Motion iWMC Series - Page 30

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BW=Speed_Fb_N*20+100[Hz]
60F90608
Speed_Mode
0: 2nd order FB LPF
1: Directly feedback the original velocity
2: Velocity feedback aer velocity observer
4: Velocity feedback aer 1st order LPF
10: Velocity feedback aer 2nd order LPF and the
velocity command is ltered by a 1st order LPF. Both
lters have the same bandwidth. 11: The velocity
command is ltered by a 1st order LPF
12: Velocity feedback aer velocity observer, the
velocity command is ltered by a 1st order LPF
14: Velocity feedback aer 1st order LPF and the
velocity command is ltered by a 1st order LPF. Both
lters have the same bandwidth
1
/
60F91508
Output_Filter_N
A 1st order lowpass lter in the forward path of the
velocity loop
1
1-127
60F90820
Kvi_Sum_Limit
Integral output limit of the velocity loop
/
0-2^15
Step of velocity loop tuning is shown below:
Step 1: Conrm the limit of the velocity loop bandwidth
Velocity loop bandwidth limits posion loop bandwidth, so it is especially important to adjust speed loop bandwidth.
The limit of the velocity ring bandwidth can be determined by several aspects:
⚫ Feel the motor vibraon and noise through your ngers and ears. It is actually an empirical story, but it's very
valid. Users can choose to increase or decrease the velocity loop bandwidth by listening and touching the
machine.
⚫ Another way is to observe the oscilloscope, where the user generates a step curve for velocity control and
samples the actual velocity and current. Comparing the sampling paerns at dierent velocity loop
bandwidths, we can nd the opmal curve – the velocity curve follows the command quickly and without
oscillaons.
Step 2: Velocity feedback lter adjustment
The velocity feedback lter can reduce noise that comes from the feedback path, e.g. reduce encoder resoluon noise.
The velocity feedback lter can be congured as 1st and 2nd order via the Speed_Mode for dierent applicaons.
The 1st order lter reduces noise to a lesser extent, but it also results in less phase shiing so that velocity loop gain
can be set higher.
The 2nd order lter reduces noise to a greater extent, but it also results in more phase shiing so that velocity loop
gain can be limited.
Normally, if the machine is s and light, we can use the 1st feedback lter or disable the feedback lter. If the machine
is so and heavy, we can use the 2nd order lter.