Motion iWMC Series - Page 33

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Besides, the velocity which feedforward to the velocity loop may be not smooth, and with some noise signal inside, so
big velocity feedforward value will also amplify the noise.
Step3: Posion loop acceleraon feedforward
It is not recommended that the user adjust this parameter. If very high posion loop gain is required, acceleraon
feedforward K_Acc_FF can be adjusted appropriately to improve performance.
The acceleraon feedforward funcon can be treated as the upper controller (e.g. PLC) have a chance to directly
control the torque in a posion operaon mode. in fact this funcon will expend part of the current loop response
ability, so if the seng can’t match the posion loop proporonal gain and the velocity loop bandwidth, the overshot
will happen.
Besides, the acceleraon which feedforward to the current loop can be not smooth, and with some noise signal
inside, so big acceleraon feedforward value will also amplied the noise.
Acceleraon feedforward can be calculated with the following formula:
ACC_%=6746518/ K_Acc_FF/EASY_KLOAD*100
ACC_%: the percentage which will be used for acceleraon feedforward.
K_Acc_FF (60FB.03): the nal internal factor for calculang feedforward.
EASY_KLOAD (3040.07): the load factor which is calculated from auto-tuning or the right inera rao input.
Note
The smaller the K_Acc_FF, the stronger the acceleraon feedforward.
Step4: Smoothing lter
The smoothing lter is a moving average lter. It lters the velocity command coming from the velocity generator and
makes the velocity and posion commands smoother. Therefore, the velocity command will be delayed in the
controller. So for some applicaons likeCNC, it is beer not to use this lter and to accomplish smoothing with the
CNC controller.
The smoothing lter can reduce machine impact by smoothing the command. The Pos_Filter_N parameter dene the
me constant of this lter in ms. Normally, if the machine system oscillates when it starts and stops, a larger
Pos_Filter_N is suggested.
Step5: Notch lter
The notch lter can suppress resonance by reducing gain around the resonant frequency.
Anresonant frequency=Notch_N*10+100