Controller Clock Synchronization With Stepwise Time Adjustment

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Solution Overview

Problem

Current time synchronization methods in device control systems face challenges in uniformly managing time across multiple devices, particularly when fluctuations in global time occur, leading to inaccuracies in device control operations.

Innovation Solution

A controller with a controller clock management unit that synchronizes the internal controller clock with an external global clock, adjusts the controller time in a stepwise manner to absorb fluctuations, and notifies local devices through periodic communication, ensuring consistent time management across the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the controller directly synchronizes with the global clock, then time synchronization accuracy is improved, but the system becomes sensitive to large time fluctuations that can disrupt device control operations

Engineering Contradiction:
Improvetime synchronization accuracyVSAvoidsystem stability under time fluctuations
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The controller introduces a buffer mechanism that absorbs time fluctuations before they reach the device control system. By accumulating time differences and releasing them gradually, the system cushions against sudden time changes from the global clock, maintaining stable device operations while still achieving accurate time synchronization.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The controller dynamically adjusts its time synchronization strategy by switching between different modes: accumulating time differences when fluctuations occur, and synchronizing with the global clock when stable. This dynamic adaptation allows the system to maintain both accuracy and reliability under varying time conditions.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the controller uses stepwise time adjustment to absorb fluctuations, then system stability is improved, but the response time to global time changes increases

Engineering Contradiction:
Improvesystem stabilityVSAvoidtime response delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The controller employs periodic time synchronization cycles, alternating between accumulating time differences and synchronizing with the global clock. This periodic action allows the system to maintain stability through gradual adjustments while ensuring timely synchronization at regular intervals, balancing stability with responsive time updates.

Inventive Principle:
Principle #19Periodic action

3Reliability

If the controller transmits time data periodically to local devices, then uniform time management across the system is achieved, but the complexity of time synchronization coordination increases

Engineering Contradiction:
Improveuniform time managementVSAvoidsynchronization coordination complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The controller acts as an intermediary between the global clock and local devices, translating and adapting global time information into locally suitable time data. This intermediary role simplifies the synchronization coordination by centralizing time management logic in the controller, allowing local devices to receive pre-processed time data without needing to directly coordinate with the global clock.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4050428B1Time synchronization of a local device
Publication Date: 2025.01.08 YASKAWA DENKI KK
  • EP4050428B1 patent drawingFigure 1
  • EP4050428B1 patent drawingFigure 2
  • EP4050428B1 patent drawingFigure 3

AI summary

A controller includes: a controller clock management unit configured to receive global time data indicating a global time associated with an external global clock, synchronize an internal controller clock of the controller with the global clock based on the global time, and set a controller time based on the synchronized controller clock; and a notification unit configured to transmit controller time data indicating the controller time to at least one local device through periodic communication.