Pediatric Prosthetic Arm

Group 17Nabeel Chowdhury, Seul Ah Kim, Dah Som Kim

• Children need a prosthesis from an early age to develop motor skills and so that a device will integrate into their social identity

• Currently the market is saturated with upper limb prosthetics aimed at adults.

• The majority of prosthetics that children have access to have little functionality

The Need

• We aim to make an affirdable lightweight, durable, and waterproof myoelectric transradial prosthetic actuated by a mckibben air muscle.

• This project aims to deliver a proof of concept of the air muscle

Scope

Design Specifications

Overview of design-Air Muscle Diagram

• Mckibben, the inventor of the muscle, used this as an orthotic allowing for a pinch grip

• The shadow arm uses air muscles to make a highly dexterous hand

• Vanderbilt used pneumatics to make a fully gas powered trans-humeral prosthetic

Feasibility-use of pneumatics

http://edge.rit.edu/edge/P14253/public/Additional%20research/Shadow%20hand%20HQ/shadow_robot_company_hand_c5_claw_back.jpg

• Our batteries have a capacity of 180mAh and the average consumption is 150mA.

• Assuming average current consumption is 10% maximum and 90% rest,

• This is much lower than our specifications and means we will either need a larger battery or a method that uses less power.

Feasibility-Battery Life

• Design specification ME03: total weight of the prosthetic arm should not exceed 2.5 kg.

• Total weight = weights of the casing and internal components. • The casing, which includes hand, lower arm, and socket, weighs

212.5g in total. • The internal components, including solenoid valve, wires, microchips,

air muscle, and metal adaptors weighs 489.92g in total.

• Note that human hand weighs about 400g, and our hand weighs less than 212.5g.

Feasibility-Weight

• The prosthetic exhibited ability to contract farther with greater weights.

• This appears to be a distinct characteristic of air muscles which is similar to the way a real muscle would behave

• The amount of mass the air muscle could pull is well above our specification.

Feasibility-Strength

Specifics-Casing

Specifics-Hand

Specifics of design-Circuit Diagram

Specifics of design-Program Flowchart

Specifics of design-Solenoid

http://www.solenoidsolutionsinc.com/images/threeWay.gif

Specifics-Air Muscle

• The prosthetic can pull a large amount of mass meaning it has a large grip force

• The parts of the device are easy to remove and exchange

• The device is water resistant in heavy rain

Conclusion-Successes

• The device is heavier than the previous version

• The device is not fully waterproof

• The socket will come off after a drop, but the device doesn’t break pro and a con

• The adaptor with all of the brass fittings was too long to fit inside the device, but it would fit if the patient grew.

Conclusion-Failures

• Custom machining the brass fittings out of aluminum• reduces weight and length

• Smaller/Refillable CO2• Internal Charging for batteries• Using a servo valve

• reduces weight, size, and power consumption• Using a pressure regulator

• eliminates the need for a needle valve• Brushing on epoxy to the surface of the 3D print or sealing the casing with a stronger rubber than hot

glue.• seals all of the layers of the print

• Using inductive charging• the qi standard allows for a universal charger and it is waterproof

• Using solar power to keep the battery alive longer

Future Directions

Budget

Design Specifications

Questions?

Prototype Demonstrations-Video

Prototype Demonstration-Length Change

Prototype Demonstration-Casing and Wrist