Musculoskeletal Modeling & Statistical Analysis of ...€¦ · muscle injury during EVA, therefore...
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Human-Space Suit Interaction: Musculoskeletal Modeling & Statistical Analysis of Injuries Introduction A. Hilbert 1 , A. Diaz 1 , A. Anderson 1 , D. J. Newman 1 1 Massachusetts Institute of Technology Results Knee-extensor muscles do not show significant changes from the unsuited to suited conditions. Extravehicular activity (EVA) is a critical and complex aspect of human spaceflight missions. Astronauts undergo extensive training in the Neutral Buoyancy Lab (NBL), involving many hours of performing repetitive motions at various orientations inside the pressurized space suit 10,14,16 .The current U.S. space suit— the Extravehicular Mobility Unit (EMU)—limits human mobility, causes discomfort, and leads to a variety of contact and strain injuries 2,5,7,9,11,12 . We focus on two particular areas of injury: the knee and the shoulder. The objective of this research is to gain a greater understanding of human-spacesuit interaction by 1) using a new musculoskeletal modeling framework and 2) performing statistical analysis to relate anthropometry, spacesuit components, and training time to injury. Limb injuries, such as to the knee, can be caused by rubbing against the soft goods or high muscle forces of the joint. Shoulder injuries are mainly attributed to the EMU’s hard upper torso (HUT). While suit related injuries have been observed for many years and some basic Common EVA injury locations (A. Anderson) countermeasures have been implemented, there is still a lack of understanding of how humans move within the space suit. Overview Methods A new musculoskeletal modeling framework is developed in OpenSim (Stanford, CA) to quantify musculoskeletal performance of astronauts during EVA and to assess their susceptibility to injury. Analysis is performed on the EMU and on NASA’s Mark III spacesuit, designed for enhanced mobility. Experimental motion capture data Scaling Inverse kinematics Residual Reduction Algorithm Computed Muscle Control Marker trajectories Subject mass Generic model Subject specific model Ground reaction forces Spacesuit model (external torques) Spacesuit model (external torque) Muscle Activation and Forces Adjusted kinematics Subject specific model adjusted Kinematics Modeling Steps: 1) Human modeling using OpenSim 2) Spacesuit modeling - EMU: Space Suit Robot Tester - MKIII: Modified fish scale method 3) Human-spacesuit interaction modeling to compute representative human performance measures Source of top image: P. Schmidt et al. Source of bottom image: D. Valish et al. £ use of non-parametric test KW ^ significance between unsuited and EMU & significance between unsuited and MKIII * significance between EMU and MKIII Knee Flexors Peak Forces (N) Total force – knee flexors FLEXION EXTENSION α = 40° α = 100° α = 40° 0 500 1000 1500 2000 2500 3000 0 25 50 75 100 Total force (N) Percentage of movement (%) Unsuited EMU MKIII * * * Total Flexion Muscles (*p<0.05) (Source of all above: A. Diaz et al.) References This project is funded through NASA Grant NNX12AC09G,”Spacesuit Trauma Countermeasure System for Intravehicular and Extravehicular Activities” . Additional support provided by the National Science Foundation Graduate Research Fellowship Program. Overview Methods A new database was compiled by NASA personnel at the Longitudinal Study on Astronaut Health (LSAH), which is the most comprehensive database of this nature and includes three major components: anthropometric measurements, training record, and an injury record. We perform statistical analysis to relate anthropometry, spacesuit HUT components, and training time to shoulder injury. Anthropometric Measurements 16 dimensions