Path tracking of underactuated ships with general form of dynamics

ABSTRACT

This article considers the path tracking problem for underactuated ships with general form of dynamics including uncertainties. By introducing certain two polar coordinate transformations, the ship's tracking kinematics and dynamics can be transformed into certain two-inputs–two-outputs nonlinear strict-feedback form. To avoid possible singularity problem in the backstepping control design, we introduce an asymptotic modification of orientation concept. Presented tracking scheme can guarantee the uniformly ultimately boundedness of closed-loop system in terms of polar coordinates. For the convenience of comparison with previous related works, where all tracking schemes were discussed in the Cartesian frame, we carry out some case studies to investigate the conditions under which the proposed tracking method can guarantee the same stability and convergence properties of tracking errors in the Cartesian frame. Numerical simulation studies are also carried out to demonstrate the effectiveness of presented tracking scheme.

Keywords:

• Path tracking
• underactuated ships
• robust control of nonlinear systems
• uniformly ultimately boundedness (UUB)
• guidance and control

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

The authors gratefully acknowledge the support from UTRC (Unmanned Technology Research Center) at KAIST, originally funded by ADD, DAPA in Korea. The part of this work was also supported by [grant number 10043928] the Industrial Source Technology Development Program of the MOTIE (Ministry of Trade, Industry & Energy), Korea.