COTS based Control System for Subsea

Abstract

This thesis looks into different topics regarding the use of Commercial off The Shelf (COTS) hardware and software for subsea control systems. COTS basically means every product which is commercially available. The idea of using COTS is that it is supposed to reduce the development costs, and ensure a shorter time to market. When doing a COTS based software development, there are many issues that need to addressed. The main issues are discussed in this report.Because of the high reliability requirements on subsea control systems, future systems might have to be certified to IEC 61508 Safety Integrity Level 3 (SIL3). IEC 61508 regulates Functional Safety of electrical/electronic/-programmable electronic safety-related systems, and a summary of the standards software requirements for SIL3 are presented.To make a SIL3 certified control system one needs a SIL3 certified controller. A broad search was performed to identify SIL3 certified controllers, suitable for subsea installation. Twenty three products were found, but only five came close to meeting the requirements for subsea installation. Many subsea control systems incorporate real time operating systems. In this thesis we perform a general evaluation of the four common COTS real time operating systems OSE, Windows CE, QNX and VxWorks. The evaluation showed that all four are good alternatives. The thesis was completed by developing a subsea control system using the COTS controller CompactRIO, from National Instruments. The control system was based on the Tyrihans subsea raw seawater injection pumping system, to see if the CompactRIO would be suitable for replacing the two programmable controllers used in the Tyrihans setup, a task it is believed to be capable of.