Redundant Control System Seamless Switchover
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Solution Overview
Problem
Dual redundant control systems with a primary/secondary hierarchy in electromechanical systems suffer from control interruptions due to failure detection time and switchover processes, particularly affecting high-speed control loops.
Innovation Solution
A redundant control system with two processors, a communication node, and signal selector, where both processors execute identical control algorithms and state variables, allowing seamless transfer of control without interruptions by synchronizing and selecting between output signals from either processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary/secondary hierarchy is used with two processors, then redundancy is achieved, but control interruptions occur during failure detection and switchover
Solution Approach 1:
The standby processor is pre-configured with identical control algorithms and state variables, and both processors simultaneously execute the control algorithm before any failure occurs. This preliminary synchronization ensures that when a failure happens, the standby processor can immediately take over without requiring failure detection or reconfiguration, thereby eliminating control interruptions while maintaining redundancy
Solution Approach 2:
The system uses two identical processor copies that both execute the same control algorithm simultaneously. Each processor has its own communication channel and output signal, creating redundant copies of the control function. This copying approach allows immediate failover without the need for detection or switchover procedures, resolving the contradiction between redundancy and control continuity
2Difficulty of detecting and measuring
If failure detection is implemented in the primary/secondary system, then processor failures can be identified, but the detection time causes control interruptions
Solution Approach 1:
Both processors continuously execute the control algorithm and generate output signals simultaneously, ensuring that the useful control action never stops. The signal selector continuously receives output signals from both processors, and the electromechanical system continuously receives control signals without interruption. This continuous execution eliminates the need for failure detection before taking over, as the standby processor is already performing the control function
Solution Approach 2:
The system performs preliminary synchronization of state variables between both processors before any failure occurs. This preliminary action ensures that both processors are already in the correct state to execute the control algorithm, eliminating the need for post-failure detection and reconfiguration actions that would cause interruptions
3Reliability
If switchover is implemented to transfer control from primary to secondary processor, then redundancy is maintained, but re-routing of input/output packets causes control interruptions
Solution Approach 1:
The system segments the control architecture by providing separate communication channels for each processor. The first processor has its own communication channel and the second processor has its own communication channel, both connecting to the electromechanical system. This segmentation eliminates the need for re-routing, as each processor can independently communicate with the system without sharing packets through a common path that would require redirection during switchover
Data Source
AI summary
A redundant control system for controlling an electromechanical system is provided. The control system includes a first processor, a second processor, an input-output node, a first communication channel, a second communication channel, and a signal selector. The first and second processors have a control algorithm and state variables resident thereon. The first and second processors each generate an output signal based on the control algorithm, the state variables, and an input signal from the electromechanical system. The first communication channel communicates the input signal and the output signal between the first processor and the input-output node, while the second communication channel communicates the input signal and the output signal between the second processor and the input-output node. The signal selector communicates either the output signal from the first processor or the output signal from the second processor to the electromechanical system.