Biblio

As multi-agent systems become ubiquitous, guaranteeing safety in these systems grows increasingly important. In applications ranging from automated cruise control to safety in robot swarms, barrier functions have emerged as a tool to provably meet safety constraints by guaranteeing forward invariance of a set. However, a single barrier function can rarely satisfy all safety aspects of a system, so there remains a need to address the degree to which multiple barrier functions may be composed through Boolean logic. Utilizing max and min operators represents one such method to accomplish Boolean composition for barrier functions. As such, the main contribution of this work extends previously established concepts for barrier functions to a class of nonsmooth barrier functions that operate on systems described by differential inclusions. To validate these results, a Boolean compositional barrier function is deployed onto a team of mobile robots.

This paper addresses the problem of event-triggered control of linear time-invariant systems over time-varying rate limited communication channels, including the possibility of channel blackouts, which are intervals of time when the communication channel is unavailable for feedback. In order to design an effective event-triggered controller that operates successfully even in the presence of blackouts, we analyze the channel data capacity, which is the total maximum number of bits that could be communicated over a given time interval. We provide an efficient real-time algorithm to estimate the channel capacity for a time-slotted model of channel evolution. Equipped with this algorithm we then propose an event-triggering scheme, which using prior knowledge of the channel information, guarantees exponential stabilization at a desired convergence rate despite intermittent channel blackouts. The contributions are the notion of channel blackouts, the effective control despite their occurrence, and the analysis and quantification of the data capacity for a class of time-varying continuous-time channels.

This chapter describes triggered control approaches for the coordination of networked cyber-physical systems. Given the coverage of the other chapters of this book, our focus is on self-triggered control and a novel approach we term team-triggered control.

The Controller Area Network (CAN) protocol has become the primary choice for in-vehicle communications for passenger cars and commercial vehicles. However, it is possible for malicious adversaries to cause major damage by exploiting flaws in the CAN protocol design or implementation. Researchers have shown that an attacker can remotely inject malicious messages into the CAN network in order to disrupt or alter normal vehicle behavior. Some of these attacks can lead to catastrophic consequences for both the vehicle and the driver. Although there are several defense techniques against CAN based attacks, attack surfaces like physically and remotely controllable Electronic Control Units (ECUs) can be used to launch attacks on protocols running on top of the CAN network, such as the SAE J1939 protocol. Commercial vehicles adhere to the SAE J1939 standards that make use of the CAN protocol for physical communication and that are modeled in a manner similar to that of the ISO/OSI 7 layer protocol stack. We posit that the J1939 standards can be subjected to attacks similar to those that have been launched successfully on the OSI layer protocols. Towards this end, we demonstrate how such attacks can be performed on a test-bed having 3 J1939 speaking ECUs connected via a single high-speed CAN bus. Our main goal is to show that the regular operations performed by the J1939 speaking ECUs can be disrupted by manipulating the packet exchange protocols and specifications made by J1939 data-link layer standards. The list of attacks documented in this paper is not comprehensive but given the homogeneous and ubiquitous usage of J1939 standards in commercial vehicles we believe these attacks, along with newer attacks introduced in the future, can cause widespread damage in the heavy vehicle industry, if not mitigated pro-actively.