Effects of fatigue on simulated space telerobotics performance : a preliminary study analysis

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.Cataloged from department-submitted PDF version of thesis. This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 82-86).Astronauts on the International Space Station must perform mission critical space telerobotics tasks consistently despite restricted and slam shifted sleep and circadian schedules and long session durations, which all potentially degrade cognitive function, response time, and attention. A ground laboratory experiment was designed to 1) Determine the effects of fatigue on performance metrics in simulated space telerobotics tasks, 2) Examine the relationships between performance on complex robotics tasks and traditional metrics of cognitive task performance and sleepiness, 3) Assess the efficacy of caffeine and blue light countermeasures, and 4) Evaluate individual subject vulnerability to fatigue. Subjects were screened for robotics aptitude, and trained on three robotics tasks and a mental workload assessing secondary task at MIT. After a week of 6-hr sleep restriction, they were admitted to the Brigham and Women's Hospital sleep laboratory, a time-cue free environment, and underwent a 13 day double blind protocol including physiologic monitoring and robotic and cognitive testing. Their sleep schedule was repeatedly slam shifted 9 hours earlier then they performed the robotics tasks under different countermeasure conditions. This thesis documents the protocol and details of the robotics training and testing, and includes a preliminary analysis of data from 16 subjects focusing on robotics and secondary task data. Since the study is continuing and investigators are blinded to countermeasure conditions, data from the countermeasure sessions is not included. Thesis goals were to 1) Analyze the predictive capability of spatial ability tests on individual robotics performance, 2) Evaluate the effects on robotics metrics of proxy measures of circadian and time-on-task, and 3) Assess individual differences in performance and vulnerability to fatigue. The Vandenberg Mental Rotation Test was found to be the best predictor of both robotics screening test and experimental performance, although an average of four spatial ability tests was slightly better for screening purposes. A comparison between a final training and non- countermeasure test session indicated that slam shifting had no significant effect on group average performance in any of the three robotics tasks or the secondary task. However, within the slam shifted session, a time-on-task related effect in secondary task performance was evident, suggesting that mental workload gradually increased even though subjects were able to maintain primary robotics task performance. Inter-subject differences were consistently larger than other effects.by Raquel Galvan.S.M

Evaluation of a Surface Exploration Traverse Analysis and Navigation Tool

SEXTANT is an extravehicular activity (EVA) mission planner tool developed in MATLAB, which computes the most efficient path between waypoints across a planetary surface. The traverse efficiency can be optimized around path distance, time, or explorer energy consumption. The user can select waypoints and the time spent at each, and can visualize a 3D map of the optimal path. Once the optimal path is generated, the thermal load on suited astronauts or solar power generation of rovers is displayed, along with the total traverse time and distance traveled. A field study was conducted at the Mars Desert Research Station (MDRS) in Utah to see if there was a statistical difference between the SEXTANT-determined energy consumption, time, or distance of EVA traverses and the actual output values. Actual traverse time was significantly longer than SEXTANT-predicted EVA traverse time (n=6, p<0.01), traverse distance was not significantly different than SEXTANT-predicted distance, and explorer energy consumption was significantly greater than SEXTANT-predicted energy consumption (n=5, p<0.01). A second study was done to see if mission re-planning, or contingency planning, was faster and less work when using SEXTANT in the habitat or in the field using an iPad. Time and workload measurements were collected for each subject under both conditions. Contingency planning in the habitat was not significantly different than contingency planning in the field. There was no significant workload difference when contingency planning in either location, however there was a trend that suggested contingency planning was faster in the habitat (n=3, p=0.07). Every subject commented that it was a hassle to carry the mission planner in the field and it was difficult to see the screen in the sunlight. To determine if gloves were a factor in the difference between mission re-planning time, subjects were asked to plan a contingency indoors with and without gloves. Performance and workload were not significantly different when re-planning with and without the gloves. The SEXTANT mission planner will continue to be improved according to the results and the recommendations of subjects in this study.United States. National Aeronautics and Space Administration (NASA Astrobiology Institute)Massachusetts Space Grant Consortiu

Using low levels of stochastic vestibular stimulation to improve locomotor stability

