Abstract
CADS (cooperative autonomous driving systems) are software-intensive and safety-critical reactive systems and give great promise to our daily life, but system errors may not be identified in the design stage until the implement stage, and the cost to correct them will be more expensive later than the early stage. For designing trustworthy autonomous software systems, we have to deal with multiclock constraint models. SysML (System Modeling Language) meets increasing adoption in order to carry out system-level modelling and verification against abstract representations, but it suffers from semantic ambiguities in the design of safety-critical autonomous systems. The main objective is to investigate methods for coping with the design and analysis models simultaneously and to achieve semantic consistency based on mathematical foundations and formal model transformation. In this paper, we propose a method to combine the requirement modelling process with analysis process together for CADS safety and reliability guarantee. Firstly, we extend SysML metamodels and construct SysML profile for the CADS domain that could improve modelling correctness and enhance reusability. An instantiated CADS model has been designed by means of adopting a profile containing different key functional and nonfunctional attributes and behaviors. Secondly, we define formal syntax and semantic notations for modelling elements in the SysML state machine diagram and show transformation rules between the state machine diagram and the CCSL (Clock Constraint Specification Language) model. Semantic preservation is also proved using the bisimulation relation between them for rigorous mapping correctness. Thirdly, a cooperative autonomous overtaking driving case study on the highway scenario is used for illustration, and we use the tool TimeSquare to simulate CCSL specification execution traces at the system design stage.
Highlights
It can be anticipated that unmanned intelligent systems are increasing rapidly. ey can adapt to hostile or hazardous environment and accomplish some extreme tasks, which are difficult or impossible for humans, such as dangerous conditions, extreme speed action or long-duration flights, and cloudy or inclement weather [1]
As for multiclock constraint and safetycritical autonomous systems, software concepts, assumptions, and terminologies may be inconsistent because of the limitation of real data. e emergent autonomous systems are composed of multiple clocks, events, and entities which benefit from agent-based modelling and simulations [54], and simulation results provide guidance to identify and avoid potential deadlocks, errors, and hazards as early as possible in the design phase, which is another motivation for our work
When CCSL starts to appear, it is a textual specification and companion language complementary to the time profile allowing us to describe the clock constraints in MARTE annexes, and CCSL has been fully developed as an independent specification language for logical clock and chronometric clock. en, we introduce CCSL relevant definitions and concepts and give primary syntax and semantics of the CCSL
Summary
It can be anticipated that unmanned intelligent systems are increasing rapidly. ey can adapt to hostile or hazardous environment and accomplish some extreme tasks, which are difficult or impossible for humans, such as dangerous conditions, extreme speed action or long-duration flights, and cloudy or inclement weather [1]. Rigorous proof for semantics preservation will ensure the correctness and effectiveness of communication and understanding among application domain experts, model designers, and system analysts [2, 13, 14] For these three challenges, our research focuses on multiclock autonomous system specification and simulation to overcome the problems mentioned. E simulation tool TimeSquare is designed to verify and validate multiclock constraint CCSL models, and we make full use of it to generate execution simulation results to analyze corresponding multiclock constrain autonomous systems.
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