1. Agenda : January 27th 8:30 – 9:00 Verify your Opensim installation
9:00 – 9:30
Introducing faculty and participants
Ilse Jonkers & Friedl De Groote
9:30 – 10:00
Musculoskeletal modeling in Opensim - Use and application
Ilse Jonkers
10:00 – 10:30
Data import, marker set definition, and scaling
Marjolein van der Krogt
10:30 – 11:00
Coffee
11:00 – 13:00
Work on your own project
13:00 – 14.00
Lunch
14:00 – 14:30
Inverse Kinematics
Friedl De Groote
14:30– 16:00
16:00-16:30
16:30-17:00
Inverse Dynamics
Giordano Valente

2. Good morning and thank you all for coming
Good morning and thank you all for coming. It’s wonderful to see every one here at the opening workshop.
The goal of the opensim project is to provide advanced simulation tools to the worldwide biomechanics community so that we can better work together to advance mobility research and improve human health.
My name is Scott Delp. I am a professor of BioE and orthopaedics at SU and I’m very pleased to be here with my colleagues to lead this workshop. Let me begin by thanking professor Ilse Jonkers (+ other names) for helping us organize the workshop. Let me also introduce Dr. Jen Hicks, Ajay Seth, Ayman Habib, Sam Hamner, Kat Steele, all simulation experts who will assist with the workshop.
We all know that maintaining mobility is essentail for health and happyness. We also know that understanding human movement is complex, and engineering simulations of movement complement experimental approaches to biomehanics.

3. Elements of a Musculoskeletal Simulation
Underlying the GUI is a set of algorithms that represent the dynamics of the musculoskeletal system. This diagram shows the key elements that for generating and simulation human movement. Review briefly. Over the next few slides I’ll give some more details.
OpenSim includes musculotendon models that are based on testing against experimental data to match physiological musculotendon dynamics
OpenSim also has mechanically-correct skeletal dynamics. You can model simple or highly complex joints.
OpenSim also has sophisticated control algorithms. There are algorithms to create muscle driven simulations that track known motions you’ve measured in an experiment. We are also working on adding controllers that can synthesize new motions, without motion capture data. Or add your own controllers (e.g. simple reflex)
In the software you can combine these elements to generate fast, accurate, muscle-driven simulated movements.

4. Purpose of modeling and simulation
Visualize
complex
movement
patterns
Probe
parameters
that
are difficult
to measure
Dynamic simulations of movement complement experimental approaches by providing estimates of important variables, such as muscle and joint forces, which are difficult to measure experimentally. Simulations also enable cause-effect relationships to be identified and allow “what if?” studies to be performed in which, for example, the excitation pattern of a muscle can be changed and the resulting motion can be observed.
Perform “what if” studies
Identify cause-effect relationships

5. Visualize human running in detail
Created by PhD candidate, Samuel Hamner, this simulation tracks experimental measurements of surface markers positions and ground reaction forces from force-plates during treadmill running. We can observe the coordination of muscles during running.

6. Probe the function of a muscle
Soleus (calf muscle) accelerates the mass center upward and forwards in mid-to-late stance
We can plot the acceleration vector as rays at different instances in time during stance …

7. OpenSim is an application
To model and visualize musculoskeletal structures, subject to the laws of physics and empirical evidence, to generate simulated movement.
Be able to run analyses and plot results to gain insights into human and animal movement.

8. OpenSim is a modeling platform
Deformation-Based Contact Forces
Hunt-Crossley for analytical shapes
Elastic foundation for an arbitrary mesh
Contact is vital for synthesizing new motion. (e.g. no experimental ground reaction force data)
OpenSim provides two types of contact forces:
HC: uses analytical shapes that is efficient to solve
EF: is mesh-based with an elastic element at the centroid of every face
In both cases, you can set stiffness and dissipation to match material properties.

9. OpenSim is a modeling platform
Muscle Actuators
OpenSim also provides Muscle actuators.
Muscles can include Complex paths that wrap around a variety of geometries.
The models of muscle force production includes:
excitation to activation dynamics
tendon compliance and
Hill type contractile elements.
Not just muscles in OpenSim - can also represent other actuators (e.g. powered assistive device).

10. OpenSim is a modeling platform
Controllers
Controllers from simple to complex. This video shows a simple stretch-based reflex controller that we’ll use in the exercise.

