title: human performance issues with helmet mounted ... history 2.pdf · to identify key human...

AIM:AIM:

Brief background of helmet mounted displays (HMD’s) as used by military rotary pilots

To identify key human factor issues in designing helmet mounted displays (HDM’s) for rotary aircraft pilots

To emphasize main physiological problems faced by users

Based on previous research, make recommendations for possible future improvements

Name: Charles AsareModule: Physical Human Factors In DesignCODE: DM5532Course: Advanced Mechanical Eng

Title: Human Performance Issues With Helmet Mounted Displays In Rotary Aircraft Cockpits

Background: Helmet Mounted Displays Background: Helmet Mounted Displays (HMD's)(HMD's)

U.S Military introduced HMD’s into fixed wing aircraft in the early 1970’s primarily for targeting air-air missiles. [5]

Current applications include virtual reality gaming; Medical visualisation; Soldiers for viewing sensor imagery; Aircraft simulation training; Fixed/rotary wing display applications etcFixed/rotary wing display applications etc.. [5]

HMD’s are data display devices worn on the head or as part of a helmet, that has a small optic display in front of the eyes [7].

Figure 1.1: Optical schematic representation Figure 1.1: Optical schematic representation of IHADSS of IHADSS [23][23]

Figure 1.2: IHADSS, A monocular, transparent Figure 1.2: IHADSS, A monocular, transparent HMD used in AHHMD used in AH--64 Apache Helicopter 64 Apache Helicopter [5][5]

By use of a miniature display technology for each eye, combined with accurate head, and in some cases, eye pupil tracking, it is possible to present a stereoscopic, full colour image to the user in any direction of view [6].

Background: Helmet Mounted Displays Background: Helmet Mounted Displays (HMD's)(HMD's)

Common HMD systems components includes: a display device attached to the head, relay optics, a combiner if the imagery is seen as superimposed on another display screen or on the outside world, and a head-tracking system [25].

They may be display-configured to occlude external vision; Configured with one/two display channels displaying graphics with/without video overlay; Use semi-transparent combiner with vision of outside world etc [1]. Or optically set-up with Monocular, Binocular, night vision configurations etc [6].

Fig. 1.5: TopOwl, a binocular, Fig. 1.5: TopOwl, a binocular, transparent HMD transparent HMD [8][8]

Figure 1.6: HIDSS, a Figure 1.6: HIDSS, a binocular opaque HMD binocular opaque HMD [8][8]

COMMON USER COMMON USER CONFIGURATIONS IN CONFIGURATIONS IN ROTORCRAFTSROTORCRAFTS

Figure 1.3: Depicts typical HMD display Figure 1.3: Depicts typical HMD display overlaying symbology on real world view.overlaying symbology on real world view.[8][8]

Fig. 1.4: AviatorFig. 1.4: Aviator’’s Night Vision s Night Vision Imaging System (ANVIS) Imaging System (ANVIS) [8][8]

Background: Design Importance of HMD'sBackground: Design Importance of HMD's

Previous ‘Head down displays’ reduced level 1 SA by engaging his attention continuously to the interior of the cockpit [5]. As a solution; HMD’s were developed to allow collimated information to be presented to the aircrew whatever their head position or orientation enabling pilots to spend more time monitoring the environment outside of the cockpit [9]. Clearly their effective use may enhance level 1 of Endsley’s SA model for the user/pilot.

Enhancing or ‘…achieving situation awareness (SA) for the pilot is the primary and ultimate goal of the HMD designer’ [2].

Endsley divides Situational awareness (SA) into three levels [3]:

Model of Situation Awareness and the continuousModel of Situation Awareness and the continuousfeedback loop necessary to maintain SA (by feedback loop necessary to maintain SA (by Endsley) Endsley) [3][3]..

A recent assessment of U.S. air traffic found that 80% of accidents occur when cognitive overload causes the pilot to lose touch with Level 1 in SA model (i.e. perceiving the environmentperceiving the environment), with the worst failures falling into the sub category (37%) of “failure to monitor” [4].

