IEEE International Conference On Rehabilitation Robotics Rehab Week Zurich, ETH Zurich Science City, Switzerland

By

JOSEPH T. BELTER AND AARON M. DOLLAR

Presented byA.C.K. Priyankara100414A

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ANTHROPOMORPHIC PROSTHESES

“suggesting human characteristics for animals or inanimate things”

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SPECIFICATIONS OF CURRENT HANDS

• PHYSICAL PROPERTIES

• HAND WEIGHT

• HAND SIZE

• DURABILITY/ CYCLE OF USE

• ACTUATION PROPERTIES

• ACTUATION TYPES

• GRIP FORCE

• GRASP SPEED

• KINEMATIC PROPERTIES

• ACHIEVABLE GRASP

• JOINT COUPLING METHOD

• THUMB DESIGN

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HAND WEIGHT

• AVERAGE HUMAN HAND WEIGHT AROUND 400G

• 79% OF USERS CONSIDERED THEIR DEVICE IS TOO HEAVY

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• RANGE OF 113-615 GRAMS IS SEEN IN CURRENT COMMERCIAL PROSTHETICS

• 350 TO 2200 GRAMS IN RESEARCH BASED HANDS

HAND SIZE

• LENGTH BETWEEN 180-198 MM

• WIDTH OF 75-90 MM

• COSMETIC APPEARANCE

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Type Overall Size Weight

Hosmer hand 124mm long 113-312g

SensorHand - 350-500g

Becker Hand 143mm long 382-467g

i-Limb 180-182mm/80-75mm/35-41mm

450-615g

Bebionic 198mm/90mm 495-539g

DURABILITY/ CYCLE OF USE

• REQUIRED ACTIVE TIME IS HIGHER THAN 8 HOURS A DAY

• 2500-3000 GRASPING MOTIONS OF THE NATURAL DOMINANT HAND

• TYPICAL PROSTHETIC HAND WILL UNDERGO 1200 CYCLES PER DAY

• LIFETIME OF PROSTHETIC HAND 300, 000 CYCLES

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• DC MOTORS

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ACTUATION TYPES

GRIP FORCE

• GRASP FORCES DEPENDING ON THE SIZE OF

THE OBJECT

• HUMAN HAND CAN EXERT AN AVERAGE OF

95.6 N OF FORCE IN PRECISION GRASP

• THE FORCES CAN REACH UP TO 400 N IN

POWER GRASP

• MINIMUM GRIP FORCE OF 45 N FOR

PROSTHETIC HANDS FOR PRACTICAL USE

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GRASP SPEED

• 100% OF FEMALES, 76% OF MALES, AND 50% OF CHILDREN STATED RESPONSE

TIME IS TOO LOW

• MAXIMUM FLEXION SPEED OF HUMAN HAND IS 2290 DEGREES/SEC

• AVERAGE HUMAN HAND SPEED IS 172 TO 200 DEGREES/SEC

• ONE SECOND CLOSING TIME IS ADEQUATE FOR PROSTHETIC ARM

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ACHIEVABLE GRASP

• TYPICAL DAILY ACTIVITIES FOR AN AMPUTEE CAN BE ACCOMPLISHED USING A FINITE

SET OF PREDEFINED GRASPS

• 35% OF POWER

• 30% OF PRECISION

• 20% OF LATERAL

• 15% OF OTHER (HOOK, TRIPOD, FINGERPOINT, AND GESTURING)

• MOVEMENT OF THE THUMB CIRCUMDUCTION AXIS TO ACCOMPLISH FIVE OF THE

SEVEN COMMON GRASP PATTERNS

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JOINT COUPLING METHOD

• NUMEROUS JOINTS WILL BE COUPLED TO ACT AS A SINGLE COMPOUND MOTION

• UNDER ACTUATION

• ADAPTIVE FINGER DESIGNS

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THUMB DESIGN

• THE THUMB ACCOUNTS FOR UP TO 40% OF THE ENTIRE FUNCTIONALITY OF THE

HUMAN HAND

• THE THUMB IS ACTUATED IN FLEXION/EXTENSION AND ALONG THE

CIRCUMDUCTION AXIS

• AVERAGE CIRCUMDUCTION MOTION IS 90.2 DEGREES

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THANK YOU

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