Haptic Rendering in Shared Collaborative Environments Transatlantic Touch

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Haptic Rendering in Shared/ Collaborative
Environments -Transatlantic Touch

• CSE 20065160
• Hwang, Inwook
• (inux_at_postech.ac.kr)
• 2006.6.12
• VRLab, POSTECH

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Outline

• Introduction
• Touch in Shared Virtual Environments
• Transatlantic Touch
• Conclusion

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Introduction Shared Virtual Environment

• SVE(Shared Virtual Environment) means the virtual
  environment where two or more user can interact
  with each other.
• Less attention has been paid to human-human and
  human-machine interaction in SVEs.
• In SVE, the participants can show their actions
  and express their emotions to each other.

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Introduction Haptic Collaboration

• Visual and auditory communications are important
  in producing positive effect on the participants
  sensory experience in VE.
• Then, how about with haptic communication?

5
Outline

• Introduction
• Touch in Shared Virtual Environments
• Transatlantic Touch
• Conclusion

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The Ultimate Goal
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The Goals of This Study

• To identify the necessary components of touch
  that are required to make a human believe that he
  or she interacts with another human being.
• To investigate the influence of haptic feedback
  on the task performance and sense of togetherness
  of participants in touch-enabled SVE.

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Experimental Setup

• Dual PII 300MHz CPU
• High-End 3D graphics accelerator
• SensAble PHANToM
• To eliminate unstable network delay, PC connected
  to two monitors and two PHANToMs is used.

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Experimental Design

• The participants cannot see the partner who is an
  expert user of the system.
• There were two experimental conditions
• Visual feedback only (V)
• Visual and haptic feedback (VH)
• Group 1 received (VH) first and group 2 received
  (V) first.

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Scenario and Task

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Haptic Interaction Models

• They used a simple spring-damper model.
• F k?p b?p (k,b coefficient, ?p
  displacement of the cursor)
• There is no deformation or rotation of object.

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Results - Performance

• They scored every trial and used maximum score.
• (a constant, T total time taken to complete the
  task,
• R the ratio of error-free time to the T)

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Results - Togetherness
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Results - Togetherness

• For males, higher social anxiety was associated
  with a lower sense of togetherness.
• For females, higher social anxiety was associated
  with a higher sense of togetherness.
• Without haptic feedback, participants guessed the
  partner is female.
• With haptic feedback, participants guessed the
  partner is male.

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Outline

• Introduction
• Touch in Shared Virtual Environments
• Transatlantic Touch
• Conclusion

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Human-Human Haptic Interaction

• Human-human haptic interaction is different from
  teleoperation.
• There are no master or slave ends and both
  ends influence each other
• Users interact mostly in virtual worlds.

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The Goal of This Study

• To investigate the influence of haptic feedback
  on the task performance of participants on the
  internet.

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Experimental Setup -Hardware

• MIT
• SensAble PHANToM
• Dual 0.9GHz PC 256MB RAM
• Nvidia GeForce 2 based graphic card
• 19 monitor
• UCL
• SensAble PHANToM
• 1GHz PC 512MB RAM
• Nvidia GeForce 2 based graphic card
• 19 monitor

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Experimental Setup - VR

• 
  gravity 9.8m/s2
• 
  mass of the cube 0.1kg
• 
  friction coefficient 1.0
• 
  (It simulates contacts between
  medium-hard- rubber and rubber
  surfaces.)

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Experimental Setup - Network

• The two sites were connected with Internet2
  network(2.4Gbps)
• A round-trip delay was approximately 90ms.
• But, actual packet latency varied.

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Experimental Setup - Software

• They used P2P architecture to eliminate the
  latency from intermediate server.
• The clocks on both systems were synchronized by
  NTP.
• In every haptic loop, they sent the forces
  applied to the local cube rather than sending the
  position of the probe.
• Because TCP has significant overhead, they used
  UDP connection in this study.

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Experimental Design

• The 20 subjects at UCL were unaware that the
  partner at MIT is an expert user of the system.
• The subjects were assigned to one of four groups.
• Subjects were provided with directional
  information or not, and haptic feedback or not.

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Haptic Interaction Models

• The motion of the cube is computed by following
  dynamic equation.
• (m mass, c damping factor, k spring constant,
  position vector of the cube)

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Network Latency Problem

• In the presence of transmission delays, force
  feedback has a strong destabilizing effect.
• In this work, the problem is dealt with by adding
  damping factors at various stages throughout the
  system.

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Damping Factors

• Dynamic equation of the cube
• c, the damping term simulates viscous friction
  forces in the VE.
• Reaction force equation
• (k contact stiffness, Ppenetration penetration
  vector)
• The velocity of hand motion is considered as the
  penetration position between the cube and the
  haptic device.

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Damping Factors

• The users interaction with the haptic device
• With the damping, the users high frequency hand
  tremor can be filtered.
• The damping works as low-pass filter.

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Collision Prediction

• The users hand has much lower motion frequency
  (order of 10Hz) than the sampling frequency of
  the system(1KHz).
• The motion of the hand can be predicted from the
  history of HIP.

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Collision Prediction

• First, we calculate probe-cube vector that is
  connecting the current position to the previous
  position.
• To remove tremors of the users hand, we take
  several points and average these points. (
  )

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Collision Prediction

• Then, we compute distance from the HIP to the
  cube in the direction of the tool path.
• The computation time for collision check is
  reduced to one distance calculation and one
  comparison.

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Scenario and Task

• To lift a virtual cube in a collaborative
  environment in time.

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Results

• With the force feedback, subjects felt 5 more
  copresence(?25.4).
• The use of directional probe reduces
  copresence(?211.85).
• Age of the subjects negatively associated with
  copresence(?25.9).

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Outline

• Introduction
• Touch in Shared Virtual Environments
• Transatlantic Touch
• Conclusion

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Conclusion

• Haptic communication produces positive effect on
  the participants sensory experience in VE.
• They used damping at various stages to eliminate
  instability.

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Reference

• C. Basdogan, C.-h. Ho, M. A. Srinivasan, and M.
  Slater, "An Experimental Study on the Role of
  Touch in Shared Virtual Environments," ACM
  Transactions on Computer-Human Interaction, vol.
  7, pp. 443 - 460, 2000.
• J. Kim, H. Kim, B. K. Tay, M. Muniyandi, M. A.
  Srinivasan, J. Jordan, J. Mortensen, M. Oliveira,
  and M. Slater, "Transatlantic Touch A Study of
  Haptic Collaboration over Long Distance,"
  Presence Teleoperators and Virtual Environments,
  vol. 13, pp. 328 - 337, 2004.