Frequency response diagnostics for characterizing servo controlled mechanisms

A method comprising:

• supplying, by a motion controller, a torque command to a triple-loop amplifier that controls a motor, wherein the motor drives a robot linkage;
• including, by the motion controller in the torque command, an alternating signal wave that is to test a frequency response of the motor and the robot linkage;
• receiving, from the triple-loop amplifier, by the motion controller, an instantaneous torque value of the motor and an instantaneous velocity value of the robot linkage at each time step of a plurality of time steps according to a sampling rate and over a period of time;
• storing, by the motion controller in memory, an aggregate of the instantaneous torque values and an aggregate of the instantaneous velocity values;
• determining, by the motion controller for a first frequency of the alternating signal wave, a magnitude and phase shift between the aggregate of the instantaneous velocity values and the aggregate of the instantaneous torque values;
• generating, by the motion controller, a fingerprint using an aggregate of magnitude and phase shift data for multiple frequencies of the alternating signal wave;
• and
• performing, using the fingerprint, frequency response diagnostics of the motor and the robot linkage.

A non-transitory computer-readable storage medium that stores instructions, which when executed by a processing device of a motion controller, cause the processing device to perform a plurality of operations comprising:

• supplying a torque command to an amplifier that controls a motor, wherein the motor drives a robot linkage;
• including, in the torque command, an alternating signal wave that is to test a frequency response of the motor and the robot linkage;
• receiving, from the amplifier, an instantaneous torque value of the motor and an instantaneous position value of the robot linkage at each time step of a plurality of time steps according to a sampling rate and over a period of time;
• storing, in memory, an aggregate of the instantaneous torque values and an aggregate of the instantaneous position values;
• calculating, based on the instantaneous position values over the period of time, an aggregate of velocity values of the robot linkage;
• determining, for a first frequency of the alternating signal wave, a magnitude and phase shift between the aggregate of velocity values and the aggregate of the instantaneous torque values;
• generating, by the motion controller, a fingerprint using an aggregate of magnitude and phase shift data for multiple frequencies of the alternating signal wave;
• and
• performing, using the fingerprint, frequency response diagnostics of the motor and the robot linkage.