identified as the most potentially relevant Training Record training day actual/estimated time in the suit HUT: planar or pivoted and size 12 proxy dimensions aggregated from database Injury Record every shoulder incident reported by an astronaut 4 groups 1) injuries not attributable to working in the suit 2) injuries attributable to the suit 3) shoulder pathologies began during active duty 4) shoulder pathologies beginning outside active duty Results For subjects with injuries attributable to the suit, a model was built from a priori knowledge of anticipated contributing variables, then reduced to relevant factors with the Wald statistic. Suit Attributable Injury Coef. Variable Wald p-value -2.075 Constant -0.48 0.629 0.025 Incidence in planar HUT 3.161 0.031* -0.011 Frequency of runs -1.38 0.19 -0.061 Recovery betweeen runs -2.22 0.069 -0.52 Inter acromium distance -2.16 0.002* -0.499 Chest breadth -1.31 0.168 0.649 Bi-deltoid breadth 1.819 0.027* 0.441 Height minus cervical height 1.45 0.147 _0 _1 _2 _3 _4 _5 _6 _7 (*p<0.05) Area under curve = .741 The Log-Likelihood fit of the overall model is p = .007 and the AIC was minimized. Marginally significant variables were kept to improve model fit. The model correctly predicted 70% of subjects, favoring type II error. Of note, neither previous injury nor HUT sizes were relevant to the model. (Kutner 2005) Logistic regression: predicts a binary (injured/uninjured) response and does not require normally distributed variables where 1. Anderson, A., Kracik, M., Trotti, G., Newman, D.J., “Preliminary Astronaut Injury Countermeasure and Protection Suit Design”, Abstract #2123, 18th IAA Humans in Space Symposium, Houston, TX, April 2011. 2. Carr, C. E., Newman, D. J., “Space Suit Bioenergetics: Framework and Analysis of Unsuited and Suited Activity”, Aviation, Space Environmental Medicine, 78:1013-1022, 2007. 3. S. L. Delp, F. C. Anderson, A. S. Arnold, P. Loan, A. Habib, C. T. John, E. Guendelman, and D. G. Thelen, “OpenSim: open-source software to create and analyze dynamic simulations of movement.,” IEEE Trans. Biomed. Eng., vol. 54, no. 11, pp. 1940–50, Nov. 2007. 4. Diaz, A., Anderson, A., Kracik, M., Trotti, G., Hoffman, J., Newman, D., “Development of A Comprehensive Astronaut Spacesuit Injury Database” 63 International Astronautical Congress, Naples Italy, 2012. 5. Gilkey, A. (2012). Space Suit Simulator for Partial Gravity Extravehicular Activity Experimentation and Training. Department of Aeronautics and Astronautics. Cambridge, MA, Massachusetts Institute of Technology. M.S. 6. Kutner, Nachtsheim, Neter , Li. “Applied Linear Statistical Models” Fifth Edition.. McGraw-Hill Irwin, New York, 2005. 7. Morgan, D. A., R. Wilmington, et al. (1996). Comparison of Extravehicular Mobility Unit (EMU) Suited and Unsuited Isolated Joint Strength Measurements. Houston, TX, Johnson Space Center. 8. Newman, D.J., Opperman, R., “EVA Injury, Comfort and Protection,” MIT, Dept. of Aeronautics and Astronautics, Technical Report, PO# 293723 for ILC, Dover, Sept. 5, 2008. 9. Opperman, R., Waldie, J., Newman, D.J. “EVA Injury, Comfort and Protection: Improving the Plight of the Hand and Shoulder for the Constellation Program”, International Conference on Environmental Systems (ICES), San Fran, IL July 2008 10. Scheuring, R., P. McCullouch, et al. (2012). Shoulder Injuries in US Astronauts Related to EVA Suit Design. Aerospace Medical Association. Atlanta, GA. 11. Scheuring, R. A., C. H. Mathers, et al. (2009). “Musculoskeletal injuries and minor trauma in space: incidence and injury mechanisms in U.S. astronauts.” Aviat Space Environ Med 80(2): 117-24. 12. Schmidt, P. (2001). An Investigation of Space Suit Mobility with Applications to EVA Operations. Aeronautics and Astronautics. Cambridge, MA, Massachusetts Institute of Technology. PhD: 254. 