About Food-Tracking Task: hand coordinates

Hi. Concerning the 3D hand position, the motion data recorded from K1 contains the following information: -index 1, A-saku-6markers:LSHO; -index 2, A-saku-6markers:LELB; -index 3, A-saku-6markers:LWRI; -index 4, A-saku-6markers:RSHO; -index 5, A-saku-6markers:RELB; -index 6, A-saku-6markers:RWRI; -index 7, Experimenter:RWRI; -index 8, Experimenter:RHND. How can I calculate K1's hand position? The paper cites: body-centered 3D hand trajectories were calculated by referencing the wrist position of the reaching hand with the sagittal plane. Can you explain me how to do this with the available information? Thank you very much for your time.

Sorry for our delayed

Sorry for our delayed reply. The answer to your question: Calculate the mid point between left and right shoulders at any given time, this mid point will be reference point for the hand position.