Practical fixed-time formation control with disturbance rejection for marine vehicles under input saturation

Area of Science:

• Marine robotics
• Control systems engineering
• Nonlinear control theory

Background:

• Marine vehicles require robust formation control despite external disturbances and actuator limitations.
• Existing fixed-time control methods can be susceptible to input saturation, impacting performance.
• Accurate estimation of ocean disturbances is crucial for effective control.

Purpose of the Study:

• To address the practical fixed-time disturbance rejection formation control problem for marine vehicles.
• To develop a novel control strategy that accounts for input saturation effects.
• To ensure stable formation tracking within a fixed-time interval, independent of initial states.

Main Methods:

• Establishing a novel practical fixed-time stability lemma.
• Developing a practical fixed-time disturbance observer for estimating ocean disturbances.
• Utilizing an auxiliary dynamic filter to mitigate control error under input saturation.
• Applying vectorial backstepping with a first-order filter to derive the anti-saturation controller.

Main Results:

• The proposed controller ensures follower vehicles effectively track leader vehicles.
• Stability is guaranteed for all states within a fixed settling time.
• The control method demonstrates robustness against initial estimation errors and input saturation.
• Simulation results validate the effectiveness of the developed control scheme.

Conclusions:

• The developed practical fixed-time disturbance rejection anti-saturation formation controller is effective for marine vehicles.
• The method provides precise formation control with guaranteed stability and fixed-time convergence.
• This approach offers a significant advancement in controlling marine vehicle formations under challenging conditions.