The invention describes a method of controlling an autonomous device (1), which autonomous device records ambient data and optionally transmits the recorded ambient data, which method comprises positioning an indicator (S.sub.1, S.sub.2, S.sub.3, S.sub.4) at a boundary (B) between a private area (P) and a non-private area (N) to optically distinguish the private area (P) from the non-private area (N) for a user of the autonomous device (1). The indicator (S.sub.1, S.sub.2, S.sub.3, S.sub.4) is detected by the autonomous device (1) and interpreted to determine whether the autonomous device (1) is in a private area (P) or a non-private area (N). Subsequently, recording or transmission of ambient data is restricted while the autonomous device (1) is within the private area (P). The invention also describes a system ( ) for controlling an autonomous device (1), an autonomous device (1), and an indicator (S.sub.3, S.sub.4) for placement at a boundary between a private area (P) and a non-private area (N), to optically distinguish the private area (P) from the non-private area (N) for a user (2), comprising a number of electronically detectable components (23, 24).