Fine Actuator Voltage Slew Control to Reduce Discharge Oscillations
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Solution Overview
Problem
Existing data storage devices experience adverse performance due to sudden voltage drops and resulting oscillations in fine actuators when switching between enabled and disabled states, leading to suspension vibrations that impact disk drive performance.
Innovation Solution
Implementing a control mechanism that generates a smooth 'S-shaped' voltage waveform to control the slew rate of fine actuators, using a slew control voltage generator and switches to manage the transition of fine actuator groups, reducing oscillations by alternating control between the inner and outer actuator groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fine actuators are switched between enabled and disabled states, then actuator response time is improved, but voltage drops and oscillations occur causing suspension vibrations
Solution Approach 1:
The control mechanism prepares the actuator for state transitions by gradually adjusting the voltage waveform before the actual switch occurs. The S-shaped voltage profile begins its transition in advance, ensuring the actuator is ready for the state change while minimizing sudden voltage drops that cause oscillations and suspension vibrations.
Solution Approach 2:
The patent changes the voltage parameter over time using an S-shaped waveform instead of an abrupt step change. This gradual parameter transition smooths the actuator's response during state switching, reducing mechanical oscillations and maintaining suspension stability while still achieving fast response times.
2Measurement precision
If control signal is applied to fine actuator groups, then head positioning precision is improved, but oscillations occur during state transitions
Solution Approach 1:
The control mechanism uses an S-shaped voltage waveform that gradually changes the voltage parameter from 0% to 100% over a defined transition period. This smooth parameter transition eliminates abrupt voltage changes that cause actuator oscillations, while still achieving precise head positioning through controlled voltage application.
Solution Approach 2:
The S-shaped voltage waveform acts as an intermediary between the digital control signal and the fine actuator. This intermediate analog waveform smooths the transition, preventing direct abrupt voltage application that would cause oscillations, while still delivering the necessary control signal for precise positioning.
3Speed
If voltage is applied to fine actuators, then actuator activation speed is improved, but sudden voltage drops cause performance degradation
Solution Approach 1:
The patent implements gradual parameter changes using an S-shaped voltage profile instead of abrupt voltage application. The voltage transitions smoothly from 0% to 100% over a controlled time period, maintaining fast activation speed while eliminating sudden voltage drops that would cause oscillations and reliability issues.
Solution Approach 2:
The control mechanism applies a cushioning voltage waveform that gradually increases voltage before full activation occurs. This beforehand cushioning prevents sudden voltage drops and mechanical shocks during actuator activation, improving reliability while maintaining activation speed through the efficient S-shaped transition profile.
Data Source
AI summary
A data storage device may include an outer fine actuator group, an inner fine actuator group, and control circuitry comprising: a slew control voltage generator, a first switch, and a second switch. The control circuitry is configured to: generate a control signal; control the first switch to apply the control signal to a first fine actuator group for a first duration; control the first switch to apply the control signal to a second fine actuator group for a second duration, wherein each of the first and the second fine actuator groups comprises one of the inner or the outer fine actuator groups, and wherein the first and second fine actuator group are different; concurrently discharge the first fine actuator group during the second duration, based at least in part on controlling the second switch to couple the first fine actuator group to the slew control voltage generator.