GRF prediction trouble shooting - AnyBody/support GitHub Wiki

Here are some things to check if a GRF prediction model fails running inverse dynamic:

• Remember to always have a full body model when using GRF predictions, otherwise results will be wrong
• Direction of gravity is it specified correctly? this needs to be correct in two places the Gravity property of the study in the LabSpecific.any data and in the definition of the forceplates setting the variable NORMAL_DIRECTION .
• In the file Forceplate_GRFprediction.any try to increase the property LimitDistHigh, this controls when contact can occur so if the number is higher the foot do not need to be as close to the ground before contact can occur, see also LimitVelHigh it controls speed limit.
• Unrealistic accelerations of the model could be the reason if your data are not filtered correctly
• The model is using a weak residual to the ground that helps holding the balance in the model if the feet contact are not enough, this is defined in the file "Tools/GRFPrediction/Weakresidual.any" here you can increase the strength of the artificial muscles, but this will lead to higher residuals so be carefull.