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World Congress 2018

We are excited to be participating at the World Congress of Biomechanics 2018 in Dublin, Ireland. We have planned a number of activities to bring together the OpenSim and musculoskeletal modeling and simulation community, including:

  • Demos highlighting some of the latest research with OpenSim
  • Opportunities to meet OpenSim users with similar research interests as you or who are located near you
  • Raffles and a competition to win the cool, new OpenSim apparel

Visit us at Booth #6. We look forward to seeing you in Dublin! 

Find out more about:

Booth Schedule




Meetup: OpenSim Users in the United Kingdom  (Led by Luca Modenese)


Demo: Introduction to the Hopper Competition  (Nick Bianco)


Meetup: OpenSim Beginner Users  (Led by Christine Dailey)


Demo: Introduction to OpenSim 4.0   (Ajay Seth)


Meetup: Predictive Simulations  (Led by Jeff Reinbolt)





Demo: SimCP - A Simulation Platform to Predict Gait Performance After Orthopedic Interventions in Children with Cerebral Palsy  (Lorenzo Pitto)


Demo: Integration of Kinect and OpenSim  (Gil Serrancoli)


Meetup: OpenSim Users in the U.S. - Utah, Colorado, Arizona, Nevada, New Mexico (Led by Jon Mortensen)




Demo: Introduction to OpenSim 4.0  (Ajay Seth and Jen Hicks)


Meetup: OpenSim Users in the U.S.  - Wisconsin, Minnesota, Michigan, Illinois, Iowa, Indiana (Led by Josh Roth)


Meetup: OpenSim for Teaching (Led by Jen Hicks and Joy Ku)


Meetup: OpenSim Users in Korea  (Led by Dongho Park)


Meetup: Upper-Limb Modeling and Simulation  (Led by Kate Saul)


Meetup: Knee Biomechanics (Led by Colin Smith)





Meetup: Neck and Spine Modeling  (Led by Dario Cazzola)


Demo: Predictive Simulation of Walking  (Friedl DeGroote and Antoine Motte dit Falisse)


Hopper Competition: Highlights and Awards (Nick Bianco)


Meetup: Exoskeletons (Led by Matthew Millard)

Abstracts Featuring OpenSim

We searched the abstract book for talks and posters featuring OpenSim and discovered more than 80!

See the full list of abstracts here.

Try Out OpenSim 4.0

OpenSim 4.0 is available to download from our simtk.org project page. A few notes about the new software:

  • The release is still labeled as a beta, but we believe the current version is close to the final 4.0 version. We will continue to fix minor bugs and interface issues. We encourage users to start using OpenSim 4.0 in their research and teaching and report any issues they encounter.

  • We’ve updated the major tutorials and examples for 4.0, but we are still in the process of updating the user’s guide and some of the other documentation.

  • Read more about the new features and how to upgrade in our page on What's New in OpenSim 4.0?

Hopper Competition

We will be running a friendly competition for the biomechanics community at WCB. Stop by the booth to design a device that will help the hopper jump as high as possible. Or follow the steps below to set-up the hopper on your own computer and email us your solution. The winner will receive an OpenSim sweatshirt. Second and third place will receive an OpenSim t-shirt.


Submit your hopper design to hopper.wcb2018@gmail.com by Thursday, July 12 at 10:30am. Winners will be announced at 1pm the same day at the OpenSim booth.

Details for setting up the competition software and creating a submission are below.


Coming soon!

Software requirements

  • Windows 10 (64-bit) or Mac (macOS 10.10 or later)
  • Matlab 2014b or later (64-bit)


  1. Download and the OpenSim beta software (see section "Try Out OpenSim 4.0" above)
  2. Find the main OpenSim installation directory; perhaps C:\OpenSim4.0-beta (on Windows).
  3. If you use Windows, edit your PATH environment variable to include OpenSim’s bin directory (e.g., C:\OpenSim4.0-beta\bin). See here for instructions. Make sure to remove any previous OpenSim installations from your PATH (alternatively, rename the folder containing the previous OpenSim installation).
  4. Find the doe and model resources folder that was installed with OpenSim. It may be in separate location from the main installation directory (e.g. C:\Documents\OpenSim4.0-beta-resources).
  5. Configure OpenSim with Matlab by starting Matlab and running configureOpenSim.m, located in C:\Documents\OpenSim4.0-beta-resources\Code\Matlab.
  6. After the script completes, restart Matlab and test the configuration by checking the timestamp from running 




     in the Matlab command window; the date should be in July 2018. Test that the visualizer is working by running the following:


    >> m = org.opensim.modeling.Model()
    >> m.setUseVisualizer(true);
    >> m.initSystem();

    You should see an empty visualizer window.

Designing a jump

  1. Navigate to the folder \Code\Matlab\Hopper_Device under the OpenSim resources folder (e.g. C:\Documents\OpenSim4.0-beta-resources\Code\Matlab\Hopper_Device).
  2. Run the following command in the Matlab Command Window to load the hopper design graphical user interface (GUI):

    >> InteractiveHopper


  3. Use the hopper design GUI to choose one of the preset Hill-type muscles and the type of device (make sure to select the With Device radio dial in the top left).

  4. Muscle excitation patterns can be set by clicking "New Muscle Excitation" and adding nodes within the black box in the top right. Click outside the box (on the GUI window) to finalize your excitation pattern.
  5. A passive device, active device, or both can be added to the hopper model. For either device, check "Enable" to add, and check or uncheck "Wrap Around Patella" or create a knee extension or knee flexion device respectively.
  6. For the passive device, use the slider to set the stiffness and mass for a bidirectional PathSpring.
  7. For the active device, click "New Device Control" to create a device control pattern (same as muscle excitation) or check "Proportional Myoelectric" to use the muscle excitation pattern as the device control. Use the slider to set the active device mass and either max tension (if designing a custom device control) or gain (using a proportional myoelectric control). A gain of one corresponds to a max tension of 2000 N.
  8. When finished with your current design, click Simulate to run your control strategy on your model. A plot of your jump will appear in the bottom right window. 
  9. Check "Visualizer Enabled" to view an animation of your design in a separate window. Press any key to play the animation as many times as you like, and hit the Esc key to exit the visualizer. (If you accidentally closed the window without hitting Esc, you may need to Ctrl-C in the Command Window and re-open the hopper design GUI).
  10. Use the "Clear Figures" button to clear the excitation and plotting windows if desired.
  11. Use the "Reset To Defaults" button to set the GUI back to its default settings.
  12. To save design, enter a file name into the textbox under Setup File and click Save. A Matlab MAT file with the name you chose should now appear in your working directory. To load the design later, make sure your setup MAT file is still in the working directory, re-enter the file name into the textbox, and click Load.
  13. Finally, submit your design! Send the MAT file with your best design to hopper.wcb2018@gmail.com with your name and a brief description of your design approach. 





OpenSim is supported by the Mobilize Center , an NIH Biomedical Technology Resource Center (grant P41 EB027060); the Restore Center , an NIH-funded Medical Rehabilitation Research Resource Network Center (grant P2C HD101913); and the Wu Tsai Human Performance Alliance through the Joe and Clara Tsai Foundation. See the People page for a list of the many people who have contributed to the OpenSim project over the years. ©2010-2024 OpenSim. All rights reserved.