Fault-tolerant control network architecture of deep water Manned submersible MATSYA 6000

The deep-water manned submersible MATSYA 6000 is being developed by NIOT for carrying out scientific exploration and studies. Due to the human presence in the deep-water manned submersible, operations during the mission have to be carried out safely and reliably amidst hardware, software and network failures. A fault-tolerant architecture is required for the submersible control and monitoring system and meet the IEC 61508 Safety Integrity Level standards and also comply with the classification rules for certification of manned submersibles. In this paper, the failure analysis and safety assessment with and without a redundant control system for critical and emergency operations are analyzed and explained using reliability modelling and simulation software. Based on the simulation results, a fault-tolerant control system is designed. The proposed control network architecture shows the redundancy in each subsystem level and improves the system reliability, availability and safety. The reliability of different network topologies has been modeled and the probability of failure of the network is reduced from 22 % to 2 % with fault-tolerant ring topology.