  We present Distributed Simplex Architecture (DSA), a new runtime assurance
technique that provides safety guarantees for multi-agent systems (MASs). DSA
is inspired by the Simplex control architecture of Sha et al., but with some
significant differences. The traditional Simplex approach is limited to
single-agent systems or a MAS with a centralized control scheme. DSA addresses
this limitation by extending the scope of Simplex to include MASs under
distributed control. In DSA, each agent has a local instance of traditional
Simplex such that the preservation of safety in the local instances implies
safety for the entire MAS. We provide a proof of safety for DSA, and present
experimental results for several case studies, including flocking with
collision avoidance, safe navigation of ground rovers through way-points, and
the safe operation of a microgrid.
