Start-up Deadline Mechanism for Distributed Control Packet Synchronization
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Solution Overview
Problem
In distributed control systems, communication uncertainties lead to communication delays and packet losses, making it difficult to ensure reliable and efficient control operations, especially when using shared networks like public networks, which can result in issues like double start-ups or delayed start-ups of control operations.
Innovation Solution
A communication method that includes a packet with a command for controlling devices, identification information, and a start-up deadline, allowing the central control device to synchronize with individual control devices and prevent malfunctions such as double start-ups or excessive outputs by setting appropriate start-up deadlines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a public network is used for economic efficiency, then cost is reduced, but communication reliability and real-time performance deteriorate due to packet loss and delays
Solution Approach 1:
The patent applies preliminary action by setting a start-up deadline in advance within the control packet. This deadline is determined before transmission based on the time-out period and processing time. The individual control device uses this pre-set deadline to determine whether to execute the control command, preventing double start-ups without requiring complex real-time communication protocols or redundant acknowledgment mechanisms that would increase system cost.
2Reliability
If a time-out mechanism is used to handle packet loss, then communication reliability improves, but double start-ups occur due to retransmission of control packets
Solution Approach 1:
The patent applies preliminary anti-action by equipping the individual control device with the ability to autonomously determine whether to execute a control command based on the start-up deadline. When the current time exceeds the deadline, the device prevents execution, counteracting the potential harmful effect of retransmitted packets causing double start-ups. This eliminates the need for complex acknowledgment mechanisms while maintaining reliability.
3Reliability
If the central control device waits for acknowledgment packets to confirm transmission, then communication reliability improves, but communication delay increases due to acknowledgment packet loss
Solution Approach 1:
The patent extracts the transmission confirmation function from the traditional acknowledgment packet mechanism. Instead of relying on acknowledgment packets that are susceptible to loss and delay, the central control device determines transmission success based on whether the individual control device executes the control command within the start-up deadline. This separates the confirmation mechanism from the control command transmission, eliminating acknowledgment-related delays and packet loss issues.
4Reliability
If a dedicated communication network is used for real-time performance, then communication reliability improves, but system construction cost increases
Solution Approach 1:
The patent applies self-service by enabling the individual control device to autonomously determine whether to execute a control command based on the start-up deadline embedded in the packet. This self-determination mechanism allows the use of cost-effective public networks while maintaining real-time performance, as each device independently ensures timely execution without requiring expensive dedicated network infrastructure or complex network-level quality of service mechanisms.
Data Source
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AI summary
The present invention is applied to a distributed control system in which a plurality of control devices (a central control device, an individual control device, and the like) are connected via a network. For example, the central control device executes a start-up deadline determination processing for setting a start-up deadline in consideration of the performance of a device to be controlled, and communication processing for transmitting a packet including identification information of a command and information of the start-up deadline to the individual control device. For example, when receiving the packet transmitted from the central control device, the individual control device controls execution of the command on the device to be controlled on the basis of the start-up deadline included in the packet.