A heave compensation system is one of the absolutely necessary instruments to secure mining operation. The system is too large to do the testing in field. So hardware-in-the-loop simulation is used for designing the system and developing the control strategy. The hardware-in-the-loop simulation system is composed of a mathematical model and physical models designed according to the similarity principle. The simulation of a nonlinear model based on PID control and fuzzy PID control are performed. The results also show that fuzzy PID control is much better than PID control and the compensation function decreases rapidly with the increasing of mining ship motion frequency.
At present, the pipeline lifting mining system is the most popular mining system. The nodules collected by the miner are lifted by the fluid rising force through the lifting pipeline to the mining ship (Liu, 2003). Under the sea wave, the lifting pipeline moves with the motion of mining ship, which causes large axial stress on lifting pipeline. To make mining operation secure, a heave compensation system is absolutely necessary. Since the 1970s, various studies and analysis have been carried out about heave compensation systems of pipelines in deepsea mining. In 1968, a heave compensation system between travelling block and hook used in oil drilling platform was proposed by VETCD Company, USA. It was composed of hydraulic cylinders, accumulator, locking device and etc. The hydraulic cylinder displacement is larger than the heave amplitude of wave height and the load of hydraulic cylinders is nearly 600 tons. In 1976, a heave compensation device for marine use was proposed by William David Stevenson of Scotland Brown Brother Company. It included a passive load supporting system and an active force adjusting system. In the 1970s, Glomar Explorer was built in USA (Chung, 2009).
