Continuous and Periodic Event-Triggered Sliding-Mode Control for Path Following of Underactuated Surface Vehicles.

Area of Science:

• Robotics and Control Systems
• Marine Engineering
• Applied Mathematics

Background:

• Underactuated Surface Vehicles (USVs) present unique control challenges due to fewer actuators than degrees of freedom.
• Path following is critical for autonomous navigation, requiring robust control strategies.
• Sliding-Mode Control (SMC) offers robustness but often requires continuous control signals, leading to high energy consumption.

Purpose of the Study:

• To develop continuous and periodic event-triggered SMC algorithms for enhanced path following in USVs.
• To establish theoretical bounds for quasi-sliding modes in USV path following.
• To investigate energy-saving potential through event-triggered control mechanisms.

Main Methods:

• Design of a continuous path-following control law based on SMC principles.
• Incorporation of continuous and periodic event-triggered mechanisms into the SMC scheme.
• Utilizing hyperbolic tangent functions and stability analysis to ensure performance and boundary layer integrity.

Main Results:

• The upper bounds of quasi-sliding modes for USV path following were established for the first time.
• Event-triggered mechanisms were shown not to disrupt the quasi-sliding mode boundary layer with proper parameter selection.
• The proposed strategies enable sliding variables to reach and maintain quasi-sliding modes, reducing energy consumption.

Conclusions:

• The developed continuous and periodic event-triggered SMC strategies effectively ensure USV path following.
• The methods demonstrate improved energy efficiency compared to traditional continuous control.
• Simulation results validate the effectiveness and robustness of the proposed control algorithms.