Automatic Failure Explanation in CPS Models

Abstract

Debugging Cyber-Physical System (CPS) models can be extremely complex. Indeed, only the detection of a failure is insufficient to know how to correct a faulty model. Faults can propagate in time and in space producing observable misbehaviours in locations completely different from the location of the fault. Understanding the reason of an observed failure is typically a challenging and laborious task left to the experience and domain knowledge of the designer. In this paper, we propose CPSDebug, a novel approach that by combining testing, specification mining, and failure analysis, can automatically explain failures in Simulink/Stateflow models. We evaluate CPSDebug on two case studies, involving two use scenarios and several classes of faults, demonstrating the potential value of our approach.

An automated system repair framework with signal temporal logic

“…The proposed formula synthesis method as a part of the repair framework extends [17] by performing parameter synthesis in each iteration and eliminating formulae that cannot be part of the result for efficiency. In a recent work [12], STL formula synthesis is used as a part of a fault explanation framework for CPSs, where the authors synthesized a formula describing the "good" behaviors and checked it against the faulty behaviors to find a fault explanation. Their results also support the use of STL formulae for cause explanation.…”

“…In this work, we find explanatory formulae in a special form, which we call repairable, and define automated procedures to fix the system to avoid the satisfaction of the formula. Thus, while we limit the synthesis to specific formula types, we present auto-repair procedures, which was not possible in [12]. Identification of the temporal pattern leading to the violation of a temporal logic formula over a signal is studied in [20].…”

CPSDebug: Automatic failure explanation in CPS models

“…In order to verify the improvement over the approach from our preliminary work [6] which only used Daikon, we repeated the evaluation from [6] by using also TkT in addition to Daikon and compared the results. More precisely, we empirically evaluated our two approaches, i.e., with and without TkT, against three classes of faults: multiple hardware faults in fault-tolerant systems, which is the case of multiple components that incrementally fail in a system designed to tolerate multiple malfunctioning units; incorrect look-up tables, which is the case of look-up tables containing incorrect values; and erroneous guard conditions, which is the case of imprecise conditions in the transitions that determine the state-based behavior of the system.…”

On methods and tools for rigorous system design

“…This paves the way to identify feasible architecture solutions that satisfy energy footprint requirements. -The paper "CPSDebug: Automatic failure explanation in CPS models" by Bartocci, Manjunath, Mariani, Mateis and Ničković [3] is an extension of the SEFM 2019 paper [2] by the same authors. In particular, the authors introduce an approach for the detection of faults and their localisation in Stateflow/Simulink models of cyberphysical systems.…”