Virtual Reality - PowerPoint by wanghonghx

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									Virtual Reality Applications

   Department of Mechanical
 National Cheng Kung University
       Associate Professor
          Jing-Jing Fang
             Course Contents
 Introduction
 History (T1, R1, R2)
 Virtual Reality Tools (T1)
 Virtual Environment Interface Technology (R3,R6)
 Virtual Environment Systems (R1,R2)
 Touch and Force Feedback (T1,R4)
 Computing Architectures (T1)
 Geometric Modeling (T1)
 Animating in the VE(T1,R1)
 Physical Simulation (R1)
 Human Factors (R1)
 Applications (T1, R1~R6)
  Virtual Environment
Interfaces Technology
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
 Visual Display Device Types
 HMDs
 ActiveGlasses
 Passive Glasses
 Stereo Display Screens
Visual Display Device Technologies
Type   Description            Strengths            Weakness
HMDs Use dual monitors        -Encompassing        -Weight   and inertial
     (CRT or LCD) and         visual volume        burden
     special optics to        -Relative freedom    -Single viewer
     present a different      of movement          -Bulky optics that
     image to each eye.       -CRT-based: small,   introduce distortions
     The monitors and         high resolution,     -CRT-based: High
     lenses are mounted       high luminance,
     in a helmet-type                              voltages near user
                              monochrome           head, mechanical or
     device, usually with a   displays
     position tracker and                          electrical color
                              -LCD-based: color    filtering techniques
     ear phones attached.
                              displays with low    needed for color,
                              voltages near user   sources of distortion
                                                   -LCD-based: low
                                                   resolution, slow
                                                   switching time
  Visual Display Device Technologies
Type     Description                  Strengths           Weakness
Active  Special glasses with          -Low  weight        -Interocular
Glasses electronic shutters that      -Multiple viewers   crosstalk
        display images to each eye    possible (static    -Not suited for
        alternately. Require a        stereo scenes for   encompassing
        special monitor or            all but head-       visual volume
        projection screen that        tracked user)       -Effectively halves
        presents left and right eye                       frame rate
        images as sequential fields
BOOM     Use dual monitors (CRT or - Weight counter-     - User movement
         LCD) and special optics to   balanced           restricted by
         present a different image to -Low latency       mechanical
         each eye. The monitors and -Ease of switch to linkages
         lenses are mounted in        keyboard operation
         device suspended from a
         boom in front of the user
 Visual Display Device Technologies
Type      Description                  Strengths                 Weakness
Passive   Special glasses with         -Low  weight              -Not suited for
Glasses   filters that pass only the   -Multiple viewers         encompassing
          image intended for each      possible (static stereo   visual volume
          eye. Require a special       scenes for all but        -Poor contrast
          monitor or screen in         head-tracked user)        -Color coding
          which perspective views      -Inexpensive glasses      results in eye
          for each eye are encoded     (though projection        fatigue
          in form of color or light    display may be
          polarization                 expensive)
  Visual Display Device Technologies
Type         Description          Strengths           Weakness

Auto-        Common               -Un-encumbering     -Low  resolution
stereoscopic approaches use       -Multiple viewers   -Slow switching time
Display      either lenses        possible            -User movement
             positioned behind or -Ease of switch     restricted to limited
             before a display     to keyboard         viewing area
             screen, or physical  operation           -Not suited for
             barriers in front of
             the display to cause                     encompassing visual
             each eye to see a                        volume
             different image
        Commercial Available Devices
   HMD
     CRT-based: Datavisor NVG, VirtualResearch Systems, etc.
     LCD-based: CyberEye, Datavisor LCD, I-glasses, etc.
   Shutter glasses
       CrystalEyes
   Passive glasses/ Projection system
     VR-1100
     VR-2000

   BOOM
     BOOM 3C
     Cyberface 4
     PUSH

   Autostereoscopic: Virtual Window
    Commercial Available Devices
Product/Co Techn    Resolution   FOV       Overlap   Weight   Cost
mpany      ology
DataVisor   CRTs    1280x1024    32x24   50/100%   0.9Kg
NVG         Mono.                          Adjust.
Datavisor NVG
Datavisor LCD
Virtual Research V8
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
               Tracking Interfaces
   Tracking (Position and Orientation Tracking, Position
    Tracking and Mapping)
     Position – Cartesian coordinates x, y, and z
     Orientation – pitch (elevation), roll, and yaw (azimuth)

