Managing DP System Software - A Life-cycle Perspective

In a few decades, DP operations have gone from early prototyping to become a commodity and necessity to conduct most offshore operations. Today's DP vessels encompass offshore supply vessels, anchor handlers, construction and diving vessels, shuttle tankers, semi-submersibles and drillships, as well as numerous other vessel types. Although the vessel types range widely in type and purpose, the DP systems are similar in structure and usually considered to be comprised of a number of different position reference and sensor systems, a DP computer system, a power system including generation, distribution and power management, and a propulsion system including thrusters, main propulsion and possibly rudders. At the heart of all these subsystems lies computer control systems, and at the heart of all computer control systems lies software. Experience from other industries shows that software is elusive and difficult to manage properly. None the less so for a DP vessel, where software from many different vendors come together to work as one integrated DP system. As technology has evolved and matured, the level of automation and integration has increased, and the complexity of the DP system has increased correspondingly. The software systems on a modern vessel by far exceeds any mechanical, electrical or hydraulic system in complexity and more importantly in lack of transparency. Do we have the right tools available to manage the risks associated with software on DP vessels today, both in the building phase and in the life-cycle of the vessel? And if so, are they understood and used correctly? This paper aims to highlight how independent Hardware-In-the-Loop (HIL) testing can be used to test, verify and validate the individual software components of the DP system, as well as the complete integrated system. The paper continues to show how HIL testing could be incorporated in the life-cycle of the vessel to manage and mitigate control system risk, both for new builds and sailing vessels. (C) 2015, IFAC (International federation of Automatic (Control) Hosting by Elsevier Ltd. All rights reserved.