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ABSTRACT: In this paper, new methods to estimate repeatable runout (RRO) in hard disk drives are proposed. The techniques are based on adaptive feedforward cancellation (AFC). To enhance the performance, the modified filtered-X LMS (MFX-LMS) adaptive algorithm is combined with Kalman filtering. The estimated data are used in real-time control to generate the compensation signal which cancels RRO disturbances. Simulation results show the effectiveness of the proposed schemes and the resulting reduction of position errors in the track following mode.
American Control Conference, 2007. ACC '07; 08/2007
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ABSTRACT: In this paper, new methods to estimate repeatable runout (RRO) in hard disk drives are proposed. The techniques are based on adaptive feedforward compensation (AFC). To enhance the performance, two modifications (residual error shaping and Kalman filtering) are introduced to the basic AFC structure. The estimated data are used in real-time control to generate the compensation signal which cancels RRO disturbance. Simulation results show the effectiveness of the proposed schemes and the resulting improvement of tracking performance
American Control Conference, 2006; 07/2006
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ABSTRACT: This brief paper considers multirate control from the viewpoint of computation saving. When a digital control system involves multiple actuators with different bandwidths, feedback loops may be closed at different rates: a fast rate for a high bandwidth loop and a slow rate for a low bandwidth loop. Multirate implementation of a single loop controller is possible by decomposing the control algorithm to fast and slow rate blocks. Such implementations of digital controllers will reduce the total amount of computation. The slow rate part of the controller may be further decomposed and interlaced so that computation saving by multirate control may be distributed uniformly at all fast rate sampling instances. The performance of multirate control implementations for computation saving are applied to the dual actuator track following problem of computer hard disk drives (HDDs). The experimental results show that the multirate implementations achieve regulation performance of the position error signal at about the same level as the single-rate implementation while realizing significant computation saving.
IEEE Transactions on Control Systems Technology 02/2006; · 1.77 Impact Factor
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ABSTRACT: This paper presents a design method for a multi-rate digital controller with interlacing and its application to hard disk drives. In general, a digital controller contains slows modes and fast modes. The slow-mode portion can be updated less frequently in order to reduce the computational load. In other words, one can decrease the sampling rate of the slow-mode controller. Hence, the resulting multi-rate digital controller is composed of a fast-mode controller with high sampling rate and a slow-mode controller with high sampling rate. The amount of computation is uniformly reduced by interlacing the slow-mode control outputs. This design method is evaluated by simulation and the advantage of multi-rate control with interlacing is demonstrated.
American Control Conference, 2003. Proceedings of the 2003; 07/2003
