HAPTICSHAPTICS

IntroductionIntroduction

Haptics is the study of how to couple the human sense Haptics is the study of how to couple the human sense of touch with a computer generated world.of touch with a computer generated world.

Haptic refers to the sensing and manipulation through Haptic refers to the sensing and manipulation through touchtouch

Haptics is derived from the greek word ‘haptien’ which Haptics is derived from the greek word ‘haptien’ which means ‘hold’.means ‘hold’.

In combination with visual display ,haptics technology In combination with visual display ,haptics technology can be used to train people for tasks requiring hand-eye can be used to train people for tasks requiring hand-eye coordinationcoordination..

Contd..Contd..

The study of Haptics emerged from advances in The study of Haptics emerged from advances in virtual reality.virtual reality.

Virtual reality is a form of human - computer Virtual reality is a form of human - computer interaction providing a virtual enviornment that interaction providing a virtual enviornment that one can explore through direct interaction with one can explore through direct interaction with our senses.our senses.

To be able to interact with virtual enviornment To be able to interact with virtual enviornment there must be some feedback and this type of there must be some feedback and this type of feedback is called Haptic feedbackfeedback is called Haptic feedback..

Haptic interface:device for touch interaction in Haptic interface:device for touch interaction in real and virtual world.real and virtual world.

TypesTypes

Machine Haptics :machines used to Machine Haptics :machines used to simulate human touch.simulate human touch.

Human Haptics:study of human sensing Human Haptics:study of human sensing through touch.through touch.

Computer Haptics:Computational method Computer Haptics:Computational method to generate and render touch.to generate and render touch.

Two primary types of Hapticinterfaces

1.Force feedback(Force reflecting)1.Force feedback(Force reflecting)

It deals with devices that interact with the It deals with devices that interact with the muscles and tendon that give the human a muscles and tendon that give the human a sensation of force being applied.sensation of force being applied.

These devices mainly consist of robotic These devices mainly consist of robotic manipulatorsmanipulators..

Contd…Contd…

2.Tactile feedback2.Tactile feedback

It deals with devices that interact with the It deals with devices that interact with the nerve endings in the skin which indicate nerve endings in the skin which indicate heat ,pressure and texture.heat ,pressure and texture.

These devices typically have been to indicateThese devices typically have been to indicate whether or not the user is in contact with a virtual whether or not the user is in contact with a virtual

object.object.

Force feedback displayForce feedback displayTactile feedbackTactile feedback

Haptic interactionHaptic interaction

Haptic interaction uses haptic interfaces.Haptic interaction uses haptic interfaces.Haptic interface devices behave like small Haptic interface devices behave like small

robots that exchange mechanical energy with a robots that exchange mechanical energy with a user.user.

We use the term device-body interaction to We use the term device-body interaction to highlight the physical connection between the highlight the physical connection between the operator and deviceoperator and device

The interaction can be in contact with any part of The interaction can be in contact with any part of operator’s body.operator’s body.

Contd..Contd..

An avatar is created which is the the virtual An avatar is created which is the the virtual representation of haptic interface.representation of haptic interface.

User physically interacts with virtual enviornment User physically interacts with virtual enviornment through the avatar.through the avatar.

The operator controls the avatar’s position in The operator controls the avatar’s position in virtual enviornment.virtual enviornment.

Contact between the avatar and the virtual Contact between the avatar and the virtual enviornment sets off the action and reaction enviornment sets off the action and reaction force.force.

Contd…Contd…

From real world to virtual world and vice versa.From real world to virtual world and vice versa.

Two methods of interactionTwo methods of interaction

Point based:only the end point of the haptic Point based:only the end point of the haptic device interacts with the objects.device interacts with the objects.

Ray based:collision are checked between the Ray based:collision are checked between the ray and objectsray and objects

Point basedPoint based

Model the haptic probe as Model the haptic probe as a single point. a single point.

Each time the user Each time the user moves the haptic probe moves the haptic probe the collision is detected. the collision is detected.

If so then appropriate If so then appropriate forces are reflected back forces are reflected back

to the userto the user..

Ray basedRay based

The generic probe of The generic probe of haptic device is modeled haptic device is modeled as a line segment .as a line segment .

Collisions are checked Collisions are checked between the finite line between the finite line and virtual objects.and virtual objects.

This approach enables This approach enables users to touch multiple users to touch multiple objects simultaneously.objects simultaneously.

Potential benefitsPotential benefits

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

Commercially available Haptic Commercially available Haptic interfacesinterfaces

3DOF omega haptic device

The novint falcon

Haptic masterThe freedom s7

• Pantograph

Haptic devicesHaptic devices

Sensory information in haptic devices include: Tactile:presence of heat,texture and pressure.Kinesthetic:position,body movements and the

forces which act on it.Haptic devices can also be classified according

to the no:of degrees of freedom of the force or motion at the haptic interface device.

DOF is the no:of dimensions characterizing the possible movements of forces exchanged b/w the user and device.

Computer hapticsComputer haptics

Haptic technology:technology that interfaces Haptic technology:technology that interfaces with the user through touch.with the user through touch.

Haptic rendering:process of displaying Haptic rendering:process of displaying synthetically generated 2D/3D stimuli to the synthetically generated 2D/3D stimuli to the user.user.

Computer haptics is the heart of haptics.Computer haptics is the heart of haptics.

Haptic renderingHaptic rendering

Haptic rendering has two main parts:Haptic rendering has two main parts: Collision detectionCollision detection Collision responseCollision response

Collision detection:Collision detection: As a user manipulates the probe of a haptic As a user manipulates the probe of a haptic

device,the new position and orientation of the device,the new position and orientation of the probe are acquired and collisions are detected.probe are acquired and collisions are detected.

If no collision has occurred,then the device If no collision has occurred,then the device remains passive and no force is reflected.remains passive and no force is reflected.

Contd..Contd..

collision responsecollision response If collision is detected ,interaction forces are If collision is detected ,interaction forces are

calculated and conveyed to the user through the calculated and conveyed to the user through the haptic device which provides tactual information.haptic device which provides tactual information.

Haptic loop updates the forces around 1khz.Haptic loop updates the forces around 1khz.The opposing force acting on the user during The opposing force acting on the user during

interaction is F=k*x.interaction is F=k*x.The direction of force will be normal to the The direction of force will be normal to the

surface.surface.

illusionsillusions

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.

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)

Applications(contd.)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

Current activityCurrent 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.

Downsides of HapticsDownsides of Haptics

Haptic applications can be extremely complex Haptic applications can be extremely complex requiring specialized hardware and processing requiring specialized hardware and processing power.power.

Many haptic projects rely on fixed installations Many haptic projects rely on fixed installations and they are not easily portable.and they are not easily portable.

Cost is high .Cost is high .

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.

ReferencesReferences http://www.docstoc.com/docs/2685206/Introduction-to-

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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