Mimicking the Human Hand
David French
April 24, 2013

• Prosthetic
Image Courtesy of Luke Skywalker http://www.scifi-review.net/teenager-gets-a-bionic-hand-that-luke-skywalker-would-envy.html

• Non-Prosthetic
http://www.vrealities.com/shadowhand.html

• Prosthetic
• Humanoid robots
• Variety of small-scale dexterous operations
– Working in inaccessible or hazardous environments, e.g. radiation, chemical or biological hazards, disabling IEDs
• Research
– Rehabilitation
– Ergonomics

• Doesn’t usually use inverse kin, differential kin, or trajectory generation since the joints are usually controlled in manually mode.
• Motors are sized based on desired torques/speeds, and are very constrained by physical size.
• Up to 20 DOF, multiple independent kinematic branches (e.g. fingers)

http://blogredbox.blogspot.com/2011/09/geeky-gadgetsnewsletter_22.html

• Shadow Hand
– comparable to a human hand in size and shape, and reproduces all of its DOF
– 24 joints altogether, with 20 DOF
– Not as strong as a real human hand
YouTube link

• Available in both electric motor and pneumatic muscle driven models
– 20 motors or Air Muscles
• Every joint has a Hall effect sensor for positional feedback
• Every actuator has a force/pressure sensor
• Can add third-party tactile sensors
• $100K - $250K total cost

2
3
4
1
First, Middle, Ring finger
Distal - Middle
Middle - Proximal
Proximal - Knuckle
Knuckle - Palm http://www.vrealities.com/shadowhand.html
4
5
2
3
1
Little Finger
Distal - Middle
Middle - Proximal
Proximal - Knuckle
Knuckle - Metacarpal
Metacarpal - Palm
4
5
2
3
1
Thumb
Distal - Middle
Middle - Proximal 1
Middle - Proximal 2
Proximal - Palm 1
Proximal - Palm 2
1
Wrist
2
Palm - Wrist
Wrist - Forearm

• Controlled with a 22 sensor CyberGlove

• Integration with BioTac tactile sensor
– forces
– micro-vibrations
– temperature
– estimate radius of curvature of a contacted object
– discriminate edges, corners, and flat surfaces
– detect slip
– discriminate objects based on their texture, compliance, and thermal properties

YouTube Link
• Affordable: $10K
• Mostly produced with parts found in cellphones
• Digits attach to palm using magnets
• Can replace its own fingers http://www.popsci.com/technology/article/2012-08/video-robot-hand-runs-cellphone-parts-canreplace-its-own-digits

Video Link
• Single actuator
• Equal force at all digits, regardless of configuration or shape of object
• Digits bend and twist
• Extremely durable http://www.engadget.com/2012/08/04/rethinking-the-robot-hand-at-harvard-video/

(Pit Crew Example)
Video Link http://www.nytimes.com/2013/03/30/science/making-robots-mimic-the-human-hand.html

• 16 joints, 22 actuators
• Flesh-toned silicone rubber skin cover
YouTube Link http://www.popularmechanics.com/technology/engineering/robots/6-innovative-robot-hands#slide-2

• Balloon-like sack filled with coffee grounds
• To pick, push gripper sack onto object, then apply vacuum to the sack
Video Link http://www.popularmechanics.com/technology/engineering/robots/6-innovative-robot-hands#slide-5

• Links and joints
• DC Motors / pneumatic motors or ‘muscles’
• Position sensors
• Tactile (touch) and temperature sensors
• Controllers
• Microcontroller (e.g. Arduino)
• Software framework, e.g. Robot Operating
System (ROS), which provides packages for motion, control, planning, face recognition, etc.

• Neural interfaces http://www.youtube.com/watch?v=ppILwXwsMng

• Muscle-sensing
– Example: Bebionic3 myoelectric prosthetic hand ( video link )
– Example: iLimb Pulse hand prosthesis ( video link )
• Joystick, keyboard, mouse, other controls
Bebionic3 http://www.dvice.com/archives/2012/
11/luke-skywalkers.php

• Position-sensing gloves http://robotswillstealyourjob.tumblr.com/

• Limited range of motion
• Limited strength/power
• High cost
• Manual control is often slow, if not difficult
• Must be mounted on an appropriate fixture to be useful (e.g. human stub, robotic arm).
• “Computer vision systems have worked only in highly structured environments on a very limited set of objects.” [1]
[1] http://www.nytimes.com/2013/03/30/science/making-robots-mimic-the-human-hand.html

• Build your own
‘Grasping With
Straws’ robot -
$100-$150
http://www.sciencebuddies.org/science-fairprojects/project_ideas/Robotics_p003.shtml?gclid=CNmSvp jt3rYCFQ9eQgodk1oANg

• MechaTE Robot Hand - $900

• Professional-grade commercial robotic hands
– Usually $10K or much more [2]
– DARPA pit crew hand: potentially $3,000 in quantities of 1,000 or more [2]
– $10K for Sandia Hand
– $100K - $250K for Shadow Hand
[2] http://www.nytimes.com/2013/03/30/science/making-robots-mimic-the-human-hand.html

• Prosthetic
• Humanoid robots
• Variety of small-scale dexterous operations
– Working in inaccessible or hazardous environments, e.g. radiation, chemical or biological hazards, disabling IEDs

• Shadow Air Muscles
– Lightweight
(10 g and up)
– Little stiction
– Flexible
•work when twisted axially or bent around corners
– High power to weight ratio

• Improved control interfaces, especially neural interfaces
• Accuracy in mimicking the human hand
• Dexterity
• Modular designs
• Durable designs
• Greater strength-to-weight ratios
• Lower cost designs

• Prosthetics
• Rehabilitation
• Future humanoid robot applications
• Hazardous/dexterous operations
• Ergonomics

http://www.123rf.com