Distributed-code generation from hybrid systems models for time-delayed multirate systems

Abstract

Hybrid systems are an appropriate formalism to model embedded systems as they capture the theme of continuous dynamics with discrete control. A simple extension, a network of communicating hybrid automata, allows for modeling distributed embedded systems. Although it is possible to generate code from such models, it is difficult to provide formal guarantees in the code with respect to the model. One of the reasons for this is that, the model is set in continuous time and concurrent execution with instantaneous communication, whereas the generated code is set in discrete time with delayed communication. This can introduce semantic differences between the model and the code such as missed transitions, faulty transitions, and altered continuous behavior. The goal of faithful code generation is to minimize these differences.In this paper, we propose a relaxed criteria of relative faithful implementation. Based on this criteria, we propose dynamically adjusting the guard at runtime using estimates of errors for preventing faulty transitions. We also identify a sufficient condition to ensure no missed transitions in the code. ABSTRACTHybrid systems are an appropriate formalism to model embedded systems as they capture the theme of continuous dynamics with discrete control. A simple extension, a network of communicating hybrid automata, allows for modeling distributed embedded systems. Although it is possible to generate code from such models, it is difficult to provide formal guarantees in the code with respect to the model. One of the reasons for this is that, the model is set in continuous time and concurrent execution with instantaneous communication, whereas the generated code is set in discrete time with delayed communication. This can introduce semantic differences between the model and the code such as missed transitions, faulty transitions, and altered continuous behavior. The goal of faithful code generation is to minimize these differences. In this paper, we propose a relaxed criteria of faithfulness, coined relative faithful implementation. Based on this criteria, we propose dynamically adjusting the guard at runtime using estimates of errors for preventing faulty transitions. We also identify a sufficient condition to ensure no missed transitions in the code.

A Verifiable Language for Programming Real-Time Communication Schedules

“…Finally, the row LNet shows the execution time of sending a data packet. From similar measurements done for this hardware in [12], we know that the worst-case communication delay is described by the equation latency ¼ 0:18979 Ã datasize þ 165, which is in microseconds. This formula has been identified by an empirical latency test of about one million interchanges for data lengths of the Ethernet frame starting at size 30 up to the maximum of 1,500 bytes.…”

Generating Reliable Code from Hybrid-Systems Models

“…Thus, transitions that only occur in the software but not in the model (i.e., faulty transitions) or transitions that only occur in the model but not in the software (i.e., missed transitions) are undesired and should be prevented. This work integrates previous efforts in reliable and faithful code generation [4], [9], [10], [11] by providing a uniform representation with better elucidation of all the introduced concepts, including code snippets, and an example case study.…”