prosthetic tool system

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Table of ContentsProsthetic Aids

1. Defining the problem2. Co-creator3. Amputation Research4. A(x4) Research Method5. Interview - Preliminary6. Task Analysis - A morning in the life7. Precedent Research - Prostheses8. Empathy Study - Hook Trial9. Objectives of the Product - Global and Economic10. Design Criteria - Objectives11. Sketches - Concept I12. Sketches - Concept II13. Interview - ask an expert14. Visual Style Survey15. Logo and Name Concept16. Prototyping - Phase I17. Prototyping - Phase II

18. Prototyping - How it works19. Prototyping - Phase II - Tools20. User Trial - Comparison21. User Trial - Comparison22. Conceptual - Future23. Prototyping - Phase III24. Prototyping - Phase III25. Sketch and Render - Photoshop26. Sketch and Render - Options27. 3D Modeling and Rendering - Solidworks28. 3D Modeling and Rendering - Solidworks29. 3D Print Rapid Prototype - ABS Plastic30. Final Prototype - How to use31. Final Prototype - Moses with additio32. Final Prototype - additio with toolbox33. Final Prototype - Form Context

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1 Defining the problemadditio prosthetic tool system

The development of the additio prosthetic tool system came as a result of a co-creation partnership with a quadruple amputee. Observational studies and participant interviews revealed design opportunities for changes to deficiencies in the lives of split hook prosthetic users. Inefficiencies and deficiencies in standard household tools cause fatigue and ongoing muscular strain in these users. Market research revealed that other options did not exist to solve this problem for hook users.

Additio set out to solve this problem. It was tested using various subjective, objective, and performance measures obtained through a number of user trial methods. This data was invaluable in refining the tool system, revealing successes and opportunities for improvement.

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2 Co-creatorMoses

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3 Amputation ResearchMedical

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The term trans is used when an amputation goes across the axis of a long bone, such as transtibial (across the tibia of the leg) or transhumeral (across the humerus of the arm). When there are two bones together such as the tibia and fibula, the primary bone is identified. Amputations between long bones or through a joint are referred to as disarticulations and identified by the major body part, such as knee disarticulation.

Upper and lower extremity prostheses need to be comfortable, functional, and cosmetic. If the prosthesis is not comfortable, the individual will not wear it; pain or discomfort can be the greatest impediment to successful prosthetic rehabilitation. The prosthesis must also allow the individual to perform desired activities that could not be done without a prosthesis, and to do them with the lowest possible expenditure of energy.

Of paramount importance is the prosthetic component that will substitute for the missing hand. There is no device that completely replaces the appearance or function of the anatomic hand. Nevertheless, the prosthetic counterpart, called a terminal device, can contribute to the wearer’s function and self-esteem. The two types of terminal device are the hand and the hook. Either is secured to a plastic socket encasing the forearm.

The upper extremity has always posed a major challenge since the great complexity of hand function is difficult to duplicate mechanically. The loss of sensation limits the function of the hand or hook, and replacement for sensory function has not been developed.

Bella J. May, W. Rostoker, “Prosthesis,” in Access-Science, ©McGraw-Hill Education, LLC, 2012, http://www.accessscience.com

4 A(x4) Research Method Ethnographic

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ACTORS ARTIFACTS

ATMOSPHERE ACTIONS

The Vancouver Sun quotes Moses as saying that, “he remembers regretting he

would never be able to use a phone again.”

He is now making his way through chores with an

iPhone velcroed to his wrist above a prosthetic hook.

It is these types of adaptive technologies that Moses

requires more of in the future.

Video interviews with Moses assisted in outlining his

everyday life and provided insight into the type of

assistive technologies that would be helpful.

Secondary video interviews would take the form of user

feedback of prototypes that are to be developed as part

of the co-design process.

Moses is a single father and a large part of his life revolves around his son.

He says he is learning to cook again but everything takes a lot longer. Thus aids for the home would be very helpful.

Moses also plans to return to work in an office at some point and this is another area for the use of assistive technology.

This is Moses and at the age of 37, he lost his hands and feet.

He was in the hospital for almost 6 months.

At the G.F. Strong Rehabilitation Center, he had to regain his strength and learn to walk again on his prosthetic legs. He had to learn to use prosthetic hooks, although they were nothing compared to what his hands could do.

5

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InterviewPreliminary

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“80% of my disability is due to the loss of my hands.”

“I enjoy sleeping most of all because the prosthetics tire me out.”

“One dream product that does not currently exist that would make everything easier would be a brain controlled cursor.”

I have to plan everything before I attempt to do it and do a cost benefit analysis to decide whether the energy I must expend is worth the payout.

