Decoupled Disturbance Observers for Servo Control Systems

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Solution Overview

Problem

Existing servo control systems for hard drives face challenges in accurately maintaining position due to internal and external disturbances, such as vibrations, which cause read/write head misalignment and performance errors, due to coupled disturbance observers that complicate design and performance.

Innovation Solution

The implementation of decoupled disturbance observers for voice coil motor (VCM) and microactuator control circuits allows for independent design and optimization of VCM and microactuator disturbance compensation, using model plants to simplify the servo control system and reduce the impact of disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coupled disturbance observers are used in servo control systems, then disturbance compensation can be achieved, but design complexity increases and performance deteriorates

Engineering Contradiction:

Improvedisturbance compensation performanceVSAvoiddisturbance observer design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the disturbance observer system into separate VCM disturbance observer and microactuator disturbance observer blocks, each operating independently. This segmentation allows each observer to be designed and tuned separately, reducing overall design complexity while maintaining effective disturbance compensation for both actuation stages.

Inventive Principle:

Principle #1Segmentation

2Reliability

If coupled disturbance observers are used, then disturbance compensation is attempted, but positioning accuracy decreases due to misalignment

Engineering Contradiction:

Improvedisturbance suppression capabilityVSAvoidpositioning accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By segmenting the disturbance observation into separate VCM and microactuator observers, each observer can be optimized for its specific actuation stage, leading to better disturbance compensation and improved positioning accuracy through reduced coupling effects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements feedback mechanisms where each disturbance observer processes feedback signals from its respective actuation stage independently. This feedback approach allows each observer to accurately track and compensate for disturbances specific to its stage, improving overall positioning accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20180090163A1Loop shaping methods and devices for disturbance observer in servo control systems

Publication Date: 2018.03.29 SEAGATE TECH LLC

AI summary

An apparatus includes voice coil motor (VCM) control circuitry and microactuator control circuitry. The VCM control circuitry includes a VCM disturbance observer configured to generate a VCM disturbance compensation signal. The microactuator control circuitry includes a microactuator disturbance observer configured to generate a microactuator disturbance compensation signal. The VCM disturbance observer and the microactuator disturbance observer are decoupled from each other.