What is the difference between COM (center of mass ) & COP (center of pressure) ?
The Center of Mass represents the point where the weighted relative position of the distributed mass of a subject sums to 0. Tracking the CoM indicate the general displacement of this subject in space and time. To get the CoM, you need a system measuring the kinematics.
The Center of Pressure is the term given to the point of application of Ground Reaction Force vector. It only exists if the subject is in contact with the ground and exchange forces. To get the CoP, you need a system measuring vertical forces on the ground.