Rough Road Detection System Used in an On-Board Diagnostic System

A rough road detector for a vehicle, comprising:

• a high pass filter configured to receive input of non-driven wheel speeds from wheel speed sensors, and to determine changes of wheel speed to produce an output indicating a current magnitude of roughness of a road surface;
• a rolling average filter configured to process the output of the high pass filter such that an average roughness of the road surface is determined over a predetermined time interval;
• and
• a comparator configured to compare an output from the rolling average filter to a first predetermined calibratable threshold to determine whether the average roughness of the road surface has exceeded the first threshold to determine a type of road surface;
• wherein the rough road detector is configured to output a flag to disable an error output of a diagnostic component of the vehicle or switch to an alternate calibration for the diagnostic component, to reduce false errors of the diagnostic component.

A method to reduce false positive error determinations from a diagnostic component in a vehicle traveling on a road, comprising:

• receiving input signals from wheel speed sensors;
• determining changes of the input signals using a high pass filter so that output signals from the high pass filter indicates a current magnitude of external roughness of the road surface;
• processing the output signals from the high pass filter using a rolling average filter so that a roughness level is determined over a predetermined time interval;
• comparing the output signals from the rolling average filter to a predetermined threshold;
• and
• disabling an error output of the diagnostic component if the roughness level has exceeded the predetermined threshold.