Control Scheduler for Fixed-Cycle Task Timing Under CPU Load

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In control devices with CPUs and OS, executing sophisticated information processing tasks alongside fixed cycle tasks leads to increased execution times for fixed cycle tasks due to CPU load, causing potential delays and incomplete processing in subsequent cycles.

Innovation Solution

A control device with a scheduler program that estimates the execution time of the next fixed cycle task and adjusts the execution time of the information processing task accordingly, ensuring the fixed cycle task is completed within the predetermined cycle by either stopping or reducing the information processing task's execution time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an information processing task is executed in the control cycle under execution, then CPU resource utilization is improved, but the execution time of the fixed cycle task in the next control cycle increases

Engineering Contradiction:

ImproveCPU resource utilizationVSAvoidexecution time of fixed cycle task

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The scheduler estimates the execution time of the fixed cycle task in the next control cycle before actually executing the information processing task in the current control cycle. Based on this preliminary estimation, the scheduler decides whether to execute the information processing task or suspend it, thereby preventing excessive execution time in the next control cycle while maximizing CPU utilization when safe

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If a sophisticated information processing task is executed in the control cycle under execution, then the variety of processes that can be executed is improved, but the reliability of the fixed cycle task execution is worsened

Engineering Contradiction:

Improvevariety of processes that can be executedVSAvoidreliability of fixed cycle task execution

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The scheduler continuously monitors the execution time of fixed cycle tasks and uses this feedback to make real-time decisions about whether to execute information processing tasks. When the execution time of a fixed cycle task exceeds a predetermined threshold, the scheduler suspends information processing task execution, thereby ensuring the reliability of fixed cycle task execution while still allowing sophisticated information processing when conditions permit

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20230401090A1Control device, control method, and non-transitory computer readable medium

Publication Date: 2023.12.14 OMRON CORP

AI summary

Provided is a control device which can reliably execute a fixed cycle task within a control cycle. A schedule program (212) executed in the control device (1): estimates an execution time of a fixed cycle program (230) as a fixed cycle task that is to be executed in a next control cycle, which is a following control cycle, in a control cycle under execution in which a prescribed cycle program is executed; and sets an execution time of an information processing program (235) as an information processing task that is executed in the control cycle under execution in response to the length of the estimated execution time as the estimation result.