Tingting Hu

Software-based assessment of the synchronization and error handling behavior of a real CAN controller

Although the Controller Area Network (CAN) technology is very mature, the behavior of real CAN controllers under marginal operating conditions is still of practical interest as CAN is being deployed in a variety of application domains. In this paper, we propose a test software architecture able to extensively investigate the reaction of a typical CAN controller when subject to various kinds of error and different timing scenarios. Both the analysis technique and the test software use a black-box approach and do not require any modification of, or access to, the internal structure of the controller itself. They are therefore readily applicable with low effort to different hardware. Possible applications include diagnostic and reliability analysis tools for CAN.

Improving compatibility between CAN FD and legacy CAN devices

To overcome the performance limitations of Controller Area Network (CAN), the CAN with Flexible Data-rate (CAN FD) specification has been recently released, which features increased network throughput by combining bit rate overclocking and frame oversizing. CAN FD ensures good backward compatibility with existing applications and higher protocol layers conceived for CAN. Unfortunately, high-performance transmission services shall not be used in networks where also legacy CAN controllers are connected, as doing so raises serious compatibility problems, which in turn undermine system reliability severely and lead to unsafe behavior. In this paper, the above problem is analyzed carefully and a number of solutions are proposed, which carry out a negotiation among CAN nodes so as to improve interoperability between legacy and CAN FD controllers.

Model-based design languages: A case study

Fast-paced innovation in the embedded systems domain puts an ever increasing pressure on effective software development methods, leading to the growing popularity of Model-Based Design (MBD). In this context, a proper choice of modeling languages and related tools — depending on design goals and problem qualities — is crucial to make the most of MBD benefits. In this paper, a comparison between two dissimilar approaches to modeling is carried out, with the goal of highlighting their relative advantages and shortcomings. It focuses on a case study involving a well-known distributed agreement protocol, a choice motivated by the fact that embedded systems are nowadays quickly evolving towards distributed, fault-tolerant architectures.

Towards seamless integration of N-version programming in model-based design

The ever-growing complexity of present-day software systems raises new and more stringent requirements on their availability, pushing designers to make use of sophisticated fault tolerance techniques far beyond the areas they were traditionally conceived for, and bringing new challenges to both the modelling and implementation phases. In this paper, we propose a design pattern to model in a domain-specific language one of the prominent fault-tolerant techniques, namely the N-version programming. It can be integrated seamlessly into existing applications to enhance their functional correctness, while still preserving the timing characteristics, in particular the sampling times. Besides, it is also designed in a way to ease the automatic code generation. A counterpart of the same framework is also implemented in a lower-level programming language, for use when direct model execution is impractical, like in severely resource-limited embedded targets.

Optimized event notification in CAN through in-frame replies and Bloom filters

Thanks to its distributed and asynchronous medium access control mechanism, CAN is the ideal choice for interconnecting devices in event-driven systems. When timing requirements of applications are not particularly demanding, as in the case of, e.g., reactive and proactive maintenance, constraints on event delivery can be relaxed, so that their notification may rely on best-effort approaches. In this paper, a number of techniques are taken into account for notifying events in such a kind of systems, and their performance has been evaluated. Besides conventional CAN, a recent proposal for extending this protocol, termed CAN XR, is considered. Moreover, the adoption of Bloom filters to cope with rare events in very large systems has also been evaluated.

Supporting security protocols on CAN-based networks

The ever-increasing variety of services built on top of the Controller Area Network (CAN), along with the recent discovery of vulnerabilities in CAN-based automotive systems (some of them demonstrated in practice), stimulated a renewed attention to security-oriented enhancements of the CAN protocol. The issue is further compounded nowadays because, unlike in the past, security can no longer be enforced by physical bus segregation. This paper describes how CAN XR, a recently proposed extension of the CAN data-link layer, can effectively support the distributed calculation of arbitrary binary Boolean functions, which are the foundation of most security protocols, without necessarily disclosing their operands on the bus. The feasibility of the approach is then shown through experimental evaluation and by confirming its applicability to a shared key generation protocol proposed in literature.

Software patterns for fault injection in CPS engineering

Software fault injection is a powerful technique to evaluate the robustness of an application and guide in the choice of fault-tolerant mechanisms. It however requires a lot of time and know-how to be properly implemented, which severely hinders its applicability. We believe software fault injection can be made more “affordable” by automating it and have it integrated within a model-driven engineering design flow. We first propose in this paper a framework supporting these objectives. Then, illustrating on the domain-specific language CPAL, we present injection patterns that can be embedded in the application code and discuss the types of faults each supports, as well as implementation issues.

CAN With eXtensible In-Frame Reply: Protocol Definition and Prototype Implementation

Controller area network (CAN) has been the de facto standard in the automotive industry for the past two decades. Recently, CAN with flexible data-rate (CAN FD) has been standardized, which achieves noticeably higher throughput. Further improvements are still possible for CAN, by exploiting its peculiar physical layer to carry out distributed operations among network nodes, implemented as atomic transactions mapped on quasi-conventional frame exchanges. In this paper, a proposal is made for an extension to the CAN protocol, termed CAN with eXtensible in-frame Reply (CAN XR), which enables upper protocol layers to define new custom services devoted to, e.g., network management, application-specific functions, and high-efficiency data transfer. The key point is that CAN XR retains full backward compatibility with CAN, therefore, there is no need to change the protocol specification once again.