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A Six Degree of Freedom Open Source Hand for Evaluating Myoelectric Control. Nili E. Krausz 1,2 , Ron A.L. Rorrer 1 , and Richard F. ff. Weir 3 1 Dept. of Biomedical Engineering, Northwestern University 2 Dept. of Mechanical Engineering, University of Colorado Denver
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A Six Degree of Freedom Open Source Hand for Evaluating Myoelectric Control Nili E. Krausz 1,2 , Ron A.L. Rorrer 1, and Richard F. ff. Weir 3 1Dept. of Biomedical Engineering, Northwestern University 2Dept. of Mechanical Engineering, University of Colorado Denver 3Dept. of Bioengineering, University of Colorado Denver
Objective Design and fabricate an inexpensive rapid prototype hand that could be used to test and validate the effectiveness of control and intent recognition methods using a physical prosthesis, rather than a virtual hand.
Goals • Standard prehensile patterns • Independent fingers and thumb • Total cost less than $2000 • Anthropomorphic size and weight • Open source
Design Gen. 3 Gen. 2 Gen. 1
Finger Design Finger Motor Proximal Finger Shell Distal Finger Shell Proximal shaft Middle shaft Distal shaft • Each finger utilizes a 1724 Faulhaber motor, and after gearing this yields 56 N grip force at the fingertips.
Thumb Design Flex/Extension motor Rotation axis • Flex/extension uses a 1516 Faulhaber motor, and this is equal to 4.5 N at the tip of the thumb. • Rotation 1016 motor yields 0.23 N-m of torque for the thumb rotation. Thumb Base Thumb Shell Flex/Extension shaft
Prehension Postures Palmar Prehension Tip Prehension Lateral Prehension
Anthropometrics 99th percentile male 50th percentile male 50th percentile female 1 cm 1 cm Hand Thickness (metacarpals) 2.4 cm Hand Height 20 cm Hand Circumference (metacarpals) 22 cm Hand Breadth 10 cm Hand Thickness (thenar pad) 6 cm Wrist Breadth 5 cm Wrist Circumference 14.7 cm
Prototype • Total cost is $2200. • High torque motors and gearheads are $1680. • Prototype weighs 584 g • 50th percentile male hand • All CAD files and relevant details will be uploaded to www.opensourcehand.wordpress.com
Conclusions Designed and fabricated a 6 DOF rapid prototyped hand that: • Can produce standard prehensile patterns. • Has independently actuated fingers and thumb. • Is inexpensive, with total cost of $2200. • Is within the size and weight of anatomical hands. • Is open source.
Future Work • Hand Improvements: • Decrease the overall size and weight of the hand. • Increase strength of the thumb flexion/extension mechanism. • Consider metal fabrication for improved durability. • Development of open source control hardware and software for controls testing. • Mechanical tests to compare the hand to other multi-DOF hands.
Acknowledgements UC Denver Center for Faculty Development Denver VMAC- VA Eastern Colorado Health Care System NSF GK-12 Transforming Experiences Grant UC Denver Dept. of Mechanical Engineering Northwestern University Graduate Travel Grant UC Denver CEAS Machine Shop Biomechatronics Development Laboratory Children’s Hospital Colorado Center for Bionic Medicine
Questions?? All CAD files, part numbers, fabrication and assembly instructions, and other information regarding the hand will be uploaded and freely shared at www.opensourcehand.wordpress.com