Hi 

I have been reading the blog : 

Teaching Your PI Controller to Behave ,

in part III : https://e2e.ti.com/blogs_/b/industrial_strength/archive/2013/03/09/teaching-you-pi-controller-to-behave-part-iii

I quote: "The transfer function from motor current to motor torque will vary as a function of what type of motor you are using.  Assuming we are using a Permanent Magnet Synchronous Motor under Field Oriented Control, the transfer function between q-axis current and motor torque is:"

what is the equivalent of this parameter in PMDC motor ( Brushed motor )

my initial guess is kt (Nm/A)