system identification

Hello,
My task is the system identification of a two axis gimbal system from closed loop frequency response data. My open loop system is unstable. So I took closed loop data using PI controller. Using the ident GUI(system identification) ,I found the transfer function that suits for my system. System dynamics are poles:4,zeros:0. Now I have to design a controller. My question is ,the transfer function which is estimated from ident tool is plant transfer function alone or I have to divide the estimated transfer function by a PI controller to get plant transfer function.Please give reply to my question.
                                                                            Warm regards
                                                                          Sudhakar bendi