“Paper is my enemy.”

“My hooks slip on everything, some friction could make tasks easier.”

“My hooks do not work on any touch screens and there are touch screens everywhere”

6 Task AnalysisA morning in the life

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7 Precedent Research Prostheses

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Concealed

Discreet Flamboyant

Mainstream

Kinesthetic

Tactile values

Haptic Feedback

Material Qualities

“Amputees are the architects of their own identities.” Aimee Mullens, Amputee

Joy

Warmth

FriendlinessSensuality

Beauty

EasyNatural

IntuitiveUnambiguous

Resonant

Attuned

Simple

ElegantElevating

EnablingEnergizing

8 Empathy StudyHook Trial

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An afternoon was spent using a terminal hook simulator and observations were as follows:

1. Tasks became difficult2. Simple hand tools were not simple3. Some tasks were impossible4. Frustration level rose5. Decreased self-reliance6. Reduced self-esteem

9 Objectives of the ProductGlobal and Economic

For many transradial amputees, harness and cable-operated limbs are the only accessible prosthetic option. More responsive myoelectric hands are at least twice as expensive, while the cost of a neuroprosthetic arm is upward of ten times that of a split-hook system. These barriers mean that the majority of the world’s millions of arm amputees do not have access to the devices that would best facilitate their daily lives. One of the main drawbacks of the split-hook and cable prosthesis it its inability to flex tightly enough to hold small objects in a firm grip. This makes it very difficult to use vital everyday tools.

The additio system is a solution to this critical quality-of-life issue. Developed in collaboration with Moses Chan, a bilateral below-the-elbow amputee , additio consists of an adapter that attaches easily to a split-hook limb and a range of household tools, such as: •    Kitchen implements (knives, peelers, graters)•    Cleaning tools (brooms, mops, vacuums)•    Maintenance devices (hammers, paintbrushes, box-cutters)•    Personal items (Umbrellas, hair dryers, hairbrushes)

By connecting tools directly to a limb, amputees can use them without the need to grip. The additio system leverages powerful, rare-earth magnets that enable users to easily load, remove, and switch tools without twisting or bending. additio’s modular design is future-proof, as tomorrow’s innovations in hand-held tools can be incorporated into today’s system.

Best of all, additio’s durable stainless and high-density injection-molded plastic construction makes it a long-lasting, low-cost solution that is accessible even to amputees in the developing world. Through further development, the additio system will provide gripless solutions for sporting equipment such as golf clubs, hockey sticks and ski poles.

It is estimated that there are 3 million upper extremity amputees worldwide.

http://www.stanford.edu/class/engr110/2011/LeBlanc

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10 Design CriteriaObjectives

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PRIMARY OBJECTIVE:

To explore and develop objects to aid in the use of hook style terminal prosthetics.

MUST HAVE:

1. Multi-purpose2. Functionality3. User friendly4. Strong and durable

NICE TO HAVE:

1. Attractive2. Can pry objects3. Universal4. Capacitive

Objectives

PRIMARY OBJECTIVE:

To explore and develop objects to aid in the use of hook style terminal prosthetics.

MUST HAVE:

1. Multi-purpose2. Functionality3. User friendly4. Strong and durable

NICE TO HAVE:

1. Attractive2. Can pry objects3. Universal4. Hold golf clubs

11 SketchesPreliminary

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12 SketchesPreliminary

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13 InterviewAsk an expert

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An interview was conducted with owner and chief prosthetist, Tony van der Waarde, of Award Prosthetics for more information and clarification on points raised by G.F. Strong. He is also Moses’ prosthetist.

There are 7 basic hook styles, Moses uses the most common, so this is a good staring point for prototyping.

Moses’ range of accessible angles is less or equal to most hook users and having a limited number of tool connection points on additio should suffice.

I learned that plastic can be made strong enough and light enough to be used as a base material for a product like additio.

Tony was also a good source for references of other adaptive technologies for arm amputees.

As far as Tony was aware all current existing adaptive technologies connect into the wrist connection of the prosthetic socket. There is nothing currently on the market that attaches directly to split hooks.

14 Visual Style SurveySummary

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Results of visual style survey tended to lean to a more conservative style and design.

15 Logo and Name ConceptPreliminary

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Latin for addition:

It summarizes the function of the product and the emotion of the goal of life enhancement.

16 PrototypingPhase I

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Tool attachment with rare earth magnetic end and ring to allow for removal by prosthetic hook.

Soft rubber ball was used thinking that it would improve grip by the split hook prosthetic. This proved not to be the case and another method was needed.

Rare earth magnetic core was inserted into the ball to be tested as connector for tool inserts. It appeared that it would be strong enough.