 Used to measure the motion of the user’s head,
  hands, limbs, eyes
 Trackers are mounted on glove, body suit, or visual
  display devices
             Tracking Technologies
 Head/hand/body tracker technologies – magnetic,
  mechanical, optical, acoustic (ultrasonic), inertial,
 Eye tracker technologies – electro-ocular, electro-
  magnetic, optical
 The registration problem in correctly aligning real
  and virtual objects
       Due to lags in the time interval between measuring the
        (head) location and superimposing the corresponding
        graphic images on the real world
Trackers Performance Evaluations
 Resolution – measures the exactness with which a
  system can locate a reported position
 Accuracy – the range within which a reported
  position is correct
 Frequency (system responsiveness)
     Sample rate – The rate at which sensors are checked for
     Data rate – the number of computed positions per second
     Update rate – the rate at which the system reports new
      position coordinates to the host computer
     Latency (lag) – the delay between the movement of the
      remotely sensed object and the report of the new position
      (measure in milliseconds)
 Latencies of greater than 10 msec may contribute to
  simulator sickness
 1993, Bryson defined a real-time interaction system
  only if system latency less than 0.5 second
 Several sources of latency
     Delays in the tracker signal
     Delays in communication between the tracker and the
      computer system
     Delays due to computations required to process the
      tracker data
     Delays due to graphical rendering
              Tracking Technologies
Type     Description                         Strengths             Weakness
Inertial Use accelerometers and              -Unlimited   range    -Only    3 DOF
         gyroscopes. Orientation of the      -Fast                 -Drift
         object is computed by jointly       -No  LOS problems     -Not
         integrating the outputs of the                            accurate for
                                             -No magnetic
         rate gyros whose outputs are                              slow
         proportional to angular velocity    interference
                                             problems              position
         about each axis. Changes in                               changes
         position can be computed by         -Senses orientation
         double integrating the outputs of   directly
         the accelerometers using their      -Small size
         known orientations.                 -Low cost
             Tracking Technologies
Type      Description             Strengths      Weakness

Magnetic Use sets of coils        -Inexpensive   -Ferromagnetic   and/or
         (transmitter) that are   -Accurate      metal conductive surfaces
         pulsed to produce        -No LOS        cause field distortion
         magnetic fields.         problems       -Electromagnetic
         Magnetic sensors                        interference from radios
                                  -Good noise
         (receivers) determine                   -Accuracy diminishes with
         the strength and         immunity
                                  -Map whole
         angles of the fields.
                                  body motion    -High latencies due to
         Pulsed magnetic field
         may be AC or DC                         filtering
Type           Description              Strengths                 Weakness
Mechanical     Measure change in        -Accurate, low lag        -Intrusive, due to
               position by physically   -No line of sight (LOS)   tethering
               connecting the remote    or magnetic               -Subject to
               object to a point of     interference problem      mechanical part
               reference with jointed   -Good for tracking        wear-out
               linkages                 small volumes
Sourceless,    Use passive magnetic     -Inexpensive              -Only  3 DOF
Non-inertial   sensors, referenced to   -Transmitter not          -Difficult to mark
               the earth magnetic       necessary                 movement
               filed, provide           -Portable                 between
               measurement of roll,                               magnetic
               pitch and yaw, as a                                hemispheres
               derivative, angular
               acceleration and
Type        Description                     Strengths          Weakness
Optical     Use a variety of detectors,      -High availability -LOS necessary
            from ordinary video cameras -Can work over -Limited by
            to LEDs, to detect either        a large area       intensity and
            ambient light or light emitted -Fast                coherence of light
            under control of the position                       sources
                                             -No magnetic
            tracker. Infrared light is often                    -Weight
            used to prevent interference     interference
            with other activities.           problems           -Expensive
                                             -High accuracy

Acoustic,  Use three microphones and        -Inexpensive       -Ultrasonicnoise
Ultrasound three emitters to compute        -No  magnetic      interference
           the distance between a           interference       -Low accuracy
           source and receiver via          problem            -Echoes cause
           triangulation. Use ultrasonic    -Light weight      reception off
           frequencies (>20kHz) so
           that the emitters will not be
            Human Hands Tracking
   Fast motion of Human hands
     Arm movements 0.5ms
     Wrist velocities 3m/s, accelerations 5-6g (pitcher 25g)

