BIOMECHANICS-Hand Prostheses
By: John Poidevin
2
Overview
• Hands• History of Prostheses• Current Developments• Need and Requirements• Foreseeable Future• Questions
3
What are concidered Hands
• Appendages connected to the forearm
• Identifiable by opposible thumbs
• Only found in mammalian order of primates– Humans– Apes and Monkeys
4
Importance of Hands
• Primary organ for physical interaction
• Dense collection of nerve endings
• Dominate area for pressure perception
• Controled by opposite side of the brain
5
Make up of the Hand
• Bones– 8 Carpus– 5 Metacarpus– 14 Phalanges
• Distal• Middle• Proximal
6
Make up of the Hand
• 27 Degrees Of Freedom (D.O.F)– 21 in fingers and thumb
• 4 for fingers• 5 for thumb
– 6 in wrist
7
Control nerves
• Extrinsic control nerves– Radial– Deep redial– Ulnar– Median
• Intrinsic control nerves– Median– Ulnar
8
Make up of the Hand
• Muscles– Extrinsic
• Flexor– Superficial anterior (4)– Deep anterior (2)
• Extensor– Superficial Posterior (5)– Deep Posterior (4)
– Intrinsic• Thenar (4)• Hypothenar (3)• Intermediate (3)
9
History
• Originally made of leather and wood
• Roman General had a iron hand• Hook “hands”• German Knight Gotz Von
Berlichingen - “Robin Hood”
10
Advancements in History
• 1500’s Ambroise Pare - “father of prosthetics”– Artificial joint
• Improved Medicine– Drugs and anesthesia
• Wars– Civil War– WWI– WWII
11
Current hand prosthetics
• Mechanical– Cineplasty– Body-powered
• Advantages– Decent Feedback – Durable– Cheaper– Weight
• Disadvantages– Uncomfortable– Restrictive– Appearance
12
Current hand prosthetics
• Electrical – Prosthetic Control by an EEG-
based Brain-Computer Interface– Myoelectric prostheses
• Advantages– Functionality– Appearance
• Disadvantages– Price– Weight– Recharge
13
Prosthetic users preference
• Survey results– Increase of functionality
• Hand grasps• D.O.F
– Reduced weight– Better cosmetic appearance– Tactile feedback system
• Sensory feedback
14
Common hand grasps
• Cylindrical Grasp• Precision grasp• Lateral grasp
15
Importance of touch
16
Hydraulic Hand Prostheses
• Flexible fingers• Fluidic actuators• Light weight frame• Microvalves• Micropump• Reservoir
• Controller / Interface
17
Hydraulic Hand Prostheses
• Low power – Increased surface area – Oil fluidic actuators
• Light weight – External Gear pumps– Center of gravity
• Moveable thumb– 3 D.O.F
• Multiple hand grip
18
Hydraulic Hand Prostheses
• Most used Hand grasps– Cylindrical Grasp– Precision grasp– Lateral grasp– Hook grasp– Index position
• 6 microvalves– 6 D.O.F
19
Hydraulic Hand Prostheses
• Advantages– Increase in functionality– Reduced weight– Better cosmetic apperance
• Disadvantages– Control issues– Not for hard work– Leakage of hydraulic fluid
20
Mechanomyography
• Mechanomyography (MMG)– Low frequency sound (5-50 Hz)
vibration produced by contracting muscles
– Mimics 2-site electromyograph(EMG)
• Non specific• Lacks skin impedance• Cheaper
21
Mechanomyography
• Soft Silicone Socket– Embedded array of sensors
• Hard Socket– Battery pack
• EMG Emulator board– Reduced cost
• Otto-Bock
22
Mechanomyography
• Trial run– Two participants– Three 30min visits
• Soft Silicon• Hard socket• Training
– Success• Relative to previous prosthetic• 88% and 71%
23
Mechanomyography
• Advantages– Emulated electromyograph– Potential of multiple control– Heightened sensitivity
• Disadvantages– Extrinsic frequencies perceived– Lack of response under force– Use of emulator
24
Direct Neural Feedback
• Need for referred sensations of touch and joint movement– Appropriate, discrete and graded
• Avoiding– whole never stimulation– Unrelated motion control
• Phantom hand– 80 % of amputees
25
Direct Neural Feedback
• Solution– Peripheral nerve stump interface– Platinum-iridium wire
• Teflon insulate (30 cm long)– Planted in Medial nerve
• Fascicle • 1mm stimulus zone
– Amplified and listened to– Computer interface– Robotic hand control
26
Direct Neural Feedback
• Future testing– Tactile and proprioceptive
• Strain gauge• Flexion/Extention
– Grip control and elbow position• Match forces• Match angles
– No visual assistance• Next would be Closed Loop
27
Conclusion
• Hand Prosthetic – Come a long way– May new advancements
• D.O.F.• Control• Feedback
– Problems• Not a high need• Funding
28
Questions?
www.geocites.com/kwenndb/prostheticluke 09 April 2004
29
References
• Wu, Ying. Lin, John. Huang, Thomas S. “Analyzing and capturing articulated hand motion in image sequences.”,IEEE Trans Pattern Anal Mach Intell. 2005 Dec;27(12):1910-22.
• Kulley, Marlowe “Hand Prosthetics” April 28, 2003 http://biomed.brown.edu/Courses/BI108/BI108_2003_Groups/Hand_Prosthetics/index.html
• Langan, Ryan “Advanced Prostetic Hand Project” 2006, http://www.advancedprosthetichand.com/4436.html
• Wikipedia, Hand“”10 October 2006, en.wikipedia.org/wiki/Hand
• Guger, Christoph, Harkam, Werner, Hertnaes, Carin, Pfurtscheller, Gert “Prosthetic Control by an EEG-based Brain-Computer Interface (BCI)” viewed 2006 www.gtec.at/research/Publications/aaate.pdf
• Dhillon, Gurpreet Singh. Horch, Kenneth W. “Direct Neural Sensory Feedback and Control of a Prosthetic Arm” IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol, 13,No. 4, December 2005
• Pylatiuk, Christian. Schulz, Stefan. Kargov, Artem. Bretthauer, Georg “Two Multiarticulated Hydraulic Hand Prostheses”Artificial Organs 28(11):980-86, Blackwell Publishing, Inc.
• Silva, Jorge. Heim, Winfried. Chau, Tom. “Self-Contained Mechanomyography -Driven Externally Powered Prosthesis”Arch Phys Med Rehabil 2005;86:2066-70
Top Related