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Prosthesis Design and Control Introduction Fall 2014.

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Presentation on theme: "Prosthesis Design and Control Introduction Fall 2014."— Presentation transcript:

1 Prosthesis Design and Control Introduction Fall 2014

2 Earliest amputation recorded by Herodotus, Greek historian, 480 BC Persian soldier Hegesistratus arrested by Spartans, facing torture and execution, one foot in stocks, cut off foot to escape, later obtained a prosthetic (wooden) foot 2 Stump, or residual limb

3 Disarticulation: Amputation between bone surfaces 3 2% 33% 1% 54% 3% Upper limb amputations: 7%

4 Causes of amputation Accident – 23% Disease or infection – 74% – Cancer – 2% – Vascular (circulatory) – 54% Diabetes – 70% – Tripled between 1980 and 2005 – Diabetic survival rate is improving – 1/3 of adults diabetic by 2050 Birth defect – 3% Paralysis – less than 1% 4

5 As of 2014: 2 million people with limb loss in the United States 185,000 amputations in the United States each year In 2009, hospital costs associated with amputation totaled more than $8.3 billion African‐Americans are four times more likely to have an amputation than white Americans Nearly half of those who have an amputation due to vascular disease die within 5 years Diabetics who have a leg amputation have a 55% of a second amputation within 3 years 5

6 Amputations by age Below 10 years old: 3% years old: 7% years old: 7% years old: 7% years old: 9% years old: 18% years old: 28% years old: 17% Over 80 years old: 4% A Primer on Limb Prosthetics, p. 9 6

7 7 Corset-style interface, pre-1960s rehab-prosthortho-pictures/deck/ Patellar-tendon-bearing socket, introduced in the 1960s

8 8 Silesian bandage (Silesia is a region in Poland) Total elastic suspension belt Pelvic belt Museum/Surgery/orthopedics/ Limb-prostheses

9 Socket Knee Shank Ankle Foot 9 Mechanical interfaces between leg components are standard, which provides a “plug and play” prosthesis. Socket interfaces Liner / lock – low activity Suction – medium activity Vacuum – high activity

10 Gait Cycle: 2 steps = 1 stride 10 Heel strike 12%50%

11 Lower limb amputee activity levels Level 0 – Does not have the ability or potential to ambulate safely and a prosthesis does not enhance their quality of life or mobility. Level 1 – The ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed pace. This prosthesis is typical for the household ambulator. Level 2 – The ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces. This prosthesis is typical for the limited community ambulator. Level 3 – The ability or potential for ambulation with variable pace, with the ability to traverse most environmental barriers while participating in activities of daily living that require prosthetic use beyond simple locomotion. Level 4 – The ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels. This prosthesis is typical of the child or active adult functioning in the community. 11

12 Prosthetic Feet More than 50 models available today Some design for special activities Feet with no hinged parts: Low activity level 12 and-services/feet/low-activity/sach Solid ankle cushioned heel (SACH) Elastic keel: more flexible

13 13 solutions/products/feet/feet/flex- foot-assure Flex foot Oscar Pistorius, 2012 South African Olympic sprinter

14 Articulated Prosthetic Feet 14 instep/feet.html iWalk product BiOM Hugh Herr’s company Google “Hugh Herr TED”

15 15 Odyssey – motorized 1 KHz control JackSpring – motorized Thomas Sugar, Professor Arizona State University

16 Prosthetic Knees More than 100 models available Single axis or polyaxial Passive: no electronics – Mechanical friction Constant Variable – Hydraulic – Pneumatic Active: motor control Semi-active: computer control but no motors Ottobock, Ossur, Trulife, Freedom Innovations, Endolite (Dayton, Ohio), … 16 medi OHP3/KHP3

17 Mauch SNS (swing and stance) – Ossur – Passive – Hydraulic – $5, Hans Adolph Mauch ( ) German engineer until the end of WW II Jet engine and prosthesis development in Germany Moved to USA in 1945

18 18 C-Leg – Ottobock – Semi-active – Hydraulic – Introduced in 1997 – First microprocessor leg – $50,000 retail Otto Bock, German prosthetist

19 Rheo Knee Ossur Semi-active Hydraulic Introduced in 2005 $17, Magnetorheological fluid has viscosity that depends on the surrounding magnetic field

20 Plie Knee Freedom Innovations Semi-active: 100 Hz Hydraulic 20

21 21 Image: National Institute of Biomedical Imaging and Bioengineering F. Sup et al., “Self-Contained Powered Knee and Ankle Prosthesis” Vanderbilt Leg (aka bionic leg, or Goldfarb leg) Freedom Innovations Integrated knee and ankle motors Currently in testing Controller gain scheduling depending on “walking phase”

22 22 Power Knee Ossur First active transfemoral prosthesis Introduced in 2009 $60,000

23 Increase in energy consumption Amputee with walker or crutches – 65% Below-knee unilateral amputee – 15% Below-knee bilateral amputee – 30% Above-knee unilateral amputee – 65% – Three times normal hip power on amputated side Above-knee bilateral amputee – 200% “Microprocessor Prosthetic Knees,” by D. Berry “Self-contained power knee and ankle prosthesis,” by F. Sup et al. 23

24 Coordinate system 24 Direction of walking Z Y, right to left X Knee angle (positive) Thigh angle (positive as shown)

25 Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic) 25 Able-Bodied Gait Data FlexionExtensionFlexionExtension Heel Strike Toe Off Stance PhaseSwing Phase

26 26 Able-Bodied Gait Data Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic) kg subject Positive: Power Generated by the Joint Negative: Power Absorbed by the Joint Does not match published data well

27 27 Discriminating age and disability effects in locomotion: neuromuscular adaptations in musculoskeletal pathology, by Chris A. McGibbon and David E. Krebs Toe Off “Energy generation and absorption at the ankle and knee during fast, natural, and slow cadences,” by D. Winter, 1983 Figure 3 and Table 1 Able-Bodied Gait Data Power = Torque * (Angular Velocity) Normal walking speed steps/minute (52.2 strides/minute) Ankle work = – = 17.8 J Knee work = – – 9.6 – 8.4 = –20.6 J The ankle requires energy The knee absorbs energy The net work done by the knee/angle combination is negative

28 28 Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg ® and Mauch SNS ® prosthetic knees, by Ava D. Segal et al. Prosthetic Limb C-leg: solid line Mauch leg: dashed line Control group: dotted line 1.More hip power required for amputees 2.No stance knee flexion in prostheses 3.More negative knee power in prostheses 4.No ankle push-off with prostheses

29 29 Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg ® and Mauch SNS ® prosthetic knees, by Ava D. Segal et al. Intact Limb C-leg users: solid line Mauch leg users: dashed line Control group: dotted line 1.Limping (shorter steps) by amputees 2.More hip power in amputees 3.More ankle push-off by amputees ancillary health issues

30 Prosthetics Research at CSU Fall 2009 – Davis and van den Bogert (CC) contact Simon about hydraulic prosthesis control Spring 2010 – CC provides funding to CSU Summer 2010 – Davis leaves CC for Austen BioInnovation Fall 2010 – van den Bogert leaves CC for self-employment Fall 2011 –Richter begins design of hip robot Spring 2012 – Richter completes hip robot Fall 2012 – CC project concludes Fall 2012 – van den Bogert moves to CSU Summer 2013 – Wright Center funds CSU for 1 year Fall 2013 – NSF funds CSU for 4 years 30

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