Investigating and Coordinating Safety-critical Feature Interactions in Automotive Systems Using Simulation

Abstract

Automotive systems are safety-critical cyber-physical systems. In particular, undesired feature interaction can lead to safety-critical behavior. In order to address this problem, we investigate physical feature interaction in this context using simulation (with more than one physical variable). This allows us to visualize both the behavior of features in isolation and their interaction. Our major result is a new insight about feature coordination. In such a cyberphysical context, it can be insufficient to coordinate as usual by giving one feature priority over another one. Instead, coordinating based on a physical variable involved in the feature interaction appears to be both necessary and sufficient. In summary, we present our investigation of safetycritical feature interactions and their coordination in automotive systems using simulation, and its results.

Semi-symbolic Simulation and Analysis of Deviation Propagation of Feature Coordination in Cyber-physical Systems

“…We build upon our previous simulation model defined in [6] and keep its physical simplifications for creating here an ACC model using AAF. Physical quantities are reduced to speeds of vehicles and the distance between them.…”

“…Apart from these linear blocks, ACC includes a discontinuity given by the coordinator behavior of switching between the system's CC and DC modes. In contrast to [6], we performed a semi-symbolic simulation, where a specific symbol represents a defined uncertainty. We included two such symbols for parameter deviations, according to the two deviation causes shown in red in Figure 2.…”

“…In a previous simulation study of a cyber-physical system [6], we provided new insights into feature coordination, which is more intricate in such a context than, e.g., in telecommunications as studied already long time ago in [5]. However, this study only involved single simulations runs with presumably exact values of physical variables.…”

“…While ACC is already well understood as a single feature from an engineering viewpoint [11], we model it as a composite feature that coordinates CC and DC. Still, we follow the engineering-approved coordination scheme selecting the minimum speed request of both features [11], which was also shown to work as desired in [6,8].…”

“…Much as in [6], we study here only the typical scenario where Vehicle A is approaching first until the selected target distance is reached, while vehicle B does not change . Vehicle A may also increase its speed now, but it must not exceed the selected CC cruise speed.…”