Application Of Parameters Setting Algorithm Of Dual-stage Servo Control System In Magnetic Head Performance Test

Dynamic performance test of magnetic head of Hard Disk Drive(HDD)is an important step in production of head,whose precondition is that head can read and write data stably.However,this system exists some problems.For example,the errors in the mechanical parts processing and assembly of fixture make the disk move irregularly during highspeed rotation.The undesirable factors like noise caused by the input current of the plant result in the unstable state of head track tracking and a large position error signal(PES).The system introduces multiple types of compensators to reduce these bad effects,while too many parameters make the system setting process complicated,tedious and timeconsuming.This paper mainly studies the problem that system parameters are difficult to set quickly in the magnetic head positioning,and proposes an offline,automatic,rapid and adaptive system parameter adjustment algorithm to make the PES of head reach a certain reasonable range and realize stable R/W.It provides a theoretical basis for the application of parameters setting during the dynamic performance test of the magnetic head on the assembly line.The technical route of the article is as follows.First,the control scheme of the dual-stage servo control system(DSSCS)is introduced in detail,involving PIDD controller,feedforward controller and two types of digital filters,and the design principle of the controller PIDD's pole placement is given.Aiming at the impact of system disturbance and noise on system performance,the frequency response characteristics of analog filters are used to design the parameters of two types of adaptive digital filters,namely notch filters and low-pass filters.The frequency response simulation results of the two types of digital filters show that the designed filter can effectively and accurately suppress the resonance of the controlled object at each frequency and noise from sensor measurement.Then,the relationship between the Bode plot of the system sensitivity transfer function,the system parameter adjustment and the system disturbance and noise is studied,It also analyzes the reason why the sensitivity itself limits the system parameters,and thus laid the foundation of reducing the PES by proposing a parameter adjustment algorithm to adjust the parameters.On the basis of realizing the parameterization of each compensator,it is proposed to calculate the parameters of the notch filter based on the frequency response data of the plant of the DSSCS,and based on the feature of sensitivity transfer function of the voice coil motor(VCM)of DSSCS is used to obtain the PIDD controller parameters,Based on the feature of the sensitivity of overall DSSCS is used to obtain the parameters of the Estimation model(EM)and micro-actuator controller parameters.Finally,a verification experiment is designed,that is,the frequency response of the system sensitivity transfer function and the PES of head are obtained by using the algorithm adjustment parameter results and the artificial adjustment parameter results.The two ways of the VCM and overall system sensitivity Bode plot is compared and analyzed,which shows that the proposed automatic tuning algorithm for multiple compensator parameters involved in the DSSCS is feasible and effective.