haptic display of informationtams- · “active exploration by touch ... rutgers no 5 in 5 5...

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June 10, 2004Haptic Display Slide 1

Advanced Visualization and ControlUniversity of Hamburg, Russ Taylor, Summer ‘04

Haptic Display of Information

Russell M. Taylor II



Haptics

• Definition from Perceptual Psychology“Active exploration by touch”

• Implementation with current technology– Active exploration with a point-contact tool

• Only bi-directional sensory modality– Useful when user coupled both directions (pushing and

feeling results of pushing)– Useful when the data to be displayed is force field



Note: Tactile is Different

• Tactile array from Karlsruhe Research Center in Germany– Finger-tip display

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Outline

• Haptic Devices• Haptic Applications• Description of specific benefits found in

applications at UNC• Haptics for Multivariate Display• Haptic Implementation Issues• Cue Conflicts• Haptic Display Characteristics





Sarcos Device

• Dextrous Master– 7 D.O.F. input– 7 D.O.F. output– three fingers

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Virtual Technologies

• CyberGrasp– 5 half-DOF (finger pull)– Ungrounded feedback

• CyberForce– Adds 3DOF position– Grounded feedback



Rutger’s Master

• Attempt to simulate flexible objects



Immersion Devices

• Immersion Corporation– Impulse Engine

• 2DOF in, 2DOF out• 0.008” resolution, 6”x6”

working volume– Laparoscopic Impulse

Engine• 5DOF in, 3DOF out• 0.0009” resolution, 4”x9”x9”

working volume

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SensAble Devices



Cybernet Devices• Joystick:3DOF in, 3DOF out

– ??? Resolution, 80 degree range of motion in RPY

• CyberImpact:– 6DOF in, 6DOF out– 0.0003” resolution, 4”x4”x4”

working volume



UC Boulder

• Used for flow fields– 5DOF in– 5DOF out

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Select IT Systems AGLap-SimOne

• www.select-it.de– Complete simulated endoscopic

surgery simulator– Came out of work at KISMET– Uses Laparoscopic Impulse

Engines for feedback



Consumer 2D Haptic Displays

• Logitech Wingman– Joystick– Mouse

• Microsoft Sidewinder 2



Glove-Based Characteristics

56 + 5 in3 + 5 pull out

YesCyberForce

44 in4 push-only out

NoRutgers

55 in5 pull-only out

NoCyberGrasp

37 in7 out

YesSARCOSFingersD.O.F.GroundedDevice

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Stick-Based Characteristics

Buttons5 in, 5 outYesUC Boulder

Buttons, throttle, hihat

3 in, 2 outYesSideWinder

Button2 in, 2 outYesImpulse

Button6 in, 3 or 6 outYesSensAble

Buttons6 in, 6 outYesCyberImpact

Pinch5 in, 3 outYesLaparascope

AdditionalD.O.F.GroundedDevice





Medical Training Application

• Forschungszentrum Karlsruhe Technik und Umwelt• KISMET

– The Karlsruhe Endoscopic Surgery Trainer– Deforming objects (organs)

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Medical Illustration Application

• GE: Volume feeling, painting, sculpting



Electronics Training Simulation

• MIT/RLE Virtual Environment Technology for Training



Molecular Dynamics Application

• VMD: Visual Molecular Dynamics

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Vector Field Display

• University of Colorado at Boulder• Haptic presentation of vector fields• Show IEEE Visualization 2000 Movie



Medical Volume Visualization

• Avila and Sobierajski (1996)– Feeling neuron dendrites– Gentle attraction used

• Opposite of gradient• Repulsion was too hard to

follow for twisting dendrites



Flow Volume Visualization

• Iwata and Noma combined HMD and haptics to display volume data in 1993– Provided force based on density gradient– Provided torque based on density– Either method improved positional accuracy

• Describe presenting flow field– Force for flow velocity– Torque for vorticity

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When is Force Useful?UNC Experiences:

