Friction-torque characteristics of DC servomotor in the range of lower speed have not been measured because the motor, in this range, could not even sustain rotation, not to speak of rotating with constant speed.
In this report, measuring method of such characteristics using rate feedback and experimental results on conventional motors are described.
Furthermore it is clarified that the friction-torque of the DC motor in the range of lower speed are concerned with not only motor speed but also angular position of rotor of the motor.