Runtime Analysis with R2U2: A Tool Exhibition Report

We present R2U2 (Realizable, Responsive, Unobtrusive Unit), a hardware-
supported tool and framework for the continuous monitoring of safetycritical
and embedded cyber-physical systems.With the widespread advent of autonomous
systems such as Unmanned Aerial Systems (UAS), satellites, rovers,
and cars, real-time, on-board decision making requires unobtrusive monitoring
of properties for safety, performance, security, and system health. R2U2 models
combine past-time and future-time Metric Temporal Logic, “mission time” Linear
Temporal Logic, probabilistic reasoning with Bayesian Networks, and modelbased
prognostics. The R2U2 monitoring engine can be instantiated as a hardware solution, running
on an FPGA, or as a software component. The FPGA realization enables R2U2
to monitor complex cyber-physical systems without any overhead or instrumentation
of the flight software. In this tool exhibition report, we present R2U2 and
demonstrate applications on system runtime monitoring, diagnostics, software
health management, and security monitoring for a UAS. Our tool demonstration
uses a hardware-based processor-in-the-loop “iron-bird” configuration.