13. Schmidt, P.B., Newman, D.J., Hodgson, E. “Modeling Space Suit Mobility: Applications to Design and Operations,” in 31st International Conference on Environmental Systems, 2001, no. 01. 14. Strauss, S. (2004). Extravehicular Mobility Unit Training Suit Symptom Study Report. Houston, TX, Johnson Space Center. 15. Valish, D., Eversley , K. “Space Suit Joint Torque Measurement Method Validation,” in International Conference on Environmental Systems, 2012, pp. 1–14. 16. Williams, D. R. and B. J. Johnson (2003). EMU Shoulder Injury Tiger Team Report. Houston, TX: 104. Our musculoskeletal model can be used to assess the potential for knee muscle damage. In the future, we could apply these methods to other joints and other spacesuits. The resulting torque limits could be imposed on future suit designs to decrease the chance of injury A similar statistical analysis was performed on subjects whose injury pathologies began in active duty. Future work will involve cross-validation of the model coefficients and tuning of the cut-off parameter. Due to the small sample size, bootstrap and resampling techniques will be used. Overall, we can use these models to make generalizations about suit fit and training conditions. Eventually, we would like to create an injury susceptibility tool that takes into account all possible mechanisms of injury and weights them to assess muscle injury during EVA, therefore allowing us to determine the feasibility of individual EVA tasks. Musculoskeletal Modeling Injury Statistics Discussion & Future Work Flexor Muscles Unsuited EMU MKIII Biceps femoris long head (BFL) ^& 1316±57 1448±33 1428±40 Biceps femoris short head (BFS) £ 673±20 669±24 674±19 Gracilis (GR) ^& 135±6 147±2 145±4 Gastrocnemius medialis (GM) ^&* 105±25 296±33 175±24 Sartorius (SR) £^ 134±23 153±2 153±3
Transcript of Musculoskeletal Modeling & Statistical Analysis of ...€¦ · muscle injury during EVA, therefore...
Human-Space Suit Interaction: Musculoskeletal Modeling & Statistical Analysis of Injuries
Introduction
A. Hilbert1, A. Diaz1, A. Anderson1, D. J. Newman1 1Massachusetts Institute of Technology
Results
Knee-extensor muscles do not show significant changes from the unsuited to suited conditions.
Extravehicular activity (EVA) is a critical and
complex aspect of human spaceflight missions.
Astronauts undergo extensive training in the
Neutral Buoyancy Lab (NBL), involving many
hours of performing repetitive motions at
various orientations inside the pressurized
space suit10,14,16.The current U.S. space suit—
the Extravehicular Mobility Unit (EMU)—limits
human mobility, causes discomfort, and leads
to a variety of contact and strain
injuries2,5,7,9,11,12. We focus on two particular
areas of injury: the knee and the shoulder.
The objective of this research is to gain a greater
understanding of human-spacesuit interaction by 1) using a
new musculoskeletal modeling framework and 2) performing
statistical analysis to relate anthropometry, spacesuit
components, and training time to injury.
Limb injuries, such as to the knee, can be
caused by rubbing against the soft goods or
high muscle forces of the joint. Shoulder injuries
are mainly attributed to the EMU’s hard upper
torso (HUT). While suit related injuries have
been observed for many years and some basic
Common EVA
injury
locations
(A. Anderson)
countermeasures have been implemented, there is still a lack
of understanding of how humans move within the space suit.
Overview
Methods
A new musculoskeletal modeling framework is developed in
OpenSim (Stanford, CA) to quantify musculoskeletal
performance of astronauts during EVA and to assess their
susceptibility to injury. Analysis is performed on the EMU and
on NASA’s Mark III spacesuit, designed for enhanced mobility.
