How to adjust the PID parameter in a drive?

put the brushes holder  in line  of main winding

 controll of speed by change the signal pulse widht modulation ,change the duty by micocontroller pic 16877a and we put the sortie in the gate of mosfet ,in order to use the parameter PID first find function transfert by give to motor impulsion and traces the output after identifate the systeme by method of moindre carre or strejch after by bloc p or pi or pid correct the systeme by mehode placement of pole to correct in order to precis the output of system we use matlab in the simulation for exemple