HAPTICS

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HAPTICS
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Introduction

• Haptics is the study of how to couple the human
  sense of touch with a computer generated world.
• Haptic refers to the sensing and manipulation
  through touch
• Haptics is derived from the greek word haptien
  which means hold.
• In combination with visual display ,haptics
  technology can be used to train people for tasks
  requiring hand-eye coordination.

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Contd..

• The study of Haptics emerged from advances in
  virtual reality.
• Virtual reality is a form of human - computer
  interaction providing a virtual enviornment that
  one can explore through direct interaction with
  our senses.
• To be able to interact with virtual enviornment
  there must be some feedback and this type of
  feedback is called Haptic feedback.
• Haptic interfacedevice for touch interaction in
  real and virtual world.

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Types

• Machine Haptics machines used to simulate human
  touch.
• Human Hapticsstudy of human sensing through
  touch.
• Computer HapticsComputational method to generate
  and render touch.

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Two primary types of Hapticinterfaces

• 1.Force feedback(Force reflecting)
• It deals with devices that interact with the
  muscles and tendon that give the human a
  sensation of force being applied.
• These devices mainly consist of robotic
  manipulators.

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Contd

• 2.Tactile feedback
• It deals with devices that interact with the
• nerve endings in the skin which indicate
• heat ,pressure and texture.
• These devices typically have been to indicate
• whether or not the user is in contact with a
  virtual object.

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Force feedback display
Tactile feedback
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Haptic interaction

• Haptic interaction uses haptic interfaces.
• Haptic interface devices behave like small robots
  that exchange mechanical energy with a user.
• We use the term device-body interaction to
  highlight the physical connection between the
  operator and device
• The interaction can be in contact with any part
  of operators body.

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Contd..

• An avatar is created which is the the virtual
  representation of haptic interface.
• User physically interacts with virtual
  enviornment through the avatar.
• The operator controls the avatars position in
  virtual enviornment.
• Contact between the avatar and the virtual
  enviornment sets off the action and reaction
  force.

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Contd

• From real world to virtual world and vice versa.
• Two methods of interaction
• Point basedonly the end point of the haptic
  device interacts with the objects.
• Ray basedcollision are checked between the ray
  and objects

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Point based

• Model the haptic probe as a single
  point.
• Each time the user moves the haptic probe the
  collision is detected.
• If so then appropriate forces are reflected back
  to the user.

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Ray based

• The generic probe of haptic device is modeled as
  a line segment .
• Collisions are checked between the finite line
  and virtual objects.
• This approach enables users to touch multiple
  objects simultaneously.

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Potential benefits

• Reduction in fatigue.
• Increase in productivity and comfort.
• Decreased learning times.
• Reduction in manipulation errors.

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Commercially available Haptic interfaces
3DOF omega haptic device
Haptic master
The freedom s7
Pantograph
The novint falcon
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Haptic devices

• Sensory information in haptic devices include
• Tactilepresence of heat,texture and pressure.
• Kinestheticposition,body movements and the
  forces which act on it.
• Haptic devices can also be classified according
  to the noof degrees of freedom of the force or
  motion at the haptic interface device.
• DOF is the noof dimensions characterizing the
  possible movements of forces exchanged b/w the
  user and device.

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Computer haptics

• Haptic technologytechnology that interfaces with
  the user through touch.
• Haptic renderingprocess of displaying
  synthetically generated 2D/3D stimuli to the
  user.
• Computer haptics is the heart of haptics.

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Haptic rendering

• Haptic rendering has two main parts
• Collision detection
• Collision response
• Collision detection
• As a user manipulates the probe of a haptic
  device,the new position and orientation of the
  probe are acquired and collisions are detected.
• If no collision has occurred,then the device
  remains passive and no force is reflected.

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Contd..

• collision response
• If collision is detected ,interaction forces are
  calculated and conveyed to the user through the
  haptic device which provides tactual information.
• Haptic loop updates the forces around 1khz.
• The opposing force acting on the user during
  interaction is Fkx.
• The direction of force will be normal to the
  surface.

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illusions

• Tendon of right arm vibrated.
• Feeling of right elbow rotating away.
• If subjects held their left index finger with
  their right hand , they felt their left index
  finger getting longer.

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Applications

• Games Gaming experience can be greatly enhanced
  by applying force feedback
• Multi-media publishing Currently include text,
  sound, images and video.
• 'Mechanical Documents' could be transmitted
  conveying material properties
• Scientific Discovery Data display
• Remote sensing, mining in geology (oil and gas
  prospecting)?

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Applications(contd.)

• Other fields of application
• Arts and Creation Artists and musicians, virtual
  exhibitions of paintings and sculpture
• Vehicle operation iDrive in BMW and Rolls Royce
• Engineering CAD
• Education and Training surgical training, pilot
  training

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Current activity

• TapTap is a wearable haptic interface.
• It can record and play back patterns of tactile
  information so that people can experience the
  emotional and physical benefits of human touch in
  different times and places.
• Actuators are present to provide the various
  touch sensations.

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Downsides of Haptics

• Haptic applications can be extremely complex
  requiring specialized hardware and processing
  power.
• Many haptic projects rely on fixed installations
  and they are not easily portable.
• Cost is high .

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Conclusion

• Haptics plays an important role in constructing
  an autonomous robot.
• Although haptic interface devices are available,
  further improvements are needed to match the
  performance of the human user.
• Tactile display is one of the most challenging
  technologies that needs to be developed in moving
  towards realistic haptic displays.

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References

• http//www.docstoc.com/docs/2685206/Introduction-t
  o-Computer-Haptics
• V. Hayward, O. Astley, M.C. Hernandez, D Grant,
  G. Torre, Haptic Interfaces and devices, Sensor
  Review, Vol.24. 2004.
• Mandayam A Srinivasan, What is Haptics?,
  Laboratory for Human and Machine Haptics The
  Touch Lab, Massachusetts Institute of Technology.
• L. Bonanni, J Lieberman, C Vaucelle, O Zuckerman,
  TapTap A haptic wearable for asynchronous
  distributed touch therapy, Proc CHI 2006.
• M Srinivasan,C. Basdogan, Haptics Display in
  Virtual Environment,Computer Graphics,Vol. 2,
  1997

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