Electronic traction control

A computer program product, tangibly stored on a non-transitory computer-readable storage medium, for performing vehicle traction control, the product comprising computer program instructions operable to cause a processor to perform operations comprising:

• measuring time intervals between points of rotation on a rotating vehicle output shaft, wherein the discrete points are substantially equally spaced around a circumference of the discrete shaft, wherein measuring the time intervals between the points of rotation includes:
• (a) measuring a time interval between (i) receiving an indication that a first discrete point on the shaft has rotated past a fixed reference point, and (ii) receiving an indication that a second discrete point on the shaft has rotated past the fixed reference point, or
• (b) measuring a time interval between (i) receiving an indication that a discrete point on the shaft has rotated past a first fixed reference point, and (ii) receiving an indication that the discrete point on the shaft has rotated past a second fixed reference point;
• generating indicators of shaft rotation rate using, for each generated indicator, a set of time intervals equivalent to one or more full rotations of the shaft, wherein each generated indicator identifies a rate of shaft rotation for a different period of time;
• using at least two generated indicators of shaft rotation rate to determine a value indicating a rate of change in shaft rotation rate;
• computing an indicator of a maximum allowable output shaft rotation rate by adding to a previous indicator of output shaft rotation rate the value indicating the determined rate of change in shaft rotation rate and a threshold value associated with an acceptable increase in a rate of change in shaft rotation rate;
• determining that a current indicator of output shaft rotation rate exceeds the maximum allowable output shaft rotation rate, wherein the current indicator is for a time that is subsequent to a time for the previous indicator, wherein the maximum allowable output shaft rotation rate is computed as a maximum rotation rate for a same time as the current indicator;
• and
• outputting, in response to determining that the current indicator exceeds the maximum allowable output shaft rotation rate, a signal to trigger application of a traction control mechanism, wherein the signal is not output if the current indicator is not determined to exceed the maximum allowable output shaft rotation rate.

A system for performing vehicle traction control, the system comprising:

• a means to determine time intervals between each rotation of multiple points of rotation of an output shaft of a vehicle power unit past a position sensor, wherein determining the time intervals includes:
• (a) measuring a time interval between (i) receiving an indication that a first discrete point on the shaft has rotated past a fixed reference point, and (ii) receiving an indication that a second discrete point on the shaft has rotated past the fixed reference point, or
• (b) measuring a time interval between (i) receiving an indication that a discrete point on the shaft has rotated past a first fixed reference point, and (ii) receiving an indication that the discrete point on the shaft has rotated past a second fixed reference point;
• a rate determination unit to generate indicators of shaft rotation rate using, for each generated indicator, a set of one or more of the identified time intervals, wherein each generated indicator identifies a representation of a rate of shaft rotation over a different time interval;
• an acceleration determination unit to determine values indicative of acceleration of the shaft, the values determined using two or more of the generated indicators of shaft rotation rate a maximum rate determination unit to compute indicators of maximum allowable shaft rotation rate based on previous indicators of shaft rotation rate and values indicative of acceleration of the shaft;
• and
• a comparator to determine that a current indicator of output shaft rotation rate exceeds a maximum allowable shaft rotation rate that was computed for a same time interval as the current indicator, and to output, in response to the determination that the current indicator exceeds the maximum allowable shaft rotation rate, a signal to trigger application of a traction control mechanism.