   Motion bandwidth
     Arm movements 2Hz (1972)
     Hand writing 5-6Hz (1990)
     Tele-operation maximum 10Hz (1990)

   The sample rate should be around 20 times the
    bandwidth, e.g. if normal arm movements are 5Hz,
    then a sampling rate of roughly 100Hz is called for.
            Human Eyes Tracking
 Eye movements can be as fast as 600 deg/s
 The smallest time constant for saccades is around
  50ms; the smallest saccades can be finished in
 Eye movement
     50Hz for position, 74Hz for velocity (1981)
     Sample rate 1kHz (=20*50Hz)

   Eye sees continuous images when display temporal
    frequency is 60Hz. With 1 kHz sampling rates for
    eye movement, display targets can be well chosen
    every 1/60th of a second.
               Human Head Tracking
 Head movements in usual peak velocities can be
  600deg/s in yaw, and 300 deg/s for pitch and roll
 At least 30Hz sampling rate
 Delay 60ms or more may cause simulator sickness
 Accuracy requirements are very application dependent
 Maintain perfect registration
       Accuracy 0.01degree for orientations, and about 0.03mm for
   Achieve perfectly smooth, jitter-free motion
       Resolution 0.03 degree for orientation and 0.1mm for
     Body Mapping and Tracking
 Track a few points or landmarks on limb segments
 Multiple-position measurements on a limb segment
  can be employed to derive orientation
 Accuracy requirement depends on the application,
  1mm or better are desired in medical imaging
  system, a few mm are accepted for environmental
  Body Mapping and Tracking
 Mechanical    trackers
 Magnetic trackers
 Optical sensing
 Acoustic trackers
 Inertial tracking
 Eye tracking
         Mechanical Trackers

 Goniometers   or exoskeletons – body-based
  linkages, used in biomechanics
 Ground-based linkages – used for 6DOF end-
  point tracking (hand or head), BOOM
           Magnetic Trackers
       accuracy 0.76mm, 0.15 degree with
 Static
  update rate 120Hz
 Update rate decreases due to multiplexed
            Optical Sensing
 Passive  Stereo Vision Systems
 Active Marker Systems
 Laser Interferometers
               Optical Sensing
 Passive   Stereo Vision Systems
   Distance   is measured by triangulation
   Employ ambient light and square-array CCD
   The correspondence problem: relating the same
    points in two different images
               Optical Sensing
 Active   Marker Systems
   InfRared  light Emitting Diodes (IREDs)
   Employ a number of IREDs to create very bright
    spots in the images with camera detection to
    unique identify each marker
   Multiple CCDs + IREDs
                 Optical Sensing
 Structured   Light Systems
   Structured   light – ray light or plane light
 Laser   Radar – Ladar
   Similar  to ultrasonic ranging, calculating the time
    required for a light beam to travel from the source,
    reflect off an object, and travel back to a detector
   Long distance (up to 2km)
               Optical Sensing
 Laser   Interferometers
   Used  in robot calibration and tracking
   The precision and accuracy is very high (high cost)
   A laser beam is steered to a retroreflector on a
    robot end effector
   Mirror retroreflector or solid glass retroreflector
   3D position and orientation of the retroreflector are
             Acoustic Trackers
 Acoustictrackers employ at least three
  microphones to triangulate an emitter on the
  moving body
 Reasonable price comparing with magnetic
 Poor accuracy, speed, and range
               Inertial Tracking
 Accelerometers   or angular rate sensors is
  used in sensor design
 The output of these sensors are integrated to
  derive position or orientation
 Problems
   The result is sensitive to the drift and bias of the
    sensors (problem solved in 1994 at MIT)
   Nonlinear effects of beam bending cause
    inaccuracies (problem solved in 1994)
                       Eye Tracking
   Three types
     Electroocular – measurement of the corneoretinal potential
      with skin electrodes
     Electromagnetic – measurement of magnetically induced
      voltage on a coil attached to a lens on the eye
     Optical – reflection from the eye’s surface

