Method for synchronizing a combustion engine using a camshaft target

A module (M) for determining the angular position of a camshaft target (C) rigidly mounted on a camshaft (A) and having a plurality of teeth unevenly angularly distributed around the perimeter of the target, comprising a computing unit (CU) configured to:

• acquire a signal generated by a sensor (S) associated with the camshaft target, said sensor being configured to detect the passage of the teeth of the camshaft target and in response to generate a signal comprising rising edges and falling edges respectively associated with rising edges or falling edges of said teeth;
• the plurality of teeth forming, for the sensor, a series of M significant edges when the camshaft rotates one revolution, with each significant edge being associated with a predetermined index for the identification thereof;
• and
• compute the time intervals separating two significant edges of a series of M significant edges immediately succeeding each other on said signal;
• store, for each of the M significant edges:
• a theoretical ratio CP(j), with j ranging from 1 to M, determined based on known angular deviations P(j) between known significant edges of the teeth of the camshaft target;
• an associated tolerance interval INT(j), depending on the value assumed by the theoretical ratio CP(j) and a tolerance factor Ck;
• an associated confidence interval INTC(j), depending on the value assumed by the theoretical ratio CP(j) and a confidence factor Cc, with the confidence factor Cc being less than the tolerance factor Ck;
• associate a suspicion meter SU) and set it to a zero value;
• the computing unit is also configured to:
• /a/ define a sub-list of significant edges made up of all the significant edges;
• /b/ determine a current value assumed by a real ratio CT(k) depending on a first set of time intervals Tk, where the definition of the real ratio CT(k) is similar to the definition of the theoretical ratio CP(j) except that the known angular deviations are replaced by the corresponding time intervals Tk between the significant edges of the teeth of the camshaft target;
• /c/ discriminate, for each edge j in the list of candidate edges:
• if the current value assumed by the real ratio CT(k) does not belong to the tolerance interval INT(j) associated with said edge j:
• deleting said edge j from the list of candidate edges, with the suspicion meter S(j) then being assigned a predetermined value, called maximum value;
• then,
• otherwise, if the current value assumed by the real ratio CT(k) is outside the confidence interval INTC(j) associated with said edge:
• incrementing the current value of the suspicion meter S(j) associated with said edge in the list, then removing said edge j from the list of candidate edges when the suspicion meter is greater than the maximum value;
• /d/ wait for the reception of a new significant edge, replace each edge j in the list with its immediate successor j+1 modulo M, then repeat steps /b/ and /c/ until a single candidate edge is obtained in the list of significant edges;
• /e/ determine the angular position of the camshaft target based on the angular position of the single significant edge in the list of candidate edges.