Gravitational torque estimation and compensation in electrically driven rotating system

The present invention relates to a method to measure and compensate a gravitational torque of an electric-driven rotating system, to compensate a rotating part gravitational torque value in the electric-driven rotating system comprising the rotating part having a rotating part gravitational torque value, a driving part to rotate the rotating part on a predetermined rotary shaft, and a balance weight disposed on one area of the rotating part. According to the present invention, the method to compensate the gravitational torque of the electric-driven rotating system comprises: a step of fixing the rotary shaft of the rotating part to be perpendicular to a gravitational direction; a step of rotating the rotating part at a constant speed in a first direction and a second direction opposite to the first direction on the rotary shaft by the driving part; a step of extracting first and second driving data including an inflow current value and angular data provided from the driving part while the rotary shaft is rotated in the first and second directions to measure the rotating part gravitational torque value; a step of estimating the center of gravity of the rotating part based on the rotating part gravitational torque value; and a step of calculating a mass value of the balance weight based on the center of gravity of the rotating part to make the rotating part gravitational torque value become a value so as to minimize a required torque of the driving part.