Fibre winder using Omron PLC

Hello
I am doing fire winder with traverser & dancer Control using Omron CP1H PLC & Omron Servo's, it is almost done but i am facing problem like dancer posn is not obtained as per designated to 50%

I have written program as per following step
I am calculating core dia of bobbin
then derive surface speed of winder with reference to line speed
then add dancer trim rpm to set speed as per dancer posn

this progarm is working but if i set dancer home posn to 50% , it is lagging to 45 %
there are no fibre breakage for 260 km winding

!!! any help on this Please !!!

If there is a steady state error you need to add integral control.