Softmotion control of piezoelectric linear motor

[viScience]

I am struggling to understand how to use softmotion to control a piezoelectric linear motor.  The motors position is directly related to the control voltage.  In my case a 0-100000 position range is directly mapped to a -1 to 4 V control voltage range.  My understanding is that this type of control requires a position Feedforward calculation CO=(SP/100000)*5 - 1.  I am planning on adding this FF to the FPGA PID calculation and then letting softmotion handle the trajectory generation and PID effect to close the loop on position error.  Does this make sense as a starting point?

[CertifiNATEtion]

Hi sachsm, 

I was able to find a KB on implementing Feed-Forwarding in NI-Motion, but was not able to find any documentation on implementing this in SoftMotion. I am going to forward this information onto R&D for them to review and address. 

Relevent KB:

http://digital.ni.com/public.nsf/allkb/53BF23F982C3BF17862572AD00701503?OpenDocument

Other than that, you sound like you're on track, I was able to find how SoftMotion handles velocity feed forward, but it doesn't mention much about the implementation. 

http://zone.ni.com/reference/en-XX/help/371093G-01/nismlvhlp/control_loop/

I hope this helps answer some of your questions

-N