A Fault-tolerant Distributed Library for Embedded Real-time Systems
| dc.contributor.author | Gudmandsen, Johanna | |
| dc.contributor.author | Hashem, Hashem | |
| dc.contributor.department | Chalmers tekniska högskola / Institutionen för data och informationsteknik | sv |
| dc.contributor.examiner | Karlsson, Johan | |
| dc.contributor.supervisor | Johansson, Roger | |
| dc.date.accessioned | 2020-10-29T12:35:25Z | |
| dc.date.available | 2020-10-29T12:35:25Z | |
| dc.date.issued | 2020 | sv |
| dc.date.submitted | 2020 | |
| dc.description.abstract | A distributed embedded control system (DECS) may have functionality that is safety-critical and time-sensitive, meaning if these systems malfunction the consequences could be devastating. In order to meet these requirements, a system must fulfill real-time constraints and guarantee correct functionality even in the presence of faults. In this thesis we present a software library providing clock synchronization, realtime scheduling and fault-tolerant decision making. It is intended for use with DECS communicating via controller area network (CAN). To achieve fault-tolerant decision making, we propose an early-stopping fault-tolerance algorithm solving up to t faults in a system of 2t + 1 nodes. We further propose an adaptation of this algorithm to real-world applications where there may be an interval of correct values instead of one correct value, as assumed in the base solution. The result is a lightweight and efficient library. The clock synchronization requires one message and has a precision comparable to other known solutions, but is not fault-tolerant. The scheduler runs in O(n2) time and uses a non-preemptive ratemonotonic policy. It can handle up to 63 user-defined tasks, and has a worst-case task delay of 2.5 ms for the lowest-priority task in a system with 60 tasks, assuming a task execution time of 0. The drawback is its inability to handle mixed-criticality task sets. Our proposed algorithm utilizes the properties inherent in CAN to provide an efficient way to rectify faults in the value domain. Due to the early-stopping property of the algorithm, the bus utilization increases linearly with the number of faults. We conclude that while the library is practical and efficient, fault-tolerant clock synchronization and fault handling in the time domain are necessary improvements before the library can be used in production systems. | sv |
| dc.identifier.coursecode | MPCSN | sv |
| dc.identifier.uri | https://hdl.handle.net/20.500.12380/301999 | |
| dc.language.iso | eng | sv |
| dc.setspec.uppsok | Technology | |
| dc.subject | Byzantine fault tolerance | sv |
| dc.subject | Real-time scheduling | sv |
| dc.subject | CAN | sv |
| dc.subject | Distributed systems | sv |
| dc.subject | Embedded control systems | sv |
| dc.title | A Fault-tolerant Distributed Library for Embedded Real-time Systems | sv |
| dc.type.degree | Examensarbete för masterexamen | sv |
| dc.type.uppsok | H | |
| local.programme | Computer systems and networks (MPCSN), MSc |