CGM

Before running any commands, be sure your virtual python environment is activated. Type activate pycgm39

The use of the CGM in nexus is a two-step process. First your need to calibrate your static file, then, for your gait trials, you need to fit a CGM.

We thus introduce two operations:

  • Calibration
  • Fitting

For the experienced-Vicon Plugin gait user, Calibration and Fitting are similar to the operations Process static Plugin gait calibration and process dynamic Plugin gait model

please refer to the CGM pages to know the model details

Except the CGM2.6, CGM1.0 to CGM2.5 can be run with similar commands, detailed below.

CGM1.0 to CGM2.5 commands

flowchart LR subgraph Calibration id11[Load a static file into nexus] id12[call a pyCGM2 Calibration operation] end subgraph Fitting id21[Load a gait Trial into nexus] id22[call a pyCGM2 Fitting operation] end id11-->id12 id21-->id22 Calibration--->Fitting

Calibration

Notice the Calibration process, do not accept gap. Please crop or fill gaps of your trial

The callable calibration operations are :

pycgm2.exe NEXUS CGM1.0 Calibration
pycgm2.exe NEXUS CGM1.1 Calibration
pycgm2.exe NEXUS CGM2.1 Calibration
pycgm2.exe NEXUS CGM2.2 Calibration
pycgm2.exe NEXUS CGM2.3 Calibration
pycgm2.exe NEXUS CGM2.4 Calibration
pycgm2.exe NEXUS CGM2.5 Calibration
By default
  • align the longitudinal foot axis with the ground. It's the *flat foot option*, familiar to vicon PiG user, which repositions the heel marker at the same height as the toe marker.
  • align the medio-lateral axis of the head (head flat option)
  • consider 14mm marker diameter.

To alter these default settings

  • use input arguments to the command. To know the input arguments, type pycgm2.exe NEXUS CGM1.0 Calibration -h ( or any CGM#i) or refer to the documentation API
  • manipulate the setting files. see FAQ

Fitting

The callable fitting operations are :

pycgm2.exe NEXUS CGM1.0 Fitting
pycgm2.exe NEXUS CGM1.1 Fitting
pycgm2.exe NEXUS CGM2.1 Fitting
pycgm2.exe NEXUS CGM2.2 Fitting
pycgm2.exe NEXUS CGM2.3 Fitting
pycgm2.exe NEXUS CGM2.4 Fitting
pycgm2.exe NEXUS CGM2.5 Fitting

you can replace CGM1.0 with CGM1.1, CGM2.1, CGM2.2, CGM2.3, CGM2.4 or CGM2.5

By default
  • like the Vicon Pig, the CGM1.0 projects joint moment into the distal segment
  • with CGM1.1 to 2.5 : joint moments are projected into the joint coordinate system

To alter these default settings

  • use input arguments to the command. To know the input arguments, type pycgm2.exe NEXUS CGM1.0 Fitting -h (e.g for CGM1.0) or refer to the documentation API
  • manipulate the setting files. see FAQ

CGM2.6

we recommand to collect a left and a right functional knee calibration trial separately.

The CGM2.6 incorporates a knee functional calibration into the CGM2.3 to CGM2.5 operations

flowchart LR subgraph Calibration id11[Load a static file into nexus] id12[call a pyCGM2 Calibration operation] end subgraph KneeCalibration id21[Load a left knee functional calibration trial file into nexus] id22[call a CGM2.6 operation] id23[Load a right knee functional calibration trial file into nexus] id24[call a CGM2.6 operation] end subgraph Fitting id31[Load a gait Trial into nexus] id32[call a pyCGM2 Fitting operation] end id11-->id12 Calibration--->KneeCalibration id21-->id22 id22-->id23 id23-->id24 KneeCalibration--->Fitting id31-->id32

After calibrating a CGM2.3+ model, you can refine the knee joints from functional calibration trial with the one of the CGM2.6 operations

pycgm2.exe NEXUS CGM2.6 SARA
pycgm2.exe NEXUS CGM2.6 2DOF

SARA and 2DOF refer to Baker et al. 1999 and Ehrig et al, 2007 methods

Add -h to know their input arguments or or refer to the documentation API