Numerical Control Synchronization via Reception Time History
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Solution Overview
Problem
In synchronous control systems, synchronization accuracy is compromised due to retransmission of transfer data caused by noise, leading to incorrect time information correction and subsequent synchronization errors when the number of axes to be synchronized exceeds the control axes of a single numerical controller.
Innovation Solution
A numerical control system with a master and slave unit connected by a communication path, where the slave unit includes a reception time acquiring section, a retransmission detection section, and a reception time correcting section to detect and correct retransmission delays in synchronization information, ensuring accurate synchronization even with data retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data retransmission is performed due to transfer errors, then data integrity is improved, but synchronization accuracy deteriorates due to increased time intervals and incorrect lag detection
Solution Approach 1:
The system performs preliminary actions by recording the reception time of synchronization information in advance before any retransmission occurs. This recorded reception time is then used for lag correction even when retransmission happens, ensuring that the synchronization accuracy is not affected by the retransmission delay.
Solution Approach 2:
The invention creates a copy of the reception time information by recording it in advance. This copied time value is preserved and used for lag correction, independent of whether the original synchronization information is retransmitted. This allows the system to maintain accurate synchronization measurements even when data retransmission occurs.
2Adaptability or versatility
If clocks are set for each numerical controller, then individual control flexibility is improved, but synchronization between controllers deteriorates due to time information lag
Solution Approach 1:
The master unit transfers synchronization information including time stamps to the slave unit. The slave unit uses this feedback information to calculate the time lag between master and slave clocks, then applies correction to achieve accurate synchronization while maintaining individual clock operation.
Solution Approach 2:
The system changes the parameter of time information by calculating and applying lag correction values. This allows each numerical controller to maintain its own clock operation while adjusting the time parameters to achieve synchronization, balancing individual flexibility with coordinated operation.
3Reliability
If the control period is extended to accommodate retransmission, then data reliability is improved, but synchronization responsiveness deteriorates
Solution Approach 1:
The slave unit performs preliminary recording of reception times before retransmission delays occur. This allows the system to maintain the original control period timing for synchronization calculations, preventing any extension of the control period while still accommodating retransmission through the use of pre-recorded time data.
Data Source
AI summary
A master unit that controls a master axis and a slave unit that controls a slave axis are connected via a communication path to construct a numerical control system. The slave unit acquires a reception time of synchronization information received from the master unit and records a history of the reception time of the synchronization information. Then, when retransmission of transfer of the synchronization information is detected, the slave unit corrects the reception time of the synchronization information based on history data of the reception time and corrects asynchronous position of the slave axis based on a corrected reception time.