AnyMoCap: A model framework motion caputure based models

The AnyMoCap model is an effort to create a simple and unified framework for doing any kind of mocap analysis with the AnyBody Modeling System.

This is first post in a series on the AnyMoCap framework. In a series posts I will show how to use the frame and presents some of the features that makes it much easier to do motion capture based modelling.

Current motion caputure model examples in the AnyBody Managed Model Repository (AMMR) are releative complex and quite difficult to understand for new users.

The reason is that the MoCap models are different from the other examples models in the AMMR. Most importantly, MoCap models usually require an over-determinate kinematic solver to handle the excess in information that the optical markers provide. The over-determinate solver in AMS works great, but it can only find velocities and accelerations numerically. That has some performance issue when running inverse dynamics analysis. To overcome the problem, the MOCAP analysis is split into a two-step producedure. The two steps are ‘Marker tracking’ and ‘Inverse dynamic analysis’ on the figure below:

The overdeterminate kinematic analysis solves the marker tracking problem, and writes joint angles to a a set of files. These joint angles can then be used with the determinate kinematic solver in the inverse dynamic analysis.

Model structure.

The AnyMoCap framwork contains two main folder Examples and Model.

AnyMoCap/ 
├───Model/
├───Examples/ 
│   ├───Plug-in-gait-FullBody/
│   ├───Plug-in-gait-LowerExtremity/
│   └───SpecialFeatures/

The core of the framework is located under Model/. The core files will eventually become part of the AMMR, and you shouldn’t need to change these files unless you want to help improve the AnyMoCap framework (See “Contributing” below.)

The Examples/ folder contains examples of how to use the framework. Thre are currently two full blown examples of how to create a FullBody and LowerExtremity model with the Plug-in-Gait marker protocol. Other examples with other marker protocols will come soon. The SpecialFeatures/ folder contain small examples on specific features of the framework.

Examples are self-contained and could be locaated anywhere as long they have a valid reference link to where the AnyMoCap model is located on your computer.

Usage