Low levels of bipolar binaural white noise based imperceptible stochastic electrical stimulation to the vestibular system (stochastic vestibular stimulation, SVS) have been shown to improve stability during balance tasks in normal, healthy subjects by facilitating enhanced information transfer using stochastic resonance (SR) principles. We hypothesize that detection of time-critical sub-threshold sensory signals using low levels of bipolar binaural SVS based on SR principles will help improve stability of walking during support surface perturbations. In the current study 13 healthy subjects were exposed to short continuous support surface perturbations for 60 s while walking on a treadmill and simultaneously viewing perceptually matched linear optic flow. Low levels of bipolar binaural white noise based SVS were applied to the vestibular organs. Multiple trials of the treadmill locomotion test were performed with stimulation current levels varying in the range of 0–1500 μA, randomized across trials. The results show that subjects significantly improved their walking stability during support surface perturbations at stimulation levels with peak amplitude predominantly in the range of 100–500 μA consistent with the SR phenomenon. Additionally, objective perceptual motion thresholds were measured separately as estimates of internal noise while subjects sat on a chair with their eyes closed and received 1 Hz bipolar binaural sinusoidal electrical stimuli. The optimal improvement in walking stability was achieved on average with peak stimulation amplitudes of approximately 35% of perceptual motion threshold. This study shows the effectiveness of using low imperceptible levels of SVS to improve dynamic stability during walking on a laterally oscillating treadmill via the SR phenomenon

Enhancement of perception with the application of stochastic vestibular stimulation

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 134-145).Astronauts experience sensorimotor changes during spaceflight, which may degrade their operational capabilities. A sensorimotor countermeasure that mitigates these effects would improve crewmember safety and decrease mission risk. The goal of this research was to investigate the potential use of electrical stochastic vestibular stimulation (SVS) as a sensorimotor aid to lower vestibular thresholds and improve manual control. We hypothesized that low-level, subsensory bandlimited white noise (±200 - ±700 [mu]A peak, 52 - 182 ±5% [mu]A RMS) passed between surface electrodes located on the mastoid bone behind each ear would enhance perceptual sensitivity to physical motions due to the phenomenon of stochastic resonance (SR). The goals of this research were to 1) demonstrate that SVS can significantly reduce vestibular direction recognition thresholds, 2) investigate whether the SR phenomenon involves stimulation of the semicircular canals, otoliths or both, and 3) demonstrate that SVS can improve perception-based manual control performance in a task relevant to piloting during planetary landing, docking, or other vehicle maneuvers. In a first experiment, upright roll tilt direction recognition thresholds, which elicit responses from both the semicircular canals and otoliths, were measured with varying levels of SVS applied. Upright roll tilt direction recognition thresholds exhibited characteristic SR dependency on current level that was statistically significant in 6/12 subjects. However, SR repeatability across days was found to be weak, only present in 3/12 subjects. In a second experiment, supine roll rotation (primarily stimulating the semicircular canals) and inter-aural translation (primarily stimulating the otoliths) direction recognition thresholds were measured with varying levels of SVS applied. SR was exhibited in inter-aural translation (6/11 subjects) but not supine roll rotation (1/12 subjects), suggesting that stimulation of the otolith organs may be vital to vestibular perceptual SR. Simulations of the experimental test procedure were used to create a dataset of direction recognition thresholds with several predefined underlying SR exhibition levels. A comparison of the results form Experiment I and 2 to the simulated datasets allowed us to more confidently draw conclusions from data that are prone to the existence of false positives. In a third experiment, subjects used vestibular information to null out pseudo-random vehicle disturbance in a manual control task. SVS (±300 [mu]A) improved the group mean position variability when motions were near threshold and extended the range of frequencies in which motions could be nulled out. The results of this thesis are consistent with the concept that SVS is able to extend the operating range of the vestibular perceptual system in some individuals. In the context of human spaceflight, results from this research further our understanding of how SVS may be implemented in the future as a component of a comprehensive spaceflight countermeasure plan.by Raquel Galvan-Garza.Ph. D

Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

Higher harmonic non-linear flow modes of charged hadrons in Pb-Pb collisions at sNN\sqrt{s_{\rm{NN}}} = 5.02 TeV

International audienceAnisotropic flow coefficients, v$_{n}$, non-linear flow mode coefficients, χ$_{n,mk}$, and correlations among different symmetry planes, ρ$_{n,mk}$ are measured in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. Results obtained with multi-particle correlations are reported for the transverse momentum interval 0.2 < p$_{T}$< 5.0 GeV/c within the pseudorapidity interval 0.4 < |η| < 0.8 as a function of collision centrality. The v$_{n}$ coefficients and χ$_{n,mk}$ and ρ$_{n,mk}$ are presented up to the ninth and seventh harmonic order, respectively. Calculations suggest that the correlations measured in different symmetry planes and the non-linear flow mode coefficients are dependent on the shear and bulk viscosity to entropy ratios of the medium created in heavy-ion collisions. The comparison between these measurements and those at lower energies and calculations from hydrodynamic models places strong constraints on the initial conditions and transport properties of the system.[graphic not available: see fulltext