USER CENTERED DESIGN FOCUSUSER CENTERED DESIGN FOCUS

o From an ergonomic point of view, the design of a helmet mounted display should aim to satisfy the following at minimum [1] [11]:

Minimum bulkiness/head support weightMaximum comfort and user acceptanceEjection system compatible & impact protectionHelmet retention Maximum acoustical/audio protection and compatibilityOptimum head aiming/tracking accuracyMaximum freedomExcellent display characteristics No induced Sensory IllusionHazard free and easy to use.

The following slides will try to address human problems for HMD The following slides will try to address human problems for HMD usage while attempting to usage while attempting to frame them in the context of a userframe them in the context of a user--centric design process. Among these:centric design process. Among these:

Biomechanical User IssuesBiomechanical User IssuesOptical/Visual Perception IssuesOptical/Visual Perception IssuesSizing IssuesSizing IssuesAcoustic/Vibration IssuesAcoustic/Vibration Issues

BIOMECHANICAL ISSUESBIOMECHANICAL ISSUES

Age brings about water loss content in the spinal disk, which otherwise nominally provides intervertebral cushioning. Cadaveric investigations reported that by age 40, almost all disks are affected [11]. This degeneration is exacerbated under acceleration, shock and added G-forces [11].

Military pilots often encounter high G-forces under high acceleration manoeuvres. With the added weight/stress of wearing a HMD, effects can range from fatigue and neck strain to serious or mortal injury as well as possible long-term cervical and spinal degradation [10].

Added weights of HMD’s may force pilots to modify their neck posture such that greater deviations from a neutral upright position may be adopted. These neck posture deviations (with time) increases the stresses on the musculoskeletal system of the head and neck [14].

The stress related effects on females could be even greater as less neck muscle mass found in females [12]. Preliminary research tests have directly concurred with this hypothesis by proving that ‘females required a high percentage of their maximal voluntary effort to stabilize heavy helmets…’during a centrifuge test [12].

HMD WEIGHTHMD WEIGHT


In short, the allowable HMD weight (a critical parameter) will depend on the location relative to the head, the physical characteristics of the user, and on the intended operational use [13].

In calculating the head support weight, a specific location is defined where the HMD mass (helmet assembly + head) can be assumed to be concentrated. This is referred to as the centre of mass/gravity (CM or CG) [5][13]. The following coordinate system are defined via intersection of the Sagittal, Frankfurt, and frontal planes as shown:

Figure 2.0: Anatomical coordinate Figure 2.0: Anatomical coordinate system of head from which the headsystem of head from which the head--supported weight/mass andsupported weight/mass andCM requirements are calculated CM requirements are calculated [15][15]

Figure 2.1: Head with CG/CM Figure 2.1: Head with CG/CM located near the located near the tragiontragion notch notch and the pivot point located at and the pivot point located at the Occipital Condyles the Occipital Condyles [13][13]..

Adding mass to the head in the form of a HMD can move the CM (now HMD+head) away from this ideal location and into unacceptable regions leading to injuries during dynamic events.[5] . Ref


Research at the U.S. Air Force’s Laboratories established allowable head-supported mass and CG/CM boundaries for helicopter environments using HMD's. Using the occipital Condyles (fig 2.1) as the origin point, the CM spatial limits on an X-Z plane yields graph parameters [5]:

Figure 2.2: The USAARL weight and vertical center of Figure 2.2: The USAARL weight and vertical center of gravity curve (Adam Manikin head) gravity curve (Adam Manikin head) [11],[5][11],[5]

Figure 2.3: The USAARL weight and horizontal center of Figure 2.3: The USAARL weight and horizontal center of gravity curve. Large Adam Manikin head is used gravity curve. Large Adam Manikin head is used [11] [5][11] [5]

The addition of mass and its distance distribution in relation to the pivot points of the spine are the basic attributes by which HMD loads can be distinguished. Hence the mass moment of inertia the mass moment of inertia [i.e. mass x distance[i.e. mass x distance2 2 ] ;] ; a mechanical quantity that reflects the mass distribution of a HMD load per axis of rotation, is alternatively a key parameter in the ergonomic choice of HMD loads. [17]


For safety reasons, it is desired that a pilot’s HMD device has ability to break free from overall helmet HMD system during an extremely dynamic event. This is known as frangibility [11].

