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# Adaptive Robust Control F or Dual Stage Hard Drives - PowerPoint PPT Presentation

in GOD we trust. Adaptive Robust Control F or Dual Stage Hard Drives. استاد راهنما : جناب آقای دکتر حمید تقی راد. Dr. Hamid D. Taghirad. هادی حاجی اقراری دانشجوی کارشناسی ارشد مهندسی برق – کنترل دانشگاه خواجه نصیرالدین طوسی. H.H.Eghrary MS Student of Electrical Engineering

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Adaptive Robust Control F or Dual Stage Hard Drives

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in GOD we trust

## Adaptive Robust Control ForDual Stage Hard Drives

استاد راهنما :جناب آقای دکتر حمید تقی راد

هادی حاجی اقراری

دانشجوی کارشناسی ارشد مهندسی برق –کنترل

دانشگاه خواجه نصیرالدین طوسی

H.H.Eghrary

MS Student of Electrical Engineering

K.N.Toosi Univ.

2end Seminar Presentation

Sunday, August 12,2007

• Obstacles for Control Algorithm Design

• Strategies for Performance Improvement

• Adaptive Robust Control (ARC) For a HDD

Robust Control

• ARC via Discontinuous Projection

• ARC via Smooth Projection

• Desired Compensation ARC

Obstacles for Control Algorithm Design:

• Inherent Nonlinearity

• Unknown But Reproducible

• for example: Unknown parameters

• Unreproducable

• for example:

• model Disturbance

• Modeling Uncertainty

### Strategies for Performance Improvement:

• Nonlinear Analysis And Synthesis

Deal With Nonlinearity Directly : Nonlinear Control

Effective for both reproducible and

none Reproducible Uncertainities

• Fast Robust Feedback

• Controled Learning For Uncertainity Reduction

Effective for Reproducible Uncertainities

Robust

• Reduce the model uncertainty

• Zero Tracking Error

• (Without High gain Feedback)

• Attenuate the effect of model uncertainties through

• robust feedback.

• Instantaneous

• Reaction

• Drawbacks:

• Transient Performance of the system is not Clear.

• Unknown Nonlinear functions such as external disturbances are not considered.

• Drawbacks:

• Transient Performance of the system is not Clear.

• Unknown Nonlinear functions such as external disturbances are not considered.

Deterministic Robust Control

Conflicts

• Used to Design Supervisor

• Use to Design Base Line Controller

Guarantee

Transient Performance

Prescribed final tracking accuracy

Improved

Asymptotic Input Tracking

Conventional Adaptation Law  Estimated Parameters May not be Bounded

Conflicts

Deterministic Robust Control  Requires Bounds On Uncertainties

Bounded Estimation Parameters

### Adaptive Robust ControlForHard Disk Drive Servo System

Problem Formulation:

Robust Control scheme:

Stability Analysis:

Lyapanov Function:

Parameter Estimation

Estimation Error

### Results:

• Transient Performance is Unknown

• Uncertain nonlinearity are not Considered

Robust Control scheme:

More In Detail:

• Error Dynamics

 Choose The such that:

Stability Analysis:

Lyapanov Function:

Choose small such that:

: Stable

• Tracking Error

Decrease for decreasing Steady State Error

Conflicts

Conventional Adaptation Law  Estimated Parameters May not be Bounded

REMIND

Deterministic Robust Control  Requires Bounds On Uncertainties

Bounded Estimation Parameters

Via Discontinuous Projection

Remains in

Increases

Decreases

Remains in

Parameter Uncertainty Bounded via Adaptation Progress

RobustControlProblem Solved

Via Smooth Projection

There is a Lyapanov Function :

Stability is Guaranteed

Desired Compensation ARC

Desired Trajectory

Remind ARC Scheme

Real Parameter Measurement

(Measurement Noise)

Dynamic

Stabilizing

Feedback

Static Feedback

Desired Compensation ARC

Regressors Dose not Depend On Measurements

• Eliminate Measurement Noise Effect on Parameter Adaptation

• Off-Line Regressors Calculation

Fast Error Dynamic and Parameter Adaptation

Facilitate Control Gain Tuning Process due to

Separation of Robust Control And Parameter Adaptation