An adjustment system is disclosed for adjusting a proportional, integral, derivative controller in a limited rotation motor system. The adjustment system includes a first transform unit, a second transform unit, a model identification unit, and a PID adjustment unit. The first transform unit is for receiving a first digital signal that is representative of a motor control signal, and is for providing a first frequency domain sequence that is representative of a frequency domain representation of the motor control signal. The second transform unit is for receiving a second digital signal that is representative of a position detection signal, and is for providing a second frequency domain sequence that is representative of a frequency domain representation of the position detection signal. The model identification unit is for identifying a representation of a ratio of the first and second frequency domain sequences. The PID adjustment unit is for identifying appropriate values for the coefficient k.sub.p of a proportional unit of the system, for the coefficient k.sub.i of an integral unit for the system, and for the coefficient k.sub.d of a derivative unit for the system.