GaitSym 2015

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.

GaitSym 2015 with a human model.


The following downloads are provided:


The program is developed under MacOSX El Capitan using the Qt 5.5 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 Visual Studio 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 EXE file has been compiled dynamically under Windows 7 so should run as long as the DLLs stay in the same folder as the executavle.
  • For Linux you will need to compile the source code and also the dependencies provided.

What's New

  • Live footprint generation based on the contact force.
  • Muscles can be driven from multiple drivers to help with feedback control.
  • A lot of code refactoring which helps with maintenance.
  • Plenty of bug fixes.

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