1. E. Engeberg University of Akron, USA S. Meek University of Utah, USA
Adaptive Object Slip Prevention For Prosthetic Hands Through Proportional-Derivative Shear Force Feedback
E. Engeberg University of Akron, USA S. Meek University of Utah, USA
Adaptive grip force compensation when grasped objects slip
Use of existing sensors already incorporated into commercially available prostheses
Distinction between slip and nonslip disturbances applied to grasped objects
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2. Commercially Available Prostheses
Otto Bock’s SensorHand
Motion
Control
Hand

3. Current Prostheses Touch Bionics i-LIMB
Motion Control UA3 with Flexion Wrist and Protouch Hand
Otto Bock
DynamicArm
All suffer from high backlash and static friction.
UA3 has only three degrees of freedom controlled by 1 input.

4. The Motion Control Hand: Force Measurement

5. Force Control

6. Proportional Object Slip Prevention

7. PD Object Slip Prevention

8. Adaptive Object Slip Prevention

9. What Adaptive Slip Prevention Does

10. FFT of Nonslip Events

11. FFT of Slip Events

12. Bandpass Slip Filters For Smooth Object Slip Events With Glove

13. 7 Bandpass Filters

14. Bandpass Slip Filters For Smooth Object Slip Events With Glove

15. Test Apparatus For Slip Controllers

16. Experimental Benchtop Results
Low Friction
High Friction
Mean
STD
Force
1.2
0.4216
1.5
1.2693
Prop. Slip
1.9
0.5676
11.3
4.3474
PD Slip
2.5
0.527
17.9
6.1001
Adaptive 3
0.9428
Did Not Drop

17. Experimental Benchtop Results: U-test p-Values Low Friction
Force
Prop. Slip
PD Slip
Adaptive 1
0.0093
0.0003
0.0334
0.0111
0.2373

18. Experimental Benchtop Results: U-test p-Values High Friction
Force
Prop. Slip
PD Slip
Adaptive 1
0.0001
0.0188

19. Human Experiments: Slip Prevention

20. Human Results: Slip Prevention
Success Rates
Subjective Evaluations
Mean
STD
Force
77.50%
27.12%
5.00
0.00
Prop. Slip
97.50%
7.07%
7.46
1.22
PD Slip
100% 0%
7.68
1.19
Adaptive
95%
9.26%
7.59
1.85

21. Conclusions
Slip can be distinguished from nonslip events with existing sensors
Shear force and shear force derivative feedback is useful
Adaptive slip prevention is useful to compensate for slippery objects
Algorithms can be easily implemented into existing commercially available prostheses

22. Future Work
Test slip prevention controllers with amputees with and without direct neural feedback
Develop embedded microcontroller
Use normal force derivative feedback to decrease force overshoot when compensating for slip
Use sliding mode control to improve control of velocity while opening and closing hand

23. Overall Control Scheme: Sliding Mode Slip Prevention

24. Future Work
Overall Control Scheme: Hybrid Sliding Mode Backstepping Slip Prevention

25. References
Ashok Muzumdar, Powered Upper Limb Prostheses, Berlin, Germany, Springer, 2004
G. Puchhammer, “The Tactile Slip Sensor: Integration of a Miniaturized Sensory Device on an Myoelectric Hand,” Orthopadie-Technik Quarterly, English, edition I/2000, p. 7-12
P. Kyberd, M. Evans, S. Winkel, “An Intelligent Anthropomorphic Hand With Automatic Grasp,” Robotica, Vol. 16, United Kingdom, 1998, p
C. Light, P. Chappell, B. Hudgins, and K. Englehart, “Intelligent multifunction myoelectric control of hand prostheses,” Journal of Medical Engineering & Technology, vol. 26, No. 4, July/August, 2002, p
P. Kyberd and P. Chappell, “Object Slip Prevention Using a Derived Force Vector,” Mechatronics Vol. 2, (1), Great Britain, 1992, p. 1-13
A. Mingrino, et. al., “Slippage Control In Hand Prostheses by Sensing Grasping Forces and Sliding Motion,” IEEE International Conference on Intelligent Robots and Systems, v 3, 1994, p
Y. Yamada, H. Morita, and Y. Umetani, “Slip phase isolating: impulsive signal generating vibrotactile sensor and its application to real-time object regrip control,” Robotica, vol. 18, 2000, p
A. Cranny, et. al., “Thick-film force, slip, and temperature sensors for a prosthetic hand,” Meas. Sci. Technol. vol. 16, (2005), United Kingdom, p
A. Tura, et. al., “Experimental development of a sensory control system for an upper limb myoelectric prosthesis with cosmetic covering,” Jour. Rehab. Res. Dev., vol. 35, (1), Jan, 1998, p
K. Yoshida and R. Riso, “Peripheral Nerve Recording Electrodes and Techniques,” Neuroprosthetics Theory and Practice, Vol. 2, World Scientific Publishing Co., New Jersey, p

26. References
I. Birznieks, P. Jenmalm, A. Goodwin, R. Johansson, “Encoding of Direction of Fingertip Forces by Human Tactile Afferents,” Journal of Neuroscience, October 15, 2001, p
G. Cadoret and A. Smith, “Friction, Not Texture, Dictates Grip Forces Used During Object Manipulation,” Journal of Neurophysiology, Vol. 75, No. 5, May, 1996, p
M. Burstedt, J. Flanagan, and R. Johansson, “Control of Grasp Stability in Humans Under Different Frictional Conditions During Multidigit Manipulation,” Journal of Neurophysiology, Vol. 82, November 1999, pp
I. Birznieks, M. Burstedt, B. Edin, and R. Johansson, “Mechanisms for Force Adjustments to Unpredictable Frictional Changes at Individual Digits During Two-Fingered Manipulation,” Journal of Neurophysiology, Vol. 80, October 1998, pp S. Jacobsen, D. Knutti, R. Johnson, and H. Sears, “Development of the Utah Artificial Arm,” IEEE Transactions on Biomedical Engineering, vol. 29, 1982,
D. Childress, “Powered Limb Prostheses: Their Clinical Significance,” IEEE Transactions on Biomedical Engineering, Vol. BEM-20, May, 1973, p
T. Farrell, R. Weir, C. Heckathorne, D. Childress, “The effects of static friction and backlash on extended physiological proprioception control of a powered prosthesis,” Journal of Rehabilitation Research and Development, Vol. 42, May/June, 2005, p H. Sears, J. Shaperman, “Proportional myoelectric hand control: an evaluation,” American Journal of Physical Medicine and Rehabilitation, Vol. 70 (1), p , February, 1991

27. References
G. Dillon and K. Horch, “Direct Neural Sensory Feedback and Control of a Prosthetic Arm,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol. 13, No. 4, p , 2005
E. Engeberg and S. Meek, “Improved Grasp Force Sensitivity For Prosthetic Hands Through Force Derivative Feedback,” IEEE Transactions on Biomedical Engineering, vol. 55, p , 2008
E. Engeberg, S. Meek, and M. Minor, “Hybrid Force-Velocity Sliding Mode Control of a Prosthetic Hand,” IEEE Transactions on Biomedical Engineering, to be published, Available:

28. Questions?