"Six years after the First Workshop on Robotic Autonomous Observatories, the number of automatic astronomical facilities worldwide continues to grow, and the level of robotisation, autonomy, and networking is increasing as well, with further strong impact in many astrophysical fields, like the search for extra-solar planets, the monitoring of variable stars in our Galaxy, the study of active galactic nuclei, the detection and monitoring of supernovae, and the immediate follow-up of high-energy transients such as gamma-ray bursts. The manuscripts published in these Conference Series of the Revista Mexicana de Astronomía y Astrofísica are the fruit of the IV Workshop on Robotic Autonomous Observatories held in Torremolinos, Málaga (Spain) on September 28 - October 2, 2015. The main focus of the workshop was to deal with the new and existing astronomical facilities whose goal is to observe a wide variety of astrophysical targets with no (or very little) human interaction. The workshop became an international forum for researchers to summarise the most recent developments and ideas in the field, with a special emphasis given to the technical and observational results obtained within the last two years."--Preface.