´Soft real time´ for simulation under Windows NT using adjustable Euler time step and Six Sigma

This paper outlines a simple, robust and statistically verifiable simulation time regulator for accurate scheduling of ´soft real time´ threads under Windows NT for running simulations with real time industrial controllers that can communicate process I/O over Ethernet. Six Sigma is applied to the simulation time regulator to ascertain the best set of parameters for minimum jitter (maximum integrator accuracy on an individual time step basis). The results indicate a mean Euler Δt variance of 200 μs down from a baseline of greater than 1 ms variations without the method (an 83% reduction), with Δt<10 ms. The majority of this remaining variation appears to be caused by bimodal scheduling behavior on dual processor (SMP) PCs. Additionally, with this method the simulation automatically settles at the most optimum Δt given current PC loading, with minimum Δt variation, δT