For instance in a helicopter mishap (or pilot ejection in fixed wing aircrafts), total head-supported weight and CM may create the potential for unacceptable risk of neck injury; hence effective frangibility is needed to reduce such risks by automatically shedding mass from the pilot’s HMD system. [11]

HMDHMD’’s & FRANGIBILITYs & FRANGIBILITY

Shannon and Mason found that crew members wearing the nonnon--frangible frangible night vision goggles (NVG) were shown to have 162% greater likelihood than non-NVG users to experience head or neck injury. [18]

During breakaway, the frangible components should not come in contact with the wearer’s forehead, eye sockets, or facial regions [11].

Figure 2.4: Vector Figure 2.4: Vector limits for HMD limits for HMD breakaway force. If breakaway force. If a 9G force occurs a 9G force occurs anywhere within the anywhere within the shown limits, the shown limits, the components will components will break away break away [11][11]..


From an ergonomic perspective, the author would recommend choosing a HMD which:

Has the smallest mass i.e. maximum support weight of 5lb/2.5kg recommended in line with previous graph data recommended by U.S Air Force (with mass including all HMD components)

Has the smallest diameter; this reduces induced torques & Inertial moments around the head pivot points

Is the most symmetrically balanced and aligned to the natural heads centre of mass (CM) to minimize neck strain, fatigue, and helmet movement relative to the operator’s head.

Where appropriate, weight can be reduced through the use of frangible devices. Properly designed, these have been shown to reduce the risk of neck injury [11].

Knight and Baber found that HMD ‘..can affect posture even when it is not being used’ in extreme dynamic conditions [14]. One way to overcome this problem would be to enable the HMD screen/visor to be flipped aside when not in use (e.g. static ground conditions), away from the front of the face and be brought back when the user needs to view the HMD display.

Biomechanical Issues: RecommendationsBiomechanical Issues: Recommendations

SIZING ISSUESSIZING ISSUES

12.77

59.35

16.08

20.85

7.10

95% male

10.89

54.27

14.31

18.53

5.88

5% male

12.09

57.05

15.25

19.75

6.85

95% female

10.21Head height (ectocanthus to top of head)

52.25Head Circumference

13.66Head Width

17.63Head Length

5.66Interpupillary distance (IPD)

5% female

Critical Head Dimensions (cm)

Figure 2.5: Figure 2.5: Anthropometric Anthropometric dimensions dimensions human head human head [21][21]

Table 1: Table 1: UnivariateUnivariate (uncorrelated) anthropometric data for (uncorrelated) anthropometric data for key head features key head features [11][22][11][22]

Common mistakes made by designers is to assume a correlation between various anthropometric measurements; e.g. a person who has a 95th percentile head circumference will not necessarily have a 95th percentile interpupillary distance [20]. Table 1 below presents univariate/uncorrellatedanthropometric data for different sex size ranges:

Data suggests range of anthropometry is vast. A one-fits-all helmet is impractical; usually necessary to have a range of helmet sizes available [6].

RECCOMMENDATIONRECCOMMENDATION: to simplify head fitting systems by using liners to line entire interior contour of helmet [11]; these reduces the number of helmet shell sizes required to fit the majority of users [28]. Author recommends Thermoplastic liners due to their reported ability to reduce ‘hot spots’ and evenly distribute weight around the wearer’s head [19].

ACOUSTICS ISSUESACOUSTICS ISSUES

Rotary aircrafts produce a tri-axial vibrating frequency ranging from 0.5-100 Hz in all axes; hence HMDs are particularly susceptible to the effects of whole body vibration [1] [29]

It is documented that compensatory eye movement becomes ineffective in stabilizing images moving with the head at low frequencies (below 20 Hz), causing visual blurring when using a helmet-mounted displays [27].

