VCM Seek Control via PWM Frequency and Slew Rate Adjustments
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Solution Overview
Problem
Existing data storage devices face challenges in optimizing seek operations due to transition offsets between pulse-width modulation (PWM) and linear modes, which increase position error signals (PES) and power consumption, especially when transitioning between different actuator modes.
Innovation Solution
Implementing a data storage device with a voice coil motor (VCM) that operates in multiple PWM frequency-slew rate combinations during the PWM mode, allowing for dynamic adjustments to reduce transition offsets and coupled PES, and optimizing power consumption by extending the duration in the PWM mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the VCM operates in PWM mode to save power, then power consumption is reduced, but positioning accuracy deteriorates due to transition offsets when switching to linear mode
Solution Approach 1:
The system performs preliminary actions by adjusting PWM frequency and slew rate settings before transitioning from PWM mode to linear mode. This preparation minimizes the transition offset that would otherwise cause positioning errors, allowing the VCM to spend more time in power-efficient PWM mode while maintaining accuracy during mode switching.
Solution Approach 2:
The invention dynamically changes PWM operating parameters (frequency and slew rate) based on the seek phase. By optimizing these parameters during the transition period, the system reduces the magnitude of transition offsets and their impact on positioning accuracy, enabling extended PWM mode operation for power savings.
2Measurement precision
If the VCM transitions from PWM mode to linear mode for accurate positioning, then positioning accuracy is improved, but power consumption increases
Solution Approach 1:
The system performs preliminary adjustments to PWM parameters (frequency and slew rate) before mode transition to minimize the required correction in linear mode. This reduces the duration and power consumption of the linear mode operation while maintaining positioning accuracy.
Solution Approach 2:
The invention dynamically optimizes the transition process by adjusting PWM parameters in real-time based on the seek phase. This dynamic optimization allows the system to maintain high positioning accuracy with minimal linear mode engagement, thereby reducing overall power consumption.
3Measurement precision
If PWM frequency and slew rate settings are optimized to reduce transition offsets, then positioning accuracy is improved, but device complexity increases due to multiple settings management
Solution Approach 1:
The invention segments the seek operation into distinct phases (coarse seek and fine seek) with optimized PWM parameters for each phase. This segmentation simplifies control by providing clear guidelines for parameter selection in different operational contexts, reducing the complexity of managing multiple settings.
Solution Approach 2:
The system implements parameter changes based on predefined seek phases rather than continuous adjustment. This approach reduces control complexity by establishing clear rules for when to change parameters, making the multi-setting management more manageable while still achieving positioning accuracy improvements.
4Use of energy by moving object
If the VCM operates in PWM mode for longer duration to save power, then power consumption is reduced, but coupled PES increases due to actuator motion coupling
Solution Approach 1:
The invention optimizes PWM parameters (frequency and slew rate) to minimize coupled PES while extending PWM mode duration. By carefully selecting parameters that reduce mechanical coupling effects, the system can maintain power-efficient operation without excessive coupled position errors affecting non-seeking actuators.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces power consumption and improves positioning accuracy by minimizing transition offsets and coupled position error signals, enabling more flexible PWM frequency and slew rate settings to enhance seek settling performance.
Implementation Method 1
one or more read/write heads connected to distal ends of actuator arms, which are rotated by actuators (e.g., a voice coil motor)
Implementation Method 2
a voice coil motor (VCM), the first VCM configured to operate in a first mode and a second mode
Data Source
AI summary
Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising a voice coil motor (VCM), the VCM configured to operate in a first mode and a second, different mode, wherein the first mode corresponds to at least a first and a second setting, and a control circuitry configured to cause the VCM to seek towards a target track in the first mode using the first setting for a first duration, control transition of the VCM from the first to the second setting in the first mode, cause the VCM to seek towards the target track using the second setting for a second duration, and control transition of the VCM from the first to a second mode, wherein controlling the transitioning comprises seeking the VCM toward the target track in the second mode for a third duration.