Robotic Hands Mimicking the Human Hand April 24, 2013 David French

Types Prosthetic Image Courtesy of Luke Skywalker

Types Non-Prosthetic

Applications 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

How It Relates to Our Course 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)

Examples newsletter_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

Shadow Hand 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

Shadow Hand First, Middle, Ring finger 1Distal - Middle 2Middle - Proximal 3Proximal - Knuckle 4Knuckle - Palm Little Finger 1Distal - Middle 2Middle - Proximal 3Proximal - Knuckle 4Knuckle - Metacarpal 5Metacarpal - Palm Thumb 1Distal - Middle 2Middle - Proximal 1 3Middle - Proximal 2 4Proximal - Palm 1 5Proximal - Palm 2 Wrist 1Palm - Wrist 2Wrist - Forearm

Shadow Hand Controlled with a 22 sensor CyberGlove

Shadow Hand 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

Sandia Hand replace-its-own-digits YouTube Link Affordable: $10K Mostly produced with parts found in cellphones Digits attach to palm using magnets Can replace its own fingers

Stanford Hand Single actuator Equal force at all digits, regardless of configuration or shape of object Digits bend and twist Extremely durable Video Link

DARPA Hand (Pit Crew Example) Video Link

SQUSE 16 joints, 22 actuators Flesh-toned silicone rubber skin cover YouTube Link

Universal Gripper Balloon-like sack filled with coffee grounds To pick, push gripper sack onto object, then apply vacuum to the sack Video Link

Equipment 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.

Controls Neural interfaces

Controls Muscle-sensing –Example: Bebionic3 myoelectric prosthetic hand (video link)video link –Example: iLimb Pulse hand prosthesis (video link)video link Joystick, keyboard, mouse, other controls Bebionic3 11/luke-skywalkers.php

Controls Position-sensing gloves

Limitations 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]

Costs Build your own ‘Grasping With Straws’ robot - $100-$150 projects/project_ideas/Robotics_p003.shtml?gclid=CNmSvp jt3rYCFQ9eQgodk1oANg

Costs MechaTE Robot Hand - $900

Costs 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]

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

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

Technical Advancements 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

Industries Impacted Prosthetics Rehabilitation Future humanoid robot applications Hazardous/dexterous operations Ergonomics

Questions?