Abstract: A rough road detection system for an engine having a crankshaft includes a control module and a comparison module. The control module receives a crankshaft speed signal and determines a crankshaft rotation time and a crankshaft acceleration and jerk. The crankshaft rotation time is based on said crankshaft speed signal. The crankshaft acceleration and jerk are based on said crankshaft rotation time. The control module detects a crankshaft disturbance based on said crankshaft acceleration and jerk and counts a number of crankshaft disturbances. The comparison module determines a dispersion value and asymmetry value based on the crankshaft disturbances and determined whether rough road conditions exist based on first and second comparisons. The first comparison is between the dispersion value and a first predetermined threshold. The second comparison is between the asymmetry value and a second predetermined threshold.

Abstract: The present invention generally includes a method of detecting a misfire in an internal combustion engine. The method includes detecting a first engine speed at a first crankshaft position that corresponds to about a top dead center compression position of a first piston within a first cylinder and detecting a second engine speed at a second crankshaft position that corresponds to about a position subsequent to the top dead center compression position. The method determines whether the misfire occurred in the first cylinder based on the first engine speed and the second engine speed. The method provides an improved signal to noise ratio for engine misfire detection.

Abstract: A rough road detection system includes a collection module, a statistical module, and a comparison module. The collection module collects samples from a vibration sensitive signal. The statistical module removes a periodic anomaly from the samples and removes a random anomaly from the samples with a filter having a filter coefficient based on an engine speed signal. In addition, the statistical module calculates a statistical signal based on the samples. The rough road detection system also includes a derivative module that calculates a first and second derivative based on a rate or time. The derivative module removes negative derivatives when the derivatives are calculated with respect to the rate and positive derivatives when the derivatives are calculated with respect to time. The comparison module determines whether a rough road condition exists based on the statistical signal or the first and second derivatives.

Abstract: A cruise control system for a vehicle includes a throttle and a controller. The controller determines an open-loop speed compensation factor and calculates a closed-loop speed compensation factor. The controller determines a throttle area based on the open-loop speed compensation factor and the closed-loop speed compensation factor and operates the throttle based on the throttle area.