The present invention discloses a system and method for monitoring and diagnosing a robot mechanism. This requires adding intelligence to the diagnostics by parameters of physical robot arm linkages respecting component relative rotation or load transfer; storing rotation or translation relationship parameters characteristic of resonant frequencies between at least one mechanical link; receiving servo motor signals; digitizing and storing servo known normal data time histories; performing a time domain to frequency domain transformation on signal to identify components which are out-of band limit pre-sets.