GaitSym 2013

GaitSym is a forward dynamic modelling program. What that means is that you specify the forces and the program uses Newton's Laws to calculate the movements. It uses the Open Dynamics Engine physics library to do most of the hard work ( and provides a file format and display system so the user does not have to do any programming. It also provides various muscle models so that the forces can be generated directly from muscle activation levels and a number of hooks to allow it to be used with global optimisation tools such as genetic algorithms. The software is open source and is released under the GNU General Public License version 3.0 except for parts of the software that are covered by different licences (for example the OpenDE portions are covered by either Lesser GPL or a BSD license). If this license does not let you do what you want to do then please contact me and I am sure I can sort something out.

Screen Shot 2013
GaitSym 2013 with a chimpanzee model.


The following downloads are provided:
You can also browse the source code.


The program is developed under MacOSX Mountain Lion using the Qt 5.0 GNU GPL v. 3.0 Version cross-platform development system. It therefore compiles and runs on many of the Qt supported platforms including Linux and Windows. There is also a command line version designed for batch processing. Source code, makefiles and Qt project files are provided for MacOSX, Linux and for MinGW to allow compilation under Windows. Binary files for MacOSX and Windows are also provided.
  • For MacOSX, double-click the downloaded DMG file and drag the application to a convenient place on your hard drive.
  • For Windows, double click the downloaded ZIP file and decompress the contents to a convenient folder on your hard drive. The DLL files and the EXE files all need to be in the same folder for the program to run correctly.

What's New

  • New slider joint
  • New muscle model including tendon damping, activation kinetics, non-linear spring response, and better numerical stability
  • New box car drivers
  • New box geom
  • New muscle strap that can wrap round two parallel cylinders
  • Direct point cloud visualisation
  • Abort on excessive hinge joint limit torques, or on data target thresholds
  • The tracking position can be offset to centralise tracked simulations

All old models should still load but simulation changes may mean that there are numerical differences in the calculated outputs.