Prediction of Motion Sickness Prediction of Motion Sickness Incidence:Incidence:Modeling Efforts based on Human PhysiologyModeling Efforts based on Human Physiology

ABCD Meeting 2006“Human Performance at Sea: Influence of ShipMotions on Biomechanics and Fatigue"

By

Lieutenant P. Matsagas, M.Sc., Hellenic Navypmatsag@yahoo.com, pmatsang@nps.edu

M.E. McCauley, Ph.D., Naval Postgraduate Schoolmemccaul@nps.edu

Motion SicknessMotion Sickness

A general term that describes the discomfort A general term that describes the discomfort and associated emesis (vomiting) induced and associated emesis (vomiting) induced by motion. by motion.

Effects are evident in numerous Effects are evident in numerous environments:environments:– ShipsShips– AircraftAircraft– AutomobilesAutomobiles– Air-cushioned vehicles. Air-cushioned vehicles.

Cause of motion Cause of motion sicknesssickness

Neural mismatch theoryNeural mismatch theory

Current sensory input

Neural store

Vestibular systemVision

ProprioceptionError signal

Motion Sickness Motion Sickness Incidence (MSI)Incidence (MSI) A common index of motion sickness A common index of motion sickness

severity.severity. The percentage of people who vomit The percentage of people who vomit

when exposed to a nauseogenic when exposed to a nauseogenic environment. environment.

HFR model (1974)HFR model (1974)

Model CharacteristicsVertical AccelerationOnly true motionMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.7 [Hz]

Central nauseogenic frequency0.167 [Hz]

Proposed ModelProposed ModelCharacteristicsCharacteristics

Conceptually based on existing Conceptually based on existing theoriestheories

Observer theory conceptsObserver theory concepts MSI based on:MSI based on:

– Gravity estimation errorGravity estimation error– Residual optical flowResidual optical flow

Linear and Time InvariantLinear and Time Invariant Vertical sinusoidal motionsVertical sinusoidal motions

Proposed ModelProposed ModelAssumptionsAssumptions

Model input parametersModel input parameters– Motion characteristics detected by the Motion characteristics detected by the

vestibular system and somatosensationvestibular system and somatosensation– Motion characteristics detected by Motion characteristics detected by

peripheral visionperipheral vision

Current (2006) Model in Current (2006) Model in DetailDetail

Proposed Model

• Z-axis (Vertical Acceleration)

• Linear• Time invariant• Stable

Error Estimation SubsystemError Estimation Subsystem

Oman (1982)Glasauer & Merfeld (1997)Bles et al. (1998) Merfeld et al. (1993)

Visual SystemVisual System

Sandini et al. (2001)

Legend

Independent

variables

Intermediate

variables

Dependent

variables

Neural

Store

Current Model (2006)Current Model (2006)Adaptation MechanismAdaptation Mechanism in detailin detail

Predicted difference between sensory input and motion in the neural store

Sensory contents in Neural Store

1 2

3

Legend

Independent

variables

Intermediate

variables

Dependent

variables

Neural

Store

Normalization & Linear Normalization & Linear Combination of 2 Sources of Combination of 2 Sources of Error = MSIError = MSI

Current Model(2006)Current Model(2006)in Detailin Detail

Predicted MSIPredicted MSI

Proposed Model

CharacteristicsVertical AccelerationMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.6 [Hz]

Central nauseogenic frequency0.17 [Hz]

0.05 0.16 0.27 0.38 0.49 0.6

0.050

0.082

0.135

0.222

0.365

0.600

Amplitude ARMS

[g]

Fre

quen

cy F

[Hz]

-25

-20 -20-15

-15 -15

-15 -15

-10 -10-10

-10-10 -10

-5

-5 -5-5

-5 -5 -5

0 00

0

0 00

0

5

Model ValidationModel ValidationTrue Motion SettingsTrue Motion Settings

Proposed model

HFR model

MSI Comparison between Proposed and HFR models

1

2

3

MSI AccumulationMSI Accumulation

CharacteristicsVertical AccelerationMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.6 [Hz]

Central nauseogenic frequency0.17 [Hz]

101

102

0

50

100

MSI [%

]

Proposed modelHFR dataA

RMS=0.333 [Hz]

101

102

0

50

100

MSI [%

]

Proposed modelHFR dataA

RMS=0.222 [Hz]

10 20 30 40 50 607080 1001200

20

40

Time in [min]

MSI [%

]

Proposed modelHFR dataA

RMS=0.111 [Hz]

MSI HabituationMSI Habituation

1 2 3 4 520

40

60

80Pre

dict

ed M

SI [%

]

1 2 3 4 520

40

60

80

Exposure day

Obs

erve

d M

SI [%

]

Proposed model

HFR data

MSI Habituation and MSI Habituation and RetentionRetention

1 2 3 4 5 120

20

40

60

80

100

Retention →

Pre

dict

ed M

SI [%

]

1 2 3 4 5 120

20

40

60

80

100

Retention →

Exposure day

Obs

erve

d M

SI [%

]

Proposed model

HFR data

Model significance I.Model significance I.

ParametricParametric Easily extended to various Easily extended to various

combinations of sensory cuescombinations of sensory cues Validated but not “tuned”Validated but not “tuned” PrecisePrecise EtiologicEtiologic Linear and time invariantLinear and time invariant

Model significance II.Model significance II.

Modeled Motion sickness attributesModeled Motion sickness attributesThe known systems contributing to The known systems contributing to

motion sicknessmotion sicknessNeural Store modelNeural Store modelAdaptationAdaptation““Vection” settings for VRsVection” settings for VRs

Future ResearchFuture Research

Include motion in 6 degrees of Include motion in 6 degrees of freedomfreedom

Further development of known Further development of known physiological systems’ modelsphysiological systems’ models

Central Nervous System (CNS) non-Central Nervous System (CNS) non-linear characteristics linear characteristics

Increase ecological and external Increase ecological and external validityvalidity

Questions?Questions?