Introducing robots to provide flexible logistics in a smart factory and cohabitation of robot workers and human operators will require robots to recognize and interpret the same cues in the environment as humans do. In this paper, we describe a novel method to detect machine light signal towers as one such cue that are frequently seen on production machines. It uses color information to determine basic regions of interest and applies a number of spatial constraints to make it robust against many common disturbances. As an option, the algorithm can use laser data for machine-specific reduction of the search space for a speed up by an order of magnitude providing fast, accurate, and robust detection. It recognizes the respective activation states and even blinking lights.