A physical simulation test installation of heave compensation system is built up to validate the feasibility of hardware-in-the-loop simulation. The installation is composed of mining ship motion simulator and heave compensation system. A Stewart six-dof platform is selected to simulate the mining ship motion. The platform is able to perform smoothly under the predetermined attitude path and can meet the requirements of the mining ship motions. The heave compensation system includes a heave compensated platform which is to compensate heave motion and a gimbaled platform which is to accommodate pitch and roll. The compensation system can eliminate the heave motion almost completely (nearly 100%) under laboratory conditions.
As an important interface of the mining ship, the laying system and the lifting system, the heave compensation system is one of the absolutely necessary instruments for secure operation of the mining equipment (Liu, 2003). Some research has been carried out about model testing, which are the basis for design of the heave compensation system. In the 1990s, an actively compensating platform based on hybrid serial-parallel mechanism was proposed by Xiangzhou Zheng of Huazhong University of Science and Technology in China (Zheng, 2003). Two 3-UPU (U is universal pairs and P is prismatic pairs) parallel mechanisms were series connected to form the serial-parallel mechanism. The pure mobile parallel mechanism can compensate heave motion and eliminate pipeline excursion caused by pitch and roll motion. The pure rotating parallel mechanism can compensate pipeline inclination caused by pitch and roll motion. A 3D simulation was worked out successfully and the results show that kinematic feasibility for deep ocean mining is given. Light-load, media-load and heavy-load active heave compensation systems were proposed by Tibing Xiao of Guangdong University of Technology in China (Xiao, 2002 and Xiao, 2004).
