Virtual-Time PLC Simulation for Accurate Machine Operation Sequencing
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Solution Overview
Problem
The computing speed disparity between simulation computers and programmable logic controllers leads to differing execution orders of program modules, resulting in simulations that do not accurately represent real machine operations, necessitating complex time estimation procedures that extend simulation times.
Innovation Solution
A method where the execution pattern of software code on a simulation computer is defined using virtual time with zero execution times for processes, ensuring deterministic execution and matching real-time operations by resetting virtual time based on the simulation computer's clock, allowing for accurate simulation without estimating instruction execution times on the programmable logic controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the computing speed of the simulation computer is increased to improve simulation speed, then the execution order of program modules differs from the real programmable logic controller, but if the computing speed is reduced to match the real controller, then the simulation time is excessively extended
Solution Approach 1:
The patent introduces a timing adjustment mechanism as an intermediary between the simulation computer's fast processing and the PLC's slower processing. The simulation computer executes instructions rapidly but adjusts the timing of program module executions to match the PLC's execution order, effectively mediating between the speed advantage of the simulation computer and the accuracy requirement of matching PLC behavior
Solution Approach 2:
The patent changes the time parameter in the simulation by introducing timing adjustments that compensate for the speed difference. By modifying when program modules are executed in the simulation (rather than when they are processed), the system maintains fast processing speeds while achieving accurate temporal behavior that matches the real PLC execution order
2Reliability
If time estimation procedures are implemented to adjust execution times on the simulation computer, then the execution order accuracy is improved, but the simulation time is extended
Solution Approach 1:
The patent performs preliminary analysis of the program structure and execution priorities before running the simulation. By pre-determining the execution order and timing adjustments needed, the system avoids complex real-time time estimation procedures during simulation execution, thus maintaining both accuracy and efficiency
Data Source
AI summary
A method for computer-supported simulation of operation of a machine working in an automated manner, the machine being controllable during real operation via software on a programmable logic controller, wherein simulated control of the machine via software on a simulation computer is performed based on a predefined execution pattern, where the temporal execution sequence of processes executed by the software code and starting time points of processes are defined based on a virtual time and the execution time point of each process is set to zero in the virtual time in the predefined execution pattern, and during the simulation, the next process, which follows an ended process according to the execution sequence, is not started until a process in the real time of the simulation computer has ended, and where the virtual time is set to the starting time point of this next process when the next process is started.