Yingfu Zeng

A Core Language for Executable Models of Cyber-Physical Systems (Preliminary Report)

Recently we showed that an expressive class of mathematical equations can be automatically translated into simulation codes. By focusing on the expressivity of equations formed from continuous functions, this work did not accommodate a wide range of discrete behaviors or a dynamic collection of components. However, the interaction between continuous and hybrid components in many cyber-physical domains is highly coupled, and such systems are often highly dynamic in both respects. This paper gives an overview of a proposed core language for capturing executable hybrid models of highly dynamic cyber-physical systems.

Acumen : an open-source testbed for cyber-physical systems research

Developing Cyber-Physical Systems requires methods and tools to support simulation and verification of hybrid (both continuous and discrete) models. The Acumen modeling and simulation language is an open source testbed for exploring the design space of what rigorous-but-practical next-generation tools can deliver to developers of Cyber-Physical Systems. Like verification tools, a design goal for Acumen is to provide rigorous results. Like simulation tools, it aims to be intuitive, practical, and scalable. However, it is far from evident whether these two goals can be achieved simultaneously. This paper explains the primary design goals for Acumen, the core challenges that must be addressed in order to achieve these goals, the “agile research method” taken by the project, the steps taken to realize these goals, the key lessons learned, and the emerging language design.

Using Rigorous Simulation to Support ISO 26262 Hazard Analysis and Risk Assessment

Rigorous simulation is a new technology that can play a key role in managing uncertainty in the design of safety-critical cyber-physical systems. One of its important applications is the analysis and evaluation of functional safety for road vehicles according to international standards such as ISO 26262. Previous work presented preliminary evidence to support the feasibility of using rigorous simulation for this purpose. Here we report on advances in our implementation of rigorous simulation and show how they enable the rigorous simulation of more refined and more complete models. A larger case study highlights the benefits of these advances and helps us identify new challenges that should be addressed by future work.

Developing A First Course on Cyber-Physical Systems

Effective and creative cyber-physical systems (CPS) development requires expertise in disparate fields that have traditionally been taught in several distinct disciplines. At the same time, students seeking a CPS education generally come from diverse educational backgrounds. In this paper, we report on our recent experience developing and teaching a course on CPS. The course addresses the following three questions: What are the core elements of CPS? How should these core concepts be integrated in the CPS design process? What types of modeling tools can assist in the design of cyber-physical systems? Our experience with the first three offerings of the course has been positive overall. We also discuss the lessons we learned from some issues that were not handled well. All material including lecture notes and software used for the course are openly available online.

Compile-Time Extensions to Hybrid ODEs

Reachability analysis for hybrid systems is an active area of development and has resulted in many promising prototype tools. Most of these tools allow users to express hybrid system as automata wi ...

Developing a first course on cyber-physical systems

Effective and creative Cyber-Physical Systems (CPS) development requires expertise in disparate fields that have traditionally been taught in several distinct disciplines. At the same time, students seeking a CPS education generally come from diverse educational backgrounds. In this paper, we report on our recent experience of developing and teaching a course on CPS. The course addresses the following three questions: What are the core elements of CPS? How should these core concepts be integrated in the CPS design process? What types of modeling tools can assist in the design of Cyber-Physical Systems? Our experience with the first four offerings of the course has been positive overall. We also discuss the lessons we learned from some issues that were not handled well. All material including lecture notes and software used for the course are openly available online.

Modeling Basic Aspects of Cyber-Physical Systems, Part II (Extended Abstract)

We continue to consider the question of what language features are needed to effectively model cyber-physical systems (CPS). In previous work, we proposed using a core language as a way to study this question, and showed how several basic aspects of CPS can be modeled clearly in a language with a small set of constructs. This paper reports on the result of our analysis of two, more complex, case studies from the domain of rigid body dynamics. The first one, a quad copter, illustrates that previously proposed core language can support larger, more interesting systems than previously shown. The second one, a serial robot, provides a concrete example of why we should add language support for static partial derivatives, namely that it would significantly improve the way models of rigid body dynamics can be expressed.