LQG/LTR frequency loop shaping to improve TMR budget

Chang, J-K.; Ho, H.T.

doi:10.1109/20.800799

Cited by 13 publications

(10 citation statements)

References 3 publications

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“…Assume the disturbances and noise signals are zero, and the initial conditions , the required seek length , the controller parameters , , , as well as and are properly selected or designed such that , , the proposed UCS control law (11) will drive the system output to track the reference track asymptotically if both and are asymptotically stable matrices and (16) where (17) with minimal realization (18) and , , and are, respectively, composed of the first columns of , , and , and . The following lemma is used to prove Theorem 1.…”

Section: B Stability Issuesmentioning

confidence: 99%

“…Thus, designers should design in a way such that, the effect of disturbance and measurement noise is effectively attenuated to achieve high precision positioning performance. Any controller design methods based on the state-space approaches, such as LQG/LTR [18] or the robust and the perfect tracking design technique [3] are applicable. Note that when , the transfer function from to is given by…”

Section: Remark 2: the Conventional Cnf Control [6] Uses The Nonlineamentioning

confidence: 99%

See 1 more Smart Citation

A Unified Control Scheme for Track Seeking and Following of a Hard Disk Drive Servo System

Thum

Chen

et al. 2010

IEEE Trans. Contr. Syst. Technol.

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This paper proposes a new nonlinear time-varying unified control scheme (UCS) for track-seeking and track-following in hard disk drives (HDDs) so as to avoid problem of mode switching. The proposed control scheme utilizes the concept of the conventional composite nonlinear feedback (CNF) scheme to achieve fast and smooth seeking. In order to be advantageous over the conventional CNF control, the UCS consists of both linear and nonlinear time-dependent components, which are independent of absolute seeking error. Simulation and implementation results show that, during track-seeking mode, the proposed scheme has a significantly better performance robustness against variations in seek length as compared to the conventional CNF control. For track-following, disturbance and noise models are involved in the problem formulation and sub-optimal method is used to design the controller so as to achieve high head-positioning accuracy. It turns out that the unified controller removes 27.8% of the nonrepeatable disturbances and noise.

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Section: B Stability Issuesmentioning

confidence: 99%

Section: Remark 2: the Conventional Cnf Control [6] Uses The Nonlineamentioning

confidence: 99%

A Unified Control Scheme for Track Seeking and Following of a Hard Disk Drive Servo System

Thum

Chen

et al. 2010

IEEE Trans. Contr. Syst. Technol.

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show abstract

“…On the contrary, feedback controllers can provide robustness in the presence of variations of the resonant modes. Optimal robust controller design methods such as LQG/LTR control Chang and Ho (1999) and H 2 optimal controller Li et al (2004) can be used to suppress mechanical resonance. However, the order of controllers using LQG/LTR or H 2 /H ∞ method depends on the order of the systems.…”

Section: Introductionmentioning

confidence: 99%

Design and Implementation of Feedback Resonance Compensator in Hard Disk Drive Servo System: A Mixed Passivity, Negative-Imaginary and Small-Gain Approach in Discrete Time

Rahman

Mamun

Yao

et al. 2015

J Control Autom Electr Syst

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This paper presents a feedback resonance compensator designed in a simple and yet efficient way to suppress the effects of resonant modes of voice coil motor actuator used in hard disk drive (HDD) servo system. A velocity feedback controller is chosen as the feedback resonance compensator. Resonant modes of the actuator prohibit bandwidth to be pushed to higher frequencies and it causes large oscillations to the closed-loop system response. Therefore, effective compensation of mechanical resonant modes is one of the design challenges in HDD servomechanism. The proposed design is based on a mixed passivity, negative-imaginary and small-gain approach in discrete time which results in a robust stable controller. Firstly, stability of discrete-time interconnected system is analyzed using mixed passivity, negative-imaginary and small-gain properties. These results are analogous to previously established continuous-time case. Nowadays most of the control design is done in discrete time. Hence, this paper provides a base for discretization of mixed system with passivity, negativeimaginary and small-gain properties. Secondly, a velocity feedback controller for resonance compensation is designed using this mixed approach. Simulation and experimental results substantiate the effectiveness of the controller.

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“…In contrast to the open loop approach, the feedback controller to dampen the resonant modes provides robustness in the presence of variations of the resonant modes. Optimal robust controller design methods such as LQG/ LTR control [6], optimal control [7] and optimal control [8,9] can be employed to design to suppress the mechanical resonance of structures. The order of controllers using LQG/LTR or methods depends on the order of the systems.…”

Section: Introductionmentioning

confidence: 99%

Discrete time adaptive controller for suppression of resonance in hard disk drive servo system

Rahman

Mamun

Yao

2015

Int. J. Control Autom. Syst.

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Mechanical resonant modes of the actuator severely impede the efforts in achieving high precision in head positioning servo system of hard disk drives (HDD). Hence it is important that these modes be properly compensated. The conventional approach is to use a notch filter in cascade with the nominal controller, which works well if the resonant frequencies are known and do not vary during operation. However, in reality, frequency and damping ratio of the resonant modes vary in mass-produced systems. They also get changed over time due to wear and tear. As a result, auto-tuning or adaptation of the notch filters is required to maintain the performance at the same level. In this paper, a discrete time adaptive controller is presented in a simple and yet efficient way to suppress the effects of resonant modes. Effectiveness of the proposed compensator is demonstrated through simulation and experiments by implementing the compensator for a Voice Coil Motor (VCM) actuator used in HDD.

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LQG/LTR frequency loop shaping to improve TMR budget

Cited by 13 publications

References 3 publications

A Unified Control Scheme for Track Seeking and Following of a Hard Disk Drive Servo System

A Unified Control Scheme for Track Seeking and Following of a Hard Disk Drive Servo System

Design and Implementation of Feedback Resonance Compensator in Hard Disk Drive Servo System: A Mixed Passivity, Negative-Imaginary and Small-Gain Approach in Discrete Time

Discrete time adaptive controller for suppression of resonance in hard disk drive servo system

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