Robust Autopilot Design for Ship Steering in Waves

Article type: Research Article

Authors: Zhang, Rongjun | Sun, Zhenqi | Xu, Hanzhen

Affiliations: National Lab. of Intelligent Technology and Systems, Dept. of Computer Science and Technology, Tsinghua University, Beijing, 100084, P.R.C | Dept. of Naval Architecture and Marine Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P.R.C

Abstract: Nowadays, autopilots have been used widely in ship steering, while the robustness of the autopilots designed on the basis of the adaptive control theory is need to be enhanced. This paper presents a theoretical frame of a robust autopilot using the theory of Variable Structure Systems (VSS). Having computed the wave forces and moments acting on a ship, a Variable Structure Control System (VSCS) is investigated for the autopilot of a ship steering in random sea. A kind of nonlinear switching plane and a modified control law are employed to remove the frequent back-and-forth steering. Simulations show that the proposed simple control system is robust to the modeling errors and changes of environment and speed, so it is worthy to be applied to real ship steering/control.

DOI: 10.3233/ISP-1997-4443703

Journal: International Shipbuilding Progress, vol. 44, no. 437, pp. 59-75, 1997