments are reported. It is shown that retrospective quality ratings are poorer when the worst-quality video occurs at the end compared to the beginning of a 30 s video sequence. This recency effect was eliminated when subjects were asked to continuously evaluate picture quality. The duration of an impairment was found to have little impact on quality ratings. A regression analysis found that quality ratings were best predicted by the peak impairment intensity. The results were interpreted in terms of Hogarth and Einhorn's (1992) belief-adjustment model. The implications for television picture quality evaluation are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
To gain knowledge on how visual discomfort is built up while watching stereoscopic content an experiment was designed with two objectives: (1) to compare the continuous evaluation method with other assessment methods that potentially can substitute the continuous evaluation for the assessment of visual discomfort of e.g., feature-length movies, and (2) to relate the impact of time-variant content characteristics, such as motion and disparity, to the assessment of visual discomfort. In an experiment a 24 min 3D movie 'Spy Kids 3-D: game over' converted from 2D to 3D was displayed on a 9-view autostereoscopic lenticular LCD, and continuously assessed in terms of visual comfort by 24 participants. Additional assessment methods included the assessment of six 10 s sequences captured from the 3D movie and a single retrospective assessment of the entire 3D movie. Time-variant content characteristics, such as derivatives of motion and screen disparity values, were extracted from the 3D movie with motion and depth estimation algorithms. The moment-to-moment values of these characteristics were correlated to the continuous assessment scores of visual discomfort. With respect to the first objective, results reveal that the correlation between the assessment of the 10 s sequences captured from the 3D movie and their corresponding part within the continuous assessment is low, whereas the correlation between the retrospective assessment and the mean of the continuous assessment score over scene parts with a high screen disparity is higher. With respect to the second objective, for static scenes the visual comfort can be largely described by the screen disparity offset and range. For dynamic scenes the visual comfort is largely related to the screen disparity range, lateral motion and to the change in screen disparity.
A general formula (α) of which a special case is the Kuder-Richardson coefficient of equivalence is shown to be the mean of
all split-half coefficients resulting from different splittings of a test. α is therefore an estimate of the correlation between
two random samples of items from a universe of items like those in the test. α is found to be an appropriate index of equivalence
and, except for very short tests, of the first-factor concentration in the test. Tests divisible into distinct subtests should
be so divided before using the formula. The index
[`(r)]ij\bar r_{ij}
, derived from α, is shown to be an index of inter-item homogeneity. Comparison is made to the Guttman and Loevinger approaches.
Parallel split coefficients are shown to be unnecessary for tests of common types. In designing tests, maximum interpretability
of scores is obtained by increasing the first-factor concentration in any separately-scored subtest and avoiding substantial
group-factor clusters within a subtest. Scalability is not a requisite.
This study presents a novel motion-cueing strategy, which is applied to a motion simulator with three rotational degrees of freedom (DOF) to perform the roll, pitch, yaw, surge, and sway motions by using an online optimization algorithm. The weighting functions are adaptively tuned in each step, and the optimal Euler angles are obtained analytically. This motion-cueing algorithm is efficient since it requires no recursive search on the optimal solution. Experiments demonstrating the validity of the 5-DOF motion simulation are also included.
Motion-based driving simulators are designed to render accelerations perceived as realistic, while keeping the motion system within its physical limits. These objectives are generally contradictory, and consequently motion control strategies are difficult to customize for different simulator configurations. In this paper, a novel approach is presented for the design of motion rendering strategies, using the model-based predictive control theory. Compared to traditional cueing techniques, actuator constraints are always respected, and the use of motion workspace is maximized during simulations. Models of human motion perception can be integrated to reduce sensory conflicts. A practical implementation on a high-performance automotive driving simulator is presented.
( This reprinted article originally appeared in Psychological Review, 1927, Vol 34, 273–286. The following is a modified version of the original abstract which appeared in PA, Vol 2:527. ) Presents a new psychological law, the law of comparative judgment, along with some of its special applications in the measurement of psychological values. This law is applicable not only to the comparison of physical stimulus intensities but also to qualitative judgments, such as those of excellence of specimens in an educational scale. The law is basic for work on Weber's and Fechner's laws, applies to the judgments of a single observer who compares a series of stimuli by the method of paired comparisons when no "equal" judgments are allowed, and is a rational equation for the method of constant stimuli.
Tests consisting of one- and two-axis closed-loop tracking tasks, with and without motion, have been made to define some areas where motion cues are beneficial. Tests were made with reduced scaling on the motion input to investigate the minimum requirements of motion cues in those tests where motion was found to be of assistance. For the set of conditions tested, little or no difference in the measurement criteria was observed in the single-axis motion/no motion runs. Similar results were obtained when comparing two single-axis tests with different pitch orientation. The two-axis tests, which consisted of pitch and yaw and pitch and roll, did, however, produce a difference in the error measurements in the motion/no motion comparison. A decrease in normalized tracking error and an increase in closed-loop system frequency were observed when motion was added. Tests were also run, in pitch and yaw only, in which the scale of the motion input was reduced. These tests were performed by the subject in sequence starting with no motion all the way to full motion and back down to no motion. Each motion scale condition (none, 1/16, ¿, ¼, ½, and full) constituted a test. The normalized tracking error remained constant for full, ½, and ¼ motion scaling, but increased with a further reduction in motion scaling.
Need-Based evaluation of simulator force and motion cuing devices
- Y J Brown
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Phase coherence zones in flight simulation
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Effects of motion filter parameters on simulation fidelity ratings
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Effects of motion cueing on curve driving
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Motion parameter tuning and evaluation for the DLR automotive simulator
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Multimodal pilot behavior in multi-axis tracking tasks with time-varying motion cueing gains
- P M T Zaal
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Methodology for the subjective assessment of the quality of television pictures
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