Dual Actuator Gap Control with Overshoot Bias

Solution Overview

Problem

Existing actuator drive apparatuses face a trade-off between responsiveness and disturbance suppression, where improving responsiveness leads to decreased disturbance suppression and vice versa, due to the need for excessive control voltage during feedback-control, resulting in slow convergence of the gap distance to the target value.

Innovation Solution

An actuator drive apparatus comprising a first member, a second member, a gap sensor, a first actuator that applies a voltage signal with an overshoot larger than the bias voltage initially and then a constant bias voltage, and a second actuator that performs feedback-control to adjust the gap dimension to a target value, allowing for quick responsiveness and effective disturbance suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If feedback-control voltage is increased to improve responsiveness, then the gap dimension reaches target value faster, but disturbance suppression decreases and vibration convergence time increases

Engineering Contradiction:

ImproveresponsivenessVSAvoiddisturbance suppression

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The control system is divided into two independent actuators: a first actuator that applies a predetermined voltage signal for rapid positioning, and a second actuator that performs feedback control for disturbance suppression. This segmentation allows each actuator to be optimized for its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first actuator applies a predetermined voltage signal in advance to rapidly move the gap dimension close to the target value before the feedback control takes over. This preliminary action reduces the initial error significantly, allowing the feedback control to focus on fine-tuning and disturbance suppression rather than large corrections.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If feedback-control voltage is limited to suppress disturbance, then disturbance suppression improves, but responsiveness decreases and convergence time increases

Engineering Contradiction:

Improvedisturbance suppressionVSAvoidresponsiveness

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The control system is divided into two independent actuators: a first actuator that applies a predetermined voltage signal for rapid positioning, and a second actuator that performs feedback control for disturbance suppression. This segmentation allows each actuator to be optimized for its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first actuator applies a predetermined voltage signal in advance to rapidly move the gap dimension close to the target value before the feedback control takes over. This preliminary action reduces the initial error significantly, allowing the feedback control to focus on fine-tuning and disturbance suppression rather than large corrections.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a single actuator performs both rapid positioning and feedback control, then device complexity is reduced, but the trade-off between responsiveness and disturbance suppression cannot be resolved

Engineering Contradiction:

Improveactuator configurationVSAvoidresponsiveness

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The control system is divided into two independent actuators: a first actuator that applies a predetermined voltage signal for rapid positioning, and a second actuator that performs feedback control for disturbance suppression. This segmentation allows each actuator to be optimized for its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

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

The proposed solution enables rapid convergence of the gap dimension to the target value while maintaining effective disturbance suppression, improving responsiveness without compromising on convergence time.

Implementation Method 1

a reflective film is provided in each of the surfaces of the substrates facing each other. In addition, this variable interference apparatus includes electrodes for detecting electrostatic capacitance in the surfaces of the respective substrates facing each other

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

a first actuator that changes the dimension of the gap through input of a first voltage signal

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS11533000B2Actuator drive apparatus and method for controlling actuator drive apparatus

Publication Date: 2022.12.20 SEIKO EPSON CORP

AI summary

An actuator drive apparatus according to a first aspect includes a first member, a second member that faces the first member via a gap, a gap sensor that detects a dimension of the gap, a first actuator that changes the dimension of the gap through input of a first voltage signal, and a second actuator that changes the dimension of the gap through input of a second voltage signal, in which the first voltage signal is a voltage signal that becomes a constant bias voltage after a lapse of a predetermined time, and includes an overshoot signal larger than the bias voltage before the lapse of the predetermined time, and the second voltage signal is a voltage signal that is feedback-controlled so that a detection value detected by the gap sensor approaches a target value.