The rotational oscillation of the head causes vibration of the HMD, but the eyes, under the influence of the vestibular ocular reflex (VOR) remain space-stable[29].VOR system is shown:

However below about 1–2 Hz, pursuit eye movements can suppress the VOR [27]. Furthermore the vibrational transfer function to the helmet is different from that to the eye.[1]

Figure 2.9 : Diagram of Human vestibular ocular Figure 2.9 : Diagram of Human vestibular ocular reflex (VOR) reflex (VOR) [30][30]

Human vestibular ocular reflex (VOR) ensures best vision during head motion by moving the eyes contrary to the head to stabilize the line of sight in space. [27]

EFFECTS OF VIBRATIONEFFECTS OF VIBRATION

ACOUSTICS ISSUESACOUSTICS ISSUES

Also, the low-frequency vibrations could also cause helmet slippage/position change that may exceed the designed exit pupil dimensions of the helmet system resulting in partial or complete loss of the projected image [27]

The following is recommended:

Blurring due to vibrating visual objects could be compensated for, in part, through improved visibility techniques. E.g. lens enlargement, increased illumination and contrast, magnification [31]

Reduce vibration transmission by using improved cushions to line helmet interior [31]. Here helmet fitting issues should be optimised.

Secure, adjustable low-pressure-contact, neck/chin straps are also advised for better retention during low frequency vibrations. (As well as during dynamic manoeuvres)

Failure to adequately design HMD against unwanted vibration transmissions may also impact stress levels among users; leading to further complaints as that shown in table 2.

EFFECTS OF VIBRATION/RECCOMMENDATIONEFFECTS OF VIBRATION/RECCOMMENDATION

Optical/Visual Perception IssuesOptical/Visual Perception IssuesVISUAL CONCERNSVISUAL CONCERNS

A survey of the Apache (AH-64) helicopter pilots documented reports of health issues following flights using the monocular Helmet mounted display (IHADSS, see fig 1.2):

For the monocular HMD configuration, a number of key user ergonomic parameters must be considered. Among these:

Field of viewClearance & Viewing ComfortLuminance/Contrast

Failure to adhere to these corresponding issues can result in increased visual workload and may raise stress levels among users; leading to further complaints as that shown in table 2. [1]

Table 2: Complaint summary from 58 Apache air pilots reported whTable 2: Complaint summary from 58 Apache air pilots reported when using en using monocularmonocular HMDHMD’’s s [24][24]

HUMAN FACTORS ISSUES ADDRESSED HEREON ARE PRIMARILY AIMED AT MONOCULAR HMD SYSTEMS. (Although some issues still remain universally applicable to other configurations too)

Optical/Visual Perception IssuesOptical/Visual Perception Issues

FIELD OF VIEW (FOV):FIELD OF VIEW (FOV):

It is documented that reduced FOV designs (as with monocular HMDs) have been known to degrade many visual tasks [1].

FOV describes how extensive the image appears to the user and is measured in degrees. In HMD design, the eye piece lens limits available FOV. [11]

The field of view of the human visual system is roughly oval-shaped and extends 200°horizontal by 130° vertical, with the central 120° being the area of binocular overlap [25]. Fig 2.6illustrates:

Figure 2.6: Human visual system binocular Figure 2.6: Human visual system binocular field of view field of view [26][26]

Best design approach will be to attempt to maximise FOV while adequately matching it that of the human visual system. Type of activity (e.g. targeting, fomation flying) will also affect the size of FOV needed.[25] (see reccommendations)

In HMD designs large FOVs (i.e. >60°) are known to produce a greater sense of viewer immersion. However Patterson documented increased levels of simulation sickness for FOV up to 140°.[11] [25]

Optical/Visual Perception IssuesOptical/Visual Perception IssuesEYE CLEARANCE/VIEWING COMFORTEYE CLEARANCE/VIEWING COMFORT

Fig. 2.8: Optical eye relief (left) is defined as the distance Fig. 2.8: Optical eye relief (left) is defined as the distance from the last optical element to the exit pupil, where the eye from the last optical element to the exit pupil, where the eye would be placed. [26]would be placed. [26]

Fig. 2.8b: F, focal length of the collimating lens; H, size of tFig. 2.8b: F, focal length of the collimating lens; H, size of the he image source (or pixel size); image source (or pixel size); ƟƟ, the field of view (or the , the field of view (or the resolution) [5].resolution) [5].

Critical importance in HMDs is the physical eye relief distance. A longer eye relief improves viewing comfort and allows users to wear prescription eyewear with the HMD [1] [11] .

