This paper proposes two vibration suppression con-trol systems for industrial robots. Industrial robots often occurvibration phenomenon which is caused by the resonant frequencyand nonlinear interference force from various joints of the robot.The compact high-gear reduction without backlash, such asthe harmonic gear is frequently used in the driving systemfor the sake of high load-to-weight performance. Generally, theindustrial robots have used the sensors mounted to actuator-side because hardware setting using load-side sensor is verydifficult to mount signal lines. At first, this paper proposes anew vibration suppression control system uses the estimated loadinformation due to repress the effect of external disturbanceforce and nonlinear inertia variation due to posture change ofrobot. The robust position servo system is designed based on thestate, disturbance observer and robust speed control system usingcoprime factorization controller. Next, a zero-phase notch filter isvery useful for suppressing the resonant phenomenon. However,as the design method of zero-phase notch filter is more difficultthan that of the zero-phase low-pass filter, the high-performancezero-phase notch filter cannot be realized in motion control field.In order to overcome this problem, this paper proposes a newdesign method of the zero-phase notch filter which has no phasedelay for fast robot motion control reference. The effectivenessof both proposed systems is confirmed by experimental resultsand numerical simulation results.
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