Hardware-in-the-Loop Simulation for a Heave Compensator of an Offshore Support Vessel

Tune and verification of control system algorithms for offshore installation operations involving complex and advanced machinery and difficult due to its safety factor. It may be also very costly or even impossible to establish certain test conditions in the physical process environment of the control system. To solve this problem, the Hardware-In-the-Loop-Simulation (HILS) can be regarded as an effective method for testing the control system prior to its final development. The sophisticated HILS is composed of a control system and a HIL simulator which is a simulation model of the offshore plant developed by software. In this study, we focus on the application of HILS for a heave compensator which is used to keep the position or the lowing speed of a lifting object. This study contains three components. Firstly, a physics-based analysis component is used to develop a simulation model of an offshore plant, that is, a HIL simulator. Secondly, the programmable logic controller (PLC) component, that is a control system, is used to regulate the offshore plant model, including a proportional-integral-derivative (PID) feedback controller which aims to control the position or lowering speed of the lifting object. Thirdly, an interface component is developed to communicate the data between the HIL simulator and the control system in real-time. To evaluate the applicability of HILS for a heave compensator, it was applied to an example of an offshore support vessel (OSV) crane. In order to verify the control system for the crane operation in case of heave stabilization of the lifting object, two simulation processes had been established with both a software PLC (software-in-the-loop) and a hardware PLC (hardware-in-the-loop). HILS makes it possible to test the heave compensator without building costly prototypes and without endangering natural environment.