Integrated Design of Structure/Controller for Head Gimbals Assembly of Magnetic Recording Test Stand

Abstract

The integrated design of structure/control systems for high-speed positioning control of a head gimbal assembly (HGA) in spin stands is considered in this paper. A diamond shape structure, which is axisymmetrical to two orthogonal axes, is adopted for the displacement amplifier of a HGA. Two PZT linear actuators are built in the structure to control the position of the HGA. If the generated forces of the two actuators are acted symmetrically to the two axes and there is no disturbance force acting on the structure, non-symmetrical vibration modes to the two orthogonal axes will not be activated in the structure; moreover, only one symmetrical mode will come out. Since the natural frequency of the mode which can be excited by the symetrical operation of the two actuators is very high, there is a possibility to achieve a much higher bandwidth of the HGA positioning control system in comparison with conventional structures of displacement amplifiers. The simultaneous optimization on these parameters of the structure and the controller has been conducted, and then the effectiveness of the design result has been verified in the frequency responses. Moreover, the robustness properties against the worked accuracy on the structure and the imbalances in the generated forces of the actuators and/or the masses of suspended loads have been tested to ensure the performance.