ProANATOMY An Approach to Anatomical Surface Modeling using ProEngineer

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ProANATOMY An Approach to Anatomical Surface
Modeling using Pro/Engineer

• By
• Lars R. Chrisman, PE, CEP
• ProFICIENT Engineering Services, Inc.
• Lawton, Michigan

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Why Model Body Parts in Pro/E?

• Indirect Applications
• Human Factors Design Aids (control panels,
  furniture, etc.)
• Anatomical Size/Shape References (shoes, gloves,
  etc.)
• Design Presentation (show product with digital
  anatomical reference)
• Direct Applications
• Toys and Novelties
• Medical Training Aids
• Orthotics and Prosthetics
• Direct Applications are the focus of this
  presentation.

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What are the Traditional Approaches to Anatomical
Designs?

• Master Geometry
• Plaster Cast Replications of Actual Subject
• Digitized Copies of Actual Subject
• Hand Sculpted Artistic Renditions
• Geometry Manipulation (Design Changes)
• Plaster Cast of a New Subject
• Digitized Copies of a New Subject
• Hand Sculpted Changes

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What Can Digital Surface Copies and IGES Surfaces
Provide?

• Ability to scale the subject basic function in
  viewing tools
• Ability to mirror the subject basic function in
  viewing tools
• Convincing Anatomical Detail depending on the
  accuracy of the scanned data
• Connectivity to Suitable Manufacturing Processes
  via IGES, STEP, STL, etc

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What More Must a Viable CAD Model Provide?

• Ability to scale the subject
• Ability to mirror the subject
• Convincing Anatomical Detail
• Connectivity to Suitable Manufacturing Process
• ...Plus...
• Controlled Anatomical Movement
• Proportional Size/Shape Manipulation
• Parametric Control of Key Variables
• Pro/Engineer has the tools to handle this level
  of control

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Key Tools for Anatomical Surface Modeling in Pro/E

• 1) Datum Planes, Points and Curves these will
  establish the framework for your surface model,
  and control the desired motion and size/shape
  control of the subject.
• 2) Splines Are My Friend sketched spline
  datum curves offer both control and flexibility
  to a parametrically driven surface model. Spline
  points are either dimensioned (for parametric
  control), aligned to existing datum points, or
  left free to find their way during parametric
  manipulation. Play with them to see their real
  power.
• 3) Thru Point Datum Curves great for connecting
  vertices in 3D space to help smooth out surfaces.
  Tweaking gives added control of the surface
  between known vertices.
• 4) Projected Datum Curves when you want to
  sketch a surface boundary that does not fall on a
  flat plane.

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Key Tools for Anatomical Surface Modeling in
Pro/E (contd)

• 5) Approximate Composite Datum Curves gets rid
  of unwanted curve vertices and break points that
  cause segmented surfaces.
• 6) Surface by Boundaries (SBB) once the
  framework is complete, this tool stretches out
  the skin and allows you to control the fit to
  neighboring surfaces. WARNING this feature
  will also let you know very quickly how well you
  did (or didnt) construct your datum curve
  framework. You may have to go back to your
  framework several times to get the desired
  results in your surface.
• 7) Surface Merge, Trim, Extend and Transform
  knit those surface boundaries all together. The
  goal is to get either a solid part or a
  contiguous surface model.
• 8) Surface Analysis allows you to visualize
  your finished surface to expose kinks and bends
  that may otherwise be hard to catch.

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Key Principles for Anatomical Surface Modeling in
Pro/E

• 1) Build a good Skeleton part in this case,
  take it literally. Define all of your key shape
  and motion information here before you ever think
  about what the surface needs to look like.
• 2) Plan your datum curve framework out well
  think of where the boundaries for your SBBs will
  be, and how you will get them all connected to
  one another. The key to smooth, contiguous
  surface is how well you planned out your
  framework.
• 3) Build a SIMPLE datum curve framework first
  tie it to the skeleton and run it through the
  motions. The surface will only hold up if the
  framework stays in tact.
• 4) Build a SIMPLE SBB early see what the
  surface looks like and how much more framework
  you need to hold it up the way you want it. See
  how it holds up under skeleton manipulation.

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Key Principles for Anatomical Surface Modeling in
Pro/E (contd)

• 5) See how many segments you have in your surface
  the fewer the better. Too many segments in a
  surface will cause problems knitting boundaries
  together later. Reduce them by adding more
  approximate composite curves, and by using
  control points in your SBB.
• 6) Try hard to get all or most of your surfaces
  under one SBB. Anatomical surfaces are tangent
  to one another and have no orthogonal references
  for controlling any unsupported surface
  boundaries. It will be difficult to get all
  subsequent SBBs tangent to one another if you
  plan to patch your surface together.
• 8) Pro/Engineer definitely has a personality
  and it is most evident in this type of surface
  modeling. Dont fight it Learn it! It is only
  then that you will really see all the power it
  has to offer.

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Concept Demonstration

• 1) Simple Finger Model skeleton, framework, and
  surface
• 2) Anatomical Features adding finger nail and
  creases
• 3) Whole Hand Model merge those fingers
  together and blend in the gaps
• 4) Customer Product Demonstration what you can
  accomplish with this technique

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• Lars R. Chrisman, PE, CEP
• ProFICIENT Engineering Services, Inc.
• 10405 West TU Ave
• Lawton, MI 49065
• 616-598-5807
• fax [phone]
• lars_at_proficient-engineering.com
• www.proficient-engineering.com