Servo system for a two-dimensional micro-electromechanical system (MEMS)-based scanner and method therefor
AssigneeInternational Business Machines Corporation
InventorsSri M. Sri-Jayantha, Hien Dang, Arun Sharma, Evangelos S. Eleftheriou, Mark A. Lantz, Charalampos Pozidis
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Abstract
A servo control system for a micro-electromechanical systems (MEMS)-based motion control system (and method therefor), includes a motion generator having an inherent stiffness component.
Claims7
A servo controller for controlling movement of a scanner, comprising:
- a servo unit for generating a first-axis motion and a second-axis motion under a track-follow-scan mode and a turn-around mode,
- wherein a scan rate is programmable by choosing an appropriate slope for a ramp trajectory for the servo unit when generating the first-axis motion,
- wherein said servo unit comprises:
- a first servo for the X-axis and a second servo for the Y-axis,
- wherein said first servo comprises:
- an analog-to-digital (A/D) converter for receiving position information signals of said scanner, and converting said position information signals to digital values;
- a digital controller including:
- a position controller for receiving an output from said A/D converter;
- a velocity estimator for receiving an output from said A/D converter;
- a velocity controller for receiving an output from said velocity estimator;
- a reference trajectory for providing an input to said velocity controller;
- and
- a post filter bank for receiving an output from one of said velocity controller and said position controller, to provide a control signal;
- a digital-to-analog (D/A) converter for receiving said control signal and generating an analog signal;
- a current amplifier for receiving said analog signal;
- and
- an actuator for receiving an output from said current amplifier to drive said scanner.
A servo control system for a micro-electromechanical system (MEMS)-based motion control system, comprising:
- a motion generator having an inherent stiffness component;
- a feedback element for canceling the inherent stiffness component, and
- a node for providing an input to said motion generator and a stiffness element coupled to said node,
- wherein a term representing said inherent stiffness is fed through said stiffness element to said node to counterbalance the stiffness.
A method of controlling a scanner in a micro-electromechanical system (MEMS)-based motion control device, comprising:
- generating a velocity profile for each X-seek;
- and
- managing a stiffness of said scanner,
- wherein the velocity profile extends beyond zero as a terminal velocity, and imparts a reverse velocity equal to that of a desired scan rate, and continues to maintain the scan rate until an end of a track is reached,
- wherein at the end of a track, performing a turn-around, said performing comprising a step move performed by a Y-position servo, while an X-scan servo produces a same scan rate in an opposite direction.
A method of controlling a scanner in a micro-electromechanical system (MEMS)-based motion control device, comprising:
- generating a velocity profile for each X-seek;
- and
- managing a stiffness of said scanner,
- wherein the velocity profile extends beyond zero as a terminal velocity, and imparts a reverse velocity equal to that of a desired scan rate, and continues to maintain the scan rate until an end of a track is reached,
- wherein a step change in a controller output equal to the equilibrium value is generated, and
- wherein a velocity estimator is activated by the controller output in addition to a velocity servo output which substantially follows a reference velocity profile.
Dependencies are inferred from the claim text.