1. 1 Using vibration patterns to provide impact position information in haptic manipulation of virtual objects 13/06/2008 Jean Sreng Anatole Lécuyer Claude Andriot jean.sreng@inria.fr

2. 2 Outline Introduction Vibration patterns Evaluation Conclusion

3. 3 Introduction The impact between “rigid” objects : A low-frequency reaction force of contact (simplified model) A high-frequency force transient (more complex model) This high-frequency force transient can be used in haptic rendering of impact (open-loop haptic) : Improve the realism Convey some information about the object’s material Is-it possible to convey position information using this transient ?

4. 4 Vibrations and impact position Chosen approach : The impact generates vibrations depending on the impact position Vibration model, a first approximation Euler-Bernouilli cantilever beam

5. 5 Vibrations and impact position General solution : Impact position

6. 6 Simplified vibration patterns Simplified patterns based on the physical behavior Simplified computation Maybe easier perception ? Chosen model : exponentially damped sinusoid Amplitude changes with impact position Frequency changes with impact position Both amplitude and frequency changes

7. 7 Simplified vibration patterns Am Fr AmFr (Consistent) AmCFr (Conflicting) Near impact Far impact

8. 8 Evaluation Preliminary evaluation : Quantitative : “Between these two impacts which one was the closest one from the hand ?” Qualitative : Subjective rating of the impact realism Conducted on 15 subjects Apparatus : Virtuose6D device Sound blocking noise headphones

9. 9 Quantitative evaluation Quantitative evaluation : “Between these two impacts which one was the closest one from the hand ?” 6 models –2 realistic models (Euler-Bernoulli) (EB1, EB2) –4 simplified models (Am, Fr, AmFr, AmCFr) 4 locations 8 random repetitions Total of 576 trials (40 min) ERRATUM Page 7 § 4.3 EB1: 10Hz, 64Hz EB2: 5Hz, 25Hz Other: 15Hz to 45Hz

10. 10 Quantitative evaluation : results The ratio of “good answers” was evaluated : “How well the user was able to associate a vibration and an impact location ?” 0.50.750.25 No association Inverted association association The value was used to represent the overall performance 0 0.25 0.5 association No association

11. 11 Quantitative evaluation : results Overall performance : ANOVA Significant (p < 0.007) Paired t-tests (p < 0.05) : –Am - –EB1 –EB2 –AmCFr –Fr - –EB1 –EB2

12. 12 Quantitative evaluation : results Inversion ratio : The ratio of users who inverted the association between the vibration pattern and the position

13. 13 Qualitative evaluation : results Rate the impact realism : Paired t-tests : –Am –EB1 –EB2 –Fr –AmFr –EB2 –Fr –AmCFr

14. 14 Discussion Global weak inter – subject correlation : Each subject seems to have his/her own interpretation (inversion or not) Strong intra – subject consistency : Subjects seem to be very consistent within his/her interpretation Several strong inter – subject correlation between models : Fr and AmCFr strongly correlated

15. 15 Conclusion We proposed several vibration patterns to convey impact position information We conducted a preliminary evaluation : The user is able to use the vibration pattern to get an impact position information The simplified models Am and Fr seems to perform better Future work : Evaluate the role of the hand impedance and the haptic device bandwidth to elaborated more effective feedback Deeper analysis of the data New models

16. 16 Questions ? ?