UNIVERSAL MODEL DEVELOPMENT OF THE HUMAN ANKLE FOOT REGION

FOR PLY PATTERN GENERATION TO BE USED IN THE

MANUFACTURING OF PASSIVE DYNAMIC ANKLE FOOT ORTHOTICS

Senior Thesis Defense for Francis J. Fish

What are CompositesComposite are comprised of two or more separate materials that, when combined, lead to improved

properties over the individual contributors.

Why Use CompositesComposites have high strength to weight ratio, which far outperforms traditional materials.

Computer Aided Design Background• The utilization of computer systems to aid in the

analysis, development, modification, and optimization for design

• Software• AutoCAD• CATIA• Creo• Pro-E• SolidWorks

Current AFOsAnkle-foot orthoses (AFOs) are externally applied medical devices

• Restore functionality to the lower extremity• Limit range of motion• Reduce pain during gait cycle

Current ApproachesThermoplastic Forming

• Quickest/cheapest approach• Limited design/tunability

3D Printing• Requires full digitization of subject geometry• Questionable fatigue performance

Thermosetting Composite• Requires experienced orthotist to prescribe• Very labor intensive• Custom parts require unique tool for each part

Create Orthotic ProgramDARPA Open Manufacturing Program

• Develop a novel, rapid manufacturing process for composite AFOs

• Improve performance• Reduce production times

Previous Attempt

Tool surface made of spring steel sheetsAttached at various points to push-pull Bowden cablesCables attached to linear actuators outside ovenLabVIEW script controls linear displacements

Control Cables

OvenLinear Actuators and LabVIEW GUI

System Methodology

PRODUCTION DRAWINGS

DXF files of the flat patterns are generated to be sent for

manufacturing

PATIENT DATAWeight, Height,

Disability %(ankle stiffness)

GEOMTERICAL DATAFoot length,

Foot breadth, Knee height

AFO DESIGNSelected concept with side bands

to Manufacturing

AFO REQUIREMENTSSegment-wise specifications for each of

the three directions obtained through orthotist recommendation

Selected Ply Stack

9

FOOT SIZINGBased on actual foot

dimensions, an appropriate size is picked from the bin of

foot lengths and breadths

PLY LOOKUP TABLE

From a set of pre-populated size-based solutions, appropriate

solution set is picked up after necessary

modifications

DEVICE SPECIFICATIONSSegment-wise specifications

control

Orthotic Production Method

Retrieve binned Plies

Manufacturing

Curing Station

Edge Trim, Padding Addition Station

Casting Station

Ply Sequence Generation

Station

Model Development1. Anthropometric Data2. CATIA Ergonomics Package3. MakeHuman4. Customized Set

Fitting Scaling

Anthropometric Data

The subject’s foot length and width are measured as well as the subject’s height.The height will is used estimate the size of MakeHuman model.The foot dimensions are used for selecting the proper size foot model based on military shoe size.

CATIA Ergonomics Package

Part of the CATIA Ergonomics Package. Creates a part files

By selecting: Gender Population Percentile

Can control the foot dimensions

MakeHumanOpen Source softwareGenerates full body .stl

renderings Fast and user friendly

By selecting: Gender Age Height Ethnicity

Can control the foot dimensionsOnce weight reaches a normal

thresh-hold it no longer affects the foot dimensions

Selection

Variable Control• Attributes

• Height – Found to the main contributor to foot size• Ethnicity – Secondary contributor • Age – Held constant at 25• Weight – Found not to be a variable

22 24 26 28 30 328

8.59

9.510

10.511

11.512

12.5

Foot Breadth Horizontal vs Foot Length

ANSURMakeHuman_CaucasianMakeHuman_African

Foot Length (cm)

Foot

Bre

adth

Hor

izon

tal (

cm)

Fitting model to Data Set

Because MakeHuman creates the model based on overall height, it is reasonable to compare the height to the measured foot dimensions. From the different ethnic parameters a modeling set was established to fit the ANSUR data.

1581631681731781831881931988

9

10

11

12

Foot Breadth Horizontal

Foot Breadth Horizon-tal CaucasianFoot Breadth Horizon-tal ANSURFoot Breadth African

Height (cm)

Bre

adth

(cm

)

158 163 168 173 178 183 188 19322

24

26

28

30

32

Foot Length

Foot Length CaucasianFoot Length ANSURFoot Length African

Height (cm)

Foot

Len

gth

(cm

)

Creating a Custom Model SetIn order to get the most precise representation of the ANSUR data from the model set the ethnic divisions were spliced together.

