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 Caption is optional, use Arial Narrow 20pt

Commercially Available Prostheses Otto Bock’s SensorHand Motion Control Hand

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.

The Motion Control Hand: Force Measurement

Force Control

Proportional Object Slip Prevention

PD Object Slip Prevention

Adaptive Object Slip Prevention

What Adaptive Slip Prevention Does

FFT of Nonslip Events

FFT of Slip Events

Bandpass Slip Filters For Smooth Object Slip Events With Glove

7 Bandpass Filters

Bandpass Slip Filters For Smooth Object Slip Events With Glove

Test Apparatus For Slip Controllers

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

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

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

Human Experiments: Slip Prevention

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

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

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

Overall Control Scheme: Sliding Mode Slip Prevention

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

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. 531-536 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. 139-146 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 1803-1809 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. 43-49 A. Cranny, et. al., “Thick-film force, slip, and temperature sensors for a prosthetic hand,” Meas. Sci. Technol. vol. 16, (2005), United Kingdom, p. 931-941 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. 14-26 K. Yoshida and R. Riso, “Peripheral Nerve Recording Electrodes and Techniques,” Neuroprosthetics Theory and Practice, Vol. 2, World Scientific Publishing Co., New Jersey, p. 683-744

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. 8222-8237 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. 1963-1969 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. 2393-2405 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. 1989-2002 S. Jacobsen, D. Knutti, R. Johnson, and H. Sears, “Development of the Utah Artificial Arm,” IEEE Transactions on Biomedical Engineering, vol. 29, 1982, 249-269 D. Childress, “Powered Limb Prostheses: Their Clinical Significance,” IEEE Transactions on Biomedical Engineering, Vol. BEM-20, May, 1973, p. 200-207 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. 327-342 H. Sears, J. Shaperman, “Proportional myoelectric hand control: an evaluation,” American Journal of Physical Medicine and Rehabilitation, Vol. 70 (1), p. 20-28, February, 1991

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. 468-472, 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. 817-821, 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: www.ieeexplore.ieee.org

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