Prosthetic Arm Force Reducer Team 1 – Halliday's ... - Ohio University

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Table 3.0.1 – Customer Needs List Need # Need (In Order of Importance) 1 Manageable input force 2 Increased grip force 3 Serviceability 4 Reliability 5 Affordability (under $700 US) 6 Corrosion Resistance 7 Light weight (Less than 5 lbs) 8 Simplicity of operation (No electrical components) Table 3.0.2 – Needs Metric List Metric Need # Metric Importance # Units # (3 High, 1 Low) 1 1,2,8 Input force 3 lbs 2 1,2 Closing force 3 lbs 3 all Unit price 2 $ 4 3,8 Unit dimensions 1 in 5 1,2,3,4,6,8 Unit life 3 #cycles 6 7,8 Unit weight 2 lbs USpecification quantities include: 1. UInput forceU: A one-half decrease in input force is necessary. The input force to operate the prosthetic is human input: the user’s shrugs their shoulders, moving the cable. This cable is attached to the back harness and runs down the arm to the terminal device. This one-half decrease is necessary because the user has complained of nightly discomfort from using his current split-hook loaded with many rubber bands (up to 7). 2. UClosing forceU: Enough closing force must be provided for the user to hold a nail steady and nail it into a wall. The closing force must be greater than or equal to a traditional spilt hook utilizing 7 rubber bands of tension. 3. Unit priceU: A typical sized split hook prosthetic device made of stainless steel costs about $565 - 1,100 dollars. The entire mechanical advantage system will ideally cost under $700 which corresponds to bottom quarter of the price range. 4. Unit dimensionsU: Our system must fit into the user’s existing forearm prosthetic. In order to ensure safe operation, there shall be no extraneous parts attached to the forearm. 5. Unit lifeU: The unit life will be based on stainless steel being the favorable material for the mechanical advantage components because of its strength and corrosion resistant characteristics. An operating temperature range of -30 to 120˚F has also been specified, 6
which could limit the use of rubber bands. The life specified should be at least 3 years or 10,800 cycles (360 working days a year with 10 cycles per day). 6. Unit weightU: A typical split-hook terminal device plus forearm section weighs about 2 pounds. Since this project is concerned with enhancing functionality, some extra amount of weight will likely be incurred by the modifications. Our maximum weight is to stay under 5 pounds (approximately the weight of an average adult forearm and hand). The customer has added that extra weight will not act as a hindrance. The internally located mechanical advantage system will instead increase the strength of his currently hollow forearm section. 4.0 External Search The Disability Act of 1990 was monumental in creating equal opportunities for people with disabilities. Though this act has made significant progress, only 25% of people between the ages of 16 to 64 (commonly considered as the working age demographic) with disabilities are employed. Of the remaining 75%, two-thirds of them wish they were employed (Health Progress, May/June, 2000). Our research began by getting in contact with the Athens County Bureau of Vocational Rehabilitation (BVR). The BVR is a branch of the Ohio Rehabilitation Services Commission (ORSC) which is a state agency that is annually responsible for vocational rehabilitation of 55,000 Ohioan’s with disabilities. On average in a single year, the RSC aids 8,000 Ohioans with disabilities into obtaining and retaining a job. Since 1990, the agency has assisted nearly 100,000 citizens of Ohio with disabilities. The Athens County BVR provides rehabilitation services in ten counties of Ohio to individuals whose primary impairments range from physical, to emotional, and to mental. Many of their clients have orthopedic and mental health issues, and on average, there are 850 to 1,000 active customers with a variety of disabilities. Our main contact at the BVR was George Platounaris. George is the rehabilitation vocational supervisor at the BVR with over 30 years of experience. Upon meeting with him for the first time on October 10 th 2007, (see Appendix B for details) George was able to reference us to two rehabilitation design engineers who work in the field and mentioned he could be a contact point for information from those two individuals as well as help us obtain a potential customer. George extended the invitation to attend weekly meetings at BVR where feedback from industry professionals could be obtained. Contact with George lead to a phone interview (conducted later that same day) with rehabilitation industrial designer Mark Ficocelli (see Appendix B for details) who works on special projects for the BVR. Mark emphasized the fact that most of his work is done as a oneon-one interaction with a specific customer. He emphasized that each person required a different solution and that it is very difficult to create an adaptable solution. One area that he suggested we pursue is the field of prosthetic attachments, and referenced a recent case where he had worked with a farmer to create an attachment that could hold different sized wrenches. The solution to this problem resulted in the farmer with a type of hook-hand that could be pulled open by flexing the muscles of the back. Mark suggested buying burlap feed sack and 7
Page 1 and 2: Prosthetic Arm Force Reducer Team 1
Page 3 and 4: 1.0 Introduction Limb loss generall
Page 5: 2.1 Weighting of Customer Needs Wei
Page 9 and 10: design of the two load hook allows
Page 11 and 12: Fig. 4.1.6 - Utah Arm 3 MAGNUM Para
Page 13 and 14: Feature Hosmer Model 7 Work Hook Ot
Page 15 and 16: hook is closed. The harness idea is
Page 17 and 18: purchase it. Safety is another exte
Page 19 and 20: Figure 5.1.2 - Solid Edge Model of
Page 21 and 22: 5.1.4 Concept D - Upgraded Springs
Page 23 and 24: 6.0 Concept Selection 6.1 Data and
Page 25 and 26: Figure 6.1.4 - Input Force FBD The
Page 27 and 28: Since the torques of the both the r
Page 29 and 30: Once the design of the system was u
Page 31 and 32: 7.0.3 Professional/Ethical Standard
Page 33 and 34: Table 7.0.2 - Risk Priority Number
Page 35 and 36: The actual FEA testing involved uti
Page 37 and 38: Another sector that has aided in ou
Page 39 and 40: Figure 7.0.10 Cable Path for Mechan
Page 41 and 42: 7.2.1 Rings (Part #’s THH-001 [El
Page 43 and 44: 7.2.4 Collars 1) Using lathe turn o
Page 45 and 46: 7.3 Cost Analysis & Bill of Materia
Page 47 and 48: manufacturing costs are $525.00. Th
Page 49 and 50: operation necessary. This convertib
Page 51 and 52: Appendix A - Split Hook Sample Calc
Page 53 and 54: George Platounaris - Interview (12:
Page 55 and 56: Appendix C - Tim Lang’s Forearm D
Page 57 and 58:
Health Progress, “Disables Enteri
Page 59:
Drawing Package 1. THH‐001……
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