11. OpenSim is a set of tools
Importing and Previewing Motion Data
OpenSim is also a set of tools for studying motion and generating simulations. I’ll quickly review. GUI shown here – also Matlab and C++ environments
Preview motion capture data and grf force to make sure preprocessing was done correctly , data is in agreement with your model

12. OpenSim is a set of tools
Scaling Musculoskeletal Models
Scale tool—alter model anthropometry so it matches your experimental data as closely as possible.

13. OpenSim is a set of tools
Inverse Kinematics and Inverse Dynamics
Inverse Kinematics and Inverse Dynamics: step through time to determine the joint kinematics, net forces and/or torques at each joint in your model

14. OpenSim is a set of tools
Estimation of Muscle Forces:
Static Optimization and Computed Muscle Control
Beyond net joint moments: estimate the muscles forces that drive a model’s motion. Solve muscle redundancy using the SO tool or CMC

15. OpenSim is a set of tools
Forward Dynamics
Once you have a set of controls, like muscle excitations, or if you have a controller, then can create a forward simulation of movement. Integrate forward in time using the underlying equations of motion of the model.

16. OpenSim is a set of tools
Analyses: Induced Accelerations and Joint Reactions
OpenSim also has tools to analyze a model or simulation. For example—built in tools to perform an induced acceleration analysis, joint reactions analysis. How do individual muscles contribute to motion? What are the joint reaction loads associated with a movement?

17. OpenSim is an extensible software framework
OpenSim Graphical User Interface (GUI)
Applications
GUI Scripts
Matlab Scripts
Command Line Tools
C++ Plugins
OpenSim Modeling and Simulation Libraries
OpenSim
Application
Programming
Interface (API)
Many researchers might just need the built in features accessible with the GUI, but if not you can extend OpenSim using the API (application programing interface)
API is the set of libraries that define the models and algorithms I described in the last few slides. GUI uses the API. Can also write matlab scripts or plugins in C++ that extend the built-in functionality of OpenSIm
Simbody Dynamics Engine
SimBody
API

18. OpenSim is a resource

19. OpenSim is a worldwide community

20. OpenSim is a team of contributors:
Scott Delp
Ayman Habib
Jennifer Hicks
Jeff Reinbolt
Ajay Seth
Michael Sherman
Edith Arnold
Matt DeMers
Sam Hamner
Chand John
Kat Steele
Melanie Fox
Peter Eastman
Clay Anderson
Allison Arnold
Eran Guendelman
May Liu
Peter Loan
Darryl Thelen
You!

21. Welcome! Find your group:
Hip
Thalia Kindt
Iain Hannah CP
Filipa Joao
Antonio Veloso
Patricia Mota
Lizeth Slooth
Lynn Bar-on
Mirjam Niklash
Teresa Martin
Marta de Loma-Ossoria Garcia
Tessa Hoekstra
Antoine Falisse
Sports
Penny Hudson
Neil Bezodis
Ellen Maas
Jeroen Aeles
Knee
Norbert Kapinski
Jan Henriksson
Josh Champion
Cedric Schwartz
Sara Marreiros
Methods - Workflow
Ursula Trinler
Mathieau Menard
Christian Silva
Cedric Devivier
Junfen Shi
Kevin Tanghe
Amber Bruijnes
Tiago Malaquias
If you feel you belong to another group, feel free to change!
What data will you working on?
Upper Limb
Patrick Fasbender
Benjamin Dourthe

22. Objectives for the Workshop
Gain more insight in the Opensim workflow
using your own motion capture data:
Learn the underlying theory, best practices, and trouble shooting tips for IK, RRA and CMC through hands-on practice
Learn techniques for data management OpenSim in your own research
Become confident in your data workflow
Achieve your project goals and share your results
Advance your research!

23. The Workshop Software
OpenSim 3.2

24. Getting the most out of the workshop:
Set clear and manageable project goals
Help each other
Use your resources: lectures and online materials
Still need help? Find the right person to ask your questions
Have fun and take breaks

25. How we hope you will respond:
Continue to use OpenSim in your research
Develop musculoskeletal models and contribute them to the biomechanics community
Use OpenSim in your teaching and contribute new teaching materials
Add features to the software and share with others
Complete our survey so we can improve later workshops