Entrainment as a paradigm for modelling a planetary robot's circadian rhythm

Abstract

The Aurora Project aims to create and implement a European long-term plan for the exploration of the Solar System, culminating in a human expedition to Mars by 2030. Recognised steps along the way include the robotic exploration of Mars and a robotic outpost. Necessary to autonomous robotic missions is activity coordination with the day-night cycle. This paper describes work undertaken as part of a research project looking at using the phenomenon of entrainment as a means of generating a robotic circadian rhythm that will adapt as the day changes due to changing seasons or changing global position. This work is aimed at increasing robot autonomy without the need for explicit programming. It is based upon a model of the human sleep-wake cycle proposed by Gander et al [1][2]. The model is comprised of two coupled Van-der-Pol oscillators that represent the internal rhythms within the body, they are acted upon by a sinusoidal stimulus representing the external day-night cycle. The phase of the external stimulus was either advanced or delayed by 1 hour, 5 hours and 10 hours and the re-entrainment of the oscillators was observed. The results show that the time taken for the system to re-entrain depends on the magnitude of the phase advance or delay. Proposed future applications to space robotics are also discussed.