Multiple GRF Plate Processing for OpenSim Import

[Allison Porter]

I'm trying to get GRF the data in the correct format and file type for import into OpenSim. The GRF data is in a csv file. The data is split into 4 force places, with force coordinates, COP coordinates, and torque components for each plate, as well as force coordinates, COP coordinates, and torque components for the combined 4 plate system. For OpenSim, I need to specify Left and Right foot force coordinates, COP coordinates, and torque [x, y, and z components of the right foot's ground reaction force vector in a specific body coordinate system (ground for the model coordinate system), the x, y, and z components of the right foot's center of pressure, and x, y, and z components of the right foot's ground reaction moment vector. Same values for left foot]. I'm not 100% sure how to do this from the 4 force plate data that I have. From what I can gather, it looks like plates 1 + 4 would be on the subject's left, with 2 + 3 being on the right. I'm not sure how to go about re-calculating the COP and torque values from the two plates corresponding with the correct foot into one value. Any help converting GRF data from 4 plates into the proper format for OpenSim would be appreciated.