Shoe Size Height (in) Foot Length (in)

Foot Breadth Horizontal (in)

Heel Breadth (in)

Caucasian No ADJ 6 63 9.44 3.56 2.55

African No ADJ 6.5 64 9.57 3.63 2.61

African +1in 7 65 9.81 3.67 2.65

7.5 66 9.96 3.73 2.67

8 67 10.08 3.78 2.71

8.5 68 10.33 3.84 2.75

9 69 10.46 3.94 2.78

9.5 69.6 10.51 3.94 2.82

10 70 10.67 3.99 2.84

10.5 72 10.95 4.11 2.91

11 73 11.05 4.14 2.96

11.5 74 11.27 4.34 2.98

12 75 11.42 4.39 3.05

Refinement

The separate scaling for the length and breadth stem from there being narrow and wide shoe sizes.

150 160 170 180 190 200 21022

24

26

28

30

32

34

Foot Length

Foot Length ANSURLinear (Foot Length ANSUR)Adjusted MH Foot7% Projected Scaling

Height (cm)

Foot

leng

th (c

m)

1581631681731781831881931988

9

10

11

12

13

14

Foot Breadth

Foot Breadth ANSURAdjusted MH Foot18% Projected Scaling

Height (cm)

Foot

Bre

adth

(cm

)

Validation1. Casting 2. Scanning3. Digital Model

Utility4. Cross-sectioning5. Point Cloud

Analysis

CATIA Space

Analysis

CAD Model

Scanned Foot

Preparation

Patient removes shoe and

sits in a chair with the back

braced.

Flexible tubing is cut and the tip is sliced off at roughly a 30

degree angle.

A bag is placed over the patient’s

leg and taped so not to be loose.

The flexible tubing is

then applied to the top of the patient’s foot and held

in position with tape.

The casting sock is

opened and scrunched

until thumbs touch toe

region of the sock.

The sock is plunged in

water for ten seconds.

The sock is then put on the patient and hand

coated with water.

Casting Station

Casting

The patient then stands on a cushioned surface.

The cast should be mostly dry before the patient is allowed to sit with the cast elevated.

The cast is then cut along the tubing with a cast saw.

The cast is then cut along the tubing with a cast saw. The cast is then wrapped with tape to prevent the plaster from leaking.

Plaster is then poured into the cast and allowed to harden.

Casting Station

ScanningScans of the casts were preformed using the GoScan at ATTL to create a point cloud to compare against the models.

Digital Model Utility Analysis

Red- ModelGreen- ScanYellow- Both within .201cm of each other

7% scaling of the length and 18% scaling of the width was used.

Cross-section Analysis

Left Center Right Heel Ball1.75 .97 1.45 .94 .89

Point Cloud Analysis

The two surfaces were aligned then points were placed on the model. Those points were then projected normal to the surface onto the scanned surface. The distance between the points was then measured. Average was 0.490 centimeters.

CoverageLength• σ = .22 in or 5.58%• The standard model will provide coverage to

50% of the population that wears a size 10 shoe.

• A 7% scaling covers 88% of the population. • Larger than a 7% scaled model should be

addressed by use of the ply the next size up. • Because there is a 2% size increase the size

10.5 ply covers 95%.Breadth• σ = .35 in or 8.66%• The standard model will provide coverage to

50% of the population that wears a size 10 shoe.

• A 18% scaling covers 98.7% of the population.

• Larger than a 18% scaled model should be addressed by use of the ply the next size up.

• Because there is a 2% size increase the size 10.5 ply covers the remaining.

Length & Breadth Coverage for a Size 10 AFO

Path Forward1. Single leg model2. CFI implementation

Single Leg Model

Single leg model is being used for generating the plies for the cuff as well as for the ankle foot region.

Center for the IntrepidWill be transferring the system to the Center for the Intrepid where it will allow disabled veterans to walk again without pain.

Summary• Create a 3D CAD model of a human foot

• Based on the ANSUR Data• Establish points of measurement interest from

the model with a defined reference origin• Scaled the model to allow for 1st-99th percentile of

wears• By using shoe size or half size larger

• Will be helping disabled veterans walk again

Closing RemarksSpecial thanks to the Center for Composite

Materials at the University of Delaware for the opportunity to work on this project for the past four years and for providing materials and personal to make this program successful. This program was

also assisted by the professionals at the Application & Technology Transfer Laboratory for their

contribution of resources throughout the program.

Acknowledgements Research was sponsored by the Defense Advanced Research

Projects Agency (DARPA) and was accomplished under the Army Research Laboratory Cooperative Agreement Number W911NF07-2-

0026. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing

the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency, the Army Research

Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government

purposes notwithstanding any copyright notation heron.

Questions