1 1 Spatialized Haptic Rendering: Providing Impact Position Information in 6DOF Haptic Simulations...

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Spatialized Haptic Rendering: Providing Impact

Position Information in 6DOF Haptic Simulations

Using Vibrations9/12/2008

Jean Sreng, Anatole Lécuyer, Claude Andriot, Bruno Arnaldi

Jean.sreng@cea.fr

Introduction

• Context: Manipulation of solid objects in Virtual Reality

• Applications: Industrial virtual assembly / disassembly / maintenance

Enhancement of the information of contact

• Use of visual cues of contact (Sreng, Lécuyer, et al., IEEE TVCG 2006)

• Use of auditory cues of contact (Sreng, Lécuyer et al., ACM VRST 2007)

Haptic rendering of the information of contact

• Use of 6DOF haptic devices

• Computation of contact force : haptic rendering• Collision detection

• Force feedback

Limits of haptic rendering ?

• Importance of contact information

• In a real world • In a virtual world

Spatialized haptic rendering

• We propose to superimpose the vibrations corresponding to the 3D contact position to the classical haptic rendering

Outline

• Spatialized haptic rendering

• First experiment: Determining the optimal vibration parameters

• Second experiment: Preliminary evaluation

• Conclusion

Haptic rendering of contact position

• The impact between objects:• A reaction force

• A high-frequency transcient vibrations

• This high frequency transcient vibrations depends on:• The object material (Okamura et al. 1998)

• The object geometry

• The impact position

Haptic rendering of contact position

• How can we use vibrations to convey impact position information ?

• Different vibration models can be used (Sreng, Lécuyer, et al., EH 2008)

• Realistic model of a vibrating cantilevel beam

• Simplified model

Simulation of vibrations: Realistic model

• Realistic simulation based on the Euler-Bernouilli model

• General solution

Simulation of vibrations: Simplified model

• Simplified patterns based on the physical behavior based on an exponentially damped sinusoid:• Amplitude changes with the impact position

• Frequency changes with the impact position

• Both Amplitude and frequency changes

• Main benefits:• Easier perception

• Simplified computation

AmFr (Consistent)

Near impact Far impact

Simplified vibration patterns

6DOF Spatialized haptic rendering

• Generalizing the previous approach for 6DOF manipulation:• Virtual beam model

• Two types of information can be conveyed:• A distance of impact

• A direction providing the orientation of the impact

• The impact force

• The wrench sensed by the hand

• The wrench is then modulated by the vibration model:

• In particular the vibration torque can be expressed:

Vibration pattern Vibration orientation

Manipulationpoint

Manipulation point and circle of confusion

• Different impact positions can generate the same haptic feedback

• The total torque applied to the device is obtained by superimposing:• The classic torque obtained with closed-loop rendering

method

• The impact vibrations torque

Outline

• Conclusion

First experiment: determining the optimal vibration parameters

• Objectives1. Perceptual study : “Is it possible to perceive the contact position

in 3D space? Is it possible to perceive the vibration direction ?”

2. Technological aspect : Determine the optimal range of amplitude / frequency parameters

• Tests among: ( 4 amplitudes a ) x ( 4 frequencies f )

• Population: 10 male subjects (22 – 27 years old)

0.005 rad to 0.02 rad 12 Hz to 40 Hz

Apparatus

• Haptic device: Haption Virtuose6D 35-45

• Vibrations applied around the 3 axes

• Update rate of 1kHz

Procedure

• “On which axis is the vibration applied ? Where is the impact located ?” ● ● ● (3AFC)

• 15 blocks of 4 x 4 x 3 = 48 vibrations: total of 720 trials (35min)

Results: Effect of frequency

• Average performance : around 80% of correct responses

• Best performances achieved with low frequencies

4 frequencies f12 Hz 18 Hz 27 Hz 40 Hz

Results: Effect of amplitude

• Average performance : around 80% of correct responses

• Best performances achieved with high amplitudes

4 amplitudes a0.02 rad 0.015 rad0.01 rad 0.005 rad

Discussion

• Participants were able to perceive the vibration directions among the three axes

• Most participants reported that they did not use a particular strategy

• Best performances were achieved with low frequencies• Suggest the importance of kinesthetic cues over tactile cues

• However some participants reported that they relied on tactile cues for small amplitudes

• Best performances were achieved with high amplitudes• However some participants reported that high amplitudes made

their perception more difficult

Outline

• Conclusion

Second experiment: perliminary user evaluation

• Objective: Subjective evaluation of Spatialized Haptic Rendering in a real case

• Population: 11 naive subjects (8M, 3F) (25 – 43 years old)

• Task: 6DOF manipulation of 3D object• Subjective ratings

- Realism of the impact

- Feeling of impact position

- Overall comfort of the manipulation

• Procedure: Participants were asked to test the two rendering techniques successively (without and with vibrations) in a random order

Procedure

• Virtual scene: two 3D objects

• Spatialized Haptic Rendering parameters:

0.005 rad 0.02 rad

40 Hz 15 Hz

Manipulation point

Results

• Mean ratings from 1 (worst) to 6 (best) without and with superimposed vibration

Discussion

• Better feeling of impact position obtained with Spatialized Haptic Rendering

• Several participants spontaneously reported that the vibrations enabled them to perceive the impact position

• Most participants pointed out that they perceived different materials between the two conditions• A « crisper » or « harder » feeling with vibrations (Okamura et al. 1998,

Kuchenbecker et al. 2006)

• A feeling of « vibrating metal »

• Most participants enjoyed the manipulation using the vibrations

• Two participants (familiar with haptic rendering) reported that they associated the vibration with an unstable, an potentially harmfull rendering algorithm

Conclusion

• We proposed a 6DOF spatialized haptic rendering method to provide impact position directly on the haptic channel• using vibrations based on a vibrating beam

• We conducted two experiments to evaluate this method• Experimental study on the perception of vibration direction

- Participants can identify the vibration direction, i.e., the position of contact in 3D space

- Optimal range of model parameters: Low frequencies / High amplitudes have better results

• Subjective study on a 6DOF case- Better subjective perception of impact position

• Further work• Investigate more deeply the perceptive characteristics of vibrations• Conduct an objective evaluation on a virtual prototyping context

Thank you. Questions ?

1 1 Spatialized Haptic Rendering: Providing Impact Position Information in 6DOF Haptic Simulations...

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