Suppression Of Positioning Vibration For PMSM Servo System

In the servo system, especially for position servo, the fast trackingperformance and positioning accuracy are often mutual restrained. The fasttraceability requires the high position controller stiffness. Thus the servopositioning overshoot even vibration will occur in view of the inevitably lags inthe actual servo system. The positioning vibration will affect the steady-stateaccuracy of servo system. In addition, some elastic transmission devices arewidely used in industrial robots and other servo system applications, which willcause the position transmission error and introduce resonance point. Then theservo system positioning end vibration will happen when positioning from a highspeed. Positioning vibration phenomenon seriously affects the surface quality ofthe work-piece to be machined and damages to the machine. The long-termpositioning vibration can also wear the mechanical coupling devices down, evenlead to serious accidents in industrial manufacture.Firstly, the paper studies the positioning vibration in servo system with therigid coupling devices. The positioning vibrations occur easily in servo systembecause of long control loop and big phase lag. The paper chooses parametertuning method based on frequency domain. A mathematical model of the servosystem with the rigid coupling devices is established. Then the position loopparameters are obtained by the systematic cut-off frequency and phase marginanalysis. Thus the positioning performance of servo system with rigid couplingdevices is optimized.Then the end positioning performance in servo system with the elastictransmission device is emphatically analyzed based on the positioningperformance of the rigid servo system. A dual resilient transmission inertiatransfer function model is established and the reason of the end positioning inelastic servo system is analyzed by the transfer function model and thesimulation analysis. Then the paper chooses the passive filter to suppress thepositioning vibration and adopts the FFT spectrum identification method to getthe frequency of the positioning vibration. Based on the obtained vibratoryfrequency, we choose the low-filter and notch-filter to suppress the positioning vibration. The method with the notch filter is better than low-pass filter. In orderto decrease the phase lag, we proposed a phase angle compensation method basedon the notch filter to suppress the positioning vibration.Finally, the physical experiments which are carried out on drag platform andswing arm platform validate the effectiveness and superiority of the proposedmethods.