For the dynamic model, we will define the technical coordinate system based on the three heel cluster markers and use the parameter we calculated for the static trial to transform the technical coordinate system to the anatomical one.
To define the dynamic model:
- Click on the Data Management tab and load the Running trial.
- On the Variables tab, ensure that you choose the same variable scheme as we defined for the static model.
Notice that some of the variables are displayed in red. This indicates that the variable cannot be calculated based on the information in the trial. This includes the two ankle joint center variables as well as the anatomical coordinate systems. However, the technical coordinate system can still be calculated since this is based on the markers that have not been removed.
- Click the Edit button to edit the variable scheme, then the Add button .
- Name the variable LeftFoot, and define it using a function from the Segment group called Offset segment A using segment B.
- For segment A, choose LeftFootTechnical.
- For segment B, use the parameter that was calculated in the parameter scheme for the static trial, called LeftAnatomicalToTechnical.
Notice that the coordinate system appears in the 3D Workspace where the anatomical system would have been had the two malleolae markers not been removed.
This completes defining the dynamic model. If you were using more segments, for example, other segments of the lower body, you would have to add marker clusters and anatomical markers to these segments too, and repeat the process outlined above.
ProCalc supports clusters based on both three and four markers.