Field Device Control With Position Prediction for Network Synchronization
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Solution Overview
Problem
Existing control systems face challenges in synchronizing operations between master and slave devices due to communication cycle delays, particularly in industrial automation where devices operate in different execution formats, such as IEC and application programs.
Innovation Solution
A control device that estimates the position of a master field device in a subsequent cycle and calculates a command value for a slave device to accommodate communication delays, using a correction coefficient determined by the types of devices involved, allowing for synchronized operation across different execution formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If periodic communication is used to control field devices through a network, then device integration and communication efficiency are improved, but communication cycle delays cause asynchronization between master and slave device operations
Solution Approach 1:
The system performs preliminary estimation of the master device's position in a subsequent cycle before the actual operation occurs. By calculating the predicted position in advance and using it to determine the slave device's command value, the system compensates for communication delays proactively rather than reactively, enabling synchronous control despite periodic communication latency
2Adaptability or versatility
If different execution formats (IEC and application programs) are used to control diverse field devices, then device compatibility and control flexibility are improved, but synchronization between devices with different timing characteristics becomes difficult
Solution Approach 1:
The system changes the timing parameter by estimating the master device's position at a future time point (subsequent cycle) rather than using the current position. This parameter transformation allows the slave device to be controlled based on predicted future state, compensating for different execution formats and timing characteristics between IEC and application programs
3Speed
If command values are transmitted in every control cycle, then control responsiveness is improved, but the slave device cannot compensate for delays in receiving and processing commands
Solution Approach 1:
The system prepares the command value in advance by estimating the master device's position in the subsequent cycle before transmission occurs. This preliminary calculation ensures that when the command value is transmitted in the current control cycle, the slave device can execute it immediately with accurate timing, compensating for processing delays
Data Source
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AI summary
To cause multiple field devices to operate together in coordination in accordance with a predetermined program through a network allowing periodic communication, a control device includes an estimator that calculates, based on a position of a first field device in a first cycle, a position of the first field device operable in accordance with a first program in a second cycle following the first cycle, and a processor that determines, based on the first program, a first command value to cause the first field device to operate, transmits the first command value to the first field device through an interface allowing communication with the field devices, determines, based on the estimated position and a second program, a second command value to cause a second field device to operate in coordination with the first field device, and transmits the second command value to the second field device through the interface.