But too close and the HMD may be intrusive. This has been known to also increase the likelihood of visual problems, such as binocular rivalry; common in monocularmonocular HMD’s.[13]

Binocular rivalry causes viewing conflicts between the aided eye viewing the display imagery and the unaided eye viewing the outside world. Studies have shown that target recognition/performance and visual comfort decreases with binocular rivalry [32].

For see-through HMDs and less clearance may be acceptable. If glasses are to be used, Fischer recommends a clearance of at least 25mm for adequate comfort.[13][33]

H = F x tan ƟƟ

Optical/Visual Perception IssuesOptical/Visual Perception IssuesLUMINANCE/CONTRASTLUMINANCE/CONTRAST

Figure 2.7: Human contrast sensitivity Figure 2.7: Human contrast sensitivity function characterises visual threshold function characterises visual threshold response response [1][1]

Monocular HMD's introduce contrast issues. Contrast is defined as the difference in luminance between two adjacent areas [26].

Image information is conveyed primarily by patterned contrast. Hence data to be conveyed by a display to a pilot is fundamentally limited by the human ability to perceive contrast. [1]

For the pilot, image contrast as seen through HMD optics is degraded by the superimposed outside world image. This effect remains significant during daytime flight, when ambient illumination is utmost.[26]

Failure to provide adequate bright/high contrast has perceptual consequences e.g. poor visibility, which may affect pilot performance. [25]

The human visual contrast system is maximally sensitive, for patterns with a spatial frequency between 2-5 cycles per degree of visual angle. [1]

Optical/Visual Perception: RecommendationsOptical/Visual Perception: Recommendations

Generally visual capabilities (e.g. detection, recognition) improves when two eyes are used, as compared to one [1]. Thus author encourages use of two-eye HMD designs instead in near future.

Field of view (FOV) design shouldn’t be too large (linked to sickness) or too small (degrades pilots visual performance); But should be enough to produce a sense of immersion and adequate visual functioning. [25] [1]

For object recognition and targeting, a field of view as small as 40° may be sufficient [25]. However for flight tasks involving control of airspeed, altitude, and vertical speed Seeman recommends an instantaneous FOV of 50° (V) by 100 °(H). [16]

Contrast sensitivity; dependent on spatial frequency of image. Hence designer must carefully consider the modulation transfer function of the eye [13];Especially as there is no set of values for minimum contrast requirements [1]. Better regulations/definition is needed.

Rash reports that for a displayed text on HMD, the recommendation of a minimum contrast ratio value of 3: I, be used in benign viewing conditions. [1]

E.g. Kortelling [9] designed an experiment to test effects of computer generated grid (CGG)computer generated grid (CGG) on tracking moving targets for maritime unmanned aerial vehicles (MUAV’s). Subjects tracked target ship via two methods in a simulated camera image where :

Field of view (FOV) is overlaid with earth-fixed CGG(fig.3) for one subject; And where FOV is without CGG for other test subject [9]:

Further RecommendationsFurther Recommendations

Figure 3: A Simulated Camera View of a Figure 3: A Simulated Camera View of a Ship at Sea with the ComputerShip at Sea with the Computer--Generated Grid (CGG) as an Overlay. Generated Grid (CGG) as an Overlay. [9][9]

Subjects showed significant enhancement of user tracking performance when image in FOV was augmented by the synthetic grid, (as shown in fig 3). [9]

Possibility of integrating such a technology into current HMD’s to enhance vehicle targeting performance in combat is feasible.

OR Perhaps employing this to HMD’s in cockpit environment may yield opposite performance results. Research in this field is reasonable & recommended.

BASED ON CURRENT RESEARCHBASED ON CURRENT RESEARCH

CONCLUSIONCONCLUSION

Generally This case history addressed a number of ergonomic issues associated with use of helmet mounted display (HMD) from both user/designer perspective. Issues discussed were particularly linked with see-through monocular HMD's (e.g. IHADSS, see fig 1.2) as used in rotary aircraft environments.

