Autonomous mobile machines are becoming more common in specific applications. Technologies have developed a lot, but full autonomy has not yet been reached in various outdoor environments. Driverless cars have driven tens of millions documented kilometres and there is already some experience. Safety measures of autonomous cars rely on on-board safety sensors and intelligence, which can maintain safety in various conditions. Autonomous mobile machines have also perception and positioning sensors, but quite often safety relies on complete fleet management and area access control systems. The access to the autonomous area is usually limited when the area is in automated mode. The complete autonomous mobile machine system contains many kinds of subsystems related e.g. to perception, positioning, access control and fleet control. A failure of a subsystem can be hazardous unless safety measures of the subsystems are well integrated and interlocked with each other.