controller output maps is an array of counters the same size as the controller output maps at each controller sampling interval the nearest point to the current operating point on the grid over which the controller output map is defined is identified the corresponding element in the counter array is then incremented these counters are reset after each adaptation interval if during an adaptation interval the counter corresponding to a particular location on the grid is equal to or greater than one then the fuzzy rule which corresponds to this counter is termed 34 a modification driving fuzzy rule 34 and if the counter is zero the fuzzy rule is termed 34 a modification following fuzzy rule 34 the two types of rules are modified differently it will be appreciated that a threshold other than one could be used to distinguish between the two types of rules when modifying the controller maps the powertrain output torque should remain constant this means that if the throttle angle is reduced the demanded electric motor armature current should increase the relative amounts of change that should be made to the controller output variables is defined using information about the internal combustion engine 14 and the electric motor 16 this information defines a direction in fig3 along which the points in the controller maps defined by the crosses in fig3 should move regardless of whether the controller output sets are classified as modification drivers or followers the points represented by the crosses in fig3 are always moved in a direction which maintains the powertrain output torque the information about the internal combustion engine and electric motor used to define the direction in which the points in fig3 move relates.