Experimental motion capture
data
Scaling
Inverse kinematics
Residual ReductionAlgorithm
Computed Muscle Control
Marker trajectories
Subject mass
Generic model
Subject specific model
Ground reaction forces
Spacesuit model(external torques)
Spacesuit model(external torque)
Muscle Activation and Forces
Adjusted kinematics
Subject specific model adjusted
Kinematics
Modeling Steps:
1) Human modeling using OpenSim
2) Spacesuit modeling
- EMU: Space Suit Robot Tester
- MKIII: Modified fish scale
method
3) Human-spacesuit interaction
modeling to compute
representative human
performance measures
Source of top image: P. Schmidt et al.
Source of bottom image: D. Valish et al. £ use of non-parametric test KW
^ significance between unsuited and EMU & significance between unsuited and MKIII
* significance between EMU and MKIII
Knee Flexors Peak Forces (N)
Total force – knee flexors
FLEXION EXTENSION
α = 40° α = 100° α = 40°
0
500
1000
1500
2000
2500
3000
0 25 50 75 100
Tota
l for
ce (N
)
Percentage of movement (%)
Unsuited
EMU
MKIII
**
*
Total Flexion Muscles
(*p<0.05)
(Source of all above: A. Diaz et al.)
References
This project is funded through NASA Grant NNX12AC09G,”Spacesuit Trauma Countermeasure System for Intravehicular and Extravehicular Activities”. Additional support provided by the National Science Foundation Graduate Research Fellowship Program.
Overview
Methods
A new database was compiled by NASA personnel at the
Longitudinal Study on Astronaut Health (LSAH), which is the
most comprehensive database of this nature and includes
three major components: anthropometric measurements,
training record, and an injury record. We perform statistical
analysis to relate anthropometry, spacesuit HUT components,
and training time to shoulder injury.
Anthropometric Measurements
16 dimensions identified as the most potentially relevant
Training Record
training day
actual/estimated time in the suit
HUT: planar or pivoted and size
12 proxy dimensions aggregated from database
Injury Record
every shoulder incident reported by an astronaut
4 groups
1) injuries not attributable to working in the suit
2) injuries attributable to the suit
3) shoulder pathologies began during active duty
4) shoulder pathologies beginning outside active duty
Results
For subjects with injuries attributable to the suit, a model was
built from a priori knowledge of anticipated contributing
variables, then reduced to relevant factors with the Wald
statistic.
Suit Attributable Injury
Coef. Variable Wald p-value
-2.075 Constant -0.48 0.629
0.025 Incidence in planar HUT 3.161 0.031*
-0.011 Frequency of runs -1.38 0.19
-0.061 Recovery betweeen runs -2.22 0.069
-0.52 Inter acrom ium distance -2.16 0.002*
-0.499 Chest breadth -1.31 0.168
0.649 Bi-deltoid breadth 1.819 0.027*
0.441 Height minus cerv ical height 1.45 0.147
_0
_1
_2
_3
_4
_5
_6
_7 (*p<0.05)
Area under
curve = .741
The Log-Likelihood fit of the overall model is p = .007 and the
AIC was minimized. Marginally significant variables were kept
to improve model fit. The model correctly predicted 70% of
subjects, favoring type II error. Of note, neither previous injury
nor HUT sizes were relevant to the model. (Kutner 2005)
Logistic regression: predicts a binary (injured/uninjured)
response and does not require normally distributed variables
where
