Nonlinear output feedback control of dynamically positioned ships using vectorial observer backstepping

• Published in: IEEE transactions on control systems technology Vol. 6; no. 1; pp. 121 - 128
• Main Authors: Fossen, T.I., Grovlen, A.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.1998; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Backstepping; Computer science; control theory; systems; Control system synthesis; Control theory. Systems; Design methodology; Dynamic scheduling; Exact sciences and technology; Gain; Ground, air and sea transportation, marine construction; Kinematics; Lyapunov method; Marine and water way transportation and traffic; Marine vehicles; Nonlinear equations; Output feedback; Position measurement; Marine; Dynamic positioning; Tanker; Observer; Non linear control; Position measurement; Exponential stability; Output feedback; Thrust
• ISSN: 1063-6536
• DOI: 10.1109/87.654882

Dynamic positioning (DP) systems for ships are usually designed under the assumption that the kinematic equations be linearized about a constant yaw angle such that linear and gain scheduling techniques can be applied. This paper proposes a globally exponentially stable (GES) nonlinear control where this assumption is removed. A nonlinear observer is included in the design such that only position measurements are required. GES is proven by applying the backstepping design methodology and Lyapunov stability theory. The control law is simulated on two thruster-controlled ships.