17 PrototypingPhase II

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A rigid ring with holes all the way around was developed to accept prosthetic hook and tool attachments.

Based on recommendation from G.F. Strong personnel split hook can still function. In user trial co-designer was able to pick up all items normally. Putting some grip on this surface seems logical.

Round ring proved to be effective for tool removal by prosthetic hook in user trial. It will require modification because the tool tends to roll around too much on table.

18 PrototypingHow it works

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The user slides the adapter onto his hook. In user trial testing a bilateral amputee was able to complete this task.

Rare earth magnets hold the attachments in place with a holding force greater than 10 lbs.

Attachments slot in and out of the adapter at various angled slot points around the curved surface.

19 PrototypingPhase II - Tools

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A number of tools were developed in order to be tested during a user trial. The toothbrush was unsuccessful as there are a number of different angles required in this task.

Upon trial by the user it was deemed that it is simpler and more efficient just to hold a pen in the split hooks than have a tool attachment. Based on the user trial new tools would focus more on household tasks.

The knife attachment proved to be a very useful tool and helped the user complete food prep tasks that previously were nearly impossible.

20 User TrialComparison

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BEFORE

Comparison Video:

It was concluded after the trial that it was quicker and easier to use a pen that had been modified with tape than use additio.

Post Trial Interview:

The user commented that additio impeded vision of the paper and that it put the writing instrument further away from where he expects it to be. He commented that his brain still remembers where a pen in his hand would have been and his body reacts to that.

Further comment from G.F. Strong staff was “you can overcome muscle memory”.

AFTER

21 User TrialComparison

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BEFORE

Comparison Video:

It was concluded that using additio was three times faster for chopping vegetables and body angles fell more into an ergonomic neutral position. The user never had to stop chopping to adjust his grip which was often the case with using a modified knife.

Post Trial Interview:

The user commented that additio felt good and strong. He was really happy with performance of the tool and was interested in more tools like the knife for taking care of household tasks.

AFTER

NOTE: Yellow lines denote angle of shoulders in trial.

22 ConceptualFuture

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Given the strength that was noticed during the testing of additio it was discussed with the user that there may be the potential to develop the tool in a more rugged way in future iterations that may allow for the use of sports equipment in conjunction with existing split hook prosthetics.

23 PrototypingPhase III

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Adapter ring modified to be brought closer to hooks so attachment point is closer to where tool would normally be held in person with a hand.

In user trial it was determined that hook had enough degrees of rotation to angle most tools to the position they need to be in. G.F. Strong personnel added further comment that, “Moses may have access to angles that other people may not have”. Therefor five attachment slots needed.

Extractor ring to be changed to a hexagon shape. Tool attachment point changed to hexagon shape as well. This will allow for more angles of operation.

24 PrototypingPhase III

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A template was made and the backbone of additio was cut from extruded aluminum stock.

This material was chosen because it was light and non-magnetic.

This material proved to be too brittle as it fractured when bends with tight radii were applied.

Further materials research revealed that a non-magnetic stainless steel existed on the market.

This material was very strong, so much so that it wore on the tools being used.

Further research bore that factories are set up to deal specifically with stainless steel and that the part could be stamped and formed like any other metal.

25 Sketch and RenderPhotoshop

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Rigid injection molded plastic with secondary molded grip point. Has the look and feel of Swiss Army knife. Conveys reliability.

Aluminum back locks into position on existing tab in split hooks. Injection molded plastic to cover.

Nests between split hooks allowing user to pick up objects while wearing the tool adapter.

26 Sketch and RenderOptions

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A walnut body has a warm feel and has the resemblance of the handle of a chef’s knife.

A carbon fibre body looks cold and technical and is reminiscent of bicycle components.

27 3D Modeling and RenderingSolidworks

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28 3D Modeling and RenderingSolidworks

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Plus sign in original logo called reference to cross from Red Cross or first aid kit. This was removed.

29 3D Print Rapid PrototypeABS Plastic

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More household tools than 1st prototype and an exploration of grip patterns.

30 Final PrototypeHow to use

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+ =

slipping a split hook into the adapter

+

selecting the right tool for the right jobtools that require force are difficult to use

cut peel sweep open

31 Final PrototypeMoses with additio

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32 Final Prototypeadditio with toolbox

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rest for additio - positioned at properangle for user to slip onto hook

tool tray allows user to easilyattach and detach selected tools

drainage trsy allows user to wash toolsbefore stowing them away

toolbox has additional weightadded so it stays firmly on thecounter when slipping additio onand attaching tools

33 Final PrototypeForm Context

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Life within your grasp.