Biomechanical, Sizing, Acoustic & Optical/Visual Perception IssBiomechanical, Sizing, Acoustic & Optical/Visual Perception Issues were the ues were the ergonomic factors discussed and recommendations made where appropriate.

It was shown that failure to adequately address these corresponding issues was likely to lead to unwanted user performance consequences. Perhaps, the best design approach for HMD design is an integrated one, where the HMD is designed from the ground up, addressing all combined issues discussed.

In the future, other ergonomic issues to be possibly investigated might include:

Auditory IssuesAuditory IssuesDisplay symbology & clutter etc.Display symbology & clutter etc.

REFERENCESREFERENCES

1) Clarence E.R, W.E. McLean, B. T. Mozo, J.R. Licina, B.J McEntire. Human Factors and Performance Concerns for the Design of Helmet-Mounted Displays. U. S. Army AeromedicalResearch Laboratory. 1999.

2) Clarence E.R, James E. Melzer. The potential of Interactive HMD. In: Clarence E.R, Michael B.R, Tomasz R.L, Elmar T.S (eds.). Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. Bellingham, WA: SPIE Press; 2000. Chapter 19. p878-893.

3) Endsley M.R. Toward a theory of situation awareness in dynamic systems. Human Factors: The Journal of the Human Factors and Ergonomics Society. 1995; 37:32-64.

4) Smith D.J. Situation(al) awareness (SA) in effective command and control. http://www.smithsrisca.demon.co.uk/situational-awareness.html . (Accessed 10 Dec 2010).

5) James E.M. Head Mounted Displays. In: Cary R. Spitzer (ed.). The Avionics Handbook. Florida: CRC Press LLC; 2001. Chapter 5.

6) Malcom J. Aircraft Display Systems. London: Professional Engineering Publishing; 2004.7) World Lingo. Head-Mounted Display. http://www.worldlingo.com/ma/enwiki/en/Head-

mounted_display. (Accessed 12/12/2010)8) Micheal M.B, Clarence E.R, James H.B. Introduction to Helmet Mounted Displays. In: Clarence

E.R, Michael B.R, Tomasz R.L, Elmar T.S (eds.). Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. Bellingham, WA: SPIE Press; 2000. Chapter 3. p57-84.

9) Kortelling J.E, Van Erp J.B.F, Kappe B.Visual Support For the control of unmanned platforms’. In: Don Harris (edt.). Engineering Psychology & Cognitive Ergonomics: Volume One Transportation Systems. Great Yarmouth: Ashgate Publishing Ltd; 1997. Chapter 6. p55-63.

10) Guill F.C, Herd G.R. (1989). An evaluation of proposed causal mechanisms for “ejection associated” neck injuries. Aviation, Space and Environmental Medicine;1989:60 (7 pt 2): A26-47.


11) James E.M, Frederick T.B, Tomasz R.L, Thomas H.H, Clarence E.R. Guidelines for HMD Design. In: Clarence E.R, Michael B.R, Tomasz R.L, Elmar T.S (eds.). Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. Bellingham, WA: SPIE Press; 2000. Chapter 17. p805-839.

12) Edward S.E, Bob E, Nick S, Neck Muscle Fatigue Resulting from Prolonged Wear of Weighted Helmets under High G Acceleration. Defence Technical Information Center. Report number: ADA487277, 2008. p1 [accessed 15 Dec 2010]. Available from: http://handle.dtic.mil/100.2/ADA487277

13) Wilson J, Wright P. Design of monocular head-mounted displays, with a case study on fire-fighting. Journal of Mechanical Engineering Science. 2007; 221: 1729-1743 [accessed 4 Dec 2010]. Available from: http://www.escholarship.org/uc/item/71d278r6

14) James F. K, Chris B. Effect of Head-Mounted Displays on Posture. The Journal of Human Factors and Ergonomics Society. 2007; 49: 797-804 [Accessed 18 Dec 2010]. Available from: http://hfs.sagepub.com/content/49/5/797

15) Rash C. E. Helmet-mounted displays: design issues for rotary-wing aircraft. Washington: International Society for Optical Engineering (SPIE); 1999.

