detected using sensors by means of a sensor arrangement 1 which is assigned a sensor element 2 3 which is preferably in the form of a proximity sensor here and a sensor controller 4 the exemplary embodiment illustrated here involves a sensor arrangement 1 having precisely two sensor elements 2 3 as also explained below the sensor controller 4 is primarily used to generate an operator control message as soon as an actual operator control event is present this operator control message is then used to trigger downstream processes for example an authentication dialog or the control of a drive the generation of an operator control message is based on the results of operator control event monitoring during which the sensor controller 4 is used to monitor the sensor measured values 5 6 of at least one sensor element 2 3 for the occurrence of a behavior of the sensor measured values 5 6 which is characteristic of the operator control event to be detected the sensor controller 4 preferably operates cyclically with the result that the above monitoring is carried out cyclically in particular the operator control event monitoring is carried out continuously here that is to say constantly or in any case at particular cycle intervals over a monitoring period in this case the operator control event to be detected is preferably a foot movement of the user of.