Robust autopilot with wave filter for ship steering

Abstract

Research was done to overcome traditional problems associated with automatic steering systems of a ship in a seaway. A ship's dynamic model with wave disturbances was built and a wave filter was designed by means of an extended states observer (ESO). The model estimated the low frequency motion component from a heading measurement corrupted by colorednoise, so back-and-forth steering caused by high frequency wave disturbances was avoided. At the same time, a robust autopilot system, designed by variable structure control theory, was presented. Simulation results achieved in dangerous sea status show that the wave filter works very well and the autopilot has strong robustness to environmental disturbances and model perturbation, and more importantly, the frequency of rudder adjustments is reduced noticeably.

Keywords

autopilot / wave disturbances / variable structure control / wave filter / extended states observer (ESO)

References

[1] Kallstrom C G, Astrom AJ. Adaptive autopilots for tankers [J]. Automatica, 1979, 15: 241-254

[2] Layneir. Fuzzy model reference learning control for cargo ship steering[J]. IEEE Trans on Control Syst Mag, 1993, 13(1): 23-24

[3] Sutton R. Neuro-fuzzy techniques applied to a ship autopilot design[J]. Navigation, 1996, 49(3): 410-430

[4] Fossen T I. Guidance and control of ocean vehicles[M]. 1994, Chichester: John Wiley and Sons Ltd

[5] Saelid S, Jenssen N A. Adaptive autopilot with wave filter[J]. Modeling, Identification and Control, 1983, 4(1): 33-46

[6] Reid R E, Tugcu A K, Mears B C. The use of wave filter design in kalman filter state estimation of the automatic steering problem of a tanker in a seaway [J]. IEEE Trans on Automatic Control, 1984, 29(7): 577-584

[7] Saelid S, Jenssen N A, Balchen JG. Design and analysis of a dynamic positioning system based on kalman filtering and optimal control[J]. IEEE Trans on Automatic Control, 1983, 28(3): 331-339

[8] Fossen T I, Strand J P. Passive nonlinear observer design for ships using Lyapunov methods: full-scale experiments with a supply vessel[J]. Automatica, 1999, 35: 3-16

[9] Brown S H, Dimmick J G. Simulation analysis of steering control during underway replenishment[J]. Ship Research, 1983, 27(4): 236-251

[10] Reid R E, Parent P F. Comparison of optimal linear regulators applied to minimization of steering losses of a containership in a seaway using frequency domain representations[J]. ASME Trans J of Dynamic System, Measurement and Control, 1983, 104: 229-237

[11] Hu P N, King E. Drifting force and moment on ships in oblique waves[J]. Ship Research, 1966, 10(1): 18-25

[12] Song J L, Gan Z X, Han J Q. Study of active disturbance rejection controller on filtering[J]. Control and Decision, 2003, 18(1): 110-112

[13] Yao Q H, Huang J Q, Wu H S. Variable structure control system[M]. 1997, Chong Qing: Chong Qing University Press