Title: Response Time Analysis for PLC-based Safety-Critical Control Programs
Subject: Software engineering
Level: Advanced
Description: Nowadays, embedded systems have become important parts of our life. Real-time control programs running on embedded systems are key parts of many industrial systems like those in railway, telecommunication, and automotive. Generally, there is often a set of timing requirements such as limits on response time for performance (time)-critical control programs especially in mission-critical contexts. Correctness of the functionality of these systems not only depends on the logical correctness but also on satisfying the timing requirements as important features of these systems. Response time analysis in terms of worst-case response time (WCRT) is an essential step to verify the temporal behavior of these systems.

Many of the industrial control systems are labelled as safety-critical systems, in which failure may cause serious damages to people, environment or many economical losses. A failure occurs upon termination of the ability of the system to provide the required functionality or in general, when the delivered functionality of the system deviates from the required one.
Therefore, a safety-critical system is required to be resistant to faults in a way which can continue its functionality regardless of the occurred faults. Safety functions are functions required to be implemented in a safety-critical system to avoid hazard occurring and achieve a safe state for the system. Demand is a condition under which it requires a safety function to be activated to prevent an undesirable event from occurring or reduce the consequences of an occurred undesirable event. Arising of demand conditions often leads to an increase in the normal response time of the system and other consequences like violating the performance requirements of the system. Providing an estimation of the worst-case demand response time is of great importance for safety-critical control systems.

In this master thesis, you need to provide an automated approach to generate a suitable performance model such as probabilistic timed automata for safety functions in PLC-based industrial control systems. Many of the real-time industrial control systems like those ones in the transportation domain, are implemented based on IEC 61131-3, which is one of the main programming language standards for programmable controllers. The control programs based on IEC 61131-3, are scheduled to be executed within tasks with the pre-defined (fixed) execution orders and parameters. The behavior is deterministic, and the input space and state space of the programs are reachable.
Therefore, the generated model could be analyzed by model checkers to provide an estimation of the worst-case response time. That is our offer for this work.
Start date:
End date:
Prerequisites: What we expect you to know for this project is:
" Good programming skills
" Background knowledge of performance models for analyzing the response time like (probabilistic) timed automata
" Background knowledge of safety-critical systems
" Good spoken and written English
IDT supervisors: Mahshid Helali Moghadam
Examiner: Björn Lisper
Company contact: RISE Mahshid Helali Moghadam, Mahshid.helali.moghadam@ri.se