Download - The Advanced Prosthetic Hand Project Jessica Reddy, IMSURE Fellow Mentor: Dr. William C. Tang
The Advanced Prosthetic Hand Project
Jessica Reddy, IMSURE Fellow
Mentor: Dr. William C. Tang
Jessica’s Journey…• Hurdles:
1. Bio-major’ness• I know how a muscle works, but an artificial muscle?
2. Purchasing FEMLAB3. Where do I begin?
• Solutions:1. Read, read, and read.2. Solved.
3. Grad Student! (Shawn)
Current Artificial Limb Technology
• Myoelectric Prostheses– Electrode in prosthesis
socket detects EMG signals from residual muscle remnant
– Prosthetic Hook• Thumb-index finger pinch
Sgt. Joseph Bozik
Walter Reed Medical Center
Proposed Advancements
• Implantation of Neural Prosthetic into:– Brachial Plexus nerve (short term goal)– Cortical brain area (long term goal)
• Multiple sites
• Develop a prosthetic hand with multiple degrees of freedom– Use skeletal model of human hand for frame– Tactile sensing– Low weight, low energy consumption
Pneumatic Artificial Muscle
• Contractile and linear motion engine operated by gas pressure
• Flexible closed membrane attached at both ends to fittings
• Mechanical power is transferred to a load
Course of action:
•As contraction , volume to max force to 0 & contraction max
Pneumatic Artificial Muscle
Characterization of the Optimal Artificial Muscle
Generated force depends on…
• Type of membrane – Geometry– The way it inflates
• Length
• Gauge pressure
Braided Muscles• Gas-tight elastic tube surrounded by a braided
shell • Braid fibers run helically about the muscle’s
longitudinal axis at an angle • When pressurized the tube presses laterally
against the shell
Mckibben Artificial Muscle
• Muscle contracts axially
– (With lateral expansion)
• Causes pulling force on its load
Drawbacks:1. Friction between braid and tube
• Hysteresis
2. Requires complex control algorithm3. Deformation of rubber tube4. Pressure Threshold5. Flaws in membrane material6. Maximum displacement is limited.
• 20-30% contraction
7. Low force output• 650 N (rest); 300 N (15% contraction); 0 N (30%
contraction)– Applied pressure: 300 kPa, length=15 cm; rest diameter=1.4cm
Mckibben Artificial Muscle
1. Avoid friction: use a single layer actuator
2. Therefore, simplifying the control
3. Avoid deformation: use membrane material with high tensile stiffness
4. No pressure threshold: use elastic membrane material
Building a more suitable design…
Building a more suitable design…
• Want little stress in lateral direction to minimize elastic deformation (strain)
• How to achieve lateral expansion with a high tensile stiffness material?
• Rotationally repeated pattern
Pleats
Pleated Pneumatic Artificial Muscle
• Pack membrane into many folds along axis of muscle
• Maximum displacement: 40-50% • Force output:
– 3,300 N at 5% contraction; 1,300 N at 20% contraction; 0 N at 43% contraction
Applied pressure: 300 kPa, length=10 cm, diameter=2.5 cm
With these considerations in mind, let’s build a model!
Kevlar 49:
• High tensile strength
• High elastic modulus
• Low density
Y-Displacement Throughout Cross section
X-Displacement Throughout Cross section
Upcoming endeavors…
• Introduce pleats
• Represent other layers of muscle– Polyproylene lining
• Extend model to 3D– Include End Fittings
• Miniaturization of the Artificial Muscle
UCI Subsystem Development Team Members
Artificial Muscle
• William C. Tang (Team Lead), Professor, Biomedical Engineering Department, Electrical Engineering & Computer Science Department
– Ryan Langan, UROP SURP Fellowship
Neural Interface
• William E. Bunney, Distinguished Professor & Co-Chair, Department of Psychiatry & Human Behavior
• James H. Fallon, Professor, Department of Anatomy and Neurobiology
Communications
• Payam Heydari, Assistant Professor, Department of Electrical Engineering & Computer Science
Tactile Sensor
• Abraham P. Lee, Professor, Biomedical Engineering Department, Mechanical & Aerospace Engineering Department
Interface and Algorithm
• Zoran Nenadić, Assistant Professor, Biomedical Engineering Department
Pending DARPA Award.Pending DARPA Award.
Please visit our website:www.advancedprosthetichand.com
Webmaster: Ryan LanganDr. William C. Tang