A quick and easy way to check force plate alignment and calibration prior to testing is to place a calibration weight on the plate with a retro-reflective marker placed in the center. The 3D system reconstructs the 3D point and displays the force vector and magnitude based on plate calibration info. You can quickly check force magnitude, zeros and CoP alignment between the 3D and plate coordinate systems in the collection software. There was one case where when testing several points on the same plate that the CoP error increased (distance between 3D point and displayed force vector) the further the weight was placed from the origin of the plate, turned out there was in incorrect calibration coefficient (sensitivity) entered into the software.