Failures in fault-tolerant FPGA-based controllers - A case study

摘要

Nowadays, FPGA-based Networked Control Systems (NCSs) are frequently used. Transient and permanent faults occur often as a result of radiation in industrial environments. Accordingly, Fault-Tolerant (FT) FPGA-based NCSs are desired. In this paper, a novel NCS model is proposed composing of In-Loop and S2A architectures linked via an Ethernet switch. This architecture is used in shape detection machines with vision sensing requirements. FT techniques are applied in the controller nodes of the system along with Dynamic Partial Reconfiguration (DPR) for FPGA-based controller recovery. The reliability of the system due to changes in both the recovery rate and the conditional probability of failure occurrence (either transient or permanent), is presented in this paper. Accordingly, a Markov model is constructed for reliability calculations. A case study is used to illustrate the use of such a model to choose appropriate maintenance strategies as well as a quantitative measure for the ability of the FT techniques to increase system reliability. Coverage is then studied in the context of the same system. Furthermore, system failures are divided into safe system failures and unsafe system failures. Another Markov model is developed. Then, a case study is used to illustrate the effect of coverage on the probability of occurrence of an unsafe system failure. (C) 2018 Elsevier B.V. All rights reserved.