   RK-416 Pupil Tracking System by ISCAN Inc.
       Employ video camera to track the pupil of the eye
   Series 1000 Infrared Eye Movement Spectacles by
    Microguide Inc.
       Employ differential reflections of infrared light from two
        sides of the the iris, detected by photodiodes
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
                       Threshold (dB)
   1959, Hinchcliffe
     Randomly sampled 400 persons (ages from 18 to 74) from
      a rural population of 9000
     Investigate Conclusion
         The men had significantly higher thresholds than the women
         Threshold increases with age
         Threshold increases at high frequencies than at low
         Threshold increases rapidly after 45-54 years
         Above 1000 Hz, males usually have higher thresholds than women
          in most age groups
         At all frequencies, the threshold increases continuously with age,
          with the greatest loss at frequencies above 2000 Hz
Commercially Available 3D Audio
   Crystal River Engineering Inc.
       Acoustetron II ($12,495), Proton ($995)
   Qsound Labs
       Qsystem II ($17,000), Qexpander ($295), QSYS/TDM
   Roland Corporation
       RSS-10 ($9750), SDX-330 ($8,500), SRV-330 ($1,295),
        SDE-330 ($1,295)
   Reality By Design
       SoundStorm 3D ($20,000)
    Research & Development of
        Realistic 3D sound
 Since 1880
 NASA Ames
 Naval Postgraduate School (NPS)
   Networked   Vehicle Simulator (NPSNET)
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
    Primary User Input Interfaces
 Input   command forms
   Hand gestures
   Menu item selection
   Object selection
   Operation of buttons with preset functions
 Devices
   Gloves and exoskeleton devices
   3D pointing devices
DOFs of Human Arm
Range of Motion for Hand, Arm
    and Shoulder Joints
  Commercially Available Devices
 5thGlove (±60° roll and pitch orientation,
  weight 350g, US$500)
 CyberGlove (22 Sensors, gesture recognition,
  weight 77g, US$14500)
 Pinch Glove (both hands wear glove, contact
  between any two or more fingers, gestures
  map actions, 21g, US$100)
 Rutgers Master I, II
  Commercially Available Devices
 3D Controller (670g, $550)
 SpaceBall (653g, $600)
 RingMouse (15g, $120)
 Commercially Available Devices
 TCAS   Glove & DataWear
  Systems   are based on a washable body suit
   (5sizes) and consists of a jacket (with/without
   gloves) and pants
  8-sensor glove ($7,000)
  32-sensor suit ($30,000)
Rutgers Master I
Rutgers Master II
LRP Hand Master
LRP Hand Master
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
             Haptic Interfaces
 Provide the realism needed for effective and
  compelling applications
 VEs need to provide input to and mirror the
  outputs to the haptic system
   Inputsare in the form of haptic displays
   Outputs are motor action commands
        Haptic Sensory Information
   Tactile information
     Contact surface geometry,
     Surface texture of the object
     Slippage

   Kinesthetic information
     Position and motion of the hand and arm
     Forces acting on the hand and arm
     A sense of total contact forces
     Surface compliance
     Weight
  Human Tactile Sensory Organs
 Four   kinds of sensory organs
   Meissner  Corpuscle
   Pacinian Corpuscles
   Merkel Disks
   Ruffini Endings
 pathway for
pressure and
Structure and Location of Touch
Human Tactile Sense
Stimulus Thresholds for Strain
      Tactile Feedback Actuator
 Piezoelectric   Crystals
 Pneumatic
 Shape  Memory Alloy
 Solenoid
 Voice Coil
 Heat Pump
        Tactile Feedback Actuators
Technology    Description                   Advantage Disadvantages
Piezoelectric Changing electric fields      - High       - Restricted to
Crystals      causes expansion and          spatial      resonant
              contraction of crystals       resolution   frequency

Pneumatic     Takes many forms. As air-jets, - Low       - Poor spatial
              provided an array of air        mass on    and temporal
              nozzles that can be gated to a hand        resolution
              display pattern. As air-rings              - Limited
              (cuffs), like miniature blood              bandwidth
              pressure cuffs. As bladders
              (bellows), often the size of a
              finger pad and held against
              the finger by a glove or band.
              As an array of tiny pressurized
              bladders, many to a single
              finger pad.
           Tactile Feedback Actuators
Technology     Description        Advantages          Disadvantages

