RTLola Cleared for Take-Off: Monitoring Autonomous Aircraft

Abstract

The autonomous control of unmanned aircraft is a highly safety-critical domain with great economic potential in a wide range of application areas, including logistics, agriculture, civil engineering, and disaster recovery. We report on the development of a dynamic monitoring framework for the DLR ARTIS (Autonomous Rotorcraft Testbed for Intelligent Systems) family of unmanned aircraft based on the formal specification language RTLola. RTLola is a stream-based specification language for real-time properties. An RTLola specification of hazardous situations and system failures is statically analyzed in terms of consistency and resource usage and then automatically translated into an FPGA-based monitor. Our approach leads to highly efficient, parallelized monitors with formal guarantees on the noninterference of the monitor with the normal operation of the autonomous system.

Monitoring Cyber-Physical Systems: From Design to Integration

“…Even though the specification is rather small, it gives a glimpse at how low the resource consumption actually is. Baumeister et al [6] successfully synthesized larger specifications designed for autonomous aircraft on the same fpga.…”

“…Consider, for example, the system architecture of the autonomous aircraft su-perARTIS of the German Aerospace Center (DLR) depicted in Figure 4. When integrating a monitor for the optical navigation rail into the aircraft [6], the monitor was placed near the logging component. By design, the logger had access to all relevant data.…”

“…During the design phase of the CPS, the specifier defines properties spanning from validation of low-level input sensor readings to high-level mission-specific control decisions. The former are real-time critical, i.e., they demand a timely response from the monitor, whereas the latter include long-term checks and statistical analysis [6] where slight delays and mild inaccuracies are unsubstantial. Just like code is not a perfect reflection of what the programmer had in mind, the specification might deviate from the specifiers intention.…”

RTLola on Board: Testing Real Driving Emissions on your Phone

“…Lola combines the ease-of-use of rule-based specification languages with the expressive power of heavy-weight scripting languages or temporal logics. The eponymous framework generates runtime monitors for such specifications, which were successfully deployed, for instance, on unmanned aircraft [18,2].…”

Automatic Optimizations for Stream-Based Monitoring Languages

“…A prime application area for our optimizations is the monitoring of unmanned aircraft systems (UAS) [2]. Monitoring aircraft involves complex computations, such as the crossvalidation of different sensor modules.…”