1. Anderson, A., Kracik, M., Trotti, G., Newman, D.J., “Preliminary Astronaut Injury Countermeasure and Protection Suit Design”, Abstract #2123, 18th IAA Humans in Space Symposium, Houston, TX, April 2011. 2. Carr, C. E., Newman, D. J., “Space Suit Bioenergetics: Framework and Analysis of Unsuited and Suited Activity”, Aviation, Space Environmental Medicine, 78:1013-1022, 2007. 3. S. L. Delp, F. C. Anderson, A. S. Arnold, P. Loan, A. Habib, C. T. John, E. Guendelman, and D. G. Thelen, “OpenSim: open-source software to create and analyze dynamic simulations of movement.,” IEEE Trans. Biomed. Eng., vol. 54, no. 11, pp. 1940–50, Nov. 2007. 4. Diaz, A., Anderson, A., Kracik, M., Trotti, G., Hoffman, J., Newman, D., “Development of A Comprehensive Astronaut Spacesuit Injury Database” 63 International Astronautical Congress, Naples Italy, 2012. 5. Gilkey, A. (2012). Space Suit Simulator for Partial Gravity Extravehicular Activity Experimentation and Training. Department of Aeronautics and Astronautics. Cambridge, MA, Massachusetts Institute of Technology. M.S. 6. Kutner, Nachtsheim, Neter, Li. “Applied Linear Statistical Models” Fifth Edition.. McGraw-Hill Irwin, New York, 2005. 7. Morgan, D. A., R. Wilmington, et al. (1996). Comparison of Extravehicular Mobility Unit (EMU) Suited and Unsuited Isolated Joint Strength Measurements. Houston, TX, Johnson Space Center. 8. Newman, D.J., Opperman, R., “EVA Injury, Comfort and Protection,” MIT, Dept. of Aeronautics and Astronautics, Technical Report, PO# 293723 for ILC, Dover, Sept. 5, 2008. 9. Opperman, R., Waldie, J., Newman, D.J. “EVA Injury, Comfort and Protection: Improving the Plight of the Hand and Shoulder for the Constellation Program”, International Conference on Environmental Systems (ICES), San Fran, IL July 2008 10. Scheuring, R., P. McCullouch, et al. (2012). Shoulder Injuries in US Astronauts Related to EVA Suit Design. Aerospace Medical Association. Atlanta, GA. 11. Scheuring, R. A., C. H. Mathers, et al. (2009). “Musculoskeletal injuries and minor trauma in space: incidence and injury mechanisms in U.S. astronauts.” Aviat Space Environ Med 80(2): 117-24. 12. Schmidt, P. (2001). An Investigation of Space Suit Mobility with Applications to EVA Operations. Aeronautics and Astronautics. Cambridge, MA, Massachusetts Institute of Technology. PhD: 254. 13. Schmidt, P.B., Newman, D.J., Hodgson, E. “Modeling Space Suit Mobility: Applications to Design and Operations,” in 31st International Conference on Environmental Systems, 2001, no. 01. 14. Strauss, S. (2004). Extravehicular Mobility Unit Training Suit Symptom Study Report. Houston, TX, Johnson Space Center. 15. Valish, D., Eversley, K. “Space Suit Joint Torque Measurement Method Validation,” in International Conference on Environmental Systems, 2012, pp. 1–14. 16. Williams, D. R. and B. J. Johnson (2003). EMU Shoulder Injury Tiger Team Report. Houston, TX: 104.
Our musculoskeletal model can be used to assess the
potential for knee muscle damage. In the future, we could
apply these methods to other joints and other spacesuits. The
resulting torque limits could be imposed on future suit designs
to decrease the chance of injury
A similar statistical analysis was performed on subjects whose
injury pathologies began in active duty. Future work will
involve cross-validation of the model coefficients and tuning of
the cut-off parameter. Due to the small sample size, bootstrap
and resampling techniques will be used.
Overall, we can use these models to make generalizations
about suit fit and training conditions. Eventually, we would like
to create an injury susceptibility tool that takes into account all
possible mechanisms of injury and weights them to assess
muscle injury during EVA, therefore allowing us to determine
the feasibility of individual EVA tasks.
Musculoskeletal Modeling
Injury Statistics
Discussion & Future Work
Flexor Muscles Unsuited EMU MKIII
Biceps femoris long head (BFL)^& 1316±57 1448±33 1428±40
Biceps femoris short head (BFS)£ 673±20 669±24 674±19
Gracilis (GR) ^& 135±6 147±2 145±4
Gastrocnemius medialis (GM) ^&* 105±25 296±33 175±24
Sartorius (SR)£^ 134±23 153±2 153±3