Shape Memory   SMA wires and      - Good power-to-    - Low efficiency
Alloy          springs contract   mass ratio          during contraction
               when heated and                        - Heat dissipation
               expand again as                        problems limit
               they cool under                        relaxation rate of
               stress                                 wires
Solenoid       Magnetic coil      -High  steady-state - Relative heavy
               applies force to   forces              - Nonlinear, can
               ferrous plunger    - Better bandwidth require extra effort
                                  than other          to control
                                  materials (except
                                  for piezoelectric
                                  crystals and voice
        Tactile Feedback Actuators
Technology   Description              Advantages           Disadvantages

Voice coil   Voice coil vibrates to   - High temporal     - Poor spatial
             transmit low             resolution          resolution
             amplitude, high          - Relatively small, - Limited scalability
             frequency vibrations     does not obstruct
             to the skin              normal movement
                                      ranges of the

Heat pump    Solid state device       - No fluids          - Poor spatial and
             that moves thermal       required             temporal resolution
             energy to heat or                             - Bulky
             cool the skin                                 - Limited bandwidth
  Commercially Available Tactile
 CyberTouch  (US$14800) attached on
  CyberGlove from Virtual Technologies Ltd.,
 TouchSense from Immersion Ltd.
 TouchMaster
 Displaced Temperature Sensing System
TouchSense Mouse
Displaced Temperature Sensing System
          Kinesthetic Interfaces
 Threecomponents to providing a force
 feedback interface for VEs
   Measurement     of the movement of the user fingers,
    hands, arms and sensing any forces he exerts
   Calculation of the effect of the exerted forces on
    objects in the VE and the resultant forces that
    should act on the user
   Presentation of these resultant forces to the user
    fingers, wrist, and arm as appropriate
      Human Kinesthetic Sense
 Kinesthesiaprovides humans with an
  awareness of the position and movement of
  body parts
 Receptors
   Skin
   Joints
   muscles
   Human Kinesthetic Receptors
 Skin receptors – skin stretch and cutaneous
 Joint receptors
        torque – Golgi endings in joint ligaments
   Joint
   Capsule stretch – Ruffini endings in joint capsules

 Muscle    receptors
   Muscle  tension – Golgi tendon organs
   Muscle stretch and its rate of change – muscle
    spindle organs
   Human Kinesthetic Receptors
 Providing information about joint angles,
  muscle length and tension, the rates of
 The most important – muscle spindle organs
 None of these receptors provide awareness of
  weight or effort but from central nervous
             Force Feedback Actuators
Technology       Description             Advantages   Disadvantages
Electromagnetic Electromagnetic        - Easy to     - Heavy components
Motors          motors produce torque control        - Low power densities
                with two time-varying - Clean, quiet at small scales
                magnetic fields,       - Easy        - Heat dissipation
                caused by two coils or design and    problems
                a coil and a magnet    installation  - Low static force
Shape Memory     SMA wires and           -Good        - Low efficiency
Alloy            springs contract when   power-to-    during contraction
                 heated and expand       mass ratio   - Heat dissipation
                 again as they cool                   problems limit
                 under stress                         relaxation rate of
                                                      -Limited bandwidth
             Force Feedback Actuators
Hydraulics   A hydraulic fluid is       - Force capability, - High mass
             pressurized by a power     power output,       - Tendency for
             plant, controlled by       stiffness, and      fluid leaks
             servo-valves and           bandwidth           - Design difficulty
             delivered to rotary or     unmatched by
             linear actuators through   other technologies - Expensive
             pressurized fluid lines
Pneumatics A gas (normally air) is      -Good   static force   -Relatively   low
           pressurized by a power       capability             bandwidth
           plant, controlled by         - Lighter than         - Low actuation
           servo-valves, and            hydraulics             stiffness
           delivered to rotary or       - Pneumatic power      - Low power
           linear actuators through     plants and             capability
           pressurized fluid (air)      distribution
           lines                        systems easier to
                                        manage than
              Force Feedback Actuators
Piezoelectric Piezoelectric motors          - High      - Requires precision
              translate the vibration of    forces at   machining
              piezoelectric materials to    low         - Power gating can
              linear or rotary motion       speeds in   cause annoying and
              using frictional forces to    small       potentially hazardous
              produce usable torques or     package     noise, depending on the
              forces at low speeds,                     design
              without the need for gear
Magneto-       Magneto-restrictive          - High      - Power gating can
restrictive    materials change shape       forces at   cause annoying and
               when subjected to            low         potentially hazardous
               magnetic fields. Magneto-    speeds in   noise, depending on the
               restrictive motor also       small       design
               mechanically rectify small   package     - Heat dissipation
               oscillatory motions of the               - Requires precision
               driving elements                         machining
   Commercially Available Devices
Device        Vendor      Device    Forces to DO   Resoluti   Applied        Price
Name                      Type                Fs   on         Force

