  Collaborative Cyber-Physical Systems (CCPS) are systems that contain tightly
coupled physical and cyber components, massively interconnected subsystems, and
collaborate to achieve a common goal. The safety of a single Cyber-Physical
System (CPS) can be achieved by following the safety standards such as ISO
26262 and IEC 61508 or by applying hazard analysis techniques. However, due to
the complex, highly interconnected, heterogeneous, and collaborative nature of
CCPS, a fault in one CPS's components can trigger many other faults in other
collaborating CPSs. Therefore, a safety assurance technique based on fault
criticality analysis would require to ensure safety in CCPS. This paper
presents a Fault Criticality Matrix (FCM) implemented in our tool called
CPSTracer, which contains several data such as identified fault, fault
criticality, safety guard, etc. The proposed FCM is based on composite hazard
analysis and content-based relationships among the hazard analysis artifacts,
and ensures that the safety guard controls the identified faults at design
time; thus, we can effectively manage and control the fault at the design phase
to ensure the safe development of CPSs. To validate our approach, we introduce
a case study on the Platooning system (a collaborative CPS). We perform the
criticality analysis of the Platooning system using FCM in our developed tool.
After the detailed fault criticality analysis, we investigate the results to
check the appropriateness and effectiveness with two research questions. Also,
by performing simulation for the Platooning, we showed that the rate of
collision of the Platooning system without using FCM was quite high as compared
to the rate of collisions of the system after analyzing the fault criticality
using FCM.
