In this paper, the analysis and compensation of fluctuating force reponses in robot hybrid control using TDC are studied. Especially when the stiffness of environment is high, this fluctuating responses of force caused by the movement in position direction degrade the performance of hybrid control. This fluctuating responses occur in both transient and steady state period. Intransient period, the fluctuating responses of force are caused from dynamic coupling, close loop poles and torque ripple, and steady state period, friction and encoder resolution. We also studied step by step the situation, the theoretical background and the compensations about five causes mentioned above.