16) Seeman J, De Maio J, Justice S, Wasson J, Derenski P, Hunter M, Walrath L. Advanced helicopter pilotage visual requirements. Proceedings of the American Helicopter Society. 1992; 48: 233-252. As sited in reference [1].

17) V. Ivancevic, N. Beagley. Determining the Acceptable Limits of Head Mounted Loads. Australian government department of defence. Report number: DSTO-TR-1577, 2004. p5-6. [Accessed 1 Dec 2010]. Available from: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA426095


18) Shannon S.G, and Mason K.T. U.S. army aviation life support equipment retrieval program: head and neck injury among night vision goggle users in rotary-wing mishaps. U.S. Army AeromedicalResearch Laboratory. USAARL Report number: 98-02, 1997 [Accessed 4 Dec 2010]. Available from: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA332850

19) Gentex Corporation. Thermoplastic Liner. [Accessed 11 Dec 2010]. Available from: http://www.gentexcorp.com/default.aspx?pageid=435 .

20) Whitestone J.J, Robinette K.M. Fitting to maximize performance of HMD systems. In: Melzer,J.E.,and Moffitt, K.W. (Eds.), Head-Mounted Displays: Designing for the User. New York: McGraw-Hill; 1997.

21) Burkhard M.D, and Sachs R.M. Anthropometric manikin for acoustic research. Journal of the Acoustical Society of America. 1975; 58: 214-222.

22) Gordon C.C, Churchill T, Clauser C.E, Bradtmiller B, McConville J.T, Tebbetts I., and Walker R.A . 1988 Anthropometric survey of U.S. Army personnel: Summary statistics interim report. Army Natick Research and Development Laboratories. Technical Report TR-89/027, 1989.

23) Clarence E. Rash. A 25-year retrospective review of visual complaints and illusions associated with a monocular helmet-mounted display. ScienceDirect. 2008; 29: 7-80 (Accessed 21 Nov 2010). Available from: www.sciencedirect.com.

24) Behar I., Wiley R.W, Levine R. R, Rash C. E, Walsh D. J, Comum R. L. S. Visual survey of Apache aviators (VISAA). U.S. Army Aeromedical Research Laboratory. Report No. 90-l5, 1990.

25) Robert P, Marc D.W, Byron J.P. Perceptual Issues in the Use of Head-Mounted Visual Displays. Human Factors and Ergonomics Society. 2006;48(3): 555–573.

26) Clarence E.R, Micheal M.B, Thomas H.H, William E.M. Visual Helmet Mounted Displays. In: Clarence E.R, Michael B.R, Tomasz R.L, Elmar T.S (eds.). Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. Bellingham, WA: SPIE Press; 2000. Chapter 4. p112-129.


27) Smith S.D. Cockpit seat and pilot helmet vibration during flight operations on aircraft carriers. Aviation Space Environment Medicine. 2004; 75: 247–254.

28) Associated Industries. DH 132S and DH 132AS CVC Helmets. [Accessed 4 Dec 2010] Available from 2007: .http://www.associated-ind.com/vehicular_products_dh132s.htm .

29) Clarence E.R, Keith L.H, Robert M.W, John A.C, Ronald P.K.. Perceptual and Cognitive Effects due to operational factors. In: Clarence E.R, Michael B.R, Tomasz R.L, Elmar T.S (eds.). Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. Bellingham, WA: SPIE Press; 2000. Chapter 16. p739-749.

30) Psychology wiki. Vestibulocochlear nerve. [Accessed 20/11/2010]. Available from: .http://psychology.wikia.com/wiki/Vestibulocochlear_nerve . Image of vestibular ocular reflex (VOR).

31) R. Dale Huchingson. New Horizons for Human Factors in Design. Texas A&M University: McGraw-Hill;1998.

32) Hershberger M. L., Guerin D. F. Binocular rivalry in helmet-mounted display applications. Armstrong Aerospace Medical Research Laboratory. Report number: AMRL-TR-75-48, 1975.

33) Fischer R.E. Fundamentals of HMD Optics. In: James E.M., Kirk M (eds). In Head-mounted displays: designing for the user. NewYork, NY: McGraw-Hill; 1999. p83-116.

title: human performance issues with helmet mounted ... history 2.pdf · to identify key human...

Documents