Actuator Condition Monitoring Using Open-Loop Control Data

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Solution Overview

Problem

Complex control systems, such as lithography systems, face challenges in monitoring and maintaining the status of numerous actuators due to limited computing power and the need for precise control, especially in vacuum environments where cooling is expensive and complex, leading to potential misalignment and exposure errors.

Innovation Solution

A control system that utilizes actuator measurement data for both regulation and status monitoring, eliminating the need for additional sensors by employing a first processing unit for pre-processing data within the embedded system and a second processing unit with higher computing power outside the embedded system to determine the system's status, enabling predictive maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors are added for condition monitoring, then monitoring precision is improved, but device complexity increases

Engineering Contradiction:
Improvecondition monitoring precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes existing actuator measurement data serve dual purposes: both for real-time control regulation and for condition monitoring. By processing the same measurement data through different evaluation methods (control algorithms vs. wear analysis), the system achieves comprehensive monitoring without adding dedicated sensors, thus improving monitoring capability while avoiding increased device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own operational data (actuator measurement data) to monitor its own condition. The actuator's measurement data, originally collected for control purposes, is reutilized to detect wear and predict maintenance needs, eliminating the need for separate monitoring sensors and making the system self-diagnostic

Inventive Principle:
Principle #25Self-service

2Productivity

If computing power is increased for data processing, then productivity is improved, but use of energy increases

Engineering Contradiction:
Improvedata processing capabilityVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent divides the computing tasks into two segments: time-critical control calculations performed by the embedded control unit with limited computing power, and computationally intensive condition monitoring and wear analysis performed by an external evaluation device. This segmentation allows high productivity in data processing while distributing energy consumption across different system components, with the embedded unit consuming minimal energy for essential control functions

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If computing power is increased for data processing, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvealignment precisionVSAvoidprocessing system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces an external evaluation device as an intermediary that handles complex data processing tasks. This mediator receives actuator measurement data and control signals, performs comprehensive wear analysis and condition evaluation, and provides insights back to the control system. This approach improves manufacturing precision through advanced analysis while keeping the embedded control system simple and focused on real-time control functions

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3924793B1Open-loop control system, optical system and method
Publication Date: 2023.01.25 CARL ZEISS SMT GMBH
  • EP3924793B1 patent drawingFigure 1
  • EP3924793B1 patent drawingFigure 2
  • EP3924793B1 patent drawingFigure 3

AI summary

The invention relates to an open-loop control system (10), in particular for an optical system (100), comprising: an actuator (12), a measuring element (14) for acquiring actuator measurement data (15) of the actuator (12), a closed-loop control unit (20) for generating a control signal (13) for controlling the actuator (12) depending on the actuator measurement data (15), and a state-monitoring unit (30) for monitoring a state of the open-loop control system (10) depending on the acquired actuator measurement data (15).