Mueller, M., "Engine Stop Position Estimation," SAE Int. J. Engines 5(2):602-607, 2012, doi:10.4271/2012-01-0720.
This paper describes a method to estimate the engine stop position using any production style crank position sensor, while accounting for possible engine rock-back. The approach is based on modeling the engine speed state, achieving robustness and ease of calibration by adapting the rubbing friction model component during the first part of engine coast-down, followed by open-loop modeling when the engine speed has dropped below the sensor signal validity threshold.