Production of Λ\Lambda and KS0{\rm K}^{0}_{\rm S} in jets in p-Pb collisions at sNN=5\sqrt{s_{\rm NN}} = 5 TeV and pp collisions at s=7\sqrt{s} = 7 TeV

The production of $\Lambda$ baryons and ${\rm K}^{0}_{\rm S}$ mesons (${\rm V}^{0}$ particles) was measured in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5$ TeV and pp collisions at $\sqrt{s} = 7$ TeV with ALICE at the LHC. The production of these strange particles is studied separately for particles associated with hard scatterings and the underlying event to shed light on the baryon-to-meson ratio enhancement observed at intermediate transverse momentum ($p_{\rm T}$) in high multiplicity pp and p-Pb collisions. Hard scatterings are selected on an event-by-event basis with jets reconstructed with the anti-$k_{\rm T}$ algorithm using charged particles. The production of strange particles associated with jets $p_{\rm T,\;jet}^{\rm ch}>10$ GeV/$c$ is reported as a function of $p_{\rm T}$ in both systems; and its dependence on $p_{\rm T}$ with jets $p_{\rm T,\;jet}^{\rm ch}>20$ GeV/$c$ and on angular distance from the jet axis, $R({\rm V}^{0},\;{\rm jet})$, for jets with $p_{\rm T,\;jet}^{\rm ch} > 10$ GeV/$c$ are reported in p-Pb collisions. The results are compared with the strange particle production in the underlying event. The $\Lambda/{\rm K}^{0}_{\rm S}$ ratio associated with jets in p-Pb collisions for $R({\rm V}^{0},\;{\rm jet})<0.4$ is consistent with the ratio measured in pp collisions and with the expectation of jets fragmenting in vacuum given by the PYTHIA event generator

Higher-order correlations between different moments of two flow amplitudes in Pb−-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

International audienceThe correlations between different moments of two flow amplitudes, extracted with the recently developed asymmetric cumulants, are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV recorded by the ALICE detector at the LHC. The magnitudes of the measured observables show a dependence on the different moments as well as on the collision centrality, indicating the presence of non-linear response in all even moments up to the eighth. Furthermore, the higher-order asymmetric cumulants show different signatures than the symmetric and lower-order asymmetric cumulants. Comparisons with state-of-the-art event generators using two different parameterizations obtained from Bayesian optimization show differences between data and simulations in many of the studied observables, indicating a need for further tuning of the models behind those event generators. These results provide new and independent constraints on the initial conditions and transport properties of the system created in heavy-ion collisions

First measurement of the ∣t∣|t|-dependence of incoherent J/ψ\psi photonuclear production

International audienceThe first measurement of the cross section for incoherent photonuclear production of J/$\psi$ vector meson as a function of the Mandelstam $|t|$ variable is presented. The measurement was carried out with the ALICE detector at midrapidity, $|y|<0.8$, using ultra-peripheral collisions of Pb nuclei at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. This rapidity interval corresponds to a Bjorken-$x$ range $(0.3$$-$$1.4)\times 10^{-3}$. Cross sections are reported in five $|t|$ intervals in the range $0.04<|t|<1$~GeV$^2$ and compared to the predictions of different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a $|t|$-dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data

Data-driven precision determination of the material budget in ALICE

The knowledge of the material budget with a high precision is fundamental for measurements of direct photon production using the photon conversion method due to its direct impact on the total systematic uncertainty. Moreover, it influences many aspects of the charged-particle reconstruction performance. In this article, two procedures to determine data-driven corrections to the material-budget description in ALICE simulation software are developed. One is based on the precise knowledge of the gas composition in the Time Projection Chamber. The other is based on the robustness of the ratio between the produced number of photons and charged particles, to a large extent due to the approximate isospin symmetry in the number of produced neutral and charged pions. Both methods are applied to ALICE data allowing for a reduction of the overall material budget systematic uncertainty from 4.5% down to 2.5%. Using these methods, a locally correct material budget is also achieved. The two proposed methods are generic and can be applied to any experiment in a similar fashion.The knowledge of the material budget with a high precision is fundamental for measurements of direct photon production using the photon conversion method due to its direct impact on the total systematic uncertainty. Moreover, it influences many aspects of the charged-particle reconstruction performance. In this article, two procedures to determine data-driven corrections to the material-budget description in ALICE simulation software are developed. One is based on the precise knowledge of the gas composition in the Time Projection Chamber. The other is based on the robustness of the ratio between the produced number of photons and charged particles, to a large extent due to the approximate isospin symmetry in the number of produced neutral and charged pions. Both methods are applied to ALICE data allowing for a reduction of the overall material budget systematic uncertainty from 4.5% down to 2.5%. Using these methods, a locally correct material budget is also achieved. The two proposed methods are generic and can be applied to any experiment in a similar fashion