Robust Steering Autopilot Design for Marine Surface Vessels

Fault‐tolerant leader‐follower formation control of marine surface vessels with unknown dynamics and actuator faults

“…The environmental disturbances caused by waves, winds, and currents are broadly classified into high‐ and low‐frequency disturbances, which are created by the first‐order wave‐induced motions and slow‐varying wind, currents, second‐order wave‐induced motions, respectively . Assuming that the wave can be represented in terms of the Gaussian random process and that the spectrum is narrowbanded, a linear approximation to the spectral density function can be modeled by where y ( s ) represents the wave motion, θ ( s ) is a zero mean Gaussian white noise process, ζ is the relative damping ratio of waves, and ω e is the encounter wave frequency given by The quantity ω 0 denotes the dominant wave frequency, u is the ship speed, β is the angle between the heading and the direction of the wave, and K ω =2 ζ ω e σ ω is a gain that is dependent on the wave energy in which σ ω is the constant describing the wave intensity.…”

“…Assuming that the wave can be represented in terms of the Gaussian random process and that the spectrum is narrowbanded, a linear approximation to the spectral density function can be modeled by where y ( s ) represents the wave motion, θ ( s ) is a zero mean Gaussian white noise process, ζ is the relative damping ratio of waves, and ω e is the encounter wave frequency given by The quantity ω 0 denotes the dominant wave frequency, u is the ship speed, β is the angle between the heading and the direction of the wave, and K ω =2 ζ ω e σ ω is a gain that is dependent on the wave energy in which σ ω is the constant describing the wave intensity. Since most of the energy in the wave spectrum is located around the modal frequency, a second‐order bandstop filter such as is utilized to attenuate the high‐frequency wave motion, where represents the attenuated wave motion, ζ f is the damping factor, and ω n is the natural frequency of the filter. The filter will attenuate wave disturbance in the frequency range of 1/ T 1 to 1/ T 2 .…”

“…A first‐order transfer function such as is frequently used to represent the slow‐varying environmental disturbances owing to second‐order wave drift, ocean currents, and wind in yaw channel wherein y ′ ( s ) represents slow‐varying motion and ω ( s ) is a zero mean Gaussian white noise of unity variance.…”

“…As in the work of Das and Talole, we choose ζ =0.5, ω 0 =0.7, , β = π /4, T 1 =2.5, and T 2 =1.125. Based on and , the environment disturbances are considered as In the case that the actuation devices are rotatable, the propulsion configuration matrix A in is approximately …”

A Marine Autopilot With a Fuzzy Controller Computed by a Neural Network

“…The authors of paper [18] suggest an approach based on the extended state observer (ESO) technique for controlling the ship yaw. The reliability of the autopilot is ensured by the fact that the level of external influences on the vessel is estimated using ESO, which also evaluates the parameters of the controller.…”