Event-Based OS for Instrumentation Control Systems
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Solution Overview
Problem
Existing nuclear reactor Standby Liquid Control (SLC) systems face challenges in efficiently managing multiple timing events with limited hardware timers, leading to increased code complexity and maintenance costs due to the use of global variables and round-robin task execution in OS.
Innovation Solution
A method and system utilizing a non-preemptive event-based operating system that employs a limited number of hardware timers to manage multiple timing events by updating an event control block with time remaining, time past due, and priority information, activating timed-out events, and sending notifications to programs, allowing for efficient timing of events without the need for additional hardware timers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a round-robin task oriented OS is used to monitor multiple timing events, then all tasks can be executed systematically, but the code complexity increases and maintenance cost increases due to global variables and unnecessary task execution
Solution Approach 1:
The patent extracts the timing event management from the round-robin task structure by implementing an event-driven architecture where only relevant tasks are executed in response to specific events. This eliminates unnecessary task executions and reduces code complexity while maintaining reliable timing event monitoring through direct event handlers.
Solution Approach 2:
Instead of using a traditional round-robin approach where all tasks are executed periodically regardless of necessity, the patent inverts the control structure by having events trigger specific task executions. This event-driven inversion reduces unnecessary code execution and simplifies the overall system architecture.
2Reliability
If global static variables are used as counters for each timer to monitor multiple timing events, then timing events can be monitored, but the design of interfaces becomes more complicated and module interdependence increases
Solution Approach 1:
The patent segments the timing event monitoring into independent event control blocks, each managing specific timing events without requiring global variables. This segmentation isolates interface designs and reduces module interdependence, as each event handler operates independently with its own localized data structures.
Solution Approach 2:
The patent introduces event control blocks as intermediaries between the timer hardware and the task execution system. These blocks act as mediators that manage timing events locally without requiring global static variables, thereby simplifying interface design and reducing direct interdependence between modules.
3Adaptability or versatility
If more simultaneous timers are required than are available in a single microcontroller, then more timing events can be monitored, but additional hardware timers are needed which increases system complexity
Solution Approach 1:
The patent implements a single hardware timer that serves multiple timing events simultaneously through software management. The timer is configured to generate interrupt signals that are handled by different event control blocks, allowing one hardware timer to perform the function of multiple timers and enabling the system to monitor more timing events without additional hardware.
Solution Approach 2:
The patent creates software copies of timer functionality through event control blocks that simulate multiple timer behaviors using a single hardware timer. Each event control block maintains its own counter and timing logic in software, effectively copying the timer function for different events without requiring duplicate hardware timers.
Data Source
AI summary
A method for operating a controller having a number of timers to thereby control a plurality of events greater than the number of timers, includes, between clock ticks, receiving one or more signals from sensors, switches, executing programs, or a combination therefore that initiate one or more timed events. After a clock tick immediately following the receiving of the one or more signals, the method further includes updating entries in an event control block in accordance with the received signal or signals. The entries include a time remaining for pending events, a time past due for active events, and a priority of each event. The method further includes determining whether any pending event or events have timed out, activating any timed out events, and sending a signal notifying an executing program of the activated event having the highest priority.