• Teaching physics potential fields• Drug/protein docking• nanoManipulator



Force-Field Simulation for Training

• 2D sliding carriage device• Presented magnetic, electric, and

gravitational fields• More motivated students learned more

– Less motivated students didn’t learn more

• Dispelled misconceptions– Electric field in diode is not greater near

the plate than near the cathode– Gravity field in 3-body system does not

always point towards one of the bodies

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Docker

• Ming Ouh-Young’s dissertation project– Showed NTE factor-of-2 speedup with haptics– 6-DOF positioning task– “Lock and Key” problem– Hard surface + electrostatic



nanoManipulator: Haptics

“It was really a remarkable feeling for a chemist to be running his hand over atoms on a surface,” R. Stanley Williams, UCLA Chemistry

• Exciting and engaging, but what is it useful for?– Finding the right spot to modify– Feeling what is happening during a modification– Lightly touching delicate samples



Finding the right spot

Positionwhenscanning

Positionafter being heldstill for several seconds

Also, finding the top of an adenovirus

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Finding the right path



Light touch (haptic imaging)

Observation modifies the system



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Haptics for Multi-Dimensional Display

• Modulate surface properties– friction, stiffness, bumpiness, vibration, adhesion

• User studies done at UNC showing the perceptually-linear mapping for each– Map directly for the relevant physical parameter– Linearize for presentation of non-physical quantities

• Ongoing studies exploring cross-talk between channels



Sandpaper: Haptic Textures• Margaret Minsky dissertation (MIT, UNC)• Displayed 3D surfaces on 2D haptic device by

mapping slope to lateral force– People perceived 3D shape

• Displayed several properties– Viscosity– Spatial Frequency

• Vary properties based on data



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Force-Feedback Concerns: Safety

• It’s a robot; you’re in its working volume– Foot-pedal cutoff (dead-man switch)– Safety glasses

• Damage to the device itself– Thermal shutdown code

• These problems solved with newest devices



Concerns: High Update Rate

• Must be >500 Hz– Required for stable hard surfaces– Must be uninterrupted to prevent force discontinuities

• Much greater than graphics or simulation rates– Graphics rate ~30-60Hz– Simulation rate (as low as 1 Hz)

• Solution– Separate force-feedback server– Intermediate representation



nanoManipulator: The Old Way

Move Microscope Tip, Read HeightSend Force (Depends on Height)

Draw Image

Position

Force

Force-FeedbackDevice

Video

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User Interface controls force and

microscope

Decoupling surface update from user motion using intermediate rep.Server measures end effector location

11 User interface moves microscope tip to track end effector motion

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Two samples + “up” yield a tangent plane to the surface at contact point

33Plane is transformed into device coordinates and presented to user

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Phantom

SPM



Local Plane Equation

ProbeLocal Plane

Approximation(Used in Force Loop)

Surface

Complete Surface(known to

Application)



Preventing Discontinuity

• Discontinuity when plane updated

Probe

t = 0 t > 0Probe is beneaththe updated plane.

Result: Large force.

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Preventing Discontinuity

Probe

t = 0 t > 0Probe is broughtgradually toupdated plane.

• Recovery time over several steps



Point-to-Point Spring• Provide adjustable coupling between

application objects and force display– Sometimes it is too expensive to compute a local

approximation to the field• Molecular docking• Collision detection with large numbers of

objects• Application moves one end of the spring (>1

Hz), force server moves the other (>500 Hz)



Point-to-Point Spring

ApplicationEndpoint(Object)

ProbeEndpoint

(User)

Virtual Spring(adjustable spring constant)

Force onObject

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Cue Conflicts

• Visual/Haptic conflict– Lesson from virtual putt-putt

• Audio/Haptic conflict– Lesson from stacking blocks



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Characteristics of Haptic Display

• User directly engages the simulation or experiment– The only bi-directional sense– Adding forces into the system– Perceiving forces from the system

• Good way to directly present physical phenomena– Height fields, vector fields (2D or 3D), surface stiffness, friction

• Good for guiding user to surface or region of interest

• Point-sampled interface with today’s technology– Can’t get instant overview as with visual displays– Interact with the system as with a tool

• Vision or auditory dominates when cues conflict





Credits

• “Sandpaper” system figure: Minsky, Margaret, Ming Ouh-Young, O. Steele, Frederick P. Brooks, Jr., and M. Behensky, "Feeling and seeing: Issues in force display," Proc. of 1990 Symposium on Interactive 3D Graphics, Snowbird, Utah, March 1990. Published in Computer Graphics 24, 2 (March 1990). pp. 235-244.

haptic display of informationtams- · “active exploration by touch ... rutgers no 5 in 5 5...

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