Abstract: The authors present optimization parameters of rotary
positioner controller in hard disk drive servo track writing process
using coefficient diagram method; CDM. Due to estimation
parameters in PI Positioning Control System by expected ratio
method cannot meet the required specification of response
effectively, we suggest coefficient diagram method for defining
controller parameters under the requirement of the system. Finally,
the simulation results show that our proposed method can improve
the problem in tuning parameter of rotary positioner controller. It is
satisfied specification of performance of control system. Furthermore,
it is very convenient as a fast adjustment damping ratio as well as a
high speed response.