A method of controlling an illumination system for an autonomous vehicle is provided. The method includes: storing, in a memory, a plurality of lighting pattern definitions for controlling the illumination system; receiving, at a processor connected to the memory and the illumination system, state data defining a current state of the autonomous vehicle; at the processor, determining whether each of a plurality of ranked sub-states is active in the autonomous vehicle, based on the state data; at the processor, selecting one of the lighting pattern definitions corresponding to the highest ranked sub-state determined to be active in the autonomous vehicle; and controlling the illumination system according to the selected lighting pattern definition.