Formal Verification of Astronaut-Rover Teams for Planetary Surface Operations

Abstract

This paper describes an approach to assuring the reliability of autonomous systems for Astronaut-Rover (ASRO) teams using the formal verification of models in the Brahms multi-agent modelling language. Planetary surface rovers have proven essential to several manned and unmanned missions to the moon and Mars. The first rovers were tele-or manuallyoperated, but autonomous systems are increasingly being used to increase the effectiveness and range of rover operations on missions such as the NASA Mars Science Laboratory. It is anticipated that future manned missions to the moon and Mars will use autonomous rovers to assist astronauts during extravehicular activity (EVA), including science, technical and construction operations. These ASRO teams have the potential to significantly increase the safety and efficiency of surface operations. We describe a new Brahms model in which an autonomous rover may perform several different activities including assisting an astronaut during EVA. These activities compete for the autonomous rovers "attention' and therefore the rover must decide which activity is currently the most important and engage in that activity. The Brahms model also includes an astronaut agent, which models an astronauts predicted behaviour during an EVA. The rover must also respond to the astronauts activities. We show how this Brahms model can be simulated using the Brahms integrated development environment. The model can then also be formally verified with respect to system requirements using the SPIN model checker, through automatic translation from Brahms to PROMELA (the input language for SPIN). We show that such formal verification can be used to determine that mission-and safety critical operations are conducted correctly, and therefore increase the reliability of autonomous systems for planetary rovers in ASRO teams.

Verifiable autonomy: From theory to applications

“…Our work in this area has particularly focussed on the Brahms framework, developed by Sierhuis and utilised by NASA [75], for which we have developed a formal verification framework [76]. In addition to examples of teamwork in social robotics, we also explore human-robot teamwork in more extreme environments [77].…”

“…Although many of the programming and verification techniques for agents described above are directly relevant to multi-agent systems, some of the work of the group has specificallly targetted these multi-agent aspects. These contributions include synchronisation across multiple agents [78], verification of coalitions [22,79], model-checking [80], verification of swarms [81][82][83][84], and verification of human-agent teamwork [76,77].…”

“…Primarily through UKRI funded projects on Engineering Autonomous Space Software and Future AI and Robotics for Space (FAIR-SPACE) we have applied our techniques to the Space domain. This work includes utilising BDI agent programming and simulation in space systems [106][107][108], the development and verification of astronaut-rover teamwork [77], verification and validation across space robotics [87,91,109,110], and work (with NASA) towards verification tool-chains supporting assurance [111].…”

A Review of Verification and Validation for Space Autonomous Systems

“…State-exploration methods are also available in a probabilistic setting, in which case one uses probabilistic temporal logics [14] and most prominently the PRISM model checker [15]. Some examples of verification using state-exploration methods are [16,17]. In [16], an autonomous agent developed using an agent programming language is used for simulated satellite control.…”

“…In [17], the authors present a Brahms model of an astronaut-rover teamwork scenario in which the astronaut and the rover work together to improve and maintain a newly established outpost on another planet. Brahms [20] is a framework for modeling human-robot teamwork.…”