Controller Switching Strategy for Constrained Systems and Its Application to Hard Disk Drives

We propose a switching control strategy for systems with state and control constraints. Prior studies have proven that switching control strategies have the ability to meet performance objectives, such as fast response and good disturbance rejections, while avoiding constraint violations. The controller is selected on-line from a given set of controllers by supervisory rules based on the concept of a maximal output admissible set. The selected controller needs to be appropriately initialized during switching, but how to decide the controller's initial state is still a problem. This paper proposes a method that utilizes an initial value compensation (IVC) technique for determining the initial state of the controller. The IVC technique has the following features. First, the controller's initial state is chosen according to the plant's initial state. Therefore, the number of variables that the supervisory rules need to consider is reduced. Second, smooth and fast transient responses can be obtained after switching, therefore the region of the closed-loop initial state variables that satisfy the desired response specifications under the given constraints can be expanded. Experimental evaluations of the proposed switching control strategy were performed with a 2.5-inch form-factor hard disk drive.

[1]  Glenn Vinnicombe,et al.  Optimal transfer schemes for switching controllers , 2000, Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187).

[2]  Takashi Yamaguchi,et al.  Improvement of settling response of disk drive head positioning servo using mode switching control with initial value compensation , 1996 .

[3]  M. Johansson.  Optimal initial value compensation for fast settling times in mode-switching control systems , 2000, Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187).

[4]  Hiromu Hirai,et al.  Improvement of servo robustness for digital sector servo system , 1992, 1992. Digests of Intermag. International Magnetics Conference.

[5]  K. Hirata,et al.  Set of admissible reference signals and control of systems with state and control constraints , 1999, Proceedings of the 38th IEEE Conference on Decision and Control (Cat. No.99CH36304).

[6]  Keiko Watanabe,et al.  A design method – based on a shock-response-spectrum analysis – for reducing acoustic noise of a seeking control system in a hard disk drive , 2003 .

[7]  Masayuki Fujita,et al.  Observer based switching control for systems with state and control constraints , 2001, Proceedings of the 2001 American Control Conference. (Cat. No.01CH37148).

[8]  Roberto Oboe,et al.  Initial value compensation applied to disturbance observer-based servo control in HDD , 2002, 7th International Workshop on Advanced Motion Control. Proceedings (Cat. No.02TH8623).

[9]  Hiromu Hirai,et al.  A mode-switching controller with initial value compensation for hard disk drive servo control , 1997 .

[10]  J. Ishikawa,et al.  Head positioning control for low sampling rate systems based on two degree-of-freedom control , 1996 .

[11]  Hiromu Hirai,et al.  Mode switching control design with initial value compensation and its application to head positioning control on magnetic disk drives , 1996, IEEE Trans. Ind. Electron..

[12]  Kenji Hirata.  Measurement Feedback Switching Control for Systems with State and Control Constraints , 2000 .

[13]  Y. Li,et al.  Optimization of initial value compensation for settle control in hard disk drives , 2005, IEEE Transactions on Magnetics.

[14]  K. T. Tan,et al.  Linear systems with state and control constraints: the theory and application of maximal output admissible sets , 1991 .

[15]  K. Hirata,et al.  Controller switching strategies for constrained mechanical systems with applications to the remote control over networks , 2004, Proceedings of the 2004 IEEE International Conference on Control Applications, 2004..