4 DOF Force EXOS, Inc     Desktop   Hand via   4   N/A        5.1-12 oz-in   N/A
Feedback                            joystick                  (cont),
Master                                                        20-59 oz-in
Force         EXOS, Inc   Exoskel   Shoulder   5   N/A        3.4-56.6 lb-in N/A
Exoskeleton               eton      and                       (cont),
ArmMaster                           elbow                     29-489 lb-in
Impulse       Immersion   Desktop   Hand via   3   0.00435    8.9N (cont)    $7,950
Engine 3000                         joystick       N

Laparoscopi   Immersion   Desktop   Hand via   5   0.00435    8.9N (cont)    $8,950
c Impulse                           joystick       N
      Commercially Available Devices
Device       Vendor     Device    Forces to     DOF Resolutio Applied        Price
Name                    Type                    s   n         Force

Interactor   Aura     Vest        Torso via vest N/A   N/A      N/A          $89
Interactor   Aura     Cushion     Back via      N/A    N/A      N/A          $99
Cushion      Systems,             cushion

Haptic       Nissho     Desktop   Hand via      6      2.85gf   1.2kgf, 5.6   N/A
Master       Electron             knob                          kgf/cm (cont)
             ics                                                1.8kgf (peak)
Hand         EXOS,      Exoskele Thumb&index 4         N/A      1-5 lb (peak) N/A
Exoskelet    Inc        ton      finger joints,
on Haptic                        palm
     Commercially Available Devices
Device      Vendor     Device    Forces to DO    Resol    Applied Force     Price
Name                   Type                Fs    ution

PER-Force   Cybernet   Desktop   Hand via    3   0.035    1 lb(cont), 9lb   $9,950
3DOF        Systems              joystick        oz       (peak)

PER-Force Cybernet     Desktop   Hand via    6   12 bit   2-3 oz (min)      $60,000
Handcontro Systems               joystick                 20-25lb (peak)
PHANTOM     SensAble   Desktop   Fingertip   3   12 bit   1.5N(cont)        $24,000
            Devices              via                      10N(peak)
SAFIRE      EXOS,      Exoskele Wrist,       8   N/A      1-2 lb (peak)   N/A
            Inc        ton      thumb &                   Wrist 2lb(peak)
4 DOF Force Feedback Master
Freedom 7
Elbow Force Feedback Display
 (Hokkaido University, Japan)
Dextrous Arm Master
Hand Exoskeleton Haptic Display
PHANTOM Desktop System
   4 DOF Force Reflecting
Manipulandum (NW University)
Stewart Platform Joystick
Haptic Master
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
     Full Body Motion Interfaces
 Challenges   for full body motion in a VE, when
   Locomotion   through a large virtual space
   Locomotion over varying surface characteristics
   Motion in a direction other than horizontal
          Human Motion Sense
 Human  capabilities to sense motion and
 control posture (orientation & balance)
  Visualsystems
  Vestibular systems
         Human Eye

          Human Eye Functions
   Cornea (角膜) – 具曲光構造的透明組織 可折射光線 是氧氣進入眼球主要入
   Sclera (鞏膜) – 俗稱眼白部分 具保護及維持眼睛形狀之功能
   Conjunctiva (結膜) – 薄而透明的膜覆蓋於鞏膜上
   Ciliary Muscle (睫毛肌)
   Suspensory Ligament (懸吊腱)
   Crystalline lens (水晶體)
   Iris (虹膜) – 帶色素的眼珠部分 因人種遺傳有藍褐綠色 中央虹膜未包圍區行
    程瞳孔 可隨光線放大縮小
   Pupil (瞳孔)
   Retina (視網膜)
   Optic Nerve (視神經)
   Fovea (黃斑部)
   Blind Spot (盲點)
             Visual Systems
 Sensory  system – signal the position and
  movement of the head with respect to
  surrounding objects, provide the vertical
  directional sense
 Motor system (optokinetic reflex) – sense
  slipping of the retinal image supplement
  compensatory eye movements through a
  tracking mechanism
Ear Anatomy
              Vestibular Systems
 Sensory   systems
   Provide information about movement of the head
    and the position of the head with respect to gravity
    and any other acting inertial forces
   Semi-circular canals & otolith organs

 Motor   systems
   Provide  information in posture control,
   i.e. orienting to the vertical, controlling center of
   mass, and stabilizing the head
    Sensory Organs in Vestibular System
   Semi-circular canals – in the inner ear
     provide information about the angular velocity of head
     canals are fluid-filled and the inertial of this fluid causes
      head rotations to increase, or decrease, activity of
      specialized hair cells that fire neural signals to excite the
      vestibular nerve
     Respond to rapid head movements

   Otolith organs
     provide the information about linear acceleration and head
      tilt with respect to the gravitational axis
     Saccular otolith – vertical linear acceleration of the head
     Utricular otolith responds to horizontal accelerations
     Sensitive to slow movements
Schematic Diagram of Hearing
Output from the Vestibular System
 Goes   to
   Spinal cord – serve the vestibulo-spinal reflex in
    order to maintain head and postural stability
   Ocular muscles – enable clear vision while the
    head is in motion
          Full Body Interfaces
 Self-Motion   Interfaces
   The  user moves himself through a VE, as
    opposed to being passively moved in some type
    of vehicles
 Pass-Motion    Interfaces
        Self-Motion Interfaces
 Aerotrim from Aerotrim USA, Inc (US$7,995)
 CyberPak from Virtual Images, Inc (US$31500)
 DreamGlider from Dreamality Technologies,
  Inc. (US$26,000)
 Orbotron from Orbotron, Inc. (US$10,000)
 PemRAM Motion Bases from Denne
  Developments, Ltd (3-axis US$27,000, 6 axis
Aerotrim USA, Inc
PemRAM Motion Bases
       Virtual Environment
     Interfaces Technology
 Visual interfaces
 Tracking interfaces
 Auditory interfaces
 Primary User Input Interfaces
 Haptic/Kinesthetic interfaces
 Full body motion interface
 Olfactory interfaces
            VE Olfactory Systems
 The   least developed areas within VE
    Lack of useful applications
    The current societal mores

 Artificial   or electronic noses sense:
    Gaschromatography
    Mass spectrometry
    Chemical sensor arrays
                 Olfactory Systems
   Odorant storage
     microencapsulate odorants
     Liquids
     Gels
     Waxy solids

   Methods to released odors
     Air dilution
     Breathable membranes coated with a liquid odor
     A system of liquid injection into an electrostatic field with
      air flow control
  Olfactory Delivery Technologies
Storage   Presentation                 Advantages          Disadvantages
Liquid    -Unpowered  evaporation:     -No power           -Bulky
          Saturated cotton balls,      -Inexpensive        -Odorants   clumsy to
          Breathable membranes,                            handle
          Permeation tubes,
          Bubble chambers
          - Heat induced evaporation   -Inexpensive        -Power   hungry
Gels      Eletrostatic evaporation     -Good for large     -Never miniaturized
                                       spaces              -Requires higher
                                       -Materials easier   voltages
                                       to handle
    Olfactory Delivery Technologies
Storage         Presentation               Strengths             Weaknesses
Micro-          Two options:               Both presentations:   -Mass
encapsulation   -Mechanical release        -Could be valveless   production
                -Heat release              -Materials easy to
                                           handle                -Impractical for
                                                                 small lots
Waxy solids     Valve design options:      Each design:          -Never
                -No valves                 -Smaller, cheaper     miniaturized
                -Off-the-shelf valves      -Mass produced        -Requires

                -Ink jet printer nozzles   -Precise control      higher
                -Microvalves               -Potentially fast &
End of VR Interface

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